VSP 3 - Lecture 1 (in progress)

Which EM waves have shorter wavelength (than visible light)?

Gamma rays, X rays, UV rays

Which EM waves have longer wavelength (than visible light)?

Infrared, microwaves, radio waves

What is the only EM waves that the human eye can detect and perceive?

Those within the visible spectrum

What is a radiometer?

A device measuring radiance/radiant power

What is a photometer?

Device that measures luminance

Where does the human photopic sensitivity peak?

at 555 nm

T/F Not all color are seen at the same intensity

True

What is UVA radiation?

UV rays closer to the visible spectrum (315-400nm)

What is UVB radiation?

Burning rays/bad rays (290-315)

What is UVC radiation?

Highest energy, mostly blocked by ozone (100-290nm)

What are three types of IR?

Near IR (760-3000nm), Mid IR (3000-6000) and far IR (6000-15,000)

Where is the majority of UVB absorbed?

Cornea+Iris

Where is the majority of UVA absorbed?

Lens mostly

Where is the majority of visible light absorbed?

RPE

Which UV light can reach the retina?

UVA

T/F There's no safe wavelengths, only safe quantities

True

What causes a thermal cataract?

Absorption of heat by the iris with transfer to the underlying lens (common in glass blowing)

What causes a thermal retinal damage?

IR energy which can increase the local temperature of the retina (eclipse retinopathy)

What is the blue light hazard function?

Damage to the retina caused by excessive blue light

What EM radiation causes thermal effects?

Near IR and visible

What EM radiation causes photochemical effects?

UVA and UVB

Which EM radiation is ionizing?

UVB and UVC

What disease may involve the blue light hazard function?

ARMD

What UV photokeratitis?

Painful sloughing of the corneal epithelium after UV exposure

What can cause UV photokeratitis?

Welding process, skiing (snow blindness)

What causes snow blindness?

The reflectance of UV rays off the snow onto the eye (reflectance is about 90% for snow surface)

What are the corneal effects of chronic UV exposure?

Endothelial polymegathism, pterygium, exposure keratitis, band keratopathy

What causes pinguecula typically?

Early childhood UV-B exposure

Where are pingueculas typically located?

Nasal

What type of cataracts may be caused by UVB exposure?

Cortical

Who is more at risk for increased transmission of harmful wavelengths through the eye?

Younger children (as the lens ages, it becomes yellow which is a blue-light blocker)

Which lens material naturally blocks harmful light?

CR-39

Which tint can be used to block the general transmittance of all visible light?

Neutral gray

Which tint can be used to block blue light?

Blue blocker

What is a blackbody?

An object that absorbs all radiation falling on it without reflecting it

What happens to the blackbody as you increase the temperature?

It emits visible light

Which color temperature is used for color vision tests?

Standard illuminant C - 6770K

What is the units for radiometry?

Watts

Why is radiometry important?

The amount of light coming form non-visible sources

Which technique only considers the visible spectrum

Photometry

What are the units for photometry?

Lumens

What is the peak of the scotopic luminosity curve?

507 nm

What is flux?

Energy emitted from a point source in all direction (a sphere outward)

How many lumens/watt at 555nm?

683 Lumens/watt

What is a watt?

Total amount of energy leaving a point source per unit time

What is the difference between watts and lumens?

Watts measures the amount of power, lumens measures the brightness

What determines bulb efficiency?

How many lumens per watt you are getting

What is radiant and luminous intensity?

The light power by a point source in a solid angle or steradian (in a specific angular direction)

What is a steradian?

The area on the surface of a sphere divided by the square of the radius of that sphere

T/F Illuminance is not affected by the surface

True