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High Sensitivity Integrated Optics Spectroscopy Using a Dual Beam Technique

IP.com Disclosure Number: IPCOM000086762D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Santo, R: AUTHOR [+3]

Abstract

The absorption of a light guide is measured by a method that uses a dual beam in which the beam is ribbon-shaped.

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High Sensitivity Integrated Optics Spectroscopy Using a Dual Beam Technique

The absorption of a light guide is measured by a method that uses a dual beam in which the beam is ribbon-shaped.

As shown in Figs. 1 and 2 a light-guide film 10 is positioned on top of a substrate 12. On top of the light-guide film 10 is an input prism 14 and an output prism 16.

A laser beam is spread out in a direction perpendicular to its direction of propagation to form a ribbon shape 18. The ribbon form of the beam 18 may be obtained by a combination of cylindrical lenses and/or slits or, alternatively, by a vibrating mirror. The beam 18 is coupled into the guide film 10 through an input prism 14. The uncoupled portion of beam 18 is reflected out of prism 14 as beam 20.

The coupled portion of the beam 18 passes through film 10 to output prism 16 which is coupled thereto. Beam 22 passes out of prism 16.

Fig. 3 is a top view which illustrates two different techniques for absorption measurements. In Fig. 3a the determination of additional absorption on one-half of the film may be done by incorporating a mono-layer into that portion of the film. In Fig. 3b the measurement of the total absorption of the film is accomplished by placing two output prisms 16 and 17 in the system, with each output prism coupling out over half of the beam width. An oscillating or chopping device with period tau is used to distinguish between the upper portion A and lower portion B in Figs. 3a and 3b.

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