Two Color Sandwich Arrays

Featured Product from OSI Optoelectronics

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Dual Sandwich Detectors or Two Color Detectors are mostly employed for remote temperature measurements. The temperature is measured by taking the ratio of radiation intensities of two adjacent wavelengths and comparing them with the standard black body radiation curves. The advantages of optical remote measurement have definitely made these devices the perfect match for this type of measurements. They are independent of emissivity and unaffected by contaminants in the field of view or moving targets. In addition, measurements of targets out of the direct line of sights and the ability to function from outside RF / EMI interference or vacuum areas are possible. They also have the advantages of overcoming obstructed target views, blockages from sight tubes, channels or screens, atmospheric smoke, steam, or dust, dirty windows as well as targets smaller than field of view and / or moving within the field of view. These detectors can also be used in applications where wide wavelength range of detection is needed.

OSI Optoelectronics offers three types of dual sandwich detectors. The Silicon-Silicon sandwich, in which one silicon photodiode is placed on top of the other, with the photons of shorter wavelengths absorbed in the top silicon and the photons of longer wavelengths penetrating deeper, absorbed by the bottom photodiode. For applications requiring a wider range of wavelength beyond 1.1 µm, an InGaAs photodiode replaces the bottom photodiode. The silicon-InGaAs version is also available with a two stage thermo-electric cooler for more accurate measurements by stabilizing the temperature of the InGaAs detector. All devices are designed for photovoltaic operation (no bias), however, they may be biased if needed, to the maximum reverse voltage specified. They are ideal for coupling to an operational amplifier in the current mode. For further details refer to the "Photodiode Characteristics" section of this catalog.

Product Applications Include:

  • Pulse Detectors
  • Optical Communications
  • Bar Code Readers
  • Optical Remote Control
  • Medical Equipment
  • High Speed Photometry


Features Include:

  • High Speed Response
  • Low Capacitance
  • Low Dark Current
  • Wide Dynamic Range
  • High Responsivity

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