BC207 Series
Chapter 6: Operation Instructions
Rev: 8.1, 10-Jan-2022
Page 116
© 2022 Thorlabs
Astigmatism
is known as the effect that the beam waist in X and Y scan direction is not at the
same z position. So there is a difference between the positions of minimal spot diameters z
0y
and z
0y
.
Relative Astigmatism
is calculated from the Astigmatism values divided by the mean of the
Rayleigh Length in X and Y.
(
)
astigmatism_rel=
_Y
_ X
R Y
R X
Z
- Z
Z
Z
-
¸
01
01
1
1
2
Full Divergence Angle
is explained in section
.
Divergence Asymmetry
is the ratio of the divergence angles in Y and X axes. Values differing
from 1.0 indicate that the beam ellipticity is changing with Z position, for instance when an ellip-
tical beam is focussed to a round spot.
Note
All results are calculated from the applied fit!
140
Summary of Contents for BC207UV
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