Development of a frequency-modulated photoacoustic microscope system for thermal imaging using a picosecond laser

Krishnan Sathiyamoorthy; Michael C. Kolios

doi:10.1117/12.2650401

16 March 2023 Development of a frequency-modulated photoacoustic microscope system for thermal imaging using a picosecond laser

Krishnan Sathiyamoorthy, Michael C. Kolios

Author Affiliations +

Proceedings Volume 12391, Label-free Biomedical Imaging and Sensing (LBIS) 2023; 123910J (2023) https://doi.org/10.1117/12.2650401
Event: SPIE BiOS, 2023, San Francisco, California, United States

Abstract

This work uses a picosecond pulsed laser in frequency-domain photoacoustic microscopy (FDPAM) for thermal imaging of the sample. It uses the principle of the frequency-domain photoacoustic (PA) spectroscopy employed for trace gas detection relying on the thermal effect caused by the absorbance of the sequence of picosecond pulses. The thermal effect is modulated to a periodic thermal wave using a mechanical optical chopper. The PA signal caused by the thermal wave is measured by a PA sensor containing a microphone connected to a lock-in amplifier. The FDPAM uses a high repetitive (100 kHz, 500 ps) picosecond pulsed laser, a kHz frequency microphone, a chopper, and a lock-in amplifier. The system is tested using a USAF resolution chart. The system imaged a chrome metal strip of thickness 120 nm and width 3.1 µm of a USAF chart. The system exhibits a PA signal with a maximum amplitude of 2x10^-4 V for a modulation frequency of 760 Hz. The signal is about four times lower than those obtained (8 x10^-4) by a 532 nm CW laser of power 3 mW. The SNR of the system for the USAF chart is 5.5 dB. The system has a lateral resolution of 3.1 µm. The imaging resolution of the system can be improved by using an objective with a lower f-number.

Conference Presentation

Citation Download Citation

Krishnan Sathiyamoorthy and Michael C. Kolios "Development of a frequency-modulated photoacoustic microscope system for thermal imaging using a picosecond laser", Proc. SPIE 12391, Label-free Biomedical Imaging and Sensing (LBIS) 2023, 123910J (16 March 2023); https://doi.org/10.1117/12.2650401

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