SIGMA LBA-708 - Manual (Page 63)

• Trigger Out: If your laser is a pulsed type, and you would like the LBA-PC to provide
an output pulse that will cause the laser to be fired, use this setting. See Trigger Out
and Interval and Trigger Out Delay.
• Video Trigger: With this mode selected, the input from your camera is continuously
monitored, and when a laser pulse is detected, the frame is captured. The pulse
detector has a programmable threshold that is settable in the Video Trigger Level edit
control. The level setting is always in raw digitizer counts. A suggested trigger level
value, that will not detect noise yet remain reasonably sensitive, is the second lowest
level.
• Trigger In: If your laser can provide a compatible trigger input pulse to the LBA, then
you can use that pulse to synchronize the capture of your video frame. In general, this
technique is inferior to the preceding Video Trigger mode. Its only advantage would be
to allow you to capture an event that occurs independently of other things that might be
occurring in the video frame that preclude the use of Video Trigger. See Polarity.
Figure 20
The other settings operate and apply as follows:
• Trigger Out: Applies to Trigger Out and Video Trigger modes. Output pulses from
the LBA-PC can be programmed to output Always, or only when the frame grabber is
sampling video While Running. i.e., beginning when you click Start!, ending when
you click Stop! Note: The output trigger pulse is always positive and its pulse width is
fixed (see Specifications).
• Interval: Applies to Trigger Out and Video Trigger modes. You can program the
rate at which the LBA will produce trigger output pulses. The rate is based upon the
camera frame rate. The value entered in this edit control specifies how many frames will
occur for each trigger pulse generated. A setting of 1, will output a trigger pulse once
for every frame of the camera; 2, will output a pulse on every second frame; 3 every
third; and so on... Divide this setting into the camera frame rate to compute the rate at
which the LBA will output trigger pulses. i.e., a 3 will cause a 30 Hz frame rate camera
to fire a laser at 10 frames per second.
• Trigger Out Delay: Applies to Trigger Out and Video Trigger modes. If this item is
not checked, the trigger output pulse will occur at the same time as the camera’s vertical
sync, i.e. at the start of each video frame. For many CCD cameras, this is not a good
time to receive a laser pulse. If you check this item, the trigger output pulse will be
delayed to a time near the middle of the video frame, or field, if the camera is interlaced.
• Polarity: Applies to the Trigger In mode only. The LBA response to a trigger input is
edge sensitive. You can program the response to the input trigger pulse to be either
Positive, rising edge sensitive, or Negative, falling edge sensitive.
Operator’s Manual LBA-PC
Doc. No. 10654-001, Rev 4.10
63