Topcon BM-7AC Luminance Colorimeter

Topcon BM-7AC
Luminance Colorimeter

A step up from the BM-9A (luminance only), the BM-7AC is faster and can measure both luminance and color with greater precision. Two macro lens options allow for measurement of very small objects or light sources down to 0.06 mm (60 um).

The cost-effective BM-7AC is the instrument of choice for factory production lines requiring multiple instruments but is also at home in the R&D lab or Engineering department as a “workhorse” photometer / colorimeter.



Fast measurement speed

Measurement speed of just 0.5 seconds. Ideal for inline measurement in mass production settings


Supports luminance, chromaticity, and CCT measurements

Supports Luminance, CIE1931 and CIE1976 chromaticity coordinates, Tristimulus value XYZ, CCT and Deviation


Luminance accuracy within ±2%

Delivers luminance accuracy within ±2% (for Standard source A, 2°, luminance 5cd/ m2 or above, Auto Range)


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

Four selectable apertures

The BM-7AC luminance colorimeter is the first instrument in Topcon’s line-up of multi-aperture instruments. It utilizes an industry standard aperture mirror design which allows you to precisely see what’s being measured by each of four selectable apertures. The user selectable aperture (knob) allows you to optimize the measurement spot size (also a function of working distance) and the minimum measurable luminance level (larger apertures can measure lower levels).

Three photodiode sensors

Three dedicated silicon photodiode sensors provide direct measurement 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. All measurement data is available via an RS-232C interface if remote control is required.

Step it up to the BM-5AC

If you require lower light measurements (below 0.01 cd/m2), consider the Topcon BM-5AC PMT-based Color Filter Photometer. The BM-5AC is more sensitive than the BM-7AC and uses a tri-stimulus filter wheel and adds a fifth measurement aperture: 3° / 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 0.01 ~ 30,000 0.04 ~ 120,000 1 ~ 3,000,000 4 ~ 12,000,000
Luminance Accuracy ±4% for Luminance less than 5 cd/m2, ±2% for Luminance greater than 5 cd/m2
Color Accuracy ±0.002 in 1931 CIE x,y Space
Spot Size at 1m 32.8 mm 16.4 mm 3.3 mm 1.6 mm
Min. Spot Size at 35cm 10 mm 5 mm 1 mm 0.5 mm
Dimensions Approx 325mm (L) x 120mm (W) x 162mm (H)

Ordering Information

The base unit model number is BM-7AC and includes the instrument with standard lens, AC adapter, lens cap, and hard shell carrying case.

See the BM-7AC 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.