Mode of Operation
InSb detectors are photovoltaic and produce a current due to incident IR radiation.

The shot noise is caused by the DC current IBG produced by background radiation. As this current is proportional to the size of the active area, smaller detectors have a lower shot noise and a lower NEP. InSb detectors are usually linear up to an output signal of 1 mA.

A cooled aperture with a fan angle (FOV) of choice is contained in every detector. The standard FOV is adapted to F/1 optics by 60°. By lowering the FOV it is possible to increase D* and lower the background current IBG. The FOV should be chosen so that all usable radiation is transmitted and as much background radiation is blocked as possible.

The best performance
J10D detectors reach their optimum performance together with transimpedance preamplifiers by JUDSON. These preamplifiers transform the current produced by the detector into a voltage signal while the detector remains volt-free. The preamplifier PA-9 is individually adjusted for each InSb diode to achieve a maximum sensitivity, amplification, and bandwidth. The less expensive PA-7 preamplifiers with adjustable amplification are suitable for NF applications (DC … 10 kHz).

Choice of the amplifier
When choosing the right amplifier, you should select the biggest RF value possible in order to achieve the lowest noise. The background current IBG must also be taken into account to prevent the amplifier from going into saturation prematurely.

Types of InSb detectors
Sandwich, position-sensitive, and quadrant detectors made from InSb are also available. Please also inquire about our customized detectors of up to 7 mm.