Automotive Light Measurement

Goniophotometers
Goniometer + Photometer = Goniophotometer

A goniometer is an instrument that measures angles most accurately. Photometer derives from the Greek photon = light and is an instrument that measures light.

A goniophotometer therefore performs the measurement of the spatial distribution of a radiation source and displays the photometric properties of the light visible to the human eye in relation to a defined angular position.The automotive and general lighting industries use goniophotometers for lighting research and as a control measure in their manufacturing workflow.

Whatever the requirement, X-Rite - Optronik has the solution with 5 standard goniophotometer systems designed for specific applications to be combined with various measurement devices. Our modular goniophotometer systems enable you to assemble a system tailored to your own unique requirement.

• Measurement of illuminance E in lux
• Measurement of intensity distribution I in cd
• Measurement of luminous flux Φ in lm
• Measurement of color coordinates and correlated color temperature
• Measurement of luminance L in cd/m²
• Measurement of retro-reflection R in mcd/lx
• Test and calibration of sensors

Integrating Spheres

It is still widely used in the lamp industry for quality control during manufacture. The alternative method is a goniophotometer which would need to rotate a photodetector in a complete sphere around the lamp (or rotate the sample in relation to a detector). Each discrete intensity point (lm/sr) is then integrated over 4? steradians.

In contrast to the absolute measuring method using a goniophotometer that scans the complete intensity distribution of the lamp and integrates the flux, the integrating sphere is the relative measuring method requiring calibration of the sphere with a calibrated flux (or spectral distribution) bulb that should be traceable to a national standard (e.g. PTB or NIST).

In a sphere photometer, the lamp to be measured is mounted at the center of the integrating sphere and baffled from a viewing port equipped with a diffuser and photopic response detector. The baffle is usually positioned at 2/3 of the radius from the sphere center. Its size should be as small as possible yet large enough to screen the maximum dimension of the lamp.

The lumen output from the test lamp is determined by first calibrating the photodetector signal using a lamp standard of known luminous flux. The lamps are alternately substituted into the integrating sphere. An auxiliary lamp can be permanently mounted inside the sphere to compensate for the substitution error caused by different self-absorption from the test and standard lamps.

Photometers

Photometer derives from the Greek photon = light and is an instrument that measures light. Optronik's photometers provide a photopically-corrected (eye response) measurement of the brightness (candle power), illuminance (in lux), and tristimulus color coordinates from optical radiation sources.

Since 1968 when it constructed one of the worldwide first digital luxmeters, Optronik has specialized in the design and manufacture of photopic detectors, photometer systems, and integrated laboratory solutions for a variety of electro-optical testing, measurement, and calibration applications: Optronik is an acknowledged leader in the design and manufacture of precision photometric equipment.

X-Rite-Optronik's proprietary photopic filters consist of several elements designed to match the CIE photopic response curve to achieve an f1 to better than 1.5% at all wavelengths (f1 < 1.5 % defines the highest accuracy class L according to DIN 5032 and CIE No. 69). The sensitivity in the IR and UV range is reduced to a minimum < 0.1%. The careful design of the detectors ensures best-of-class equipment and repeatable measurement results, even for monochromatic radiation sources.