The document discusses various lens enhancements that can be applied to spectacle lenses, including anti-reflection coatings, scratch-resistant coatings, UV coatings, and hydrophobic coatings. It provides details on the principles and techniques for applying anti-reflection coatings using single or multiple layers. Hard coatings and their scratch-resistant properties are also covered. Other topics include photochromic lenses that darken in sunlight, tinted lenses, polarizing lenses and their advantages in reducing glare.
How to protect your eye?
With sunglasses? Mirror glasses? Tinted or polarized glasses?
What is right tint colour for you?
What are antireflection coat glasses?
How to protect your eye?
With sunglasses? Mirror glasses? Tinted or polarized glasses?
What is right tint colour for you?
What are antireflection coat glasses?
Crisper vision due to leser distortion on the edges.
Uniform Clarity of vision in the centre and the side.
Better cosmetic appearance.
Natural appearance of the eye does not magnify eyes.
Ex :- Our cornea is also aspheric in nature.
Aspheric lences is depend upon the shape of the Lens.
Aspheric
Tinted lenses, also known as colored or tinted eyeglass lenses, serve various purposes in optometry. These lenses are designed to provide specific benefits depending on the tint or color chosen.
Whether hiking, out skiing for the day or on holiday at the beach, good sun protection is essential.
But how can you tell if the glasses you're wearing are suitable and give you enough protection?
Navigating the Health Insurance Market_ Understanding Trends and Options.pdfEnterprise Wired
From navigating policy options to staying informed about industry trends, this comprehensive guide explores everything you need to know about the health insurance market.
One of the most developed cities of India, the city of Chennai is the capital of Tamilnadu and many people from different parts of India come here to earn their bread and butter. Being a metropolitan, the city is filled with towering building and beaches but the sad part as with almost every Indian city
CHAPTER 1 SEMESTER V PREVENTIVE-PEDIATRICS.pdfSachin Sharma
This content provides an overview of preventive pediatrics. It defines preventive pediatrics as preventing disease and promoting children's physical, mental, and social well-being to achieve positive health. It discusses antenatal, postnatal, and social preventive pediatrics. It also covers various child health programs like immunization, breastfeeding, ICDS, and the roles of organizations like WHO, UNICEF, and nurses in preventive pediatrics.
Navigating Challenges: Mental Health, Legislation, and the Prison System in B...Guillermo Rivera
This conference will delve into the intricate intersections between mental health, legal frameworks, and the prison system in Bolivia. It aims to provide a comprehensive overview of the current challenges faced by mental health professionals working within the legislative and correctional landscapes. Topics of discussion will include the prevalence and impact of mental health issues among the incarcerated population, the effectiveness of existing mental health policies and legislation, and potential reforms to enhance the mental health support system within prisons.
We understand the unique challenges pickleball players face and are committed to helping you stay healthy and active. In this presentation, we’ll explore the three most common pickleball injuries and provide strategies for prevention and treatment.
Telehealth Psychology Building Trust with Clients.pptxThe Harvest Clinic
Telehealth psychology is a digital approach that offers psychological services and mental health care to clients remotely, using technologies like video conferencing, phone calls, text messaging, and mobile apps for communication.
India Clinical Trials Market: Industry Size and Growth Trends [2030] Analyzed...Kumar Satyam
According to TechSci Research report, "India Clinical Trials Market- By Region, Competition, Forecast & Opportunities, 2030F," the India Clinical Trials Market was valued at USD 2.05 billion in 2024 and is projected to grow at a compound annual growth rate (CAGR) of 8.64% through 2030. The market is driven by a variety of factors, making India an attractive destination for pharmaceutical companies and researchers. India's vast and diverse patient population, cost-effective operational environment, and a large pool of skilled medical professionals contribute significantly to the market's growth. Additionally, increasing government support in streamlining regulations and the growing prevalence of lifestyle diseases further propel the clinical trials market.
Growing Prevalence of Lifestyle Diseases
The rising incidence of lifestyle diseases such as diabetes, cardiovascular diseases, and cancer is a major trend driving the clinical trials market in India. These conditions necessitate the development and testing of new treatment methods, creating a robust demand for clinical trials. The increasing burden of these diseases highlights the need for innovative therapies and underscores the importance of India as a key player in global clinical research.
CRISPR-Cas9, a revolutionary gene-editing tool, holds immense potential to reshape medicine, agriculture, and our understanding of life. But like any powerful tool, it comes with ethical considerations.
Unveiling CRISPR: This naturally occurring bacterial defense system (crRNA & Cas9 protein) fights viruses. Scientists repurposed it for precise gene editing (correction, deletion, insertion) by targeting specific DNA sequences.
The Promise: CRISPR offers exciting possibilities:
Gene Therapy: Correcting genetic diseases like cystic fibrosis.
Agriculture: Engineering crops resistant to pests and harsh environments.
Research: Studying gene function to unlock new knowledge.
The Peril: Ethical concerns demand attention:
Off-target Effects: Unintended DNA edits can have unforeseen consequences.
Eugenics: Misusing CRISPR for designer babies raises social and ethical questions.
Equity: High costs could limit access to this potentially life-saving technology.
The Path Forward: Responsible development is crucial:
International Collaboration: Clear guidelines are needed for research and human trials.
Public Education: Open discussions ensure informed decisions about CRISPR.
Prioritize Safety and Ethics: Safety and ethical principles must be paramount.
CRISPR offers a powerful tool for a better future, but responsible development and addressing ethical concerns are essential. By prioritizing safety, fostering open dialogue, and ensuring equitable access, we can harness CRISPR's power for the benefit of all. (2998 characters)
2. LENS ENHANCEMENTLENS ENHANCEMENT
There are various kinds of surface treatments
that are applied on either side of the spectacle
lenses
1.Anti-reflection coating (ARC)
2.Scratch resistance coating
3.UV coating
4.Hydrophobic coating
3. Anti-reflection Coated LensAnti-reflection Coated Lens
Anti-reflection coating are applied on the
lens surface to efficiently manipulate the
light transmission and reflection through it.
4. THE REFLECTION OF LIGHTTHE REFLECTION OF LIGHT
1.Frontal Reflection
2. Backward Reflection
3. Internal Reflection
4. Corneal Reflection
6. PRINCIPLE OF ANTI-REFLECTIONPRINCIPLE OF ANTI-REFLECTION
COATINGCOATING
To reduce the loss of light due to
reflection and increase the light
transmittance through the lens to
the eyes.
Based on destructive
interference.
9. SINGLE LAYER ANTI-SINGLE LAYER ANTI-
REFLECTION COATINGREFLECTION COATING
The simple principle of single layer anti-
reflection coating is that the substrate
(lens) is coated with a thin layer of
material.
10. PRINCIPLE OF ANTI-PRINCIPLE OF ANTI-
REFLECTION COATINGREFLECTION COATING
The refractive index of the coating is the
square root of that of the lens material.
The thickness of the coating, multiplied by
its refractive index, is exactly one –
quarter of a wavelength of light or any odd
number of quarter wavelengths
11. MULTILAYER ANTI-REFLECTIONMULTILAYER ANTI-REFLECTION
COATINGCOATING
The limitations of the single layer
antireflection coating can be overcome by
multilayer coating which are now capable
of almost extinguishing surface reflections
from one end of the visible spectrum to
the other.
coating may be two layers or more.
12. In a two layer coating, the outer layer is
made of a low refractive index and the
inner layer is made of a high refractive
index material compared to the
substrate.
13. ADVANTAGES OF ANTI-ADVANTAGES OF ANTI-
REFLECTION COATINGREFLECTION COATING
People see better with anti-reflection.
Ghost images, particularly while driving at
night.
Reflections from back lens surfaces can
also be annoying. This is most noticeable
with sun lenses because the dark lens acts
like a mirror.
16. TECHNOLOGY OF ANTI-REFLECTIONTECHNOLOGY OF ANTI-REFLECTION
COATINGCOATING
Done inside a vacuum chamber.
The lens to be coated must be
absolutely free of surface defects,
perfectly cleaned and rid of dust or any
other impurities before they are placed
in the vacuum chamber.
glass lenses can be heated up to 300 deg
C/570 deg F, plastics heated above 100
deg C/210 deg F.
17. HYDROPHOBIC COATINGHYDROPHOBIC COATING
Anti-reflection coating needs to be kept
clean.
This problem can be eased if hydrophobic
coating is applied to the lens surface.
The basic principle is to create a high
surface wetting angle, which allows the
water or oil to run off rather than wetting
and then drying on the surface.
21. HARD COATING orHARD COATING or Scratch-ResistantScratch-Resistant
Coatings (SRC)Coatings (SRC)
Hard coating is a procedure by which a
thin layer of material usually 0.5 micron to
10 micron thick is applied to the lens
surface.
The most common material used is
lacquer which is applied either by dipping
or by spinning procedure.
22. Thermally Cured Hard Coatings
lenses are dipped in a “varnish” and
removed from the varnish at a consistent
rate to control thickness of the coating.
The lenses are then thermally cured or
“baked” over an extended period of time.
24. HARD COATING orHARD COATING or Scratch-Scratch-
Resistant Coatings (SRC)Resistant Coatings (SRC)
25. UV light comprises approximately 5% of total
solar radiation.
Ozone in earth’s atmosphere absorb almost
all solar UV –C radiation. of the reminder
which strike the earth’s surface approximately
90% is UV-A and 10% is UV-B.
UV exposure may also come from arc
welding and UV emitting light bulbs.
Ultraviolet filtersUltraviolet filters
27. IR wavelength near 1400 nm are very
hazardous ;filters for these wavelengths are
usually incorporated into protective goggles
and face masks.
Blue light filters vary in tint between yellow
and red. They increase contrast and facilitate
distinction of light and dark areas and are
used by mountaineers and skiers.
30. A tinted lens modifies the spectral profile
of the radiation passing through it .
Tints are either absorptive or
reflective ; absorptive tints absorb
light passing through them, whereas a
reflective tint reflects unwanted
wavelengths.
Tinted LensesTinted Lenses
31. Unequal absorption of different wavelengths
produces a coloured tint. For example , a
yellow tinted filter absorb all wavelengths of
light except those in the yellow part of the
spectrum, which it transmit.
A neutral density filter absorbs all
wavelengths to the same degree and does not
alter the spectral composition of the light.
32. SURFACE TINTING OF LENSESSURFACE TINTING OF LENSES
Tints are simply the methods of absorbing
lights so that transmission is reduced.
If all wavelengths of light are equally
absorbed, then a neutral grey is produced.
If the absorption is different for different
wavelengths, then the tint has a particular
colour.
33. The purpose of tinted lenses may be to
screen out unwanted or harmful radiation
(laser protective goggles) or cosmetic.
35. PROCEDUREPROCEDURE
The lenses are placed in a suitable bath of
hot colour dye for an appropriate length of
time.
Glasses can also be coated by vacuum
process which has a unique advantage of
uniform tint throughout the lens surface
which is otherwise not possible in glass
lenses.
36. Tinting of lensesTinting of lenses
Mixing dye to molten glass material
Blowing layer of coloured glass on the
surface.
Deposition of fine layers of tint on the
surface by vaccum process or electron
beam process.
Deposition of mirror like coating
37. PHOTOCHROMICPHOTOCHROMIC
LENSESLENSESPhotochromic lenses are lenses that visibly
darken and fade indefinitely under bright
and dull light respectively.
A photochromic glass lens contains billions
of microscopic crystals of SilverHalide.
When exposed to direct sunlight or UV
light, these crystals absorb energy and
cause the formation of metallic silver
deposit on silver halide crystals..
38. Photochromic lensesPhotochromic lenses
Silver halide
Made up of two types of materials;
borosilicate glass and aluminophospahte
glass.
Transmittance range
Fading rate
Reaction time
40. TINT OPTIONS INTINT OPTIONS IN
PHOTOCHROMIC LENSESPHOTOCHROMIC LENSES
Glass photochromic lens usually come in
two basic colours – grey and brown.
Technically it is possible to obtain other
tint.
41. RESIN PHOTOCHROMIC LENSRESIN PHOTOCHROMIC LENS
Photochromic compounds can be
incorporated into a resin lens by applying
either a photochromatic coating or dye
to the lens or by penetration of the
surface, known as imbibitions
43. POLAROID LENSESPOLAROID LENSES
The principle of polarized lenses can be
best illustrated by observing Venetian
blinds.
The blinds block lights at certain angles,
while allowing lights to transmit through
it at certain angles.
Polarization implies restricting the light
waves to one direction.