Comparison of photoacoustic imaging systems using continuous-wave lasers with a chirped intensity modulation frequency to pulsed lasers

We compare imaging systems using continuous-wave (CW) lasers with a chirped intensity modulation frequency to pulsed lasers. We show that the resolution is the same in both cases. We also compare the signal-to-noise ratio (SNR) of the two systems assuming the fluence is set by the American National Standards Institute (ANSI) limits. Although the SNR depends on several parameters, we find that it is about 20 dB to 30 dB larger for pulsed lasers for reasonable values of the parameters. However, CW diode lasers have the advantage of being compact and relatively inexpensive, which may outweigh the slightly lower SNR in many applications.