Konica Minolta CL-500A Irradiance Spectroradiometer

Konica Minolta CL-500A Overview

The Konica Minolta CL-500A is a portable spectroradiometer configured for measurements of spectral irradiance, illuminance, correlated colour temperature (CCT) and colour rendering index (CRI). Being a spectroradiometer rather than a more traditional tristimulus colorimeter helps to ensure that the CL-500A gives more accurate readings with any type of light source, including LEDs. Measure the visible light spectrum (360-780nm), the illuminance (lux), the correlated colour temperature of white light sources (CCT, Kelvin), the CIE chromaticity (xy or u’v’), the dominant wavelength of coloured light sources (nm) and the CIE colour rendering index, CRI (R_a, R_1-15).

A spectroradiometer functions in a similar way to a radiometer, photometer or colorimeter but measurements are performed spectrally and the radiometric, photometric and colorimetric properties computed. For narrow band sources such as LEDs, discharge lamps, CFLs and LCDs, a spectroradiometric measurement yields more accurate results than those performed with a photometer. Also, spectral measurements are the only way to determine the colour rendering performance of a light source.

Traditional colorimeters such as the Konica Minolta CL-200A are based upon three silicon photodiodes that are spectrally matched to the CIE 1931 tristimulus colour matching functions. While suitable for most types of broadband (white) light sources, tristimulus meters struggle to give accurate colour and illuminance readings with monochromatic lamps (for example, single colour LEDs – especially blues and reds). This is where a spectroradiometer like the CL-500A comes in as the spectral power of the lamp is recorded and the appropriate photometric and colorimetric parameters computed from look-up tables stored in the instrument memory.

The CL-500A provides illuminance measurements over from 0.1 to 100,000 lux. Colour measurements require a minimum illuminance of 5 lux. In nature, illuminance typically ranges from about 0.01 lux on a dark night to about 100,000 lux on a hot summer day. Workplace illumination is normally around 500-1000 lux.

Other Important Information

Unlike traditional tristimulus colorimeters, spectroradiometers like the CL-500A have the ability to measure the colour rendering of light sources, specifically the CIE indices R_a & R_1-15. The CL-500A can also report scotopic illuminance, this being the effective illuminance of a light source to the dark adapted human eye. The CL-500A was the first compact, lightweight spectral irradiance meter in the world to conform to DIN standards, meeting the requirements for Class B per DIN 5032 Part 7. The CL-500A has an on-board memory for 100 measurements, and the standard data management software allows you to transfer your measurements to a PC for further analysis in Excel.

The standard data management software can download measurement data directly to Excel as well as display spectral irradiance values, spectral waveform, chart colour rendering indices and features an LED binning function. Multi-point measurements are also possible by connecting up to 10 CL-500A units together. For more specialised applications, the software development kit is available free of charge.