Remote laser microphone as an infrared optical sensor operating in pulsed mode

A remote laser microphone operating as an optical sensor was designed, developed, and experimentally evaluated. The system employs invisible (infrared) laser radiation and operates in a pulsed mode. Hybrid communication–sensor configurations and their circuit implementations were investigated, with particular emphasis on sensor performance and optical wavelength selection. Laser diodes operating in both visible and infrared spectral ranges were analyzed. Experimental results demonstrate that infrared radiation provides safer operation and improved stability compared with visible-light sources; therefore, the use of invisible (infrared) lasers is recommended. The signal-to-noise ratio of the developed system was experimentally measured, and a supporting theoretical analysis was performed. Based on these results, a practical circuit implementation was realized and tested. A functional block diagram incorporating multistage amplification and signal-processing stages was developed and implemented as a working prototype. Experimental measurements yielded key voltage parameters of the received signal. The advantages and limitations of individual system components were analyzed, and conclusions were drawn regarding the performance of the complete transmitter–receiver configuration.

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