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Absorption Cell With Variable Path Length

IP.com Disclosure Number: IPCOM000041591D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Schmidt, HD: AUTHOR [+2]

Abstract

An immersible absorption cell for continuously monitoring optical extinction in liquids uses two optical fibers having their ends mounted in a plastic fixture, by which the distance between the parallel planar end faces of the fibers can be mechanically controlled for adjusting the absorption length. Fig. 1 shows an embodiment where two fibers 1a, 1b are each mounted in symmetrical fixtures 2a, 2b which can be displaced relative to each other by a suitable mechanical guide system, e.g., a thread. Fixtures 2a, 2b have openings allowing the liquid to enter the space between the planar end faces of the fibers.

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Absorption Cell With Variable Path Length

An immersible absorption cell for continuously monitoring optical extinction in liquids uses two optical fibers having their ends mounted in a plastic fixture, by which the distance between the parallel planar end faces of the fibers can be mechanically controlled for adjusting the absorption length. Fig. 1 shows an embodiment where two fibers 1a, 1b are each mounted in symmetrical fixtures 2a, 2b which can be displaced relative to each other by a suitable mechanical guide system, e.g., a thread. Fixtures 2a, 2b have openings allowing the liquid to enter the space between the planar end faces of the fibers. If the range of distance d between the fiber ends is sufficiently small, the receiving fiber end captures all the light exiting from the other fiber end small variations of distance d thus do not change the light flux received. For larger distances, appropriate collimating means, e.g., lenses, should be provided at the fiber ends. A second embodiment with two absorption path lengths is shown in Fig. 2. There are two plastic blocks 20a, 20b with embedded fibers 1a, 1b, 1c. The light enters through fiber 1a, traverses a first absorption length d1 to reach the semicircularly bent fiber 1c, and a second absorption length d2 to exit through fiber 1b. The distance d1, d2 can be changed mechanically. The proposed absorption cell can be dipped in a stationary liquid to be measured or incorporated in a pipe for measuring liquid...