Systems and methods for sensing vibrational absorption induced photothermal effect via a visible light source. A Mid-infrared photothermal probe (MI-PTP, or MIP) approach achieves 10 mM detection sensitivity and sub-micron lateral spatial resolution. Such performance exceeds the diffraction limit of infrared microscopy and allows label-free three-dimensional chemical imaging of live cells and organisms. Distributions of endogenous lipid and exogenous drug inside single cells can be visualized. MIP imaging technology may enable applications from monitoring metabolic activities to high-resolution mapping of drug molecules in living systems, which are beyond the reach of current infrared microscopy.

The invention relates, inter alia, to an apparatus for analyzing a material, including an excitation emission device for generating at least one electromagnetic excitation beam, in particular an exciting light beam, having at least one excitation wavelength, further including a detection device for detecting a reaction signal, and a device for analyzing the material on the basis of the detected reaction signal.

A method includes directing a first plurality of probe laser pulses through a sample, dividing each of the first plurality of probe laser pulses to generate a first interferogram, and generating first image data reproducible as a first phase image of the sample. A plurality of pump laser bursts are directed onto the sample to heat the sample. A second plurality of probe laser pulses are directed through the sample at a predetermined time delay. Each of the second plurality of probe laser pulses are divided to generate a second interferogram. Second image data is generated that is reproducible as a second phase image of the sample. A transient phase shift is determined in the second phase image relative to the first phase image. A vibrational spectroscopy property is determined of the sample based on the transient phase shift, thereby allowing an identification of chemical bond information of within the sample.

An apparatus for photo-acoustic measurement of a measurement target in a fluid flow comprises:an ellipsoidal measurement chamber (3) having a first focal point and a second focal point; a duct (6, 7, 8) configured to guide a fluid flow through the measurement chamber (3) along a first axis (X) through the first focal point; light source means for generating an excitation light beam of modulated intensity; means configured to pass the excitation light beam through the measurement chamber (3) along a second axis (Y), which is different from the first axis (X), such that the excitation light beam crosses the fluid flow at the first focal point and that the crossing of the fluid flow and the excitation light beam defines an excitation volume (4) within which the fluid flow is excited by the excitation light beam to generate acoustic waves; and detecting means (5) arranged at the second focal point and configured to detect said acoustic waves, wherein the detecting means has no direct contact with the fluid flow, and wherein the ellipsoidal measurement chamber has inner walls that are configured to focus the acoustic waves generated by the excitation light beam within the excitation volume (4) onto the detecting means (5).

Mid-infrared photothermal heterodyne imaging (MIR-PHI) techniques described herein overcome the diffraction limit of traditional MIR imaging and uses visible photodiodes as detectors. MIR-PHI experiments are shown that achieve high sensitivity, sub-diffraction limit spatial resolution, and high acquisition speed. Sensitive, affordable, and widely applicable, photothermal imaging techniques described herein can serve as a useful imaging tool for biological systems and other submicron-scale applications.

The invention relates, inter alia, to an apparatus (10) for analyzing a material (101), comprising an excitation emission device (100) for generating at least one electromagnetic excitation beam (SA), in particular an exciting light beam, having at least one excitation wavelength, further comprising a detection device (106) for detecting a reaction signal (SR), and a device (107) for analyzing the material on the basis of the detected reaction signal (SR).

A method includes directing a first plurality of probe laser pulses through a sample, dividing each of the first plurality of probe laser pulses to generate a first interferogram, and generating first image data reproducible as a first phase image of the sample. A plurality of pump laser bursts are directed onto the sample to heat the sample. A second plurality of probe laser pulses are directed through the sample at a predetermined time delay. Each of the second plurality of probe laser pulses are divided to generate a second interferogram. Second image data is generated that is reproducible as a second phase image of the sample. A transient phase shift is determined in the second phase image relative to the first phase image. A vibrational spectroscopy property is determined of the sample based on the transient phase shift, thereby allowing an identification of chemical bond information of within the sample.

A method includes directing a first plurality of probe laser pulses through a sample, dividing each of the first plurality of probe laser pulses to generate a first interferogram, and generating first image data reproducible as a first phase image of the sample. A plurality of pump laser bursts are directed onto the sample to heat the sample. A second plurality of probe laser pulses are directed through the sample at a predetermined time delay. Each of the second plurality of probe laser pulses are divided to generate a second interferogram. Second image data is generated that is reproducible as a second phase image of the sample. A transient phase shift is determined in the second phase image relative to the first phase image. A vibrational spectroscopy property is determined of the sample based on the transient phase shift, thereby allowing an identification of chemical bond information of within the sample.

A photothermal interferometry apparatus and method for detecting a molecule in a sample, in particular for detecting a trace gas species, comprising: a Fabry-Perot interferometer with a first mirror, a second mirror and a first cavity for containing the sample extending between the first and the second mirror, a probe laser for passing a probe laser beam through the first cavity of the Fabry-Perot interferometer, an excitation laser for passing an excitation laser beam through the first cavity of the Fabry-Perot interferometer for exciting the molecule in the sample, and a photodetector unit for detecting the transmitted probe laser beam passed through the first cavity of the Fabry-Perot interferometer.

Mid-infrared photothermal heterodyne imaging (MIR-PHI) techniques described herein overcome the diffraction limit of traditional MIR imaging and uses visible photodiodes as detectors. MIR-PHI experiments are shown that achieve high sensitivity, sub-diffraction limit spatial resolution, and high acquisition speed. Sensitive, affordable, and widely applicable, photothermal imaging techniques described herein can serve as a useful imaging tool for biological systems and other submicron-scale applications.