The Model 132 Monitor features an alarm which activates when the density level goes beyond the tolerance. The tolerance value can be adjusted between 0.1 and 0.9. By providing an adjustable alarm tolerance, the monitor can be tailored to match process capability of different etchers. Alarm mode provides audible as well as visual (flasing LED display) indication of possible problems. The alarm thresholds are set low enough to provide process control warnings before scrap is generated. Additionally, the alarm will sound if the replenisher pump(s) have run for more than five minutes continuously. The Alarm Cancel button allows the user to silence the alarm for a period of five minutes while the situation is corrected. An alarm condition means any of the following has been detected:
Additionally, the alarm is inhibited during startup while control chamber fills. This prevents unnecessary alarming.