Precision Laser Pulse Radiometer.
DEPARTMENT OF THE NAVY WASHINGTON DC
Pagination or Media Count:
Apparatus for automatically detecting and measuring the energy of laser pulses over a wide range of eneregy levels and in the presence of high ambient light levels. The current produced by a laser pulse striking a photoconductive detector is integrated by a capacitor to obtain a voltage across the capacitor which is proportional to the total energy incident on the detector during the pulse. The total energy of the pulse is then determined by measuring the time from when the capacitor voltage crosses a reference level during current integration to the time when the capacitor voltage, discharging through a resistor recrosses the reference voltage. The leading edge of the capacitor charging voltage is used to couple a high frequency oscillator to the input of a counter. The oscillator is then decoupled from the counter when the voltage of the discharging capacitor crosses a reference level. The count in the counter is transferred to a shift register for transmission to a data processing device. The effects of the ambient light are automatically compensated for with an interrupted feedback loop in which the loop is opened when a laser pulse is detected and the feedback held at the prepulse level for the duration ofthe RC discharge time.
- Lasers and Masers