Radiometer
PR-1530AR NviSpot™ Photo Research, Inc.

The NviSpot Night Vision Radiometer/Photometer/Colorimeter is a multipurpose instrument designed to meet the NVIS radiance light measurement compatibility requirements of MIL-L-85762 for NVIS applications, and also perform the conventional fast and accurate luminance and colorimetric light measurements long associated with the PR-1500 SpotMeter

It consists of a modified Pritchard-type filtered photometer system with interchangeable objective lenses and an internal calibration source. For NVIS measurements it includes a proprietary filtered, extended-red gallium arsenide photomultiplier tube with overload protection, threshold detection and an NVIS-compatible digital display readout. Although the NVISpot does not replace the requirement for a laboratory-grade spectro-radiometer specified in the MIL Spec, it does provide a relatively inexpensive and highly accurate means of light measurement for all phases of production and control testing.
NVIS Radiance Mode

For the Aviators Night Vision Imaging System (NVIS) applications, the PR-1530AR includes a special filter/detector combination whose transmission curve precisely matches the NVIS relative response in MIL-L-85762.

When operated in the NVIS Mode, the NviSpot display reads out in NVIS Radiance (NRa or NRb) units. Relative colorimetric filters are optionally available for evaluating the color of the device under test, i.e., Green A, Green B, Yellow and Red.

The digital display of the PR-1530AR is specifically NVIS-filtered to eliminate any inaccuracy it's own light output might introduce into the test results.