NOCE Lens Treatments and Coatings 2

Question 1

An uncoated standard CR-39 plastic lens reflects approximately what percentage of incident light from each surface?

Accepted Answer

8%

Answer

2–3%

Answer

12–15%

Answer

20%

Question 2

Photochromic lenses typically activate in response to which type of radiation?

Accepted Answer

Ultraviolet (UV) radiation

Answer

Visible blue light only

Answer

Infrared (IR) radiation

Answer

Ambient temperature change alone

Question 3

What is the primary function of a hydrophobic coating applied over an anti-reflective coating?

Accepted Answer

To repel water, oils, and smudges from the lens surface

Answer

To prevent ultraviolet radiation from degrading the AR coating

Answer

To harden the lens and increase scratch resistance below the AR layer

Answer

To reduce electrostatic charge that attracts dust particles

Question 4

Which type of lens treatment is applied to create a reflective, mirror-like appearance on the front surface of sunglasses?

Accepted Answer

Flash or mirror coating deposited on the front surface

Answer

Polarized filter embedded in the lens substrate

Answer

Photochromic molecular treatment throughout the lens

Answer

Anti-reflective coating applied to the front surface only

Question 5

Blue light-filtering lenses are designed to reduce transmission of light in which approximate wavelength range?

Accepted Answer

380–500 nm (violet to blue visible light)

Answer

200–280 nm (UVC range)

Answer

500–600 nm (green to yellow visible light)

Answer

620–700 nm (red visible light)

Question 6

How does high ambient temperature typically affect the performance of photochromic lenses?

Accepted Answer

They do not darken as deeply at higher temperatures, resulting in reduced performance

Answer

They darken more rapidly at higher temperatures

Answer

They achieve a consistently darker final state at higher temperatures

Answer

They permanently lose photochromic capability after repeated heat exposure

Question 7

In a standard multi-coating stack applied to an ophthalmic lens, which coating is typically applied as the outermost (final) layer?

Accepted Answer

Hydrophobic/oleophobic top coat

Answer

Hard coat (scratch-resistant layer)

Answer

Anti-reflective layers

Answer

UV-absorbing treatment