Pyroelectric detectors recombines beams and directs sample

20th March 2018

Lanna Deamer

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Fourier transform infrared spectrophotometry has become a well-established alternative to dispersive spectrophotometry, using prisms or gratings. An FTIR interferometer splits one beam of light from a broadband source into two using a beam splitter, transmitting the first beam to a fixed mirror and the second to a mirror that is translated back and forth very precisely so that the paths of the two beams are different.

The device then recombines the beams and directs them through the sample to the detector. The time variation in the path difference between the two beams modulates each wavelength of the collected radiation at a frequency that is a function of the wavelength of the radiation and the velocity of the moving mirror.

Breaking down the signal generated by the detector into these frequency components reveals how the individual wavelengths from the broadband source interact with the sample under test generating a molecular fingerprint.

Infrared detectors used at the heart of the FTIR spectrophotometer must have the following characteristics; wide spectral response range, high sensitivity, wide frequency bandwidth, good linearity. LASER COMPONENTS offers DLaTGS pyroelectric detectors that are suitable for this demanding application.

From the research and production facility in Florida the company supplies customers all over the world with these industrial grade thermal detectors.

A pyroelectric infrared detector responds to a change in IR radiation (heat) absorbed on its surface and they have a very wide spectral bandwidth. A pyroelectric crystal has an atomic structure that will move slightly in response to a change in temperature, rearranging the electric charge within the solid generating a voltage.

The devices are manufactured in standard TO style packages and have long expected lifetimes making them suitable for this fit and forget application.