HCT-99D meter
CT-4501-4 Illuminance & Luminous Color Detector
SRT Front Lens for Luminance & Luminous Color

The HCT-99D instrument is an ergonomically designed lightweight photometer & colorimeter for the measurement of illuminance, color temperature, xy and u’v’ chromaticity coordinates and delta uv. Its measurement functions can be extended for luminance measurement with the SRT front lens adapters. The HCT-99D lightmeter employs the common photometer design with separate meter and cable connected detector head. A key feature is its four channel design with four line alphanumeric display allowing it to read-out the four CT-4501-4 detector sensor signals. The CT-4501-4 as illuminance detector is set-up with a precise photometric correction filter and cosine diffuser. It’s V(λ) spectral sensitivity matches the DIN CIE standard with equal to or better 3% and fulfill the DIN Class A specification. The CT-4501-4 as luminous color detector represents the classical RGB color detector with three filter corrected photodiodes in correlation with the Red, Green and Blue cones in the human eye. The color is calculated by the ratio of the four detector signals. Gigahertz-Optik has improved the standard RGB technology by adding a fourth filtered photodiode into the detector for the Xshort function for improved measurement uncertainty when measuring blue dominant light sources. The 20mm low profile height detector head allows measurement close to the reference level. The HCT-99D meter is a handheld battery operated meter with on/off back lit display. The meter offers a high linear current to voltage amplifier with seven manually or automatically selected gain ranges. The maximum error within this wide dynamic range is 0.2 %. The four signal inputs operate in multiplex mode with one amplifier. Operating the HCT-99D is simple. Once set-up all settings are stored and recalled on next power-up unless reprogrammed. Measurement values are displayed in absolute quantities for the particular detector connected. The meter set-up is supported by an easy to use menu accessed by front panel membrane buttons. The menu allows selection of the operating mode, the display mode, the detector and measurement parameter. For on-site applications the meter is operated with two standard 1.5 V AA batteries. In remote control operation the meter can be powered through its USB interface for time and battery independent use. Calibration is performed by Gigahertz-Optik’s calibration laboratory for light measurement quantities against calibration standards traceable to national and international metrology laboratories. Re-calibration is recommended every 12 months. A BHO-06 carry case is supplied.