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High emissivity cavity blackbody

BB-ASSIST is based on a cavity (conic) design approach. Its geometrical configuration insures an optimized cavity emissivity factor (13). The use of Aeroglaze coating applied with tight manufacturing specifications and rigorous quality control procedure insure to reach the highest emissivity factor.

The cavity is made of two modules. The temperature monitoring is perform using 3 high accuracy glass-thermistors properly calibrated within 5mK. The thermistors are positionned along the cavity allowing a better thermal characterization and an improved temperature reading accuracy.

The clear aperture is 2,75” (70mm) and include a flange allowing an easy installation onto the ASSIST calibration assembly.


The ASSIST Blackbody comes with a high precision temperature controller allowing to regulate the temperature of two independent channels (blackbodies) simultaneously.

Each channels, measure three independent high precision thermistors, allowing a better characterization of the blackbody cavity. Each thermistors is calibrated independently based on its respective location on the cavity. The temperature regulation is determined through the average value of the three thermistors.

The controller can be connect to an external PC using its built-in USB interface. The software runs under Linux or Windows environment and allows to:

  • Change PID settings (gains, saturation and dead zone).
  • Change set points.
  • Get temperature read by each probe and outputs’ status.
  • Calibrate the controller.
  • Change the look up table of any temperature probe.
  • Change controller’s software.
  • Read data stored by the controller’s logger.

In order to offer a better reading accuracy, each channel has its own reference resistors allowing the calibration of the entire electronic chain. This allows an accuracy of 0,0298ppm Full scale for a 24 bits ADC. The high precision resistors used to validate/calibrate the electronics ensure an accuracy of 0,3ppm/C over the full operating range.

Beside the software offered with the controller, a built-in logger can be set to punctually store the values of each thermistors. The data is then stored and can be exported as CSV file.


Spectral emissivity curve


Thermistor accuracy after calibration


Spectral Range

500 to 5000 cm-1

Effective Emissivity


Temperature Range

ambient to +65°C

Absolute Accuracy

Better than 1% of ambient radiance


Better than 0.2% of ambient radiance

Radiance uncertainty

<±0.010 K

Temperature Display Resolution

±0.001°C (as per controller BC-232)

Temperature Setting Resolution


Temperature Stability

0.03C° over 120 sec.

Temperature Gradient

<0.35C (across the cavity)

Temperature knowledge (thermistors)

± 0.003℃ Absolute (range from 0℃ to 50℃)

Aperture diameter

2,75 inch


110/230Vac, 50 or 60 Hz

Power consumption (1 source)



Controller specifications

Main power

  • Nominal voltage: 12Vdc
  • Nominal current: 300mA
  • Connector: 2.1mm, negative center

Channels’ power input

  • Type: Unipolar
  • Minimum voltage: 12Vdc
  • Maximum voltage: 30Vdc
  • Fuse protection: 3A/Bussmann AGC-3

*  Voltage supplied must exceed the maximum desired output voltage of the corresponding channel by at least 6V.

Power outputs

  • Minimum voltage: 0.2Vdc maximum
  • Maximum voltage: 24Vdc
  • Maximum current: 3A
  • Short-circuit protection: Electronic

Date and time retention

  • Duration: One month if powered at least 30 min

Temperature probe inputs

  • Probe type: NTC thermistor / 10kOhms at 25°C
  • Maximum impedance of any probe: 50kOhms
  • Maximum total impedance: 125kOhms
  • Calibration: Automatic
  • Range of measure: -65°C°C to 65°C
  • Resolution of measure: 0.001°C


  • Setpoint: 15°C to 60°C
  • Resolution of setpoint: 0.001°C
  • Maximum stability at setpoint: ±0.005°C

*Absolute precision of measure: better than 0.005°C (controller)

* Absolute precision of measure excludes intrinsic error of the probe, but includes a maximum ambient temperature variation of ±20°C.

Contact us to get more details