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Improved Polarimeter

IP.com Disclosure Number: IPCOM000112850D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+2]

Abstract

Polarimeters are widely used to measure the sugar concentration of solutions. A typical polarimeter consists of a light source, polarizer, sample tube, movable analyzer with a dial gauge and a detector, frequently the eye. While it is a simple device its use requires some skill and it is not easy to automate. The improved polarimeter described below is a rugged instrument which can be easily controlled by a simple computer interfaced with a plug in and is suitable for use by students or production workers.

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Improved Polarimeter

      Polarimeters are widely used to measure the sugar concentration
of solutions.  A typical polarimeter consists of a light source,
polarizer, sample tube, movable analyzer with a dial gauge and a
detector, frequently the eye.  While it is a simple device its use
requires some skill and it is not easy to automate.  The improved
polarimeter described below is a rugged instrument which can be
easily controlled by a simple computer interfaced with a plug in and
is suitable for use by students or production workers.

      The device consists of a conventional polarimeter with the
improvement that a Faraday modulator is introduced in the light path
between the polarizer and the analyzer.  The modulator is a film of
Bismuth doped Yttrium Iron Garnet surrounded by a small solenoid.  In
operation, the instrument is nulled by mechanically turning the
analyzer and monitoring the detector output to find an approximate
minimum.  A current is applied to the solenoid and the detector
output is monitored until the current is found that gives a minimum
output signal.  The solution to be tested is placed in the light path
and the current is varied to find the new minimum.  The difference in
current can be related to the rotation of the Faraday cell needed to
cancel the rotation of the sample.  The improved device consists of
the following parts:  A light source, which could be a visible Light
Emitting Diode (LED), plastic optical fiber, Selfoc Lens...