Infrared Fiber Systems, Inc.

Kenneth H Levin

Samuel Kerem

Vladimir Madorsky

Frank Y Li

A handheld device for infrared reflectance measurements of samples for identification of the sample materials is a self-contained portable unit built into a handheld housing. The housing includes a window and optics on a bench adjacent the window, so that the optics will be aligned with the sample when the device is placed directly against the sample. The optics include a broad-band IR light source (ordinary lamp) shining onto an acousto-optic tunable filter (AOTF), which passes narrow-band IR light with a swept frequency; a lens focussing the IR through the window onto the sample; and a reflectance detector aligned with the window of the housing to pick up reflected light. A computer, which may be mounted in the housing, compares the detected reflectance spectrum with stored sample data spectra, and identifies the material or the components of the material and their proportions. Inclusion of all the parts inside the housing allows the device to be portable; this is made possible by the alignment of the lamp, AOTF filter, lens, window, and detector, which has high optical efficiency, and by elimination of optical fibers.

Handheld infrared spectrometer

An acousto-optical filter (AOTF) is used in a spectrometer for analysis of samples. The spectrometer provides continuous wave RF excitation through the crystal, and the spectrometer provides control and modulation for said RF source. The signal to noise ratio is improved by use of a lock-in amplifier which demodulates the modulation frequency. Fiber optics are used to connect the crystal to the source, and the source to the detection system. A digital lock-in amplifier is designed which increases the efficiency, accuracy, sensitivity and decreases the cost of conventional analog lock-in amplifier.

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Silver Spring, MD, United States of America

Kenneth H Levin