Imaging sphere aids LED light measurements

Pro-Lite Technology has released the ProMetric imaging sphere from Radiant Imaging, which collects the full 2pi (hemispherical) intensity and colour information from LEDs in an instant.

Pro-Lite Technology of Cranfield, UK, has released the ProMetric imaging sphere from Radiant Imaging.

The ProMetric imaging sphere collects the full 2pi (hemispherical) intensity and colour information from LEDs in an instant.

It is a novel solution to the LED industry's biggest problem - how to obtain high speed angular light and colour measurements without an expensive goniometer and with no moving parts to worry about.

Originally developed by Philips and licensed to Radiant Imaging, the imaging sphere addresses the needs of the LED, display and solid state lighting industries for a high speed, inexpensive and low-cost means of measuring angular light intensity, colour and viewing angle performance.

The imaging sphere combines a Radiant Imaging ProMetric CCD imaging photometer/colourimeter, with a diffuse hemispheric collector.

An LED, placed centrally in the dome, illuminates the interior surface of the hemisphere which is painted with a low reflectance, diffuse coating.

A convex mirror placed on one side of the light source, images the inside of the dome.

The ProMetric video photometer views the mirror and thus captures the full hemispherical illumination from the LED in one measurement.

The angular variation of the luminous intensity and CIE colour is captured in a single measurement that takes seconds to perform.

The ProMetric camera software automatically applies corrections for image distortion, stray light and flat-field correction so that the displayed image is a true representation of the LED's angular intensity and colour distribution.

With arrays of up to 2000 x 3000 pixels, the ProMetric CCD camera is capable of high angular resolution.

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