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Basic optical design of Fourier infrared spectrometer

Apr. 27, 2021

When the Fourier infrared spectrometer is used in the laboratory, its spectral resolution is high. It is suitable for the detection of liquids, solids, and gases. Besides, it is used to detect the molecular structure characteristics of the sample and quantitatively analyze the components in the mixture. When used outdoors, the Fourier Infrared Spectrometer measures the spectrum to analyze trace substances with infrared activity in the air. It is often used in the monitoring of hazardous garbage stations, vehicle exhaust detection, atmospheric composition detection and other measurements. It is widely used in environmental monitoring, aerospace, and military.

The basic structure of a Fourier infrared spectrometer mainly has three parts: front optical system, interferometer system, data acquisition and processing system. First, the light emitted by the light source is condensed by the condenser and then passes through the diaphragm. After passing through the collimating lens, it becomes a beam of parallel light. The beam splitter divides the incident beam into two coherent beams of equal intensity: one beam is transmitted through the beam splitter to the plane mirror, and after being reflected by the plane mirror, it returns on the beam splitter. After the other beam is reflected by the beam splitter, it passes through the compensation mirror to the plane mirror, and after being reflected by the plane mirror, it returns to the beam splitter. The two beams meet again and interfere. When the plane mirror moves, the optical path difference of the two beams changes. The condenser condenses the light beam emitted by the interferometer and then enters the detector.

The front optical system is mainly composed of optical lenses, plane mirrors and off-axis parabolic mirrors. The optical lens condenses the light. The optical reflector makes the non-parallel beams become parallel beams when exiting.

The interferometer system is composed of a plane mirror group, an off-axis parabolic mirror, a beam splitter, a rotating lens, and an infrared detector. The beam splitter serves to divide one incident light into two light beams. The rotating lens is to change the optical path difference of the two beams of light generated by the beam splitter. The four plane mirror play the role of reflecting light so that the two beams of light return to the surface of beam splitting and cause interference. The function of the off-axis parabolic mirror is to focus and reflect the interference beam to the infrared detector.

The laser interference assisted positioning system consists of a laser, an interferometer, a laser mirror, a laser beam splitter and a laser detector. The function of the laser mirror is to change the direction of the laser beam emitted by the laser so that it enters the interferometer in a prescribed direction. The function of the laser beam splitter is to emit the interfered laser beam to the laser detector.

CLZ Precision Optics Co., Ltd. specializes in processing and manufacturing optical components for Fourier infrared spectrometers, including collimating lenses, plane mirrors, laser mirrors and laser splitters. Besides, we also produce optical domes that are used for lasers. If you need related optical components, please contact