Photon inc. Application Note - BeamProfiler Asynchronous Reset

Application Note

BeamPro_filer^TM Asynchronous Reset

Asynchronous Reset is a new optional feature of the BeamProfilerª Model 2320 laser beam sensor that allows the laser sensor to be synchronized to a pulsed laser source. Specifically, the Asynchronous Reset feature resets the vertical interval of the laser sensor and starts a new integration period. This feature enables capture of the next pulse after the reset occurs, and is especially useful for lasers that pulse very infrequently, e.g., 1 pulse per minute. It also improves acquisition performance for lasers pulsing at rates up to 30 Hz.

To use this new option feature, the Model 2320 must be configured at the factory with a BNC connector to provide signal to the Asynchronous Reset input to the sensor readout board. In addition, the user must provide:

a TTL pulse of proper polarity and duration to activate the reset, occurring at least 1 ms prior to the occurrence of the laser pulse;
a rising edge TTL signal for the External Trigger Input of the Model 2350 Image Capture Card

The proper signal timing is shown in Figure 1. The asynchronous reset pulse must be TTL low level (<1.7 Volts) for a minimum duration of 2.5 ms. The laser pulse should occur approximately 1 ms after the reset pulse. The External Trigger (TTL rising edge) can occur any time before the end of the next vertical reset interval of the laser sensor.

Figure 1. Asynchronous Reset and External Trigger Signal Timing

Application Note: BeamPro_filer^TM Asynchronous Reset

Rev. 1/00