Topcon BM-5AC Luminance Colorimeter

Topcon BM-5AC
Luminance Colorimeter

The new BM-5AC replaces the BM-5AS and provides higher accuracy color filters for improved chromaticity measurements.

The BM-5AC luminance colorimeter offers a dramatic improvement in luminance sensitivity and speed over the BM-7A. By adding a fifth measurement aperture (3°), larger spot sizes (at a given working distance) can be achieved and luminance down to 0.00005 cd/m2 can be measured. Its Photo Multiplier Tube (PMT) sensor, combined with a precision CIE tri-stimulus filter wheel, provides measurements of the CIE tri-stimulus values (X,Y,Z). From these, the calibrated Luminance and Chromaticity coordinates (and other derived data) are computed and displayed on the integral LCD. Measurement data is available through a USB or RS-232C interface if remote control is required.

Two macro lens options allow for measurement of very small objects or light sources down to 0.06 mm (60 um). The engineering / research grade BM-5AC forms the center piece of many low light measurement solutions. The user selectable measurement aperture (knob) allows you to optimize the measurement spot size (also a function of working distance) and the minimum measureable luminance level (larger apertures can measure lower levels).



Measure low luminance quickly

Luminance as low as 0.005cd/m2 with 2 sec intervals at 3°


Supports luminance, chromaticity, and CCT measurements

Supports Luminance, CIE1931 and CIE1976 chromaticity coordinates, Tristimulus value XYZ, CCT and Deviation, CIE1976 L*a*b*, Eab*± , CIE1976L*u*v* Euv*±


Five apertures available

Five (5) apertures 0.1°/0.2°/1°/2°/3° enable you to measure luminance from small to wide area without attachment lens


Luminance, Chromaticity, and Color Temperature measurement of LCDs, CRTs, OLEDs, LEDs, etc

Transmittance of LCD polarizing plates & filters

Luminance and color measurement of various light sources

Step it up to the SR Series

For spectral measurements and greater color accuracy, consider the Topcon SR-3AR, SR-UL1R, and SR-UL2 Spectroradiometers. This next generation of diffraction grating based instruments provides three levels of sensitivity with a minimum measurable luminance (at guaranteed accuracy) of 0.1, 0.001, and 0.0005 cd/m2 respectively. Spectral data is measured in the visible band (380 nm ~ 780 nm) with a 1 nm resolution. All models include four standard apertures: 2° / 1° / 0.2° / 0.1°.

Parameter Aperture
0.2° 0.1°
Optical System Objective lens: f=80mm F2.5
Eyepiece lens: View field 5°, Diopter adjustment range ±5 diopter
Measurement Distance 350mm – Inf.
Luminance Range cd/m2 0.00005 ~ 1,500 0.0001 ~ 3,000 0.0004 ~ 12,000 0.01 ~ 300,000 0.04 ~ 1,200,000
Luminance Accuracy ±4% (for standard illuminant A)
Color Accuracy ±0.005 in 1931 CIE x,y Space
Spot Size at 1m 49.2 mm 32.8 mm 16.4 mm 3.3 mm 1.6 mm
Min. Spot Size at 35cm 15 mm 10 mm 5 mm 1 mm 0.5 mm
Dimensions Approx 355mm (L) x 154mm (W) x 212mm (H)

Ordering Information

The base unit model number is BM-5AC and includes the instrument with standard lens, AC adapter, lens cap, and hard shell carrying case.

See the BM-5AC Brochure for available options. Popular options include:

  • AL-6 and AL-11 adapter lenses (for reducing the measurement spot)
  • Tripod and fine adjustment stand (gimbal)
  • Fiber optic probe
  • CM-700 application software

If you can’t find what you are looking for, contact us for info on Topcon options and accessories.

Want to find out more?

If you are interested in more information, send us an inquiry.