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DIP Spectrophotometric Sensor

IP.com Disclosure Number: IPCOM000041604D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Korth, HE: AUTHOR

Abstract

A miniaturized spectrophotometer integrates a dispersive element, consisting of a graded index refraction (GRIN) rod lens, a reflection grating and an optical fiber, with a self-scanning photodiode array in a standard dual in-line package (DIP) which is directly insertable into electronic circuit boards. Front, side and top views of the proposed spectrophotometer are shown above. The light to be analyzed is fed by optical fiber 1 to a front surface A near the optical axis of a specially cut GRIN rod lens 2. Within the lens, the light is collimated on reflection grating 3, attached to the rear surface, and focussed after total reflection at plane C on to a photodetector array 4 on a silicon plate 5 glued to the rod lens. The contact pins 7a, 7b of the DIP package are connected to contact points of photodiode 4.

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DIP Spectrophotometric Sensor

A miniaturized spectrophotometer integrates a dispersive element, consisting of a graded index refraction (GRIN) rod lens, a reflection grating and an optical fiber, with a self-scanning photodiode array in a standard dual in-line package (DIP) which is directly insertable into electronic circuit boards. Front, side and top views of the proposed spectrophotometer are shown above. The light to be analyzed is fed by optical fiber 1 to a front surface A near the optical axis of a specially cut GRIN rod lens 2. Within the lens, the light is collimated on reflection grating 3, attached to the rear surface, and focussed after total reflection at plane C on to a photodetector array 4 on a silicon plate 5 glued to the rod lens. The contact pins 7a, 7b of the DIP package are connected to contact points of photodiode 4. A fixture 6 stress-relieves optical fiber 1. A housing 8 encloses the whole assembly. The orientation of cutting planes A, C and D of the rod is such that plane C bisects the angle between A and D. The cut of D must be such that the light cone emitted by the fiber end is not affected. The spectrometer is adjusted by appropriately positioning the optical fiber; the width of the photodiodes is preferably larger than the diode spacing. To compensate for thermal drift, etc., one of the diodes should be left dark, e.g., by cutting the rod along plane E. The GRIN lens may be replaced by a homogeneous glass block with a holographic re...