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Fast Optical Quality Test System for Collimated Beams

IP.com Disclosure Number: IPCOM000100796D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Levenson, M: AUTHOR [+2]

Abstract

Disclosed is a method for quickly sensing the quality of a collimated light beam such as the output of a laser/collimator lens assembly undergoing alignment.

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Fast Optical Quality Test System for Collimated Beams

       Disclosed is a method for quickly sensing the quality of
a collimated light beam such as the output of a laser/collimator lens
assembly undergoing alignment.

      Fig. 1 shows the configuration of the system.  The light from
the laser/collimating lens assembly under test is circularized in
passing through the pair of prisms.  A fraction of the light is
directed to detector 1 by the beamsplitter;  this provides a measure
of the total power in the beam.  The remainder of the light passes
through a known- high-quality objective lens and is focussed onto a
special mask.  Detector 2 measures the amount of light passing
through the mask.  The mask is scanned side to side, as shown in
Figs. 1 and 2;  it is also moved slowly through focus, as shown by
the horizontal arrows in Fig.  1.

      Fig. 2 shows an enlarged detail of the mask, which consists of
a precision zigzag slit constructed, for example, of chrome on glass.

      Fig. 3 represents the output signals from the detectors.

      The criterion for acceptable quality of the laser/collimator
assembly is that any two successive peaks in the output of detector 2
must exceed a set fraction of the total beam power as sampled by
detector 1.  This indicates that the focussed spot cross section is
no larger than a predetermined dimension in two directions in the
same plane and, therefore, that the intensity distribution and
aberrations o...