Alcor/Alcor-RC Low Brightness Source

A lightweight, portable low brightness source (LBS) provides a means of calibrating low-light-level devices such as airglow and auroral imagers and photometers as well as other night-vision devices. Its small size makes it particularly useful for instruments that must be calibrated in situ, such as may be found mounted in field environments. 

Available in two versions, the manually operated Alcor and the remote-controlled Alcor-RC, the low brightness source consists of a 100W precision quartz tungsten-halogen bulb and a sophisticated system of holographic diffusers and pin-hole attenuators that illuminate a 100 mm diameter output screen. 

With the opal output diffusing screen in place, the unit serves as a standard of spectral radiance and as a luminance standard. With the screen removed, the unit can be used as a standard of spectral irradiance and as an illuminance standard. 

Long Life

Field-replaceable 100W precision quartz tungsten-halogen bulb maintains 95% of initial light output throughout it’s 2,000 hour rated lifetime.

Wide Dynamic Range

10^5 dynamic range of light attenuation attained by a pair of micro-EDM machined precision field stop discs that are rotated either manually with thumbwheels (Alcor) or remotely with servo-motors (Alcor-RC).

Highly Lambertian

Highly uniform Lambertian output and available with optional absolute calibration.

Downloads, Software, Manuals, & More


Alcor-RC Brochure



Alcor-RC User Manual

User Manual


Alcor User Manual

User Manual


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