328
4 Speckle-Optical Methods and Devices for Studying …
Fig. 4.5 Dependence of the average speckles size in the observation plane during longitudinal
shift of the diffuser for z i + R=N = const: 1—z i + R = 50 mm; 2—z i + R = 100 mm; 3—z i + R
= 200 mm; 4—z i + R=300 mm; 5—z i + R = 450 mm. Reprinted from [2] with permission
The object under study was shifted in direction of spreading the laser beam and
the amplitude A 1 (z), spectral harmonic of spectrum of intensity fluctuations was
registered in position with coordinate z 2 , then in the position with coordinates z 3 , z 4 ,
etc. Having conducted measurements and plotted values of the amplitudes A 1 (z) of
spectral harmonics against coordinates z 1 , z 2 , z 3 , etc., which characterize longitudinal
shift of the object under study, the dependences have been made for some fixed values
z i + R = N =const. The dependences were calibration curves for this measuring circuit
if z i + R = 50, 100, 200, 450 mm (Fig. 4.6). On some areas, the change of the
amplitude of spectral harmonic A 1 (z) is directly proportional to longitudinal shift of
the object, and the straight portion of this curve (for z i + R = 100 mm) is optimal
for registration of longitudinal shift (Fig. 4.7). Measurement of spectral harmonic
amplitude A 1 (z) made it possible to unequivocally determine longitudinal shift of
Fig. 4.6 Dependence of the amplitude A 1 of the first spectral harmonic with the longitudinal shift
of the rotating diffuser for z i + R = N = const: 1−z i + R = 50 mm; 2—z i + R = 100 mm; 3—z i
+R = 200 mm; 4—z i + R = 300 mm; 5—z i + R=450 mm. Reprinted from [2] with permission
4 Speckle-Optical Methods and Devices for Studying …
Fig. 4.5 Dependence of the average speckles size in the observation plane during longitudinal
shift of the diffuser for z i + R=N = const: 1—z i + R = 50 mm; 2—z i + R = 100 mm; 3—z i + R
= 200 mm; 4—z i + R=300 mm; 5—z i + R = 450 mm. Reprinted from [2] with permission
The object under study was shifted in direction of spreading the laser beam and
the amplitude A 1 (z), spectral harmonic of spectrum of intensity fluctuations was
registered in position with coordinate z 2 , then in the position with coordinates z 3 , z 4 ,
etc. Having conducted measurements and plotted values of the amplitudes A 1 (z) of
spectral harmonics against coordinates z 1 , z 2 , z 3 , etc., which characterize longitudinal
shift of the object under study, the dependences have been made for some fixed values
z i + R = N =const. The dependences were calibration curves for this measuring circuit
if z i + R = 50, 100, 200, 450 mm (Fig. 4.6). On some areas, the change of the
amplitude of spectral harmonic A 1 (z) is directly proportional to longitudinal shift of
the object, and the straight portion of this curve (for z i + R = 100 mm) is optimal
for registration of longitudinal shift (Fig. 4.7). Measurement of spectral harmonic
amplitude A 1 (z) made it possible to unequivocally determine longitudinal shift of
Fig. 4.6 Dependence of the amplitude A 1 of the first spectral harmonic with the longitudinal shift
of the rotating diffuser for z i + R = N = const: 1−z i + R = 50 mm; 2—z i + R = 100 mm; 3—z i
+R = 200 mm; 4—z i + R = 300 mm; 5—z i + R=450 mm. Reprinted from [2] with permission