Understanding Infrared Detector & Emitter Technology
- Friday, 01 July 2011
Advances in chemical deposition and post-processing operations allow characteristics like time constant, dark resistance, responsivitity, detectivity, and peak wavelength responses to be designed to meet specific application requirements. Additionally, significant developments in areas like integrated circuit design, photolithography, ion milling, hermetic sealing, and thermoelectric cooling have allowed users to more fully take advantage of the benefits of photoconductive detectors.
Over the last two years, there have been significant developments in PbS and PbSe single element, multi-element, and array sensors as well as in emitter technologies.
Single Element Detectors
New PbS single element detector technology introduced in 2011 takes advantage of process improvements and provides exceptional sensitivity at a great value. Offering typical D* peak from 9 × 1010 to 1.75 × 1011 Jones across the entire one to three micron wavelength range, they are truly cost-effective with high volume pricing of less than $25. Thanks to precise process controls and automated production equipment, they combine industry-leading price/performance with exceptional repeatability and product consistency.
Single element detectors can support a glass window or lens configuration and are typically available in a range of sizes (including 1mm2, 2mm2, and 3mm2 in industry standard TO-46 or TO-5 packages) depending on whether size is a critical concern (as in portable test equipment) or if greater field-of-view or larger element sizes is a priority.
Key applications include fire safety and flame detection, as well as process and quality control applications.
This year has also witnessed advancements in multi-element PbS and PbSe detector technology. Multi-element detectors with a two to four channel configuration provide significant opportunities for cost reduction and design simplification, minimizing the need for multiple individual detectors and complex optics. System costs and footprints can be reduced up to 60% with a four element detector versus alternative single-detector designs.
The latest generation of multi-channel detectors provide market-leading typical D* peak of 1.5 × 1010 Jones for detection of up to four distinct materials/gases with exceptional channel isolation (>99.5%) and superior quality and reliability.
A new feature is the option to integrate a thermistor within the detector package to optimize temperature compensation and maximize measurement precision. Co-locating the temperature sensor and detector material in a hermetically-sealed TO-5 package ensures they both “feel” the same temperature variations and reduce potential effects of external environmental factors.
Multi-element detectors are well-suited for a variety of applications including industrial and medical gas analysis, as well as auto and aviation emissions testing. They are ideal for environmental applications such as stack monitoring, greenhouse gas analysis, and overseeing air quality in confined spaces including tunnels and underground structures.
The latest generation of 256-element PbS and PbSe infrared detector arrays introduced in 2011 feature built-in compensation elements that enhance measurement stability by up to 25%.