The photoconductive Mercury Cadmium Telluride detectors are fabricated from ternary semiconductor compound. Spectral characteristics are determined by the composition of this compound and peak response can be varied for various applications by choosing the proper alloy.
The photoconductive process exhibits a change in conductivity coused by absorption of photons of suitable ecergy. This process requires a bias voltage, therefore, the detector configuratins are square or rectangular to assure a uniform field across the active areas. An optimum bias is determined to provide maximum signal to noise ratio for each device. These devices represent State-of-the-Art and routinely achieve background limited performance.
Typical specifications for standard detectors are outlined in the adjoining table. The D* and responsivity values reflect a 60 FOV cold stop. The FOV may be reduced or increased for customized applications.
The FTIR series HgCdTe detectors are designed specifically for Fourier Transform Infrared (FTIR) spectrometers. They are available in several models ranging from narrow band with a cut off wavelength of 13.3µm (750 cm-1) to mid-band cutting of at 16.6µm (600 cm-1). The wide band model has ranges from 22.2µm (450 cm-1) to 24µm (415 cm-1) cut off. These devices con be packaged in a variety of dewars with suitable windows. These windows vary for different spectral regions and are wedged to eliminate interference effects.
In addition to standard detector sizes from stock, custom configurations designed to customer specifications are available. Custom dewars and packages, both glass and metal, designed to function with special cooling systems such as Joule Thompson or Stirling Cycle Coolers are also available.
The new DP-8000 preamplifier has been designed for optimum performance with the HgCdTe detectors. The preamplifier offers user adjustable bias voltage control to optimize the detector signal-to-noise. Also included is an adjustable gain control to allow precise adjustment of signal response to those users who operate under a variety of signal conditions or require signal level matching for systems integration. Standard available bandwidths are from 1Hz to 1MHz.
Typical Applications
- Medical Thermography
- Thermal Imaging
- FTIR Spectroscopy/Microspectroscopy
- Missile Guidance
- Analytical Instruments
- Research
- Pollution Monitoring
The photovoltaic Indium Antimonide detectors are p-n junctions formed by mesa techniques using single crystal material. This process yields the highest quality photodiodes which exhibit excellent electro-optical performance in the 1µm to 5.5µm wavelength region. These diodes are background limited (BLIP) detectors and their performance can be enhanced by spatial (cooled FOV stops) or spectral (cooled interference filters) reduction of the background.
The photovoltaic effect is the generation of a potential across the p-n junction when radiation of the proper wavelength is incident upon it. When the photon flux irradiates the junction, electron-hole pairs are formed if the photon energy exceeds the forbidden gap energy. The field sweeps the electrons from the p region to the n region, and holes from the n region to the p region. This process makes the p region positive and the n region negative, and will produce current flow in an external circuit. An equivalent circuit of the InSb detector is represented on the adjacent sheet. This consists of both a signal and noise current generator in parallel with a resistive and capacitive term.
When background radiation shifts the operationg curve by generationg a constant output in the active element, the detector should be reversed-biased to bring it back to the optimum operating point: zero voltage. This can be acheived when operating with a matched preamplifier system operates in the detector noise limited mode. Two 12 volt batteries or a dual output power supply are required.
Custom configurations and arrays designed to customer specifications are available. In addition, custiom metal and glass dewars designed to function with various cooling techniques can be supplied.
Typical Applications
- Medical Thermography
- Thermal Imaging
- Spectroscopy
- Missile Guidance
- Radiometry
- Research
- IR Microscopy
PS series Lead Sulfide detectors are thin film photoconductors which are chemically deposited onto a quartz substrate. Photolithographic techniques are employed to define the active areas and gold electrodes provide noise-free contact between the lead-out wires and the PbS film.
The PS series Lead Sulfide detectors convert incident infrared energy into an electrical signal which can then be utilized for many functions. They are particularly suited for use in the 1µm to 3µm spectral region and provide an economical means of obtaining high performance in a rugged and compact package.
PS series Lead Sulfide detectors are offered in single and multi-element configurations and are available in flat plate cells, TO packages, and dewars. Cooling is provided by thermoelectric coolers and liquid nitrogen. Package designs are provided which can incorporate standard and custom apertures, filters, and windows. Low cost, high performance PS series Lead Sulfide detectors are routinely supplied from stock.
PS series detectors meet and exceed demanding specifications for a wide range of applications including analytical, environmental, industrial, and medical instrumentation as well as space and defense systems.
Typical Applications
- NDIR spectroscopy
- Medical Gas Analysis
- Optical Pyrometry
- Laser Definition
- Enviromental Analysis
- Flame Spectroscopy
PE series Lead Selenide detectors are thin film photoconductors which are deposited onto a quartz substrate. Photolithographic techniques are employed to define the active areas and gold electrodes provide noise-free contact between the lead-out wires and the PbSe film.
The Lead Selenide detectors convert incident infrared energy into an electrical signal which can then be utilized for many functions. They are particularly suited for use in the 1µm to 6µm spectral region and provide an economical means of obtaining high performance in a rugged and compact package.
These detectors are offered in single and multi element custom configurations and are available in flat plate cells, TO packages, and dewars. Cooling is provided by thermoelectric coolers or liquid nitrogen. Package designs are provided which can incorporate standard and custom apertures, filters and windows. Low cost, high performance Lead Selenide detectors are routinely supplied from stock.
Typical Applications
- NDIR Spectroscopy
- Medical Gas Analysis
- Optical Pyrometry
- Laser Definition
- Enviromental Analysis
- Flame Spectroscopy
Preamplifier products were designed to interface with our ingrared detectors and provide optimum performance from the detector-preamplifier combination. All preamplifiers are designed to ensure detector noise limited operation and optimum detector operating mode. The DP-8000 (HgCdTe) provides both adjustable gain. This allows the maximum versatility to the user. Both models are current mode amplifires which provide constant voltage bias to maintain stable detector operating conditions, as opposed to typical voltage divider bias schemes which vary voltage and current with applied detector radiation. High impedence and high voltage bias supplies are also avaiable for PbS and PbSe detectors. Listed below are the most commonly requested configurations, however, custom configurations are available.
