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​​Indium Antimonide Detectors​

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Indium Antimonide Short Form Catalog in PDF Format

J10D Series Indium Antimonide Detectors

J10D Series detectors are high quality Indium Antimonide (InSb)photodiodes, providing excellent performance in the 1 to 5.5 µm wavelength region. Single crystal p–n junction technology yields high speed, low noise detectors with excellent uniformity, linearity and stability.

Applications

• Thermal Imaging
• Heat-Seeking Guidance
• Radiometers
• Spectrometry
• FTIR

InSb detectors are photovoltaic and generate current when exposed to infrared radiation. Figure 2 shows the equivalent circuit for InSb, including the shunt resistance RD, junction capacitance CD and shot noise. The shot noise results from the DC current IBG produced by the background infrared radiation. Because IBG is proportional to the detector active area (Fig. 5), smaller detectors have less shot noise and lower values of NEP.

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Figure 1	Figure 2	Figure 3

Field of View: A standard cold field of view (FOV) is provided at no extra charge. A custom field of view can be supplied for a small extra charge. Detectivity can be improved and IBG reduced by restricting the FOV angle. The FOV cold stop angle should be chosen to restrict unwanted background radiation while still accepting all desired radiation from the optical system. A 60° (full-angle) FOV, corresponding to 1/F optics, is provided unless otherwise specified.

Cold Filters: Optional cold filters can improve detectivity by eliminating background radiation in unwanted wavelength regions. The D* performance with the SP29 cold filter (0.5-2.9µm) and the SP35 cold filter (1.7-3.5µm ±0.3µm) is shown in Figure 1. Other bandpass filters are available on a custom basis.

Dewar Packages: All J10D Series InSb detectors require 77°K operating temperatures. The detector comes mounted in the standard M204 or M205 metal dewar with a sapphire window and a 60° field of view. Other window and dewar options are available. All InSb detectors can be provided in the J508 or the RC2 Detector Cooler Assembly for operation without bulk liquid nitrogen.

Figure 4	Figure 5	Figure 6

Custom Detectors: InSb detectors in any size up to 7mm diameter and in any configuration can be provided on a custom basis. Contact Judson for specifications for linear position sensors, quad cells, and two-color (sandwich) detectors.

Preamplifiers: Optimum performance is achieved when the InSb detector is coupled into a Judson transimpedance gain preamplifier, which converts detector output current to voltage while maintaining the detector at the optimum zero volt bias (Fig. 3).

The PA-9 preamplifier is specifically matched to each InSb detector to provide maximum sensitivity, gain and bandwidth. The lower-cost, adjustable gain PA-7 preamplifier is suitable for lower frequency applications (DC-10KHz). When selecting preamp gain, choosing the largest practical value of RF results in the lowest overall noise. However, the detector IBG must be considered to avoid DC saturation of the preamp.

Example: The J10D-M204-R01M has a background current (IBG) of 7µA (from Fig. 5). Choosing RF= 1MW would result in a gain of 10E6, for a DC output of (7µA x 10E6 V/A) or 7V. This is near the saturation level of both the PA-7 and PA-9. Consequently, a gain of 10E6 is the maximum useable DC gain with this detector. An AC-coupled second stage may be added for further amplification. The background current IBG may be reduced by adding a cold filter or reducing the field of view.​

 Click for more information on HgCdTe/InSb sandwich detectors.​