The NearSys LED Photometer Kits
Discovered by Forest Mims in the 1970s, LEDs behave as inexpensive, spectrally sensitive photometers. The NearSys Photometer kits permit near space missions to measure the brightness of sunlight as a function of altitude in a number of colors. Each photometer contains eight selectable LEDs to measure light intensity in the following spectral regions, Infrared (940 nm), Infrared (870 nm), Red (660 nm), Orange (620 nm), Yellow (590 nm), Green (500 nm), Blue (470 nm), and Ultraviolet/Violet (400 nm). The two channel version permits you to compare the difference of the sun's intensity in two different colors. Adding a polarizing film to the LEDs converts the unit into an affordable photopolarimeter.
The One-Channel LED Photometer v2.1 kit includes one photometer with eight LEDs. The cost for the kit is $35.50 plus $4.00 S&H.
The Two-Channel LED Photometer kit includes two complete photometers with two infrared, red, orange, yellow, and green LEDs. The cost for the kit is $36.00 plus $4.00 S&H.
To make the photometers more useful, they should be combined with the NearSys Sun Sensor.
Directions for assemblying the One-Channel LED Photometer
Directions for assemblying the Two-Channel LED Photometer