US Patent 11786128 PARS imaging methods

A method for visualizing details in a sample including directing an excitation beam to an excitation location below a surface of the sample, to generate signals in the sample; directing an interrogation beam toward the excitation location of the sample; directing a signal enhancement beam to the sample, to raise a temperature of a portion of the sample by 5 Kelvin or less, compared to a temperature of the portion of the sample in absence of the signal enhancement beam; detecting a portion of the interrogation beam returning from the sample that is indicative of the generated signals.