Further resolution enhancement of high-sensitivity laser scanning photothermal microscopy applied to mouse endogenous

Abstract

Photothermal microscopy has intrinsically super resolution capability due to the bilinear dependence of signal intensity of pump and probe. In the present paper, we have made further resolution improvement of high-sensitivity laser scanning photothermal microscopy by applying non-linear detection. By this, the new method has the following advantages: (1) super resolution with 61% and 42% enhancement from the diffraction limit values of the probe and pump wavelengths, respectively, by a second-order non-linear scheme, (2) compact light source using inexpensive conventional diode lasers, (3) wide applicability to nonfluorescent materials such as gold nanoparticles (GNPs) and hematoxylin-eosin stained biological samples, (4) relative robustness to optical damage, and (5) a high-frame rate using a Galvano mirror. The maximum resolution is determined to be 160 nm in the second-order non-linear detection mode and 270 nm in the linear detection mode by the PT signal of GNPs. The pixel rate and frame rate for 300 x 300 pixel image are 50 mu s and 4.5 s, respectively. The pixel and frame rate are shorter than the rates, which are 1ms and 100 s, respectively, using the piezo-driven stage system. Published by AIP Publishing.