• 976 GEMINI R
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  • Medium Temperature Radiation Pyrometer Primary Source
  • 65mm Cavity Diameter
  • 0.995 Emissivity
  • Accepts Fixed Point Cells
  • Calibration Certificate: For the built-in Indicator and supplied probe


The Gemini R is a blackbody source with which radiation pyrometers, commonly referred to as IR sensors, can be calibrated. With a temperature range of 30 to 550°C, or 700°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" Ø x 6.3" deep (65mm x 160mm). Maximum temperature differences are ±1°C in the range of 100 to 500°C. The Gemini R is capable of accepting blackbody 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 a calibration certificate is available for the built-in indicator and/or supplied probe. The Gemini R can be supplied with RS232 or RS422 communications.

Cal Notepad software now comes standard with the Isotech 976 Gemini R. Cal NotePad Software automatically logs and displays the temperature of an Isotech calibration bath together with the sensor under test. Cal Notepad can be used with baths (or indicators) without PC interfaces by the user typing in values from the keyboard.


This product can be used in the following applications:

Here's how some of our customers use this product...

NIST Certification of Infrared Sensors

The Background: Our customer is a calibration lab who themselves have a number of customers requiring calibration for their infrared sensors and handheld infrared thermometers.

The Problem: The customer has no current means of testing infrared sensors and must send them out to a third party lab.

The Solution: The Isotech Gemini R is a blackbody source for calibrating infrared sensors and thermometers over a range of 30 to 550°C. It has a large 65mm cavity to accommodate a wide range of IR sensors. The Gemini R allows the customer to provide a wider range of services for their current customers and to develop new customers.