Lecture 10

Question 1

Solid Angle =

Answer 1

dΩ = (dAcosθ)/r^2

Question 2

The solid angle is a measure

Answer 2

of the field of view from a particular point

Question 3

The emitted radiance =

Answer 3

L(S)= d^2Φ/(cosθdΩdA)

Question 4

Radiance is

Answer 4

Flux emitted per unit projected area per unit solid angle

also known as brightness

Question 5

Where Flux is

Answer 5

conserved, the radiance emitted by a source equals the radiance measured at a receiver

L(S) = L(R)

Question 6

The total flux emitted by the source

Answer 6

Φ = L ∫∫ dA cosθ dΩ

source is now Lambertian

Question 7

Lambertian

Answer 7

Radiance independent of angle

Question 8

Ettendue or Throughput

Answer 8

G = ∫∫ dA cosθ dΩ ≈ AΩ

where G is the ettendue

Question 9

for small angles the ettendue is

Answer 9

G ≈ AΩ

Question 10

Ettendue is the product of

Answer 10

Area and Solid angle and is a measure of the flux gathering ability of an optical system

Question 11

The etendue of a system is set by the

Answer 11

Stop

Question 12

Etendue is

Answer 12

conserved in an optical system

Question 13

The Bandpass of a spectrometer is

Answer 13

the minimum wavelength resolution, achieved by matching diffraction from the entrance slit with that from the grating

Question 14

The resolution of the device in terms of wavelength is given by

Answer 14

Δλ = dλ\dx Δx(o)

dλ\dx - the inverse of the linear dispersion

Δx(o) - is the width of the exit slit

Question 15

The beam entering the focusing lens has width

Answer 15

D = Na cos θ(m)

Question 16

Upon focussing, there is a diffraction pattern at the exit slit with
width Δxd given by

Answer 16

Δx(d) = λF/D = λF/( Na cos θm)

Question 17

Δx(i) =

Answer 17

dx/dλ Δλ(BP)

where Δλ(BP) is the bandpass of the spectrometer

Question 18

Ettendue formula =

Answer 18

G = 4π A sin^2 (θ/2 )

Question 19

Area =

Answer 19

A = hΔx(entr) = hΔλ(BP) dx/dλ