Question

The figure below shows the spectral irradiance of a hypothetical source. Find the illuminance in the visible region of the spectrum for a) Photopic vision b) Scotopic vision c) Mescopic vision if the maximum luminous efficacy of radiant energy is equal to 1200 lm/W and occurs at 520 nm 0.9 g 10.8 0.7 & 0.6 3 0.5 0.4 Source 0.3 a 0.2 0.1 300 400 500 600 700 Wavelength (nm)

Answer 1

Here is the luminosity function -

1800 Scotopic 1600 1400 Misopic 1200 1000 800 Photopic 600 E 400 200 380 420 460 500 540 580 620 660 700 740

Photopic vision is the vision of the eye under well-lit conditions.Scotopic vision is the vision of the eye under low-light levels. Mesopic vision is a combination of photopic vision and scotopic vision in low but not quite dark lighting situations.

Photopic vision allows higher visual acuity and temporal resolution than available with mesopic and scotopic vision.