Lecture 9 Dispersion Chromatic Aberration

Question 1

Dispersion can be caused by ______ and ______.

Answer 1

Prisms and lenses

Question 2

White light is composed of different wavelengths (____-____ nm). Each wavelength contributes to a different ______. This is dispersion

Answer 2

380-780nm; angle of refraction or refractive index (n)

Question 3

The reference wavelength normally used by US manufacturers is the Fraunhofer d line (yellow helium) _____.

Answer 3

587.56nm

Question 4

Fraunhofer lines are specific wavelengths which are absorbed by gaseous elements in the sun’s atmosphere. Therefore, do we see these “colors?”

Answer 4

No, because they are absorbed.

Question 5

Commonly used lens materials ranked by abbe number values.

Crown glass, Cr-39, Trivex, Hi Index 1.60, Polycarbonate, and Spectralite

Answer 5

Crown glass (58), Cr-39 (58), Spectralite (47), Trivex/Phoenix (44), Hi Index (36), Poly (30)

Question 6

Abbe’s number is based on Fraunhofer lines and has no units. It evaluates the deviation of the reference wavelength in relation to the maximum ____________ dispersion range.

Answer 6

maximum spectral dispersion range

Question 7

Dispersion in eyeglasses is called _______ _______.

Answer 7

chromatic aberration

Question 8

Chromatic aberration, CA, is also called _________ ______ (w).

Answer 8

dispersive power, w

Question 9

Chromatic aberration is associated with the perception of _______ ___________ ________ and _____ ______.

Answer 9

linear magnification difference and color fringes

Question 10

Longitudinal chromatic aberration is also called….

Answer 10

Axial chromatic aberration. Important in optical instruments

Question 11

Transverse chromatic aberration is also called …..

Answer 11

lateral chromatic aberration

Question 12

TCA is in lenses/prisms and expresses _____ _____ or degrees.

Answer 12

lenses and prisms and is expressed in prism power or degrees

Question 13

LCA is in lenses/prisms and uses ______ power.

Answer 13

Lenses only and focal power

Question 14

What method is a pairing of a plus and minus lens with different refractive indices (opposite amounts of CA)? It is very common in instruments

Answer 14

Achromatic lens doublet

Question 15

Diffractive element has opposite CA, where short wavelength are bent ____ than long wavelengths?

Answer 15

less

Question 16

The average human eye exhibits approximately 2D ____ in the visible light range.

Answer 16

2D LCA

Question 17

The Red-Green eye chart takes advantage of the eye’s LCA. What is the RAM GAP?

Answer 17

Red Add Minus

Green Add Plus