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PR-1500 Spotmeter

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Light Measurement



Photo Research spotmeters are the standard of the industry

Over four decades ago, PhotoResearch invented "spot" photometry when it introduced the Spectra Screen Brightness Meter for the motion picture industry. A few years later, a military customer inquired about measuring aircraft instrument panels and Photo Research produced the first Spectra Spotmeter microphotometer

The PR-1500 Spotmeter is a sensitive, versatile photomultiplier-tube photometer that can measure luminance (photometric brightness) at any distance from 1¾ inches (44 mm) to infinity without the need for accessory lenses or changes in calibration. The PR-1600 SpectraSpot, a silicon-cell photometer/radio meter, is designed for applications requiring the inherent stability and near infrared response of the silicon cell, without requiring the higher sensitivity of photo multiplier tubes.

Typical applications

Photomultiplier tubes

The standard photomultiplier phototube supplied has an S-20 response. These are specially selected and seasoned low-noise photodetectors.

Filter Turret

A 6-position filter turret is located the aperture mirror and the photomultiplier detector. This turret contains the "photopic" filter which modifies the spectral response of the instrument to precisely match CIE or "human eye" response. This photopic filter is individual trimmed and calibrated for each SpotMeter. With this filter in position the Spot meter functions as a precision luminance photometer(photometric brightness meter).

Red and blue filters are included in standard instruments for relative tristimulus and colour temperature measurements. (If special filters, such as red LED or scotopic response filters are installed, tristimulus and/or colour temperature measurements capability is not available) Option 32 provides three individually trimmed colourimetric filters for red, blue and photopic making the PR-1500 a more accurate relative colourimeter. The filter turret has an OPEN position for use in making relative radiometric measurements. An internal calibration-reference source is mounted in the CAL position of the turret for quickly checking the instrument calibration prior to making a measurement.