Bolometer輻射熱測量計
作者: Kevin Peng 發布于: 2015-10-30 00:34 點擊:次
Basic Bolometer System
 All composite silicon bolometer systems are housed in our HDL-5 model, liquid helium dewar with a liquid nitrogen cooled radiation shield. Standard hold times are greater than 20 hours between fills for 4.2K systems and 10 hours for our 1.6K models.
The detector comes with an IR light collecting cone assembly, vacuum-sealed wedged window, field of view baffling, and low noise electronics. The bolometer system is then outfitted with a single cut-on IR filter or a cold, manually operated, 2 or 3 position filter wheel. We offer a selection of far IR cut-on long pass filters that range from 10 to 285µm.
If your application requires longer hold times, increased work height, dual detectors, or more filter positions are required, please let us know. We're committed to building a custom designed system to meet your individual needs. Special requests for custom designs are always welcome.
General Purpose 4.2K Bolometer System
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Our most popular and versatile bolometer system covers a wide range of applications. It consists of a 4.2K bolometer detector element bonded to a 2.5mm diamond absorber. It operates best in the range of 15 to 2000µm (20THz to 150GHz) with modulation frequencies in the 200 to 400Hz range. Hi-Res
4.2K Bolometer System
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This system provides a lower thermal conductivity detector and increased spectral resolution. The configuration offers a slower responding system with modulation frequencies best kept below 200Hz. This system is more sensitive and the NEP values are an order of magnitude lower than the general purpose 4.2K system.
Standard 1.6K Bolometer System
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Similar to our general purpose 4.2K system in spectral response (15 to 2000µm) with the added benefits provided by lowering the temperature of the detector. These benefits include a lower NEP, higher sensitivity, and the advantage of a quick response time. This system can work at modulation frequencies greater than 1 KHz.
Far-IR 1.6K Bolometer System
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Specifically configured to detect the lower energy signals present in the longer wavelengths of the IR spectrum and will perform well from 300µm to 5mm. It has a very low thermal conductivity compared to our other bolometer systems. This aids in providing longer integration times to capture the low signal strengths and is best operated at modulation frequency less than 300Hz.
Bolometer Specifications
Indium Antimonide Hot Electron Bolometer
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Spectral Response: 0.2mm to 5mm
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Operating Temperature: 4.2 K
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High Speed
When cooled to liquid helium temperatures, absorption of radiation by free carrier electrons causes the mean temperature of the electrons (To) to rise above that of the host lattice. Electron mobility is proportional to To 3/2, hence this temperature rise can be sensed as a change in conductivity. The very low thermal mass of the free electrons, coupled with short energy relaxation times of about 10-7 seconds, leads to a very fast and sensitive sub millimeter wave detector.
This detector uses a specially shaped high purity N-type InSb crystal which may be coupled directly to a very low noise preamplifier.
Detector Area (mm): 5 x 5
Detector Mounting: Sapphire substrate set into an integrating cavity
Operating Temperature (K): 4.2 & 1.5
Spectral Response (mm): 0.2 - 5
Frequency Response - 3db (kHz): 600
NEP (w/Hz½): < 8 x 10-13
What is a Bolometer?
Bolometers are detectors used to measure incident Infrared radiation. They are very sensitive to thermal radiation and are predominantly used in the infrared spectrum between 10 to 5000µm (30THz to 60GHz). The detector element is an extremely sensitive thermistor that is cooled to LHe temperatures in order to decrease the thermal background. Any thermal radiation that impinges upon the detector will cause a temperature change. This will cause a change in resistance which is amplified and measured as a voltage difference.
Because bolometers measure a change in temperature, the incident radiation must be modulated. This allows the bolometer to excite and relax, thus a measurement of the change in resistance is made that corresponds to the energy of the incident radiation. The speed at which the bolometer reacts to this temperature change is dependent upon several factors that can be altered, if desired, at the time the system is ordered.
Basic System
All composite silicon bolometer systems are housed in our HDL-5 model, liquid helium dewar with a liquid nitrogen cooled radiation shield. Standard hold times are greater than 20 hours between fills for 4.2K systems and 10 hours for our 1.6K models. The detector comes with an IR light collecting cone assembly, vacuum-sealed wedged window, field of view baffling, and low noise electronics.
The bolometer system is then outfitted with a single cut-on IR filter or a cold, manually operated, 2 or 3 position filter wheel. We offer a selection of far IR cut-on long pass filters that range from 10 to 285µm.
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