Design of modulated infrared laser as a radiation source of portable photoacoustic spectroscopy

Photoacoustic spectroscopy can appl in various fields including in the fields of biology (measuring trachea volume and observing insect breathing patterns), medicine (a measurement of internal disease biomarkers through respiratory gases), environment (measuring NO₂ gas in the environment near roads), and agriculture (measurement ethylene gas in postharvest fruit). The existing photoacoustic spectroscopy still has a large size and high operating costs, so it is necessary to design photoacoustic spectroscopy that is portable and low operating costs. In this research, designing an infrared diode laser that can be modulated using software using Visual Studio. There are two tests to see the characteristics of the devices made in this study, namely Arduino testing and testing of the software programs created. Arduino testing resulted in a calibration factor of f_o = 0.9068f_i + 109.33. Meanwhile, software testing resulted in a calibration factor of f_o = 0.7343f_i + 462.74. The two tests that have been carried out have different output results. The software output that is created has a smaller calibration factor than the direct output of the Arduino program. (paper)