User`s manual

Biaxial Displacement Follower User’s Manual Version 1.4, April 19, 2004 IM1013
Page
17
Operating Procedures
General Operating Procedure
1
Prepare the target and lighting as specified. Note that the light source should be DC to eliminate the 120 Hz intensity
modulation, and that the light intensity should be uniform over the target area to be measured.
2
Connect the optical head to the control unit with the cable supplied.
3
Connect the control unit to a 100-120 VAC, 50/60 Hz power source.
4
Estimate the maximum displacement you expect from the target during operations.
5
From the Standard Lens Set, and using the Lens Calibration data at the end of this manual, find a lens system that will
give a range of measurement comparable to the estimated maximum displacement for the target.
6
Attach the selected lens system onto the tracking head and place the tracking head at the proper working distance from
the target. Mount the head in a way that will minimize relative motion between the head and the target.
7
Observe the target through the viewer. If the target is approximately at the specified distance from the lenses, it should
be visible in the viewer. Adjust the head position until the target is in sharp focus. The full-scale measurement range of
the target is represented in the viewer by the 0.15” square. The system is capable of tracking a 20% target to
approximately 120% full scale, although linearity cannot be guaranteed beyond the normal full-scale limits.
8
Set the vertical and horizontal gain to the values specified in the System Calibration. The gain potentiometer simply
adjusts the proportionality between target displacement and output voltage. Note that this applies to the fixed focus
105-mm lenses only. For variable-focus lens systems, the output gain will have to be determined by actual calibration.
9
Set the output filter to
OFF
(widest bandwidth).
10
Set the biaxial target to be tracked, light over dark, dark over light, etc. These switches must be set properly or the
normal negative feedback servo action becomes positive and renders the system inoperative.
11
Set the Mode Switch to Light level.
12
Turn the control unit and allow approximately 15 minutes warm- up time.
13
When the Mode Switch is set to Light level, the system will measure the amount of light on the target exactly in the
center of the range of measurement. The target position should be adjusted so that the small circle within the
measurement range is totally within the dark area of the target. Adjust the lock control until the horizontal meter reads
–20%.
14
Move the target or tracing head so that the circle is totally within the light area of the target. The meter will now
properly read the amount of light at the target. Adjust the lens aperture or light source for a reading of +20% (refer to
Focusing and System Noise).Repeat steps 13 and 14 until the light and dark readings are repeatable.