The document discusses electron microscopes. It begins by explaining that Ernst Ruska built the first electron microscope in 1931 using a beam of accelerated electrons for illumination. It then describes the key components of an electron microscope, including the electron gun, condenser lenses, specimen holder, and viewing system. Electron microscopes use electromagnetic lenses and have very high magnification and resolution, allowing observation at the nanoscale. However, specimens must be dried and ultra-thin to be viewed. Electron microscopes are used widely in science and industry.
The scanning electron microscope (SEM) was first developed in 1937 and improved upon in later decades. It uses a beam of electrons to scan sample surfaces at high magnification and resolution. Unlike light microscopes, SEM is able to produce high-quality images of a sample's surface topography and detect the presence of different elements. SEM functions by emitting electrons that interact with the sample, producing signals containing information about the sample's surface and composition that are detected and used to form an image. It has various applications in fields like industry, nanoscience, medicine, and microbiology due to its high magnification and quality imaging abilities.
Phase-contrast microscopy is a technique that converts phase shifts in light passing through a transparent specimen to brightness changes in the image, allowing living cells that are otherwise invisible to be seen. It works by separating light rays that pass through a specimen unchanged from those that are diffracted, using an annular diaphragm and phase plate in the light path. Phase-contrast microscopy is widely used in biological research for observing living cells, microorganisms, and other transparent specimens without staining or fixing.
The document discusses the transmission electron microscope (TEM). It begins by explaining that a TEM uses a beam of electrons rather than light to produce highly magnified images of thin specimens. It then provides details on the history and development of the TEM. The body of the document describes the main components of a TEM, including the electron gun, image producing system, and image recording system. It explains how each component works and its role in producing a magnified image. Applications of the TEM in fields like biology and nanotechnology are also mentioned.
This document provides an overview of light microscopy and imaging. It discusses key concepts related to light and color, including how color is determined by wavelength and how white light is comprised of a combination of colors. It also explains how the color we see in objects is generally due to light absorption and reflection. Different color models are described, including HSI (hue, saturation, intensity) which is used to characterize the color green. The document aims to clarify fundamental optical and color principles for microscopy and imaging.
The document provides an overview of light microscopes, including their history and key components. It discusses how the first microscopes were developed in the 1600s using simple lenses. Modern light microscopes use lenses to magnify specimens up to 1000x their actual size and include features like brightfield, darkfield, phase contrast and fluorescence microscopy. Brightfield microscopes produce a dark image on a bright background while darkfield shows bright specimens on a dark background. Microscopy has many applications in diagnostic microbiology like rapid identification of pathogens and determination of clinical significance.
This document provides information about transmission electron microscopy (TEM). It describes the principle, parts, and working of the TEM. The TEM uses electron beams rather than light to image specimens. It has greater magnification than light microscopes. The key parts are the electron gun, image producing system, and image recording system. The electron gun produces electrons, the image system focuses electrons through the specimen, and the recording system views and captures the image. TEM allows study of structures down to the nanoscale and is used across many fields including biology, nanotechnology, and materials science.
Presentationon optical and electron microscopy by deepak kumar Drx Kumar
This document provides information on optical and electron microscopy. It discusses the basic principles and components of simple microscopes, compound microscopes, transmission electron microscopy, and scanning electron microscopy. Compound microscopes use lenses to magnify real images, allowing higher magnification than simple microscopes. Transmission electron microscopy uses electron beams and electromagnetic lenses to image very thin samples at resolutions up to 2.5 nm. Scanning electron microscopy scans sample surfaces with an electron beam to produce 3D images at magnifications up to 10,000x. Both electron microscopy techniques provide higher resolution than optical microscopy but have specific sample preparation and imaging requirements.
The document discusses electron microscopes. It begins by explaining that Ernst Ruska built the first electron microscope in 1931 using a beam of accelerated electrons for illumination. It then describes the key components of an electron microscope, including the electron gun, condenser lenses, specimen holder, and viewing system. Electron microscopes use electromagnetic lenses and have very high magnification and resolution, allowing observation at the nanoscale. However, specimens must be dried and ultra-thin to be viewed. Electron microscopes are used widely in science and industry.
The scanning electron microscope (SEM) was first developed in 1937 and improved upon in later decades. It uses a beam of electrons to scan sample surfaces at high magnification and resolution. Unlike light microscopes, SEM is able to produce high-quality images of a sample's surface topography and detect the presence of different elements. SEM functions by emitting electrons that interact with the sample, producing signals containing information about the sample's surface and composition that are detected and used to form an image. It has various applications in fields like industry, nanoscience, medicine, and microbiology due to its high magnification and quality imaging abilities.
Phase-contrast microscopy is a technique that converts phase shifts in light passing through a transparent specimen to brightness changes in the image, allowing living cells that are otherwise invisible to be seen. It works by separating light rays that pass through a specimen unchanged from those that are diffracted, using an annular diaphragm and phase plate in the light path. Phase-contrast microscopy is widely used in biological research for observing living cells, microorganisms, and other transparent specimens without staining or fixing.
The document discusses the transmission electron microscope (TEM). It begins by explaining that a TEM uses a beam of electrons rather than light to produce highly magnified images of thin specimens. It then provides details on the history and development of the TEM. The body of the document describes the main components of a TEM, including the electron gun, image producing system, and image recording system. It explains how each component works and its role in producing a magnified image. Applications of the TEM in fields like biology and nanotechnology are also mentioned.
This document provides an overview of light microscopy and imaging. It discusses key concepts related to light and color, including how color is determined by wavelength and how white light is comprised of a combination of colors. It also explains how the color we see in objects is generally due to light absorption and reflection. Different color models are described, including HSI (hue, saturation, intensity) which is used to characterize the color green. The document aims to clarify fundamental optical and color principles for microscopy and imaging.
The document provides an overview of light microscopes, including their history and key components. It discusses how the first microscopes were developed in the 1600s using simple lenses. Modern light microscopes use lenses to magnify specimens up to 1000x their actual size and include features like brightfield, darkfield, phase contrast and fluorescence microscopy. Brightfield microscopes produce a dark image on a bright background while darkfield shows bright specimens on a dark background. Microscopy has many applications in diagnostic microbiology like rapid identification of pathogens and determination of clinical significance.
This document provides information about transmission electron microscopy (TEM). It describes the principle, parts, and working of the TEM. The TEM uses electron beams rather than light to image specimens. It has greater magnification than light microscopes. The key parts are the electron gun, image producing system, and image recording system. The electron gun produces electrons, the image system focuses electrons through the specimen, and the recording system views and captures the image. TEM allows study of structures down to the nanoscale and is used across many fields including biology, nanotechnology, and materials science.
Presentationon optical and electron microscopy by deepak kumar Drx Kumar
This document provides information on optical and electron microscopy. It discusses the basic principles and components of simple microscopes, compound microscopes, transmission electron microscopy, and scanning electron microscopy. Compound microscopes use lenses to magnify real images, allowing higher magnification than simple microscopes. Transmission electron microscopy uses electron beams and electromagnetic lenses to image very thin samples at resolutions up to 2.5 nm. Scanning electron microscopy scans sample surfaces with an electron beam to produce 3D images at magnifications up to 10,000x. Both electron microscopy techniques provide higher resolution than optical microscopy but have specific sample preparation and imaging requirements.
The document discusses scanning electron microscopy (SEM). It begins by defining microscopy and the different types, including electron microscopy. It then focuses on SEM, describing its key characteristics like viewing surface topography and composition. The document outlines the basic workings of an SEM, including how it scans a sample with electrons to form an image. It also discusses sample preparation, advantages/disadvantages of SEM, and concludes that SEM is a technologically advanced tool used extensively in scientific investigation.
This document provides an overview of microscopic anatomy and various microscopy techniques. It discusses that [1] cells are the basic building blocks of living organisms and come in varied shapes and sizes, [2] microscopy involves using probes like light or electron beams that interact with tissue components to produce images, and [3] important considerations in microscopic analysis include the probe size and its ability to interact with and observe the object being investigated. It then describes various microscopy methods like light, fluorescence, polarization, and electron microscopy as well as tissue preparation techniques and important microscopy terms.
The document summarizes different types of microscopes used to observe cells. It describes how Robert Hooke first observed cork cells in 1632 using a rudimentary microscope. Electron microscopes provide higher resolution than optical microscopes and can observe cell structures at smaller nanometer scales. Transmission electron microscopes transmit electrons through thin specimens, while scanning electron microscopes scan electron beams across surfaces to generate 3D images of cells and structures.
The document discusses scanning electron microscopes (SEMs), which use focused beams of electrons to obtain high-resolution, three-dimensional images of samples. SEMs have higher magnification and resolving power than light microscopes. The document describes the key parts of an SEM, including the electron gun, vacuum chamber, lenses, sample chamber, and detectors. It also discusses sample preparation and the advantages and disadvantages of SEMs.
This document discusses light microscopes. It begins by defining a microscope as an instrument used to view objects too small to see with the naked eye. It then describes the basic components and workings of light microscopes, including lenses that magnify objects, different types like brightfield and phase contrast, and applications in biology and medicine like pathology. Phase contrast microscopy is explained in more detail, noting how it uses interference of light waves passing through a specimen to visualize differences in brightness of structures. In closing, the document outlines several uses of light microscopes across various fields.
The scanning transmission electron microscope (STEM) uses a finely focused electron beam that scans across the sample in a raster pattern. The STEM provides atomic resolution imaging and analysis through detectors like the EELS spectrometer, bright-field detector, and annular dark-field detector. Scan coils are used to scan the beam across the sample, while the condenser lens demagnifies the electron crossover point for high magnification imaging. The STEM has various applications in materials science and biology for characterizing nano- and atomic-scale structures.
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
The document describes the electron microscope, including transmission electron microscopes (TEM) and scanning electron microscopes (SEM). TEMs use electron beams to create higher magnification images of ultrathin samples. SEMs scan samples with electron beams to produce surface topography and composition images. Both require extensive sample preparation and produce detailed images of small objects through electromagnetic beam manipulation.
The document discusses microscopy and different types of microscopes. It begins by defining microscopy as the technology that makes small objects visible to the human eye using microscopes. It then describes different types of microscopes, focusing on light microscopes and electron microscopes. Electron microscopes use a beam of electrons rather than light, allowing them to achieve much higher magnifications and resolving power than light microscopes. The document discusses the basic components and working principles of transmission electron microscopes and scanning electron microscopes. It also covers sample preparation techniques, applications, limitations, and recent research using electron microscopy.
Microscopy is a technique used to produce visible images of structures too small to be seen by the human eye. There are several microscopy techniques including optical microscopy, electron microscopy, and scanning probe microscopy. Optical microscopy uses visible light and lenses to magnify samples, but is limited to resolving structures larger than 400-700 nm. Electron microscopes like the transmission electron microscope (TEM) and scanning electron microscope (SEM) use electron beams instead of light to image much smaller nano-scale structures, but require vacuum conditions. Different microscopy techniques are suited to different applications depending on the sample and desired resolution.
Darkfield microscopy uses oblique illumination to make specimens appear bright against a dark background. Light is directed around the specimen so that it is scattered and refracted off of it. This allows thin structures like bacteria to be seen more easily compared to brightfield microscopy. Some applications of darkfield microscopy include viewing unstained live samples, motile organisms, fibers, and external surface details of cells. It has advantages like simplicity, quality images, and lack of artifacts, though light levels are lower.
Today, scanning electron microscopy (SEM) is a versatile technique used in many
industrial labs, as well as for research and development. Due to its high lateral resolution, its great depth of focus and its facility for X-ray microanalysis, SEM is ofen
used in materials science – including polymer science – to elucidate the microscopic
structure or to differentiate several phases from each other.
Pollen photos using a Scanning Electron MicroscopeChris Cardew
The document compares the scanning electron microscope (SEM) to the light microscope. It states that the SEM can achieve much higher magnifications than the light microscope, up to 500,000x compared to 1000-1500x, because electrons have a much shorter wavelength than visible light. This allows the SEM to achieve much higher resolving power and see finer detail, around 4nm, versus around 200nm for the light microscope. It also notes some key differences in their operation, such as the SEM using electrons rather than visible light and requiring a vacuum rather than air-filled interior.
A scanning electron microscope is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the sample's surface topography and composition.
SEMs can magnify an object from about 10 times up to 300,000 times. A scale bar is often provided on an SEM image. From this the actual size of structures in the image can be calculated.
This document provides an overview of fluorescent microscopy. It begins with the history and basic principles, including Stokes shift and the advantages and disadvantages of fluorescent microscopy. Different types of fluorescent microscopes are described such as epifluorescent and confocal microscopes. Various fluorescent microscopic techniques are outlined, including wide-field, laser scanning, spinning disk, multi-photon, light sheet, and super-resolution microscopies. Sample preparation methods for fluorescent microscopy are also summarized, such as using synthetic fluorescent stains, immunofluorescence labeling, and genetically encoded fluorescent proteins.
Transmission Electron Microscope (TEM), RESOLVING POWER, Scanning Electron Microscope, PRINCIPLE AND WORKING OF SEM, SEM SAMPLE PREPARATION, Limitations of Scanning Electron Microscopy (SEM), ADVANTAGES & DISADVANTAGES OF SEM, APPLICATIONS OF SEM, PRINCIPLE, AND WORKING OF TEM, SAMPLE PREPARATION FOR TEM, ADVANTAGES & DISADVANTAGES OF TEM, APPLICATIONS OF TEM, Differences between SEM and TEM.
This document provides an overview of scanning electron microscopy. It begins with an introduction to microscopy and the need for electron microscopy due to limitations of optical microscopy. It then describes the components and operating principle of a scanning electron microscope. The document explains how electrons interact with matter by producing backscattered electrons and secondary electrons, which are used to form images. It also covers specimen preparation and applications of SEM, concluding with references.
Phase Contrast Microscopy - Microbiology 1st RAHUL PAL
Phase contrast microscopy uses differences in phase shifts of light waves passing through a specimen to visualize unstained living cells. It allows biologists to study living cells and cell division. Dark field microscopy produces a dark background and bright specimen image using oblique illumination. It is used to view unstained or little absorbed objects like bacteria, algae, and diatoms. Electron microscopy uses a beam of accelerated electrons instead of light for higher resolution imaging of nano-scale structures. Types include analytical electron microscopy, scanning transmission electron microscopy, scanning electron microscopy, and transmission electron microscopy.
The document describes the parts and working of a polarizing microscope. It has optical components like polarizers, analyzers and lenses, and mechanical components like the rotating stage. Light from the specimen is polarized and its interaction with the optical components is used to identify properties of minerals and rocks. The polarized microscope allows examination of anisotropic materials and determination of their optical characteristics, which has applications in geology and mineral exploration.
The document provides an overview of scanning electron microscopes (SEMs), including their history, key parts, working principle, applications, and sample preparation process. Some key points:
- SEMs use a beam of electrons to produce high-resolution images of sample surfaces, allowing examination of microscopic structural features. They have greater depth of field than light microscopes.
- Early development began in the 1930s. Commercial instruments became available in the 1960s. Continued improvements have increased resolution to the atomic scale.
- Key components include an electron gun, electromagnetic lenses, vacuum system, specimen stage, and detectors. Secondary electrons emitted from the sample are used to form images.
- Applications span biology, materials
The document discusses scanning electron microscopy (SEM). It begins by defining microscopy and the different types, including electron microscopy. It then focuses on SEM, describing its key characteristics like viewing surface topography and composition. The document outlines the basic workings of an SEM, including how it scans a sample with electrons to form an image. It also discusses sample preparation, advantages/disadvantages of SEM, and concludes that SEM is a technologically advanced tool used extensively in scientific investigation.
This document provides an overview of microscopic anatomy and various microscopy techniques. It discusses that [1] cells are the basic building blocks of living organisms and come in varied shapes and sizes, [2] microscopy involves using probes like light or electron beams that interact with tissue components to produce images, and [3] important considerations in microscopic analysis include the probe size and its ability to interact with and observe the object being investigated. It then describes various microscopy methods like light, fluorescence, polarization, and electron microscopy as well as tissue preparation techniques and important microscopy terms.
The document summarizes different types of microscopes used to observe cells. It describes how Robert Hooke first observed cork cells in 1632 using a rudimentary microscope. Electron microscopes provide higher resolution than optical microscopes and can observe cell structures at smaller nanometer scales. Transmission electron microscopes transmit electrons through thin specimens, while scanning electron microscopes scan electron beams across surfaces to generate 3D images of cells and structures.
The document discusses scanning electron microscopes (SEMs), which use focused beams of electrons to obtain high-resolution, three-dimensional images of samples. SEMs have higher magnification and resolving power than light microscopes. The document describes the key parts of an SEM, including the electron gun, vacuum chamber, lenses, sample chamber, and detectors. It also discusses sample preparation and the advantages and disadvantages of SEMs.
This document discusses light microscopes. It begins by defining a microscope as an instrument used to view objects too small to see with the naked eye. It then describes the basic components and workings of light microscopes, including lenses that magnify objects, different types like brightfield and phase contrast, and applications in biology and medicine like pathology. Phase contrast microscopy is explained in more detail, noting how it uses interference of light waves passing through a specimen to visualize differences in brightness of structures. In closing, the document outlines several uses of light microscopes across various fields.
The scanning transmission electron microscope (STEM) uses a finely focused electron beam that scans across the sample in a raster pattern. The STEM provides atomic resolution imaging and analysis through detectors like the EELS spectrometer, bright-field detector, and annular dark-field detector. Scan coils are used to scan the beam across the sample, while the condenser lens demagnifies the electron crossover point for high magnification imaging. The STEM has various applications in materials science and biology for characterizing nano- and atomic-scale structures.
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
The document describes the electron microscope, including transmission electron microscopes (TEM) and scanning electron microscopes (SEM). TEMs use electron beams to create higher magnification images of ultrathin samples. SEMs scan samples with electron beams to produce surface topography and composition images. Both require extensive sample preparation and produce detailed images of small objects through electromagnetic beam manipulation.
The document discusses microscopy and different types of microscopes. It begins by defining microscopy as the technology that makes small objects visible to the human eye using microscopes. It then describes different types of microscopes, focusing on light microscopes and electron microscopes. Electron microscopes use a beam of electrons rather than light, allowing them to achieve much higher magnifications and resolving power than light microscopes. The document discusses the basic components and working principles of transmission electron microscopes and scanning electron microscopes. It also covers sample preparation techniques, applications, limitations, and recent research using electron microscopy.
Microscopy is a technique used to produce visible images of structures too small to be seen by the human eye. There are several microscopy techniques including optical microscopy, electron microscopy, and scanning probe microscopy. Optical microscopy uses visible light and lenses to magnify samples, but is limited to resolving structures larger than 400-700 nm. Electron microscopes like the transmission electron microscope (TEM) and scanning electron microscope (SEM) use electron beams instead of light to image much smaller nano-scale structures, but require vacuum conditions. Different microscopy techniques are suited to different applications depending on the sample and desired resolution.
Darkfield microscopy uses oblique illumination to make specimens appear bright against a dark background. Light is directed around the specimen so that it is scattered and refracted off of it. This allows thin structures like bacteria to be seen more easily compared to brightfield microscopy. Some applications of darkfield microscopy include viewing unstained live samples, motile organisms, fibers, and external surface details of cells. It has advantages like simplicity, quality images, and lack of artifacts, though light levels are lower.
Today, scanning electron microscopy (SEM) is a versatile technique used in many
industrial labs, as well as for research and development. Due to its high lateral resolution, its great depth of focus and its facility for X-ray microanalysis, SEM is ofen
used in materials science – including polymer science – to elucidate the microscopic
structure or to differentiate several phases from each other.
Pollen photos using a Scanning Electron MicroscopeChris Cardew
The document compares the scanning electron microscope (SEM) to the light microscope. It states that the SEM can achieve much higher magnifications than the light microscope, up to 500,000x compared to 1000-1500x, because electrons have a much shorter wavelength than visible light. This allows the SEM to achieve much higher resolving power and see finer detail, around 4nm, versus around 200nm for the light microscope. It also notes some key differences in their operation, such as the SEM using electrons rather than visible light and requiring a vacuum rather than air-filled interior.
A scanning electron microscope is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the sample's surface topography and composition.
SEMs can magnify an object from about 10 times up to 300,000 times. A scale bar is often provided on an SEM image. From this the actual size of structures in the image can be calculated.
This document provides an overview of fluorescent microscopy. It begins with the history and basic principles, including Stokes shift and the advantages and disadvantages of fluorescent microscopy. Different types of fluorescent microscopes are described such as epifluorescent and confocal microscopes. Various fluorescent microscopic techniques are outlined, including wide-field, laser scanning, spinning disk, multi-photon, light sheet, and super-resolution microscopies. Sample preparation methods for fluorescent microscopy are also summarized, such as using synthetic fluorescent stains, immunofluorescence labeling, and genetically encoded fluorescent proteins.
Transmission Electron Microscope (TEM), RESOLVING POWER, Scanning Electron Microscope, PRINCIPLE AND WORKING OF SEM, SEM SAMPLE PREPARATION, Limitations of Scanning Electron Microscopy (SEM), ADVANTAGES & DISADVANTAGES OF SEM, APPLICATIONS OF SEM, PRINCIPLE, AND WORKING OF TEM, SAMPLE PREPARATION FOR TEM, ADVANTAGES & DISADVANTAGES OF TEM, APPLICATIONS OF TEM, Differences between SEM and TEM.
This document provides an overview of scanning electron microscopy. It begins with an introduction to microscopy and the need for electron microscopy due to limitations of optical microscopy. It then describes the components and operating principle of a scanning electron microscope. The document explains how electrons interact with matter by producing backscattered electrons and secondary electrons, which are used to form images. It also covers specimen preparation and applications of SEM, concluding with references.
Phase Contrast Microscopy - Microbiology 1st RAHUL PAL
Phase contrast microscopy uses differences in phase shifts of light waves passing through a specimen to visualize unstained living cells. It allows biologists to study living cells and cell division. Dark field microscopy produces a dark background and bright specimen image using oblique illumination. It is used to view unstained or little absorbed objects like bacteria, algae, and diatoms. Electron microscopy uses a beam of accelerated electrons instead of light for higher resolution imaging of nano-scale structures. Types include analytical electron microscopy, scanning transmission electron microscopy, scanning electron microscopy, and transmission electron microscopy.
The document describes the parts and working of a polarizing microscope. It has optical components like polarizers, analyzers and lenses, and mechanical components like the rotating stage. Light from the specimen is polarized and its interaction with the optical components is used to identify properties of minerals and rocks. The polarized microscope allows examination of anisotropic materials and determination of their optical characteristics, which has applications in geology and mineral exploration.
The document provides an overview of scanning electron microscopes (SEMs), including their history, key parts, working principle, applications, and sample preparation process. Some key points:
- SEMs use a beam of electrons to produce high-resolution images of sample surfaces, allowing examination of microscopic structural features. They have greater depth of field than light microscopes.
- Early development began in the 1930s. Commercial instruments became available in the 1960s. Continued improvements have increased resolution to the atomic scale.
- Key components include an electron gun, electromagnetic lenses, vacuum system, specimen stage, and detectors. Secondary electrons emitted from the sample are used to form images.
- Applications span biology, materials
5. Microsocope ELECTRON MICROSCOPE (TEM & SEM ) - BasicsNethravathi Siri
Basics only
Electron beam is the source of illumination.
Image is produced by magnetic field.
Contrasting features between light microscope and electron microscope are
construction, working principle, specimen preparation, cost-expenses and designed
room (vacuum chamber).
The document discusses electron microscopes. It begins by explaining that electron microscopes use accelerated electrons rather than light to image specimens, allowing for higher resolutions than light microscopes. It describes the two main types - transmission electron microscopes (TEM), which use transmitted electrons to form images, and scanning electron microscopes (SEM), which detect electrons bounced off surfaces. TEMs use electromagnetic lenses to focus electron beams and form magnified images. SEMs scan specimens with a narrow electron beam and detect emitted secondary electrons to construct images. Proper specimen preparation, like fixation and staining, is also outlined.
The document discusses electron microscopes and optical microscopes. It describes the basic components and working principles of transmission electron microscopes (TEM) and scanning electron microscopes (SEM). TEM uses electron beams to form images with very high resolution, while SEM scans the sample surface with a focused electron beam to produce 3D images. Optical microscopes like compound microscopes use lenses and light to magnify samples, but have lower resolution than electron microscopes. Examples of applications for each type of microscope are also provided.
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
This document discusses different types of microscopy and their principles. It begins by defining a microscope and microscopy. It then explains principles of light microscopy, including magnification, resolution, numerical aperture, and illumination sources. Specific types of light microscopy are described in more detail, including brightfield microscopy, darkfield microscopy, phase contrast microscopy, differential interference contrast (DIC) microscopy, and fluorescence microscopy. Their basic optical setups and principles are summarized.
The document discusses the scanning electron microscope (SEM). The SEM uses a focused beam of electrons to scan the surface of a sample and produce images with high magnification and resolution. It has several advantages over optical microscopes, including higher magnification, greater depth of field, and the ability to provide 3D images and determine sample composition. The SEM has many applications in science and industry such as structural analysis, measurements, and failure inspection. It provides valuable but has some limitations like requiring solid samples and being costly.
Electron microscopy by SIVASANGARI SHANMUGAM.
Electron microscopy is a technique for obtaining high-resolution images of biological and non-biological specimens.
This document provides an overview of microscopy used in diagnostic microbiology. It discusses the history and types of microscopes including bright field, dark field, phase contrast, fluorescence, transmission electron, and scanning electron microscopes. It describes how each microscope works and its applications. Key aspects covered include the use of microscopy to identify microorganisms, detect viruses, and examine cellular structures in detail not visible to the naked eye. Microscopy is an important tool in diagnostic microbiology.
Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are techniques used to image samples at very high magnifications. SEM works by scanning a sample's surface with a focused beam of electrons, while TEM transmits electrons through an ultra-thin sample. Both techniques use electron detectors and electromagnetic lenses to form images with resolutions better than optical microscopes. Key applications include examining biological structures, materials science, and semiconductor manufacturing.
The document discusses different types of microscopy techniques including bright field microscopy, dark field microscopy, fluorescence microscopy, confocal microscopy, transmission electron microscopy, scanning electron microscopy, and sample preparation methods for light and electron microscopy. Bright field microscopy uses transmitted white light while dark field excludes unscattered light. Fluorescence microscopy uses fluorescent dyes and confocal microscopy excludes out-of-focus light to generate thin optical sections. Electron microscopy has much higher resolution than light microscopy and is used to view ultrastructures. Proper fixation, staining, sectioning and coating are required for electron microscopy specimens.
This document provides an overview of different microscopy techniques, including bright field microscopy, dark field microscopy, fluorescence microscopy, confocal microscopy, transmission electron microscopy, and sample preparation methods. Bright field microscopy uses transmitted white light and contrast is created by absorption of light in dense areas of the sample. Dark field microscopy excludes the unscattered light beam, resulting in a dark background around specimens. Confocal microscopy creates sharp images by excluding out-of-focus light. Transmission electron microscopy has much higher resolution than light microscopy due to the shorter wavelength of electrons. Sample preparation for microscopy may involve fixation, staining, sectioning, and mounting.
This document discusses various techniques for material characterization testing. It describes microscopy techniques like optical microscopy and electron microscopy. Optical microscopy uses visible light and lenses to magnify small objects, while electron microscopy uses accelerated electron beams which have much shorter wavelengths than visible light, allowing for higher resolution. Spectroscopy techniques like UV-Vis spectroscopy, atomic spectroscopy, and infrared spectroscopy are also covered. These techniques involve measuring the interaction of electromagnetic radiation with matter to determine material properties. Electrical, magnetic, and electromagnetic characterization methods are also summarized.
This document provides information on electron microscopy. It discusses the history and invention of the electron microscope in the 1930s by Germans Ernst Ruska and Max Knoll. It describes two main types of electron microscopes - transmission electron microscopy (TEM) and scanning electron microscopy (SEM). TEM uses a beam of electrons to transmit through a thin specimen to form a magnified image, while SEM detects scattered electrons from a specimen's surface to produce 3D topological images. Specimen preparation and imaging principles are explained for both techniques. Other advanced microscopy methods like scanning probe microscopy are also briefly covered.
The document provides information about scanning electron microscopes (SEMs), including:
- A brief history of the development of SEMs from the 1930s to modern commercial versions.
- An overview of the basic components and working principles of SEMs, such as using an electron beam to scan samples and detect signals to form images.
- Descriptions and diagrams of key parts like the electron gun, electromagnetic lenses, detectors, and vacuum system.
- Explanations of imaging modes and how SEMs can be used for chemical analysis of samples.
- Advantages and limitations of SEM technology.
This document provides an overview of microscopy including:
1. It outlines the historical development of the microscope from the 1500s to present.
2. It describes key microscope components and variables like magnification, resolution, numerical aperture, aberration, and contrast.
3. It explains different microscope types like compound light, darkfield, phase contrast, fluorescence, electron, confocal, and scanning probe microscopes as well as their principles and uses.
4. It provides guidance on microscope care and proper storage, handling of lenses, and care of oil emersion objectives and lamps.
Similar to Microscopy by S.D.Mankar, Assistant Professor, Department of Pharmaceutics, Pravara Rural College Of Pharmacy,Loni (20)
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Phase contrast microscopy
definition:-Unstained living cells absorb practically no light. Poor light
absorption results in extremely small differences in the intensity
distribution in the image. This makes the cells barely, or not at all, visible
in a brightfield microscope.
Phase-contrast microscopy is an optical microscopy technique that
converts phase shifts in the light passing through a transparent
specimen to brightness changes in the image.
It was first described in 1934 by Dutch physicist Frits Zernike.
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When light passes through cells, small phase shifts occur,
which are invisible to the human eye.
In a phase-contrast microscope, these phase shifts are
converted into changes in amplitude, which can be observed as
differences in image contrast.
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The Working of Phase contrast Microscopy
Partially coherent illumination produced by the tungsten-halogen
lamp is directed through a collector lens and focused on a
specialized annulus (labeled condenser annulus) positioned in the
substage condenser front focal plane.
Wave fronts passing through the annulus illuminate the specimen
and either pass through undeviated or are diffracted and retarded
in phase by structures and phase gradients present in the
specimen.
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Undeviated and diffracted light collected by the objective is
segregated at the rear focal plane by a phase plate and
focused at the intermediate image plane to form the final
phase-contrast image observed in the eyepieces.
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Applications of Phase contrast Microscopy
To produce high-contrast images of transparent specimens, such as
living cells (usually in culture),
microorganisms,
thin tissue slices,
lithographic patterns,
fibers,
latex dispersions,
glass fragments, and
subcellular particles (including nuclei and other organelles).
Applications of phase-contrast microscopy in biological research are numerous.
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Advantages
Living cells can be observed in their natural state without previous
fixation or labeling.
It makes a highly transparent object more visible.
No special preparation of fixation or staining etc. is needed to study an
object under a phase-contrast microscope which saves a lot of time.
Examining intracellular components of living cells at relatively high
resolution. eg: The dynamic motility of mitochondria, mitotic
chromosomes & vacuoles.
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It made it possible for biologists to study living cells and how they
proliferate through cell division.
Phase-contrast optical components can be added to virtually any
brightfield microscope, provided the specialized phase objectives
conform to the tube length parameters, and the condenser will accept
an annular phase ring of the correct size.
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Limitations
Phase-contrast condensers and objective lenses add considerable cost to a
microscope, and so phase contrast is often not used in teaching labs except
perhaps in classes in the health professions.
To use phase-contrast the light path must be aligned.
Generally, more light is needed for phase contrast than for corresponding
bright-field viewing, since the technique is based on the diminishment of the
brightness of most objects.
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Electron microscope definition
An electron microscope is a microscope that uses a beam of
accelerated electrons as a source of illumination.
It is a special type of microscope having a high resolution of images, able to
magnify objects in nanometers, which are formed by controlled use of electrons
in vacuum captured on a phosphorescent screen.
Ernst Ruska (1906-1988), a German engineer and academic professor, built the
first Electron Microscope in 1931, and the same principles behind his prototype
still govern modern EMs.
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Working Principle of Electron microscope
Electron microscopes use signals arising from the interaction of an
electron beam with the sample to obtain information about structure,
morphology, and composition.
1. The electron gun generates electrons.
2. Two sets of condenser lenses focus the electron beam on the
specimen and then into a thin tight beam.
3.To move electrons down the column, an accelerating voltage (mostly
between 100 kV-1000 kV) is applied between tungsten filament and
anode.
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4.The specimen to be examined is made extremely thin, at least 200 times thinner
than those used in the optical microscope. Ultra-thin sections of 20-100 nm are cut
which is already placed on the specimen holder.
5.The electronic beam passes through the specimen and electrons are scattered
depending upon the thickness or refractive index of different parts of the specimen.
6.The denser regions in the specimen scatter more electrons and therefore appear
darker in the image since fewer electrons strike that area of the screen. In contrast,
transparent regions are brighter.
7.The electron beam coming out of the specimen passes to the objective lens, which
has high power and forms the intermediate magnified image.
8.The ocular lenses then produce the final further magnified image.
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In TEM a beam of electron is projected from electron gun and pass
through a series of electromagnetic lenses.
They get scattered and transmitted through the object and pass through
objective lens which magnifies image of object.
The projection lens further magnifies the image and project it on
fluorescent screen.
The electron image is converted into visible form by projecting of
fluorescent screen.
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An electron beam has low penetration power through solid matter.
Hence very thin section of specimen is required.
Application:-
TEM is useful in shadow casting, ultra thin sectioning, localization of
cells constituents & enzymes & autoradiography.
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In SEM the specimen is subjected to a narrow electron beam which rapidly
moves over the surface of specimen. ( Scann).
These causes the release of secondary electrons from the specimen surface.
The intensity of secondary electrons is depends on shape and chemical
composition of the object.
The secondary electrons are collected by detector which generates the
electron signals.
This signals are then scanned in the manner of a television system to produce
an image on cathode ray tube.
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Applications
Electron microscopes are used to investigate the ultrastructure of a wide range of biological
and inorganic specimens including microorganisms, cells, large molecules, biopsy samples,
metals, and crystals.
Industrially, electron microscopes are often used for quality control and failure analysis.
Modern electron microscopes produce electron micrographs using specialized digital
cameras and frame grabbers to capture the images.
Science of microbiology owes its development to the electron microscope. Study of
microorganisms like bacteria, virus and other pathogens have made the treatment of
diseases very effective.
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Limitations
The live specimen cannot be observed.
As the penetration power of the electron beam is very low, the object should be
ultra-thin. For this, the specimen is dried and cut into ultra-thin sections before
observation.
As the EM works in a vacuum, the specimen should be completely dry.
Expensive to build and maintain
Requiring researcher training
Image artifacts resulting from specimen preparation.
This type of microscope is a large, cumbersome extremely sensitive to vibration and
external magnetic fields.
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Dark Field Microscopy:
A dark field microscope is arranged so that the light source is
blocked off, causing light to scatter as it hits the specimen.
This is ideal for making objects with refractive values similar to the
background appear bright against a dark background.
When light hits an object, rays are scattered in all azimuths or
directions. The design of the dark field microscope is such that it
removes the dispersed light, or zeroth order, so that only the
scattered beams hit the sample.
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The introduction of a condenser and/or stop below the stage ensures
that these light rays will hit the specimen at different angles, rather than
as a direct light source above/below the object.
The result is a “cone of light” where rays are diffracted, reflected and/or
refracted off the object, ultimately, allowing the individual to view a
specimen in dark field.
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The dark-ground microscopy makes use of the dark-ground microscope,
a special type of compound light microscope.
The dark-field condenser with a central circular stop, which illuminates
the object with a cone of light, is the most essential part of the dark-
ground microscope.
This microscope uses reflected light instead of transmitted light used in
the ordinary light microscope.
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It prevents light from falling directly on the objective lens.
Light rays falling on the object are reflected or scattered onto the
objective lens with the result that the microorganisms appear brightly
stained against a dark background.