Polytec PSV-500, Руководство по оборудованию

Страница: 97 / 109

A-27
A Optional Accessories
A.7 PSV-A-525 Protective Window
A.7.1 Introduction
The PSV-A-525 protective window covers the laser beam exit as well as the
aperture of the video camera on the scanning head. Furthermore the
protective window dampens the acoustic excitation of the scanner mirrors.
Metrological
limitations
The protective window is not suitable for default use, because the use entail
the following limitations:
•
In the case of perpendicularly incidence of the laser beam to the
protective window, the direct reflection of the protective window is
mirrored to the detector of the vibrometer. Instead of the object under
investigation, the vibration of the protective window is measured.
•
The disturbed scan range depends on the focused stand-off distance. At a
stand-off distance with less than 1 m, because of the direct reflection a
centralized scan range of up to ± 3° must be precluded from the
measurement. For measurements with a stand-off distance of more than
1 m, the disturbed scan range is limited to ≤ ± 1°. In this disturbed scan
range, it is possible that also the autofocus is not working properly.
•
Geometry measurements are not possible with mounted protective
window.
•
The scan area is limited to ± 15°.
•
When using the wide angle setting of the video camera a shading of the
video image on the right edge occurs. The specified scan range of ± 15° is
visible in all stand-off distances on the video image.
•
Depending on the scanning angle of the laser beam, a lateral
displacement of the beam occurs. This can be widely compensated by
carrying out the alignment with the mounted protective window.
NOTE!
Soiling on the protective window will taint the measurement results. Thus the protective
window has to be free of dirt and dust. Remove dust only with compressed air from an air
duster. Remove dirt with a lint-free cellulose cloth and only use water-based or alcohol-
based glass cleaner if necessary. Do not use any acidic or ammoniacal detergents.
Figure A.19: PSV-A-525 protective window