Image Capture#

Great minds discuss ideas; average minds discuss events; small minds discuss people.

Eleanor Roosevelt

Let’s get the ideas in order before discussing equipment and processes.

References#

Main Reference

Miikki, K; Karakoc, A. et al. An open-source camera system for experimental measurements, SoftwareX, 2021, 14, 100688 (freely accessible @ https://www.sciencedirect.com/science/article/pii/S2352711021000339#appA) Also see rpi-camera github repository.

Secondary References

Wilkes, Thomas C., et al. “Ultraviolet imaging with low cost smartphone sensors: Development and application of a raspberry Pi-based UV camera.” Sensors 16.10 (2016): 1649. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5087437/) pdf
Deep Ultraviolet Imaging Using the Raspberry Pi HQ Camera Steropi Blog
Raspberry Pi Documentation: Camera (https://www.raspberrypi.com/documentation/accessories/camera.html)
Giving Linux a Camera Stack: libcamera’s 3 Years Journey and Exciting Future (YouTube video)

Radiometry vs Photometry

Radiometry: Measuring light in any portion of the electromagnetic spectrum, typically infrared, visible, ultraviolet
Photometry: Measuring light in units weighted by sensitivity of the human eye.

SI Units for Photometry

Candela (cd): SI unit of luminous intensity
Luminous power per unit solid angle emitted by a point light source. 1 cd = 1 lumen/SR
1 candela is approximately equal to light emitted by a common wax candle
Luminous intensity is weighted to match human perception.

Property of light in an optical system
Area of the entrance pupil times solid angle the source subtends viewed from the pupil
Etendue is like entropy, always increases in an optical system