Four short, independent…

PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Geometrical optics and imaging · Geometrical optics and imaging

Optics and Photonics, Ch Radiometry and photometry

Problem

Four short, independent calculations. ((a)) A circular skylight of diameter

0.60\ \text{m}

is viewed face-on from directly below, at a distance of

3.0\ \text{m}

. Treating the skylight as small compared with the distance, find the solid angle it subtends at the observer. ((b)) A lamp has radiant intensity

I_\Omega = 120\ \text{W sr}^{-1}

in the relevant direction. It stands

2.0\ \text{m}

from a small desk surface whose normal makes an angle of

35^\circ

with the line to the lamp. Find the irradiance on the desk. ((c)) A monochromatic source emits a radiant flux of

2.0\ \text{W}

610\ \text{nm}

, where the luminous efficiency function

V(610\ \text{nm}) = 0.50

. Using

K_m = 683\ \text{lm W}^{-1}

, find the luminous flux. ((d)) A camera photographs a matt (Lambertian) wall of radiance

L = 250\ \text{W m}^{-2}\text{sr}^{-1}

with the lens set to

f/5.6

. Find the irradiance delivered to the sensor.