This document provides information on different types of microscopy techniques including bright field, dark field, phase contrast, and polarized light microscopy. It begins with explaining the basics of light and microscopy. It then describes each technique in more detail, including their principles, applications, advantages, and how they are set up optically. Bright field microscopy uses illumination and forms a dark image on a bright background. Dark field uses oblique illumination to see small particles as bright objects on a dark background. Phase contrast converts phase differences into contrast changes to see transparent specimens. Polarized light microscopy uses polarized filters to reveal structural details not otherwise seen.
this presentation deals with the introduction of some of the commonly used optical microscopes in forensic labs; compound microscope, stereoscopic microscope, comparison microscope, fluorescence microscope and polarized microscope.
this presentation deals with the introduction of some of the commonly used optical microscopes in forensic labs; compound microscope, stereoscopic microscope, comparison microscope, fluorescence microscope and polarized microscope.
Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.
during this ppt of microscopes we will be able to know
INTRODUCTION
DEFINITION
HISTORICAL BACKGROUND
VARIABLES USED IN MICROSCOPY
VARIOUS TYPES OF MICROSCOPES
COMPOUND MICROSCOPE - Structure and Function
USE OF MICROSCOPE
CARE OF MICROSCOPE
defintion
A microscope (Greek: micron = small and scopos = aim)
MICROSCOPE - An instrument for viewing objects that are too small to be seen by the naked or unaided eye
MICROSCOPY - The science of investigating small objects using such an instrument is called microscopy
BRIGHT FIELD MICROSCOPY by SIVASANGARI SHANMUGAM
bRIGHT FIELD MICROSCOPY is also called a compound microscope. The name bright - field is derived from the fact that the specimen is dark and contrasted by the surrounding bright viewing field.
DARK FIELD MICROSCOPY by SIVASANGARI SHANMUGAM
Dark-field microscopy is ideally used to illuminate unstained samples causing them to appear brightly lit against a dark background.
This type of microscope contains a special condenser that scatters light and causes it to reflect off the specimen at an angle
as a partial requirement for one of my subject for this semester
I would like you to view my presentation and comment as well
I will be very glad if you find my presentation interesting, or comment on how I can improve my craft, THANK YOU :)
Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.
during this ppt of microscopes we will be able to know
INTRODUCTION
DEFINITION
HISTORICAL BACKGROUND
VARIABLES USED IN MICROSCOPY
VARIOUS TYPES OF MICROSCOPES
COMPOUND MICROSCOPE - Structure and Function
USE OF MICROSCOPE
CARE OF MICROSCOPE
defintion
A microscope (Greek: micron = small and scopos = aim)
MICROSCOPE - An instrument for viewing objects that are too small to be seen by the naked or unaided eye
MICROSCOPY - The science of investigating small objects using such an instrument is called microscopy
BRIGHT FIELD MICROSCOPY by SIVASANGARI SHANMUGAM
bRIGHT FIELD MICROSCOPY is also called a compound microscope. The name bright - field is derived from the fact that the specimen is dark and contrasted by the surrounding bright viewing field.
DARK FIELD MICROSCOPY by SIVASANGARI SHANMUGAM
Dark-field microscopy is ideally used to illuminate unstained samples causing them to appear brightly lit against a dark background.
This type of microscope contains a special condenser that scatters light and causes it to reflect off the specimen at an angle
as a partial requirement for one of my subject for this semester
I would like you to view my presentation and comment as well
I will be very glad if you find my presentation interesting, or comment on how I can improve my craft, THANK YOU :)
The microscope has evolved a lot from the time of Leeuwenhoek. This presentation gives a brief overview about the types of microscope their principle of function and application.
STAINING TECHNIQUES IN MICROBIOLOGY & CELL BIOLOGYManu Bhardwaj
Although living microorganisms can be directly examined with the light microscope, they often must be fixed and stained to increase visibility of specific morphological features, and preserve them for future study.
Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye. There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.
Microscopy is the technique of using microscopes to observe and analyze objects that are too small to be seen by the naked eye. Microscopes are instruments that magnify and resolve the details of objects, allowing scientists and researchers to study the structure, composition, and behavior of materials and specimens at a microscopic level
Microscopy is the technique of using microscopes to observe and analyze objects that are too small to be seen by the naked eye. Microscopes are instruments that magnify and resolve the details of objects, allowing scientists and researchers to study the structure, composition, and behavior of materials and specimens at a microscopic level
To Study Principles of Microscopy: Light Microscope, Phase Contrast Microsco...Om Prakash
To Study Principles of Microscopy: Light Microscope, Phase Contrast Microscope & Electron Microscope
ByOm Prakash
June 13, 2022
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on To Study Principles of Microscopy: Light Microscope, Phase Contrast Microscope & Electron Microscope
Aim: To study principles of Microscopy: Light Microscope, Phase Contrast Microscope & Electron Microscope
Table of Contents
THEORETICAL BACKGROUND:
Light Microscopy
History:
SIMPLE MICROSCOPE
Principles of Microscopy:
THE COMPOUND MICROSCOPE
Phase Contrast Microscope
Electron Microscopes
SCANNING ELECTRON MICROSCOPE (SEM)
Also Read
THEORETICAL BACKGROUND:
Light Microscopy
The light microscope is an instrument designed for the study of cells and tissues. It comprises of lenses that produce a magnified image of the object under study. The light microscope is considered to be a simple important invention that has contributed to the advancement of biological research.
History:
The ancient Greeks and Romans knew the use of Glass and quartz lenses. In the 14th century, spectacles and lenses were used to magnify objects. Galileo had constructed a microscope at the same time (1610). It was employed for the study of the arrangement of the compound eye of insects. Anton Von Leeuwenhoek (1674), the father of biology was the first to use the microscope for biological studies. His microscope has consisted of a single lens with a higher power of magnification. The compound microscope was constructed by Robert Hooke (1665) and is the forerunner of the present-day compound microscope.
SIMPLE MICROSCOPE
The simple microscope distinguishes between two points that are less than 0.1mm apart when placed at a normal viewing distance of 25cm. The two points appear as one and the eye fails to resolve or distinguish them as two distinct points. Another limitation of the human eye is that it cannot resolve any image less than 5µm.
A simple microscope consists of a single convex lens or a combination of lenses that functions as a convex lens. A convex lens magnifies the objects and also helps to produce a magnified image of a near object which appears to be at the distance of distinct vision.
The magnification obtained with a convex lens can be easily calculated by the formula
M = 25/f + 1
Where f= focal length, 25 is the distance of distinct vision in cm.
Principles of Microscopy:
1. Resolving power: It is defined as the capacity of the microscope to distinguish images of two pointed objects lying very close together. If two points are at a distance of more than 0.2 µm, they will appear as two points in the microscope.
2. Limit of resolution: It is defined as the minimum distance at which two objects appear as two distinct objects or entities. It can be calculated as:
Limit of Resolution: 0.61λ/NA = 0.61λ/n Sin θ
Where 0.61 is the constant representing the minimum detectable difference in contrast λ = wavelength of illumination
NA = Numerical aperture, light gathering capa
Introduction to microscopy
Different parts of a microscope & their function
Different types of microscopy
Different types of optical microscopy
Different types of electron microscopy
Different terms used in microscopy
Staining- Simple, Differential, Special
Gram Staining
This presentation is all about Microscope .... The miracle instrument which revolutionised the study of microbiology and Biological science . Be it Cell studies, molecule studies, pathogen studies, virology etc etc ..... All has become possible for this instrument. let us understand the functioning , applications of this instrument .
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
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Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
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Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
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2 Case Reports of Gastric Ultrasound
2. BASICS
Visible Light:
Electromagnetic spectrum detected by human
eye- 400nm(deep violet) to 800nm(Far red).
Human eye doesn’t see much beyond
700nm(deep red).
White light:
Mixture of light containing some % of
wavelength from all visible portion.
3. BASICS
Color Temperature:
Measure of mixture of light given off by light
source.
Higher the color temp closer is to natural
daylight.
Natural daylight color temperature~5200kelvin
Incandescent light from Tungsten Bulb~3200k
Higher color temp- more blue/white to eye.
Lower color temp- more red to yellow to eye &
regarded as being ‘warmer’ in color.
4. BASICS
The Amplitude (i.e. brightness):
Decreases as light gets further from source
because of absorption in media it passes.
Energy Level:
Energy content of light, expressed as electron
volt per photon (the particle representation of
light).
Visible light-1electron volt/photon.
Soft x-ray portion-50-100ev/photon
Energy increases moving towards violet &
ultraviolet range of spectrum.
5. BASICS
Spherical aberration:
Light rays hitting periphery will be more
refracted than the rays hitting centre of lens.
Chromatic Aberrations:
White light of passing through simple lens, each
wavelength will be refracted to different extent.
Blue brought to a shorter focus than red, results
in a un-sharp image with color fringes.
Corrected with ‘Achromat’ & ‘Apochromat’ lens.
6. BASICS
Magnification:
For variable tube length=From 160-250mm
Optical tube length X Magnification of eye piece
Focal length of the objective
Resolving Power:
Capacity of the optical system to produce
separate images of objects very close to each
other.
Resolving power of std LM=200nm
7. BASICS
Illumination:
Critical illumination-when the light source is
focused by condensor in the same plane as the
object, when the object is in focus.
The illuminating light consists of rays or waves
that are nearly parallel to one another.
This quality of light is called partially coherent
light. The ultimate resolving power of the
microscope depends on the use of partially
coherent illumination.
The condenser in Köhler illumination is used to
create and focus this light onto the specimen
8. BASICS
Real Image:
The real image forms on the side of the lens
opposite the object.
A slide projector produces a real image on a
projection screen.
The objective lens produces a real image in
the intermediate image plane.
9. BASICS
Virtual Image:
A virtual image cannot be seen on a screen. A
second lens is required to see a virtual image and
this would cause the image to be inverted
relative to the specimen.
To a human, the virtual image appears to be on
the same side of the lens as the object.
The image we see in a compound microscope is a
virtual image.
In upright microscopes the virtual image is
inverted. In inverted microscopes the image is
made to be upright by optics in the binocular.
10. BASICS
Back Focal Plane:
The side of a lens where an image is formed is called
the image side or back side of the lens. The plane at
one focal length on this side is the back focal plane.
The back focal plane of the objective lens is on
the inside of the microscope tube.
Coma:
Resulting in the images of structures out from the
center being smeared outwards.
Astigmatism:
Resulting in light in the X plane being focused
differently to light in the Y plane.
11.
12. •NUMERICAL APARTURE:
• Is a dimensionless number that characterizes
the range of angles over which the system can
accept or emit light.
•It is the acceptance cone of an objective (and
hence its light-gathering ability and resolution).
The numerical aperture
with respect to a
point P depends on the
half-angle θ of the
maximum cone of light
that can enter or exit the
lens.
where n is the index of refraction of the medium
in which the lens is working, and θ is the half-
angle of the maximum cone of light that can
enter or exit the lens
BASICS
13. BASICS
Compound Lenses:
There are four basic lens shapes: double
convex, double concave, plano convex and
plano concave.
In the 1830’s, the solution to chromatic
aberrations was found by cementing two lenses
made of different glasses (one Double convex and
one Plano-concave) together into an Achromatic
Doublet to make a compound lens.
Today, compound lens consists of many lens
elements. These elements are necessary for
magnification and correction of various lens
aberrations.
14. REFRACTIVE INDEX
•Refractive index is the
light-bending ability of a
medium.
• The light may bend in air
so much that it misses the
small high-magnification
lens.
• Immersion oil is used to
keep light from bending.
RI of Air- 1.0
RI of Water -1.3
RI of Glycerol- 1.47
RI of Glass(avg)- 1.5
RI of Oil- 1.52
15. UNITS OF MEASUREMENT
1 µm micrometer = 1/1000 mm
1 nm nanometer = 1/1000 µm
Parfocal distance: Distance between objective
shoulder and specimen(45 mm for most
microscopes).
Working Distance Focal Length
Scanning- 17-20mm 40mm
Low power- 4-8mm 16mm
High power- 0.5-0.7mm 4mm
Oil immersion- 0.1mm 1.8-2.0mm
16.
17.
18.
19.
20. INFINITY CORRECTED MICROSCOPES
A majority of modern research microscopes are
equipped with infinity-corrected objectives that
no longer project the intermediate image directly
into the intermediate image plane. Light
emerging from these objectives is instead focused
to infinity, and a second lens, known as a tube
lens, forms the image at its focal plane.
21. INFINITY CORRECTED MICROSCOPES
Wavetrains of light leaving the infinity-focused
objective are collimated, allowing beam-splitters,
polarizers, Wollaston prisms, etc., to be
introduced into the space between the objective
and tube lens.
22. INFINITY CORRECTED MICROSCOPES
In a microscope with infinity-corrected optics,
magnification of the intermediate image is
determined by the ratio of the focal lengths of the
tube lens and objective lens.
Because the focal length of the tube lens varies
between 160 and 250 millimeters (depending
upon the manufacturer and model), the focal
length of the objective can no longer be assumed
to be 160 millimeters divided by its
magnification.
Thus, an objective having a focal length of 8
millimeters in an infinity-correct microscope with
a tube lens focal length of 200 millimeters would
have a lateral magnification of 25x (200/8).
23. MODERN TECHNOLOGY IMPROVING MICROSCOPY
The invention of the microscope allowed scientists and
scholars to study the microscopic creatures in the world
around them.
When learning about the history of the microscope it is
important to understand that until these microscopic
creatures were discovered, the causes of illness and
disease were theorized but still a mystery.
The microscope allowed human beings to step out of the
world controlled by things unseen and into a world where
the agents that caused disease were visible, named and,
over time, prevented.
24. MICROSCOPES CAN BE SEPARATED INTO SEVERAL
DIFFERENT CLASSES
One grouping is based
on what interacts with
the sample to generate
the image:
-Light or photons(optical
microscopes)
-Electrons (electron
microscopes)
-Probe (scanning probe
microscopes).
Whether they analyze
the sample via:
-Scanning point (confocal
optical microscopes,
scanning electron
microscopes and scanning
probe microscopes)
-Analyze the sample all at
once (wide field optical
microscope and
transmission electron
microscopes).
25. BRIGHT-FIELD MICROSCOPY
The useful magnification of Light microscope is
limited by its resolving power.
The resolving power in limited by wavelength of
illuminating beam.
Resolution is determine by certain physical
parameters like wave length of light and light
generating power of the objective & condenser lens.
Higher N.A Better light generation Better Resolution
Shorter the Wavelength Better Resolution.
The ordinary microscope is called as a bright field
microscope. It forms dark image against bright
background.
26. Dark objects are visible
against a bright
background.
Light reflected off the
specimen does not
enter the objective lens.
27. ADVANTAGES
Bright field compound microscopes are commonly
used to view live and immobile specimens such as
bacteria, cells, and tissues.
For transparent or colorless specimens, however,
it is important that they be stained first so that
they can be properly viewed under this type of a
microscope.
Staining is achieved with the use of a chemical
dye. By applying it, the specimen would be able
to adapt the color of the dye. Therefore, the light
won’t simply pass through the body of the
specimen showing nothing on the microscope’s
view field
30. PRINCIPLE
When observing unstained/living cells, such specimens & their
components have refractive indices close to that of the medium
in which they are suspended & are thus difficult to see by bright
field techniques, due to their lack of contrast.
Dark field microscopy overcomes these problems by
preventing direct light from entering the front of the
objective & the only light gathered is the reflected or
diffracted by structures within the specimen.
This causes the specimen to appear as a bright image on
a dark background, the contrast being reversed &
increased.
Dark field permits the detection of particles smaller than the
optical resolution that would be obtained in bright field, due to
high contrast of scattered light.
In the microscope, oblique light is created by using a
modified or special condensor that form a hollow cone of
direct light which will pass through the specimen but
outside the objective.
31. DARK FIELD MICROSCOPY
Light enters the microscope for illumination of
the sample.
A specially sized disc, the patch stop blocks
some light from the light source, leaving an
outer ring of illumination.
A wide phase annulus can also be reasonably
substituted at low magnification.
The condenser lens focuses the light towards the
sample.
32. DARK FIELD MICROSCOPY
The light enters the sample. Most is directly
transmitted, while some is scattered from the
sample.
The scattered light enters the objective lens,
while the directly transmitted light simply
misses the lens and is not collected due to
a direct illumination block.
Only the scattered light goes on to produce the
image, while the directly transmitted light is
omitted.
33.
34. DARK FIELD MICROSCOPY
Dark field microscopy is a very simple yet
effective technique and well suited for uses
involving live and unstained biological samples:
-Spirochetes
-Flagellates
-Cell Suspension
-Flow Cell Techniques
-Parasites
-Autoradiographic grain counting
-Once used in Fluorescence Microscopy
35. DARK FIELD MICROSCOPY
In Dark Field Illumination the objective must
have a lower Numerical Aperture than the
condensor.
In Bright Field Illumination optimum
efficiency is obtained when the Numerical
Aperture of both the Objective and the Condensor
are matched.
Dark Field Condensor may be:
-Dry, low power objective
-Oil immersion, high power objective
36. ADVANTAGES
The advantage of darkfield microscopy also becomes
its disadvantage: not only the specimen, but dust and
other particles scatter the light and are easily
observed For example, not only the cheek cells but the
bacteria in saliva are evident. The dark field
microscopes divert illumination and light rays thus,
making the details of the specimen appear luminous.
Dark field light microscopes provide good results,
especially through the examination of live blood
samples. It can yield high magnifications of living
bacteria and low magnifications of the tissues and
cells of certain organisms. Certain bacteria and fungi
can be studied with the use of dark field microscopes.
39. DEFINITION
Phase contrast microscopy is an optical
illumination technique in which small phase
shifts in the light passing through a transparent
specimen are converted into amplitude or
contrast changes in the image. The technique
was invented by Frits Zernite in the 1930s for
which he received the Nobel prize in physics in
1953 .
40. Accentuates
diffraction of
the light that
passes through
a specimen.
Direct and
reflected light
rays are
combined at the
eye. Increasing
contrast
PHASE CONTRAST MICROSCOPY
41. APPLICATION
Applications for phase contrast microscopy
equipment range from the study of living
biological specimens, medical applications, study
of live blood cells, and other biological and science
applications.
Most commonly used to provide contrast of
transparent specimens such as living cells or
small organisms.
Useful in observing cells cultured in vitro during
mitosis.
42. PHASE CONTRAST MICROSCOPY
Unstained/living biological specimens have little
contrast with their surrounding medium.
To see them clearly involves:
A-Closing down the iris diaphragm of condensor
which decreases the Numerical Aperture producing
diffraction effects & destroy the Resolving Power of
the Objective.
B-Or when using dark field illumination, which
enhances contrast by reversal, but often fails to reveal
internal details.
The Phase Contrast microscopy overcomes these
problems by controlled illumination using the full
aperture & thus improving the Resolution.
The high the refractive index of the structure, the
darker it will appear against the light background,
i.e. with more contrast.
43. PHASE CONTRAST MICROSCOPY
If a diffraction grating is examined under the
microscope, diffraction spectra are formed in the
Back Focal Plane of the objective due to
interference between the direct & diffracted rays
of light.
The grating consists of alternate strips of
material with slightly different refractive indices,
through which light acquire small phase
difference & these form the images.
44.
45. PHASE CONTRAST MICROSCOPY
By converting the phase differences, between
light passing through a specimen and that
passing through the surrounding medium, into
amplitude (brightness) differences, phase
contrast microscopy provides a difference in
brightness between the object and the
background, which the eye can then see.
46. PHASE CONTRAST MICROSCOPY
Phase contrast microscopy uses an annular stop in
the condenser and a phase plate within the objective
lens, which is aligned with the annular stop.
In this configuration, the light path can be split and
each of the separated beams will pass through the
same transparent medium at the specimen stage.
The light passes through the annular stop and forms
a cone of light, which comes to its vertex at the focal
point of the specimen.
Any background light, which is un-deviated by the
specimen, will go through the phase ring in the phase
plate and is advanced by a quarter of a
wavelength. Deviated light passing through the
specimen is retarded by a quarter of a wavelength
and passes through the phase plate without going
through the ring.
47. PHASE CONTRAST MICROSCOPY
When the beams are recombined further along
the light path, the differences in the phase of the
deviated and un-deviated light beams become
additive and subtractive.
The resultant wave is the sum of the two waves
which have their crests and troughs opposite
each other. The difference in amplitude can be
seen as a change in brightness, since brightness
is proportional to the square of the amplitude.
The net result is that features of the object are
either lighter or darker than the surrounding
field.
53. PRINCIPLE
Light is a series of pulse of energy radiating away from
a source & shown diagrammatically as sine curve,
with wavelength & amplitude.
Light can also be described as electromagnetic
vibration, which travels outwards from source of its
propagation, much in the same way as vibration along
a rope.
Natural light vibrates in many directions but polarized
light in only one direction.
54. POLARIZED LIGHT MICROSCOPY
Polarization can be achieved with the use of
substance/crystals which allow vibration only in one plane
& called birefringent.
Light entering a birefringent crystal such as calcite is split
into two light paths, each determined by a different
refractive index & each vibrating in one direction only, but
at right angle to each other.
The higher the RI, the greater the retardation of the ray, so
that each ray leaves the crystal at a different velocity.
The high RI ray is called slow and low RI ray is called
fast.
There is also a phase difference between the rays, so that if
they are recombined interference occurs & various spectral
colors are seen.
55. POLARIZED LIGHT MICROSCOPY
Two discs made up of prism are placed in a path
of light, one below the objective known as
Polarizer & another placed in the body tube
which is known as Analyzer.
Polarizer sieves out ordinary light rays vibrating
in all directions allowing light waves of one
orientation to pass through.
The lower disc (polarizer) is rotated to make the
light plane polarized. During rotation, when
analyzer comes perpendicular to polarizer, all
light rays are cancelled or extinguished.
Birefringent objects rotate the light rays &
therefore appear bright in a dark background.
56. Analyzer (upper polarizer) -- a
polarizing prism located above the
microscope stage, between the
objective lens and the eyepiece. This
restricts the transmission of light
vibrating perpendicular to the
polarizer. The analyzer can be
slipped in or out of the light path or
rotated for partially crossed polarized
light. Light passing through the
polarizer will not pass through the
analyzer unless the vibration
direction of the light is changed
between the two prisms. Anisotropic
minerals can perform this deed.
Polarizer (lower polarizer) -- a
polarizing prism located beneath the
microscope stage (between the light
source and the object of study). This
restricts transmission of light to that
vibrating in only one (N-S) direction.
Some microscopes have a different
orientation direction. In effect, it
plane polarizes the incident light
beam.
57. POLARIZED LIGHT MICROSCOPY
Numerous crystals, fibrous structures (both natural &
artificial), pigment, lipid, protein, bone & amyloid
deposits exhibit birefringence.
Originally, polarizer's, made from calcite & known as
Nicol Prism, were cemented together with Canada
balsam in such away that the slow rays was deflected
away from the optical path & into the mount of the prism,
leaving only the polarized fast rays to pass through (optic
axis).
Some substances & crystals can produce plane polarized
light by differential absorption & give rise to phenomenon
of Dichorism. These absorb the slow rays & are pleochoric
(absorbing all colors equally) and are the most useful in
microscopy.
Such crystals suspended in thin plastic films & oriented in
one direction have replaced bulky Nicol Prism.
58. POLARIZED LIGHT MICROSCOPY
Two phenomenon detected in polarized light-
Birefringence & Dichroism.
When a birefringent substance rotated between two
crossed polarizers, the image appears & disappears
four times each in 360 deg rotation (at 45̊ each).
Dichroism- Only the polarizer is used &, if no
rotatory stage is available the polarizer itself can be
rotated. Changes in intensity & color is seen during
rotation at 90 deg. This is due to differential
absorption of light, depending upon the vibration
direction of the two rays in a birefringent substance.
Weak birefringence in biological specimen is
increased by addition of dyes or impregnating metals,
in a orderly linear alignment e.g. amyloid fibrils.
60. DIFFERENTIAL INTERFERENCE
CONTRAST
In this complex form of polarised light microscopy two
slightly separate, plane polarised beams of light are
used to create a 3D-like image with shades of grey.
Wollaston prisms situated in the condenser and
above the objective produce the effect, and additional
elements add color to the image.
Care must be taken to interpreting DIC images as the
apparent hills and valleys in the specimen can be
misleading. The height of a "hill" (e.g. the nucleus) is
a product of both the actual thickness of the feature
(i.e. ray path length) and its refractive index.
Variations of the DIC system are named after their
originators, Nomarski and de Senarmont. Options
can be selected to maximize either resolution or
contrast.
61. Accentuates
diffraction of
the light that
passes through
a specimen;
uses two beams
of light. Adding
color
Differential Interference Contrast Microscopy
68. INTRODUCTION
Electron microscope is a type of microscope that
uses a particle beam of electrons to illuminate a
specimen & create a highly-magnified image. Co-
invented by Germans, Max Knoll and Ernst
Ruska in 1931
69. ELECTRON GUN
2 types of guns are used in electron microscopy-
Thermionic Emission Gun & Field Emission Gun.
Thermionic: Electrons emitted from heated filament (
tungsten, Lanthanum Hexaboride). Most common, cheap &
ultra high vacuum not required.
Field Emission: Strong electron field used to extract
electrons from filament. High vacuum needed.
70. ELECTROMAGNETIC LENS
An electromagnet designed to produce a suitably
shaped magnetic field for focusing &
deflection of electrons in electron optical
instruments.
A strong magnetic field is generated by passing a
current through a set of windings.
This field acts as a convex lens in case of electron
microscope.
71. CONDENSER LENS
The first lens(controlled by "spot size knob")
largely determines the "spot size"; the general
size range of the final spot that strikes the
sample.
Second condenser lens: The second
lens(controlled by the "intensity/ brightness
knob" changes the size of the spot on the sample;
changing it from a wide dispersed spot to a
pinpoint beam.
72. OTHER PARTS
The other parts include:
-Condenser aperture,
-Objective lens,
-Objective aperture,
-Selected area aperture(to examine diffraction
patterns),
-Intermediate lens(magnifies initial image formed
by objective lens) &
-Projector lens.
73. TYPES OF ELECTRON MICROSCOPES
There are 2 types of electron microscopes:
Transmission Electron Microscope: Process
is carried out under vacuum to avoid friction. The
"Virtual Source" at the top represents
the electron gun, producing a stream of
monochromatic electrons. The usual potential is
around 10000 – 15000V.
SCANNING ELECTRON MICROSCOPE
75. •Ultrathin sections of specimens.
•Light passes through specimen, then an
electromagnetic lens, to a screen or film.
•Specimens may be stained with heavy metal salts.
Transmission Electron Microscopy (TEM)
76. TRANSMISSON ELECTRON MICROSCOPE
This transmitted portion is focused by the objective
lens into an image.
The Objective & Selected Area
metal apertures restrict the beam.
The image is passed down the column through the
intermediate and projector lenses, being enlarged all
the way.
The image strikes the phosphor image screen & light
is generated, allowing the user to see the image.
The darker areas represent areas that fewer
electrons were transmitted (thicker or denser). The
lighter areas represent areas that more electrons
were transmitted (thinner or less dense)
77. TRANSMISSION ELECTRON MICROSCOPE
Transmission electron microscopy (TEM) involves a high voltage
electron beam emitted by a cathode and formed by magnetic
lenses. The electron beam that has been partially transmitted
through the very thin (and so semitransparent for electrons)
specimen carries information about the structure of the
specimen.
The spatial variation in this information (the "image") is then
magnified by a series of magnetic lenses until it is recorded by
hitting a fluorescent screen, photographic plate, or light
sensitive sensor such as a CCD (charge-coupled device) camera.
The image detected by the CCD may be displayed in real time on
a monitor or computer.
Transmission electron microscopes produce two-dimensional,
black and white images.
Resolution of the TEM is also limited by spherical and chromatic
aberration, but a new generation of aberration correctors has
been able to overcome or limit these aberrations.
81. •An electron gun produces a beam of electrons that scans the
surface of a whole specimen.
•Secondary electrons emitted from the specimen produce the
image.
Scanning Electron Microscopy (SEM)
82. SCANNING ELECTRON MICROSCOPE
Unlike the TEM, where the electrons in the primary beam
are transmitted through the sample, the Scanning Electron
Microscope (SEM) produces images by detecting secondary
electrons which are emitted from the surface due to
excitation by the primary electron beam.
In the SEM, the electron beam is scanned across the
surface of the sample in a raster pattern, with detectors
building up an image by mapping the detected signals with
beam position.
83.
84.
85. SCANNING ELECTRON MICROSCOPE
The 1st scanning electron microscope (SEM)
debuted in 1938 by Von Ardenne with the first
commercial instruments out around 1965.
In this case electrons are not used to directly
image the specimen, but to excite it in such a way
that it gives out secondary electrons which are
collected by detectors & used to form the image.
The first scanning electron microscope (SEM)
debuted in 1938 ( Von Ardenne) with the first
commercial instruments around 1965.
86. SPECIMEN
For electron microscopy, tissue is fixed in 4%
glutaraldehyde at 4°C for 4 hours.
Fixation - In chemical fixation for electron
microscopy, glutaraldehyde is often used to crosslink
protein molecules and osmium tetroxide to preserve
lipids.
Dehydration - Organic solvents such as ethanol or
acetone for SEM specimens or infiltration with resin
and subsequent embedding for TEM specimens.
Embedding - Resin (for electron microscopy) such as
araldite or LR White, which can then be polymerised
into a hardened block for subsequent sectioning.
87. SPECIMEN
Sectioning - Typically around 90nm cut on an
ultramicrotome with a glass or diamond knife. Glass
knives can easily be made in the laboratory and are
much cheaper than diamond, but they blunt very
quickly and therefore need replacing frequently.
Staining - uses heavy metals such as lead and
uranium to scatter imaging electrons and thus give
contrast between different structures, since many
(especially biological) materials are nearly
"transparent" to the electron beam.
By staining the samples with heavy metals, electron
density is added to it which results in there being
more interactions between the electrons in the
primary beam and those of the sample, which in turn
provides us with contrast in the resultant image.
88. ARTIFACTS
It must be emphasized from the outset that every
electron micrograph is, in a sense, an artifact.
Artifacts present themselves in many ways:
-There could be loss of continuity in the
membranes,
-Distortion or disorganization of organelles,
-Empty spaces in the cytoplasm of cells or
sharp bends or curves in filamentous structures
that are usually straight, such as microtubules
and so on.
With experience, microscopists learn to recognize
the difference between an artifact of preparation
and true structure.
89. DISADVANTAGES OF ELECTRON MICROSCOPY
Electron microscopes are very expensive to buy and maintain.
They are dynamic rather than static in their operation: requiring
extremely stable high voltage supplies, extremely stable currents to
each electromagnetic coil/lens, continuously-pumped high/ultra-high
vacuum systems and a cooling water supply circulation through the
lenses and pumps.
As they are very sensitive to vibration and external magnetic
fields, microscopes aimed at achieving high resolutions must be
housed in buildings with special services.
A significant amount of training is required in order to operate
an electron microscope successfully and electron microscopy is
considered a specialised skill.
The samples have to be viewed in a vacuum, as the molecules that
make up air would scatter the electrons. This means that the samples
need to be specially prepared by sometimes lengthy and difficult
techniques to withstand the environment inside an electron
microscope.
Recent advances have allowed some hydrated samples to be imaged
using an environmental scanning electron microscope, but the
applications for this type of imaging are still limited.
92. PRINCIPLE
Confocal microscopy is an optical imaging
technique used to increase optical
resolution and contrast of a micrograph by using
point illumination and a spatial pinhole to
eliminate out-of-focus light in specimens that are
thicker than the focal plane.
It enables the reconstruction of three-
dimensional structures from the obtained images.
93. •Uses fluorochromes
and a laser light.
•The laser illuminates
each plane in a
specimen to produce a
3-D image.
Confocal Microscopy
94. INTRODUCTION
Although conventional light and fluorescence microscopy
allow the examination of both living and fixed specimens,
certain problems exist with these techniques.
-One of the main problems is out-of-focus blur degrading
the image by obscuring important structures of interest,
particularly in thick specimens.
In conventional microscopy, not only is the plane of focus
illuminated, but much of the specimen above and below
this point is also illuminated resulting in out-of-focus blur
from these areas.
This out-of-focus light leads to a reduction in image
contrast and a decrease in resolution.
95. APPLICATIONS IN CONFOCAL MICROSCOPY
The broad range of applications available to laser
scanning confocal microscopy includes a wide
variety of studies in neuroanatomy and
neurophysiology, as well as morphological studies
of a wide spectrum of cells and tissues.
In addition, the growing use of new fluorescent
proteins is rapidly expanding the number of
original research reports coupling these useful
tools to modern microscopic investigations.
96. OTHER APPLICATIONS
Include-
-Resonance energy transfer,
-Stem cell research,
-Photobleaching studies,
-Lifetime imaging,
-Multiphoton microscopy,
-Total internal reflection,
-DNA hybridization,
-Membrane and ion probes,
-Bioluminescent proteins, and
-Epitope tagging.
97. Confocal reflection microscopy can be utilized to gather
additional information from a specimen with relatively
little extra effort, since the technique requires minimum
specimen preparation and instrument re-configuration.
In addition, information from unstained tissues is readily
available with confocal reflection microscopy, as is data
from tissues labeled with probes that reflect light.
The method can also be utilized in combination with more
common classical fluorescence techniques.
Examples of the latter application are detection of
unlabeled cells in a population of fluorescently labeled cells
and for imaging the interactions between fluorescently
labeled cells growing on opaque, patterned substrata
99. FLUORESCENT MICROSCOPY
This method is used for demonstration of
naturally occurring fluorescent material and
other non-fluorescent substances or micro-
organisms after staining with some fluorescent
dyes e.g. Mycobacterium tuberculosis, amyloid,
lipids, elastic fibres etc.
UV light is used for illumination.
100. •Uses UV light.
• Fluorescent
Substances absorb
UV light and emit
visible light.
• Cells may be
stained with
fluorescent dyes
(fluorochromes).
Fluorescence Microscopy
101. WHY FLUORESCENCE MICROSCOPY?
In all types of microscopes, cell constituents are
not distinguishable, although staining dose, but
not totally.
In fluorescent microscopy, various fluorescent
dyes are used which gives property of
fluorescence to only specific part of the cell and
hence it can be focused.
Fluorescent microscopy depends upon
illumination of a substance with a specific
wavelength (UV region i.e. invisible region)
which then emits light at a lower wavelength
(visible region).
102. FLUORESCENCE PRINCIPLE
When certain compounds are illuminated with
high energy light, they then emit light of a
different, lower frequency. This effect is known as
fluorescence.
Often specimens show their own characteristic
autofluorescence image, based on their chemical
makeup.
The key feature of fluorescence microscopy is that
it employs reflected rather than transmitted
light, which means transmitted light techniques
such as phase contrast and DIC can be
combined with fluorescence microscopy.
103. COMPONENTS
Typical components of a fluorescence microscope
are:
the light source (xenon arc lamp or mercury-
vapor lamp),
the excitation filter,
the dichroic mirror and
the emission filter.
104. STAINING
Many different fluorescent dyes can be used to
stain different structures or chemical compounds.
One particularly powerful method is the
combination of antibodies coupled to a
fluorochrome as in immunostaining.
Examples of commonly used fluorochromes are
fluorescein or rhodamine.
105. FUNCTIONING
A component of interest in the specimen is
specifically labeled with a fluorescent molecule
called a fluorophore.
The specimen is illuminated with light of a
specific wavelength (or wavelengths) which is
absorbed by the fluorophores, causing them to
emit longer wavelengths of light (of a different
color than the absorbed light).
107. The distance between the focal plane of the objective (f1) and the
focal plane of the eyepiece (f2) is called the tube length (l).
The object to be viewed is placed just outside the focal point at the
left side of the objective lens. The enlarged image is formed at a
distance l + f1 from the objective.
109. X-RAY MICROSCOPY
less common,
developed since the late 1940s,
resolution of X-ray microscopy lies between that
of light microscopy and the electron microscopy.
X-rays are a form of electromagnetic radiation
with a wavelength in the range of 10 to 0.01
nanometers, corresponding to frequencies in the
range 30 PHz to 30 EHz.
111. RECENT ADVANCES IN MICROSCOPY
In the recent times, computers and chip
technology have helped in developing following
advances in microscopy.
112. IMAGE ANALYSERS AND MORPHOMETRY
In these techniques, microscopes are attached to
video monitors and computers with dedicated
software systems.
Microscopic images are converted into digital
images and various cellular parameters (e.g.
nuclear area, cell size etc) can be measured. This
quantitative measurement introduces objectivity
to microscopic analysis.
113. TELEPATHOLOGY (VIRTUAL MICROSCOPY)
It is the examination of slides under microscope
set up at a distance. This can be done by using a
remote control device to move the stage of the
microscope or change the microscope field or
magnification called as robobic telepathology.
Alternatively and more commonly, it can be used
by scanning the images and using the highspeed
internet server to transmit the images to another
station termed as static telepathology.
Telepathology is employed for consultation for
another expert opinion or for primary
examination