The Gemini R is a black body source with which radiation pyrometers, commonly referred to as IR sensors, can be calibrated. With a temperature range of 50°C to 550°C, the temperature of the cavity can be set with 0.1°C resolution. The temperature of the furnace is set and indicated on a PID controller. An independent indicator is also provided for higher accuracy with a standard probe, which indicates the actual radiance temperature. Temperature variation over a 5-minute period, as viewed on the temperature controller, is ±0.2°C, and a radiation thermometer directed into the cavity detects similar variations.

The Gemini R's cavity's size is 2.5" x 6.3" deep (65mm x 160mm). Maximum temperature differences are ±1°C in the range of 100°C to 500°C. The Gemini R blackbody cavity is capable of accepting black body fixed points to achieve the highest level of a radiation measurement possible. Typical fixed-point uncertainties are ±0.25°C. Gallium, indium, tin and zinc cells are available.

Emissivity is greater than 0.995, and traceability may be established with a NIST certificate for the built-in indicator and/or supplied probe. The Gemini R can be supplied with RS232 or RS422 communications.