Photothermal microscopy: optical detection of small absorbers in scattering environments

Abstract

SummaryPhotothermal microscopy enables detection of nanometersized objects solely based on their absorption. This technique allows efficient observation of various nano-objects in scattering media notably gold nanoparticles in cells. The extreme sensitivity of the method and the stability of the signals open numerous applications in spectroscopy, analytical chemistry and bioimaging. This review briefly describes the principle and the main characteristics of photothermal microscopy, with its major advantages and limitations, and exposes the principal applications that have been carried out since its first implementation.

Integrated Micro-Optics for Microfluidic Detection

“…Photothermal spectroscopy is well known as a highly sensitive tool for detecting nonfluorescent compounds, 20,21 where thermal lens detection is often used in microfluidic applications. 22 In thermal lens detection, a non-fluorescent sample solution absorbs the excitation laser, and the absorbed light energy is released as thermal energy via non-radiative relaxation to increase temperature around the excitation beam.…”

Nonlinear spectroscopy of plasmonic nanoparticles

“…The combination of an infrared pump beam and a visible probe beam leads to an optical resolution defined by the visible wavelength in combination with spectroscopic information of the infrared wavelength [59]. A recent review gives a more detailled overview on this technique [60].…”

Photothermal Microscopy for High Sensitivity and High Resolution Absorption Contrast Imaging of Biological Tissues

“…In previous reports, a low-NA condenser or an iris diaphragm placed after the condenser was used to pass only a part of the probe beam at a small angle for maximization of SNR [13,20,21]. However, as the probe beam at a large angle is modulated out of phase with respect to that at a small angle, signal intensity improves by up to two times if the inner portion and outer portion of transmitted probe beam is separated into two and then detected by a balanced (differential) detector [22].…”

“…However, in PT microscopy, an integration time of 1 to 10 ms per pixel is typically needed to attain a sufficient signal-to-noise ratio (SNR) [13]. Thus, the image acquisition time is still slower than that achieved by conventional laser scanning fluorescence microscopy, with integration times as low as 1 to 10 µs per pixel.…”