A Simple and Low-Cost Method for Generating Short Laser Pulses

A simple, portable method is described and demonstrated for generating short optical pulses (~ 1 μsec) from a continuous wave (CW) source using a rotating pinhole. A CW 633nm HeNe beam was focused onto a 225 μm diameter stainless steel pinhole, which was rotated up to 1000 Hz using an optical chopper wheel. The pulsed light was then focused onto a silicon photodetector and read by an oscilloscope. This novel setup aims to bridge the gap between pulsed laser performance and price for wide application in spectroscopy methods, industrial laser peening, and medical treatments. This will be the first publication of the described pulsed laser method and its techniques and limits. The peak voltage, integral, and width of photodetector pulses of were compared to lend credence to the validity and utility of the experimental setup. The peak of gaussian fits ranging from 2.08 V to 3.67 V was higher than the previous study's basepoint value of 0.0743 V. The integral of pulses increased from the basepoint data of 0.1 V ⋅ μs to a range of 296.8 V ⋅ μs at 1000 Hz to 2698.3 V ⋅ μs at 50 Hz. The average pulse width was longer at a range of 47 μs to 326 μs, compared to the basepoint pulse width of 0.735 μs. Buckingham Pi theorem dimensionless approximations were developed as a versatile method for computing photovoltaic pulse parameters under similar experimental conditions. Finally, a Fisher-Pravica number was derived using non-dimensional analysis.