This Product is discontinued, please contact us if you are still interested. An alternative is e.g:

This Product is discontinued, please contact us if you are still interested. An alternative is e.g: BTS256-EF, MSC15, CSS-45 with CSS-D.

The HCT-99D is portable photometer & luminous color meter for the measurement of illuminance, color temperature, xy and u’v’ chromaticity coordinates and delta uv. 

Separate Meter and Light Detector 

The HCT-99D employs the common photometer design with separate meter and cable connected detector head to enable the operator to stay clear of the detector head to prevent reflected light or shadows from effecting the measurement. The 20mm low profile height detector head allows measurement close to the reference level.

Illuminance (lx) Meter 

As an illuminance meter or luxmeter the HCT-99D features a precise photometric corrected photodiode detector with cosine diffuser. It’s V(λ) spectral sensitivity matches the DIN CIE standard with f1’ error of equal to or better than 3% fulfilling the DIN Class A specification.

Luminous Color Meter 

As a luminous color meter the HCT-99D represents the classical RGB tristimulus color meter with three filter corrected photodiodes in correlation with the Red, Green and Blue cones in the human eye. Color readings are calculated by the ratio of the detectors signals. Gigahertz-Optik has improved the standard RGB technology by adding a fourth filtered photodiode into the detector for the x short function for improved measurement uncertainty when measuring blue dominant light sources.

Luminance (cd/m²) Meter 

Optional SRT front lens adapters extend the measurement functions of the HCT-99D for luminance measurement.

Simple to use

The HCT-99D meter is ergonomically designed as a hand-held battery operated meter with back lit display. Operating the HCT-99D is simple. The meter set-up is supported by an easy to use menu accessed by front panel buttons. The menu allows selection of the operating mode, the display mode, the detector and measurement parameter. Once set-up all settings are stored and recalled on next power-up unless reprogrammed. In remote control operation the meter is powered through its USB interface for time and battery independent use.

Traceable Calibration 

Calibration is performed by Gigahertz-Optik’s calibration laboratory for light measurement quantities against calibration standards traceable to national and international metrology laboratories.

Menu System Overview

Menu item Submenu item Function
Mode CW
CIE Yxy & T
CIE Yuv & T
CIE Yu'v' & T
CCT & Δuv
Measurement respective of any offset and calibration factors programmed is displayed
CIE Color Values Yxy & Color Temperature are displayed
CIE Color Values Yuv & Color Temperature are displayed
CIE Color Values Yu'v' & Color Temperature are displayed
Color Temperature and Δuv are displayed
Setup Zero Adjust
Meas. Mode
Auto Pow. Off
Performs a zero adjustment of the internal amplifier and ADC
Sets the measurement (integration) time
Selects measurement mode (DC, Chopper, Pulse Synchronisation, Peak-Peak)
Enables / disables auto power off
Detector   Selects calibration data to calculate the measurement result
Offset   Performs an automatic offset adjustment ("Offset = CW" or "Offset = 0")
Range   Sets the measurement range (auto, manual)
HCT-99D RGB Tristimulus Detector with two-cell x-Sensor for improved BLUE color matching
HCT-99D for Luminance and Luminous Color

Compact size in ergonomic design with hand-held housing


LCD Graphic Display with switchable LED-backlight text display 4 rows each 14 characters

Detector interface

ITT (-4) type connector

CW integration time

Adjustable in preset steps from 1ms - 1s

Parameter adjustment

Front panel keys, adjusted values permanently stored (eeprom),


remote control via USB interface

Front panel control

3 keys, menu system

Power Supply

Two battery (AA size) (operating time about 250 hrs. without display backlight)
USB: powered by USB-Interface


145 mm x 63 mm x 30 mm / 150 g

temperature range

Operating: (5 to 40) °C

Storage: (-10 to 50) °C

Integral Detector

Light and Color detector with cosine diffuser


Diameter: 45 mm, Height: 20 mm, Cable length: 2 m / 150 g


0.5 to 199999 lx with 0.01 lx resolution

Luminance with optional lens

1° Lens / ≈ 2.5 to ≈ 5 x 108 cd/m²
5° Lens / ≈ 0.1 to ≈ 2 x 107 cd/m²
10° Lens / ≈ 0.02 to ≈ 3 x 106 cd/m²

min. illuminance for Color Measure

0.5 lx (CIE standard illuminant A)

0.5 lx (CIE standard illuminant D65)

Color uncertainty

Within reproducibility uncertainty (no filter)

< 1 % with BG 34, nominal x = 0.3914 / y = 0.3925

< 1 % with BG 7, nominal x = 0.2646 / y = 0.4057

< 1 % with OG 530, nominal x = 0.5417 / y = 0.4538

< 1 % with VG 3, nominal x = 0.3656 / y = 0.5272

< 2 % with RG 6, nominal x = 0.6860 / y = 0.3135

< 20 % with SFK 100, nominal x = 0.1450 / y = 0.0426

< 1 % with SFK 101, nominal x = 0.4299 / y = 0.5376

< 2 % with SFK 102, nominal x = 0.5457 / y = 0.4511

(Reference light source at 2856 K (A) for filter illumination nominal x = 0.4476 / y = 0.4074)


x short: 8.5 %


x long: ≤ 7 %


y: ≤ 4 % (also photopic vision detector)



z: ≤ 3 %

f2 Cosine Error

≤ 3 % (for illuminance measurements)

Calibration uncertainty

≤ 3.5 %





12 month

Transport case

Hard case for transportation (identical to model BHO-06)

Type Description File-Type Download
Datasheet HCT-99D PDF
Produktname Product Image Description Show product
S-SDK-X20 Software Development Kit for X20 variants (X1 and HCT99).
S-X1 Application software for X1 variants.
Article-Nr Modell Description Request / Compare
101859 HCT-99D

Meter with (2) battery and manual, detector with calibration certificate, hard case, USB cable, manual

15300682 K-CT4501-SRT-I

Luminance and luminous color calibration of HCT-99D detector with lens

15300671 K-X1-C

Calibration of the HCT-99D meter

15300676 K-CT4501-I

Illuminance and luminous color calibration of HCT-99D with calibration certificate.

100427 SRT-M45/37B

Adapter/holder for 45 type detectors with SRT-M37 components

100428 SRT-M37L-1

Luminance lens with 1° field of view

100429 SRT-M37L-2

Luminance lens with 2° field of view

100430 SRT-M37L-5

Luminance lens with 5° field of view

100499 SRT-M37L-10

Luminance lens with 10° field of view

100707 SRT-M37Z-01

Ambient light shade

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