1Erb C., 2Dähn W., 2Fenk S.

1Medizinische Hochschule Hannover, Department of Ophthalmology, Carl-Neuberg-Str. 1, D-30625 Hannover; 2Gigahertz-Optik GmbH, Fischerstr. 4, D-82178 Puchheim

Purpose: To develop a compact hand-held tristimulus colorimeter for general application measurements.
Methods: The HCT-99 is a well defined tristimulus colorimeter, also to be used as class B luxmeter (DIN 5032-7) providing a reading range from 0.01 lx to 199.9 klx. The chromaticity coordinates are displayed with a 0.001 resolution. In addition to that, the instrument calculates and displays the correlated colour temperature within 1700 K to 20000 K. The colorimeter head uses four channels matching the CIE tristimulus functions. The matching provides an actinity range of maximum 2% for generally used light sources. The directional evaluation follows the cosine law. The high contrast LCD features a backlight function, allowing to use the instrument also in dark environment. Computer controlled measurements are possible using the built-in USB interface.
Conclusion: The HCT-99 meter is the first hand-held tristimulus colorimeter, where it is possible to provide the spectral matching for the tristimulus functions using four channels. The tristimulus function x(l) is separated for the short wavelength part and the long wavelength part in order to optimise the spectral matching using separate detectors. Therefore it is now possible to determine illumination conditions for colour testing and other applications very easily in a few seconds.

Copyright © Deutsche Ophthalmologische Gesellschaft, 2001. All rights reserved.

Last updated: 

Webdesign: SPALLEK.COM