The document summarizes key optical principles related to the human visual system. It discusses:
1) The basics of light, photons, and units of measurement for light such as lumens.
2) How different wavelengths of light such as UV, visible light, and X-rays interact with human skin and tissues, including uses in phototherapy and risks of skin cancer.
3) Principles of reflection, refraction, lenses, and image formation and their relevance to the anatomy and functioning of the human eye.
4) Common visual impairments like myopia, hyperopia, and astigmatism as well as methods for testing visual acuity and visual fields.
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.
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.
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.
Types of Microscopes with their applications - Microbiologynote.com
https://microbiologynote.com/types-of-microscopes-with-their-applications/
Youtube Lecture Video:
https://www.youtube.com/watch?v=nuJZtXohFFQ&ab_channel=MicrobiologyNote
Bright field microscopy, Principle and applicationsKAUSHAL SAHU
Introduction
History
Basic Component of Microscope
Light Microscopy
Types of Light Microscopy
What Are Bright Microscopy
Principle of Bright Microscope
Advantage
Disadvantage
Application
Conclusion
Reference
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.
Types of Microscopes with their applications - Microbiologynote.com
https://microbiologynote.com/types-of-microscopes-with-their-applications/
Youtube Lecture Video:
https://www.youtube.com/watch?v=nuJZtXohFFQ&ab_channel=MicrobiologyNote
Bright field microscopy, Principle and applicationsKAUSHAL SAHU
Introduction
History
Basic Component of Microscope
Light Microscopy
Types of Light Microscopy
What Are Bright Microscopy
Principle of Bright Microscope
Advantage
Disadvantage
Application
Conclusion
Reference
. Introduction Biomicroscope derives its name from the fact that it enables the practitioner to observe the living tissue of eye under magnification. It not only provides magnified view of every part of eye but also allows quantitative measurements and photography of every part for documentation.
3. • The lamp facilitates an examination which looks at anterior segment, or frontal structures, of the human eye, which includes the –Eyelid –Cornea –Sclera –Conjunctiva –Iris –Aqueous –Natural crystalline lens and –Anterior vitreous.
4. Important historical landmarks De Wecker 1863 devised a portable ophthalmomicroscope . Albert and Greenough 1891,developed a binocular microscope which provided stereoscopic view. Gullstrand ,1911 introduced the illumination system which had for the first time a slit diapharm in it Therefore Gullstrand is credited with the invention of slit lamp.
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Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
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June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
Let’s explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
A Strategic Approach: GenAI in EducationPeter Windle
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A workshop hosted by the South African Journal of Science aimed at postgraduate students and early career researchers with little or no experience in writing and publishing journal articles.
2. Basics• LIGHT:
– it is an electromagnetic wave. Composed of an oscilant electric and
magnetic field mutually perpendicular to each other. Visible light: 400-700 nm
• Photon:
– a particle representing a quantum of light or other electromagnetic
radiation. A photon carries energy proportional to the radiation frequency
but has zero rest mass
• Photometry:
– science of the measurement of light, in terms of its perceived brightness
to the human eye
• Lumen:
– the SI unit of luminous flux, equal to the amount of light emitted per
second in a unit solid angle of one steradian from a uniform source of one
candela.
3.
4.
5. UV Radiation
• More energy than visible light
• Convert some molecules into
vitamins (Vit D)
• Phototherapy:
– Highly recommended for
neonatal jaundice. BR
• risk for skin cancer
• UV-A = long wave (400-315nm)
• UV-B = medium wave (315-280)
• UV-C= short wave (280-100; germicide)
Phototherapy for Psoriasis with UVB
light, or UVA light combined with psoralens
(PUVA, furocoumarin*)
*chemical substances that sensitize the skin to the effects of the sun, thus leading to irregular pigmen-tation and increasing the
risk of sunburn and phototoxicity.
8. Skin Cancer
• It’s the most common Ca in the US
• The most frequent types: basal cells and squamous cells
• Median erithema dose (MED) is the amount of radiation needed to
develop red skin
9. ¿How UV rays affect human
skin?
• Erythema is one of the most obvious efects
of UV-B rays on human skin.
– superficial reddening of the skin as a result of
injury or irritation causing dilatation of the
blood capillaries
• UV can harm genetic material causing Ca
– (timidine dimers)
• For those white skin people, UV-B long time exposure can cause skin Ca
• Everytime the ozone layer 1% the cancer risk 2%
11. X Ray
• An electromagnetic wave of high energy and very short wavelength, which
is able to pass through many materials opaque to light
• They can be produced by deceleration of cathode-produced electrons
(generally a tungsten filament) by hitting a metal
– An aluminun cathode inside a tube with gas accelerates particles
towards tha anode where the target is located
• Interaction with biological material: they are absorbed, transmitted and
they generate ions
• They can pass through opaque objects and print photographic film
• Widely used in Medicine
– To study bones and joints
– To help in diagnosis of soft tissue
14. Optics Principles
The reflected angle r has the same
value as the incident i with respect
to a perpendicular surface• Light rays can be...
• Incident; Reflected; Refracted
15. • Refraction
• Refraction index n: is defined as
the ratio of the sine of the angle
of incidence to the sine of the
angle of refraction
• Snell´s law: n1 sen i = n2 sen r
• Optic fiber: It sends information
coded in a beam of light down a
glass or plastic pipe
• Endoscope
• Cystoscope
Fibers in bundles are clad by a
material that has a lower index of
refraction than the core to ensure
total internal reflection, even when
fibers are in contact with one another.
This shows a single fiber with its
cladding.
16.
17. Energy is absorbed
• Absorbed energy generates heat
• In medicine, infrared rays are used to warm-up tissues and create images
– Thermogram
– With modern technology, a single image may contain several
thousands of temperature points, recorded in a fraction of a second
• Thermal imaging can be applied in medicine either as a diagnostic test or
as outcome measure for clinical trials
– presence of inflammation: Inflammatory arthritis
– blood flow is increased or decreased due to a clinical abnormality
from Infrared thermal imaging in medicine. E F J Ring and K Ammer 2012 Physio
18. Fluorescence
• the property of absorbing light or other
electromagnetic radiation (X ray, UV ray)
of short wavelength and emitting light of
longer wavelength
• Fluoroscopy
• is a type of medical imaging that
shows a continuous X-ray image on a
monitor, much like an X-ray movie.
During a fluoroscopy procedure, an X-
ray beam is passed through the body.
The image is transmitted to a monitor
so the movement of a body part or of
an instrument or contrast agent (“X-ray
dye”) through the body can be seen in
detail.
19. Fluorescence
• Fluorescent microscope
• is an optical microscope that uses fluorescence and phosphorescence instead
of, or in addition to, reflection and absorption to study properties of organic or
inorganic substances.
21. Light deviation by lenses.
A. Converging lens (+) concentrates light rays .
B. Diverging lens (-) separates light rays .
22. Basic stuff...
• FOCUS: the point on the axis
of a lens or mirror to which
parallel rays of light converge
or from which they appear to
diverge after refraction or
reflection
• Focal distance : distance
between optical center of the
lens.
• The focal length of a lens is
determined when the lens is
focused at infinity
• A lens system with a focal
length of 1.8 cm (0.018 m) is
a 56-diopter lens. A lens
system with a focal length
of 1.68 cm is a 60-diopter
lens. A healthy eye is able to
bring both distant objects
and nearby objects into
focus without the need for
corrective lenses
• The ability of the eye to
adjust its focal length is
known as accommodation
23. Diopter D=1/F
The lens strength in diopters is defined
as the inverse of the focal length in
meters
This unit is expressed with positive
(converging) or negative (diverging) the
refraction power.
A lens with focal lenght +1 m, will have 1 diopter
potency; a lens with +2 diopters is a convergent lens
with focal lenght 0,5m
25. Image formation: real & virtual
REAL Image
1. Inverted (if located beyond f)
2. Smaller
3. Behind the convex lens
closer than object
VIRTUAL Image
1. Upright
2. Same size as object
3. Left-right reversal
4. As far behind the mirror as
the object is in front of the
mirror.
27. Reduced eye model
Useful to calculate
image size
AP eye diameter 2,3 cm
N= 0,6 cm
N = nodal point. Where the light
rays are not deviated
Object ?
Distance ?
28. Q’F’
QF
=
F’N
FN
N= nodal point
Q’F’ =
F’N
FN
(QF)
FN
F’N
AP
Tree size 1,8 m
Object distance = 5m
Eye dimeter 2,3 cm
N= 0,6 cm
N
Q’F’ =
AP-N
FP+N
(QF)
Q’F’ =
2,3cm-0,6cm
500cm+0,6cm
(180cm)
Q’F’ = 1,7
500,6
(180cm) = 0,611 cm
Image
Object
=
image-N
Object+N
29. Common visual acuity deffects
A common form of visual impairment in
which part of an image is blurred due to
an irregularity the cornea.
With ASTIGMATISM, light rays entering the
eye are not uniformly focused on the
retina. The result is blurred vision at all
distances.
ASTIGMATISM
34. LENS
• Lens refraction power depends on its proteins hence its
higher refraction power as compared to neighboring
structures.
• MIP26 protein (“major intrinsic protein”) of the lens Works as
ionic channel, allowing proteins to work as an electrical
sincitium with gap junctions
– MIP26 extracts water from lens and keep transparency
– Using patch clamp technique 9-11 K+ channels has been
identified, as well as non-selective cations channels
– This lens allows focusing objects and concentrates light
36. During phacoemulsification — the most
common type of cataract surgery — the
rapidly vibrating tip of the ultrasound probe
breaks up the cataract, which your surgeon
then suctions out (top). After removing the
cataract, your surgeon inserts the lens
implant into the empty capsule where the
natural lens used to be (bottom).
51. • sharpness of vision, measured by the ability to discern letters or numbers at a
given distance according to a fixed standard
• Usefulness
» Neurological status of the visual system
» Macular function
» Need of correction lens
» Following-up of surgical procedures
52. Clinical evaluation
• Snellen’s chart
– Every line of letters
(optotypes) has a fraction
pointing out subject’s
visual acuity as the line
he/she can read.
• Normal: 20/20
• 20/200 see less = 10% of
vision, myopia
53. Astigmatism test
Verify if any line looks blurry
http://www.opeluce.tecnoplace.co
m/test/testagudeza.php#
54. • Human eye is able to see color. This property is based upon the
photosensitive pigments in the retina, especially in cones
• Opsins are the photosensitive pigments present in cones and rods as well.
RHODOPSIN is the most studied. The pigment undergoes chemical
changes triggered by light.
• Cones are sensitive to BLUE,GREEN and RED
• Eritrhopsin – 560-570 nm red light
– Cloropsin – 530-535 nm green light
– Cianopsin – 430-445 nm blue light
RHODOPSIN 505 nm