Large Signal Analysis of the Infrared Semiconductor Mercury-Cadmium-Telluride Detectors
- PDF / 232,295 Bytes
- 10 Pages / 439.37 x 666.142 pts Page_size
- 41 Downloads / 194 Views
Large Signal Analysis of the Infrared Semiconductor Mercury-Cadmium-Telluride Detectors Muhammad Taher Abuelma’atti
Received: 20 May 2007 / Accepted: 2 July 2007 / Published online: 3 August 2007 # Springer Science + Business Media, LLC 2007
Abstract A mathematical model for the relationship between the output voltage and incident radiation of the infrared semiconductor mercury-cadmium-telluride (MCT) detector is presented. The model, basically a sine-series function, can easily yield closedform expressions for the harmonic and intermodulation performance of the MCT detector with large-amplitude multisinusoidal incident radiation. The special case of two-tone equalamplitude incident radiation is considered in detail. The results show that the second-order harmonic and intermodulation products are always higher than the third-order components. Moreover, the results show that the second-order intermodulation is always dominant. Keywords Infrared spectroscopy . Mercury-cadmium-telluride detector . Intermodulation distortion . Harmonic distortion 1 Introduction Over the years the infrared photovoltaic detectors were employed for a wide range of applications including military, medical imaging, fire control, industrial quality control, environmental monitoring and surveillance [1]. Of particular interest here is the detector based on the mercury-cadmium- telluride (MCT) semiconductor material. This material has for many years been the preferred material for high performance long wave infrared detectors. For mid-infrared applications, MCT is also used for many simple photoconductive detectors. These detectors are widely used for instrumentation, thermal imaging, thermography and radiometry [2]. In general, MCT detectors offer the highest detection performance flexibility of any infrared detector system [3]. Recently the MCT technology has been challenged by microbolometer-based detectors, which are capable of delivering acceptable performance when used in high-speed optical systems [4]. However, while the major advantage of microbolometer detectors is the absence of a cryogenic cooler system, their major drawback is the need for tight temperature control of the operational environment [4]. M. T. Abuelma’atti (*) King Fahd University of Petroleum and Minerals, P.O. Box 203, Dhahran 31261, Saudi Arabia e-mail: [email protected]
850
Int J Infrared Milli Waves (2007) 28:849–858
The MCT semiconductor element is usually cooled with liquid nitrogen and its electric resistance changes rapidly with the incident radiation. To measure this resistance the electronic circuit shown in Fig. 1(a) is usually used [5]. In Fig. 1(a) Rm represents the resistance of the MCT detector to be measured, Il represents a constant current source, the operational amplifier senses the changes in the voltage across the resistance Rm, resulting from the variation of the incident radiation intensity, amplifies it and produces the output voltage Vout.
Fig. 1 (a) MCT detector electronic circuit (b) Equivalent circuit of the Rm.
l
f
m REF
a
s
p
Data Loading...
