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Model 10722A
Instruction Manual
PRINCIPLES OF OPERATION
PLANE MIRROR INTERFEROMETER PRINCIPLES
Figure 7 illustrates the operation of the Plane Mirror Interferometer. The laser light beam
containing frequencies fl and f2, of orthogonal linear polarization, leaves the center aperture of
the laser head and enters the inlet port of 10702A Plane Mirror Interferometer. The polarized
beam splitter in the interferometer splits the laser beam into its fl and f2 components. The fl
component is deflected to a cube-comer (retroreflector), which reflects the fi component back
to
the polarized beam splitter.
Figure 7. 5501A Laser Measurement System Plane Mirror Interferometer
The f2 component passes through the polarized beam splitter and the plane mirror converter
where it is changed from vertical polarization to circular polarization by the plane mirror con-
verter. The f2 component is reflected back on itself by the plane mirror reflector, resulting in
f2
*
Af by 90° to change the polarization from circular to horizontal. As a result, the polarized
beam splitter reflects the f2
*
Af to the second cube-comer, as shown in Figure 7. The cube-
comer reflects the f2
*
Af back to the polarized beam splitter, where it is again reflected through
the plane mirror converter. The plane mirror converter changes the beam polarization from hori-
zontal to circular. The plane mirror reflects the f2
*
2Af back through the plane mirror converter,
which rotates the f2
*
2Af polarization by 90°, resulting in a vertically polarized beam. The f2
2Af beam is passed through the polarized beam splitter and
a
beam composed of fi
-
f2
*
2Af is
applied to the inlet port of the 10780A Receiver. The 2
A
f frequency change is a result of the dual pass
feature of the plane mirror interferometer (double Doppler shift).
LINEAR
INTERFEROMETER
HP 10702A
PLANE
MIRROR
CONVERTER
//
Any tilting of the plane reflector relative to the beam axis results only in an offset of the return beam.
Tilting of the reflected wavefront is compensated by the second reflection.
H P 1 0722A
FI
F 2 f 2 A F
F 2 f A E
F 2 f 2 A F
C
C
4
C
5
/
9 9
-
+
-
C
I
FI
F2
F2
F 2 f AF
3
PLANE MIRROR
-
REFLECTOR
RETROREFLECTOR
HP 10703A
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