Isotech 976 Gemini R High‑Temperature Blackbody Source

The Isotech Gemini R is a robust and portable high‑temperature blackbody source designed for calibrating infrared thermometers and thermal imagers across the range 30 °C to 550 °C. With its deep cavity, emissivity of >0.995 and excellent temperature uniformity, the Gemini R delivers laboratory‑grade performance in a compact, field‑ready instrument. It is widely used as a primary radiation source for IR instruments in both laboratory and industrial environments where reliability and low uncertainty are essential.

Deep cavity with high emissivity

At the core of the Gemini R is a 65 mm diameter, 160 mm deep cavity engineered to produce a stable and uniform radiation field. With an emissivity greater than 0.995, the source behaves as an almost ideal blackbody, enabling accurate and repeatable IR measurements. Uniformity is achieved through distributed heating technology, ensuring consistent radiance throughout the cavity, even at elevated temperatures.

Precise control and built‑in traceability

The Gemini R features a digital controller that allows any temperature between 30 °C and 550 °C to be set with precision. Traceability is ensured through a built‑in temperature indicator and a supplied platinum resistance thermometer (PRT). Each unit includes a three‑point traceable calibration certificate, and optional UKAS calibration is available for both the PRT and the radiometric output.

Thermal performance and test results

The Gemini R offers:

• > Stability: ±0.1 °C
• > Emissivity: >0.995
• > Display resolution: 0.01 °C to 99.99 °C, then 0.1 °C
• > Cavity dimensions: 65 mm diameter, 160 mm deep
• > Power consumption: 1000 W
• > Supply: 100–130 V or 208–240 V

Test data show controller variations of only ±0.2 °C over five minutes. A 13 mm radiation thermometer surveying the 65 mm target found maximum differences of +1 °C between 100 °C and 500 °C. Using a fibre‑optic probe, temperature differences of up to +4 °C were measured along the inner 100 mm of the cavity at 400 °C and 500 °C. The controller temperature typically agrees with radiometric measurements to within ±2 °C.

Compatible with ITS‑90 Fixed‑Point Cells

For the lowest uncertainties, the Gemini R can be used with Isotech ITS‑90 fixed‑point cells, including:

• > Gallium (29.7646 °C)
• > Indium (156.5985 °C)
• > Tin (231.928 °C)
• > Zinc (419.527 °C)

These hockey‑puck cells are supplied with metal‑purity certificates and provide exceptionally stable reference temperatures.

Design and portability

Weighing 10 kg and measuring 310 × 265 × 200 mm, the Gemini R is compact enough for field use yet robust enough for daily laboratory operation. A dedicated carrying case is available for transport and protection. The Isotech Gemini R is a powerful, accurate and versatile high‑temperature blackbody source. With its deep cavity, high emissivity, excellent uniformity and compatibility with ITS‑90 fixed‑point cells, it is an outstanding choice for demanding infrared calibration in both laboratory and industrial settings.