Imaging Photometer vs Goniophotometer

SubLGT

Flashlight Enthusiast
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Nov 18, 2013
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For evaluation of automotive headlights, is an imaging photometer equal in usefulness and accuracy to a goniophotometer?

An alternative approach for in-house product development testing is an imaging photometer or colorimeter. Those from Westboro Photonics are powerful, CCD-based light and colour measurement instrument that provides for increased productivity compared with traditional goniometric measurements. Whereas a goniophotometer measures the illuminance and colour from a headlamp one direction at a time, a CCD-based imaging photometer can measure millions of angles simultaneously. Moreover, because the imaging photometer views the whole illumination pattern at once, localised illuminance and colour differences can be easily detected – artefacts that goniometric measurements performed at defined angles might miss. In addition, the capital cost of an imaging photometer is much less than that required for a typical motorised goniophotometer.

http://www.pro-lite.co.uk/File/automotive_applications.php

http://www.pro-lite.co.uk/File/case_study_automotive_headlamps.php
 

-Virgil-

Flashaholic
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Mar 26, 2004
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Camera-based photometry has been making big leaps. Westboro Photonics makes good ones. So does Sapphire. I've seen demos of both company's products, and they can do some seriously marvelous tricks. Like, you don't need a totally dark test chamber; you can do the job right out in normal light, as long as the ambient light is constant. And while camera systems like this can be set up for use in aiming headlamps (like at the end of an assembly line -- no service facility is going to spend the $100K +/-) they can also be set up for use in actual headlamp photometric testing, in which case you don't have to spend tedious time meticulously physically aiming the headlamp prior to the test. You tell the system what kind of headlamp it is (VOL, VOR, mechanical aim, ECE, fog lamp, whatever) and/or put in desired aim specifics and it just shifts the instantly-recorded data to match. This saves huge amounts of time and hassle in research (of many kinds) and development, and the results with a good system are close enough to gonionphotometer values for most purposes. The regs worldwide still call for a gonionphotometer to be used in compliance-testing headlamps, however.

(And yes, their utility goes far beyond just headlamps to most lights and lamps on or in a car)
 
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