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A NEW DERIVATIVE RECORDING SHEARING INTERFEROMETER

IP.com Disclosure Number: IPCOM000022912D
Original Publication Date: 1976-Apr-30
Included in the Prior Art Database: 2004-Mar-27
Document File: 2 page(s) / 225K

Publishing Venue

Xerox Disclosure Journal

Abstract

An interferometer that displays the azimuthal derivative in a polar coordinate system a-'~ A wavefront ~< (n~) is generated which is split up and a shear is introduced. Combining the two wavefronts will give:

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XEROX DISCLOSURE JOURNAL

A NEW DERIVATIVE RECORDING Proposed Classification
SHEARING INTERFEROMETER U.S. Cl. 356/106
0. Bryngdahl Int, Cl. GOlb 9/02

An interferometer that displays the azimuthal derivative
in a polar coordinate system a-'~

A wavefront ~< (n~) is generated which is split up and
a shear is introduced. Combining the two wavefronts
will give:

2I ~ + ~.~A,~+4)J __ Constant x

   is a constant displacement in the azimuthal direction.
In order to introduce this ~- displacement, one wave-
front is rotated J'~=~(fl~~i.e. the rotation is
inversely proportional to the radius,

An image rotator which rotates the image inversely pro-
portional to the radius is shown in the Figure. The
wavefront U is radially inverted by the radial grating

      In the frequency plane S1 a spiral grating is
introduced which again inverts the wavefront in the
radial direction, At the same time, however, a dis-
placement in the azimuthal direction is introduced which
is largest for small r (higher frequency of Sl). S2,
another spiral grating, placed in the image plane of

Rl (Ll and L2 forms a telecentric optical system)
corrects finally the phase of the wanted wavefront
which has been sheared,

U

R~

L2

Volume 1 Number 4 April 1976 85

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A NEW DERIVATIVE RECORDING SHEARING INTERFEROMETER (Cont~d)

In case absorption gratings are used only half of the
object plane can be imaged at a time because of over-
lapping of different diffraction order, Howe...