What is InSb (Indium Antimonide)?

Indium Antimonide is a type of semiconductor material, more specifically a type of microbolometer sensor used in some cooled thermal cameras. Indium Antimonide is a crystalline semiconductor made of indium and antimony. It belongs to the III-V group and is a narrow gap semiconductor material. Detectors made of indium antimonide are sensitive between a wavelength of 1-5 µm [MWIR]. InSb sensors must be cryogenically cooled and have much lower temperature requirements than MCT or Infiniti's line of X-HOT sensors. Unlike Microbolometer Type detectors that are photoresistant for LWIR uncooled thermal cameras, InSb detectors are photovoltaic and operate on 3-5µm mid-wave infrared. This means they detect heat rather than light by generating a small voltage when they are hit with thermal radiation energy, rather than generate a resistance like a VOx microbolometer thermal core.

Undoped InSb possesses the largest ambient-temperature electron mobility (78000 cm2/V⋅s), electron drift velocity, and ballistic length (up to 0.7 μm at 300 K) of any known semiconductor, except for carbon nanotubes.

InSb was one of the first types of FLIR Forward Looking Infrared materials used and is a very important Infrared detector type for MWIR Cooled thermal imaging. InSb Cooled (IR) camera sensors have many military and scientific applications. Military applications include the use of IR sensors include long range night vision thermal imaging cameras for ISR and surveillance often using the MWIR 3-5um wave lengths, Scientific applications include IR detector arrays in telescope sensors for astronomy and IR detectors for spectrometers and radiometers.

Infiniti can use InSb or MCT sensors but for most applications we prefer to use the latest technology for our cameras which is our X-hot material as it provides many of the benefits of InSb and MCT but with improved reliability and 30% less cooling compared to MCT with improved resolution up to 5MP and smaller pixel pitch of 5μm and 10μm making it the best technology for long range surveillance and defense applications.

Since cooled thermal IR cameras are so sensitive to tiny temperature differences, they can detect and track a target with minimal temperature difference from its background. They work on mid-wave infrared wavelengths (MWIR) and typically use wavelengths of 3-5µm (3000nm to 5000nm). The combination of the cooled image core and the ability to work on the MWIR spectrum, when used with Infiniti’s long-range optics, means ultra-long range detection capabilities (up to 34miles or 55km) even if there is only a few degrees temperature variance between the target and background. While cooled cameras are a significant investment and are considerably more expensive then uncooled, their superior range and performance allows them to deliver results that uncooled thermal cameras simply can’t achieve, making them a vital solution for certain applications such as coastal surveillance, and a cost-effective solution in applications such as border security, where the longer range of cooled thermal can cover the same perimeter length of up to 5-8 individual uncooled thermal cameras.

Infiniti optics custom builds all types of EO/IR solutions and can offer them as open frame modules (lens and sensor attached) or as complete integrated PTZ cameras with Visible and SWIR sensors for ultra long range imaging required by a host of military and defense applications.

Learn more about Thermal Cameras on our Thermal Camera Technology Page.