The definition of goniophotometer is for measuring light lamps and light performance, that’s lamp light source luminosity, color values in different spatial directions distribution, and export to IES files applying on the lighting design software DiaLux. The CIE121-1996 and IES-LM-79-08 standard’s are mentioned the types of goniophotometer, the CIE121-1996 mentioned two type goniophotometer:: one is moving mirror goniophotometer or moving detector goniophotometer; another is Rotation Luminaires Goniophotometer. The IESNA-LM-79 Clause 9.3.1 have clear recommended to use Type C Goniophotometer that’s moving mirror goniophotometer or moving detector goniophotometer. In practice, the solution and choose of goniophotometer are different.
First we need explain the moving detector/mirror goniophotometer and rotation luminaires goniophotometer: moving detector goniophotometer which means the measured light’s test position keep stable, the mirror reflection the light source from measured lamp to detector, like Lisun engineer developed.
LSG-3000 Moving Detector Goniophotometer; another is rotation luminaires goniophotometer which means the measured lamp always keep moving around horizontal axis and vertical axis during testing, like LSG-1800B Rotation Luminaires Goniophotometer. The difference of both goniophotometer focus on whether the measured lamp is keep stable or keep moving. For some fixtures, the position of measured lamp during testing is important. For above two kind of goniophotometer, polarization of instrument and the air flow have large influence for test data of high-pressure gas discharge lamp, because we know the high-pressure gas discharge lamp HID class will generate a lot of heat when lighting, if the lamp always keep moving during working, in the air flow driven, the lamp heat are always in an unstable state and sometimes higher and sometimes lower, this is bound to affect the accuracy of the data results. But for LED lamps, these influence are very small, the LED lamp and HID lamp are two different light source, both light emission characteristics are different. We use LSG-2000 and LSG-1800B to do comparison test, when use moving mirror goniophotometer and rotation luminaires goniophotometer to testing a same LED lamp, the test data and results are almost the same; but when use both types goniophotometer to test a same HID lamp(note: the output power more than 500W), there have around 15% data tolerance(note: this tolerance mainly on lumen output), if there have other factors effect, the tolerance will reach to 20%. So we can make a conclusion that when testing LED lamp or LED luminaires, two kind of goniophotometer are can meet test demand, the actual test data and result can meet standard’s requirement. For the LSG-2000 Goniophotometer, there have a obviously disadvantage that the total cost is not cheap, not all the user can afford it, this is why the CIE121:1996 mentioned another goniophotometer. The Lisun Shanghai office developed the LSG-1800B/LSG-1700B Rotation Luminaires Goniophotometer. Based on good test accuracy and high cost performance, almost all users can afford it, not only the price, but also the test accuracy. At the same time, with advances in technology, there developed another goniophotometer which combined CCD Spectroradiometer to measuring Spatial color & spectrum parameters, like CCT and CRI, we call it as Goniospectroradiometer. Comparing with traditional goniophotometer, goniospectroradiometer combined all functions of integrating sphere & spectroradiometer system and goniophotometer, but the disadvantage that the total cost is not cheap, operation is little complex and test speed is slow. Now days, this kind of goniospectroradiometer haven’t wide range application, only have few research institutions and laboratories adoption it.
Here also mention another type of goniophotometer, that’s goniophotometer for automotive and signal lamps. As the car headlights, traffic lights and light-emitting properties have different luminescence characteristics with normal LED lamps, so here need another more efficient test equipment. Lisun Electronic Shanghai office designed the LSG-1950/LSG-1950S Goniophotometer. The LSG-1950is recommend by CIE A-α, this kind of goniophotometer fully meet ECE, SAE, JIS, KS and FMVSS108 standards, but this kind of goniophotometer’s cost is too high, considering the cost factor, we also designed the economy solution LSG-1950S goniophotometer for traffic signal lamps, the software of this meet relevant standard’s requirement.