LED Laboratory

Optical Measurements

EVATEG optical technologies laboratory with over 90 m2 is fully equipped with state of the art optical measurement systems such as integrating sphere, photogoniometer, luxmeters that provides highly precise measurements of total lumen output, CRI, CCT, spectral distribution, peak and dominant wavelengths, as well as radiometric power (optical power) and micro scale thermal measurements. EVATEG OPTOLAB has multiple measurement systems to determine the optical performance of LED systems. Those technical systems are used by EVATEG technical team consists of R&D engineers who received their graduate degrees (master’s degrees) from much respected schools such as University of Stuttgart and Middle East Technical University. Our highly skilled team is ready to serve for scientific research, journal and conference quality studies as well as service for global lighting companies. One of equipment is a high-end integrating sphere has a 2 m diameter and it is suitable for IESNA lm79-08 standards for measuring the correlated color temperature (CCT), total luminous flux and CRI index. It has a high reflectivity coating since the reflectivity of sphere inner surfaces is extremely important to obtain accurate results [Figure 1].

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Figure 1: Integrating sphere (2m diameter)

Having this high reflectance which is about 98% inside the sphere prevents non homogenous light distribution errors which occur usually with PAR lamps even at about 80% reflectance coating. Thus, we can accurately compare the solid state lighting based designs with other lumen equivalent lamps. Moreover the spectral distribution of the light can be determined with its user friendly spectrometer screen [Figure 2].

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 Figure 2: Typical integrating sphere results (Spectral graph,CCT,Total luminous flux)

Another significant optical capability of OPTOLAB is measurement of optical distribution of lighting systems. EVATEG has a high-end photogoniometer system. Light distribution is determined by the goniometer in a standard darkroom. Slice graph of angular distributions for llumination systems up to 1900 mm length and 50 kg weight can be measured in our laboratory. This device have three rotational speeds for horizontal and vertical turning axis for luminaire and It has the absolute angle encoder with 0.1⁰ accuracy for both axis.

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Figure 3: Photogoniometer, luminaire and control units.

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 Figure 4: Lightmeters

There are also two types of lightmeters for illuminance measurement [Figure 4]. Therefore, one can see how much illuminance comes onto any point which is far from the source. To keep the high technical and quality standards evateg technical team pays extra attention to have
experimental instruments always calibrated and measurements are perfomed with high accuracy. These photometric results can be also turned into radiometric results with calculations of engineers. Here is a table to compare photometry and radiometry for informative guide :

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LIST OF DEVICES:

  • SPHERE
  • GONIOPHOTOMETER
  • AC SOURCE  ANALYZER
  • POWER METER
  • DC POWER SUPPLY
  • DATA DATA ACQUISITION
  • OSCILLOSCOPE
  • VARIAC
  • MULTIMETER