Pyrocam IV Oper
ator’s Manual
Document No. 50337-001
Rev F
2/21/2017
Page 21
WARNING:
Before exposing the Pyrocam detector to a CW Laser, be sure that you will
not exceed the safe operating levels of the array. Refer to APPENDIX A for
damage threshold limits. Permanent damage to the array may result if
these limits are exceeded.
Proper operation of the chopper requires that the readout of the array be performed
synchronous with the motion of the chopper across the array. More specifically, the scan is
synchronized with the leading edges of the chopper as it just covers or uncovers a row of
pixels. If the chopper is running erratically, or is mechanically rubbing on a surface within
the Pyrocam, scan timing may not be properly sync’d and service of the Pyrocam may be
needed.
CAUTION:
DO NOT MOVE THE PYROCAM WHEN RUNNING IN CHOPPED MODE
DAMAGE to the Pyrocam could result.
The Pyrocam chopper blade is an etched metallic disk made from laminated
layers of thin blackened metal that rotates at a high rate of speed. The
rotation and mass of the disk creates a gyroscopic effect. Movement of the
camera while the chopper is rotating will cause the blade to deflect against
the direction of the camera’s movement. This deflection can bring the
rotating blade into contact with the position encoder and/or the imager’s
protective bezel risking costly damage to the chopper and the imager’s
bezel.
When repositioning the Pyrocam it is best to turn off the chopper by placing
it into
Pulsed
mode. If you must move the Pyrocam with the chopper
running, move it very slowing and do not jar or bump the camera into
another object.
3.4.1
Chopped (CW) Setup Procedure
With the Pyrocam set to
Pulsed
trigger mode, align the Pyrocam imager with the beam
path of the laser. Next place the Pyrocam into
Chopped
(CW) trigger mode and wait for
the chopper to spin up to the selected
Chop
Rate.
Hint:
In general, it is best to start with the 50Hz chop rate.
While in CW mode, no external
TRIGGER
source is required, and any source connected
to the
TRIGGER
input will have no effect so long as the Pyrocam is in
Chopped
mode.
The YELLOW trigger LED will appear to glow steadily (it is actually blinking at the
chopping frequency) when the chopper is running and locked onto a stable chopping
rate. When switching to
Chopped
mode from
Pulsed
mode, the YELLOW trigger LED
will go off while the chopper is syncing to the chopping frequency.