Energy measuring system for short pulse lasers

Generally it is difficult to measure the amplitude of the pulses of short pulse lasers using electronic devices, their response time being longer than the duration of the laser pulses. An oscilloscope-based measurement is not capable to perform complex data processing. A compact, cheap, small device is developed for short pulsed lasers. It includes an analog peak-hold unit and a microprocessor driven digitization. This device measures the energy of UV short (fs) pulses shot-by-shot, digitizes and sends the data to the PC across USB interface. After collecting the data there are additional opportunities on the computer side e.g. it is possible to make statistics or to calculate distribution functions. Besides measuring the energy of the short pulses one of the main advantages of it is the noise reduction due to fiber optical coupling. Using fiber optical coupling instead of BNC cable between the PC and the device is a significant improvement to avoid electromagnetic interference (EMI). One order of magnitude noise level reduction is achieved as compared to former devices.


Schematic drawing of the measuring system
Schematic drawing of the measuring system

The energy monitor contains the diode and all the electronics in a single box together with a microprocessor unit. After designing and testing the device two measuring systems were used in a plasma-mirror experiment where the energy of the laser pulse was monitored.


Block diagram of the energy monitoring
Block diagram of the energy monitoring

The measuring system for the plasma mirror experiment
The measuring system for the plasma mirror experiment

Besides using it as an energy monitor in interaction experiments the device can be used in several other applications as investigating the fluctuation of the laser pulse, i.e. applying it as a standard diagnostics of the laser system.

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