A photothermal absorbance detection apparatus comprises a flow cell comprising a first temperature responsive device on an input side, a second temperature responsive device on an output side, and a detection region between the first temperature responsive device and the second temperature responsive device; and a light-emitting device positioned proximate to the detection region and configured to transmit electromagnetic radiation towards the detection region; wherein the first temperature responsive device and the second temperature responsive device together measure a change in temperature of a fluid passing through the detection region.

Systems, methods and devices to detect target substances in confined or open spaces, and from the ground or remote locations are disclosed. A system includes a radiation emission source and one or more transducers configured to detect target substances. The transducer to detect target substances includes a filter that allows various wavelengths of light to pass through while attenuates or reflects others; and one or more chambers disposed within the optical path of the filter. The transducer may also include electromagnetic radiation detectors to detect electromagnetic radiation at wavelengths different from the wavelengths transmitted by the filter. The systems, methods, and devices disclosed allow shifting the detection range of phenomena in which the detection/observation technology is not efficient to other detection ranges where detection can be optimized.

Systems and methods are provided for performing thermophotonic imaging using cross-correlation and subsequent time-gated truncation. Photothermal radiation is detected with an infrared camera while exciting a sample with a chirped set of incident optical pulses and time-dependent photothermal signal data is processed using a method that involves performing cross-correlation and subsequent time-gated truncation. The post-cross-correlation truncation method results in depth-resolved images with axial and lateral resolution beyond the well-known thermal-diffusion-length-limited, depth-integrated nature of conventional imaging modalities. An axially resolved photothermal image sequence can be obtained, capable of reconstructing three-dimensional visualizations of photothermal features in wide classes of materials.

An apparatus includes an integrated waveguide structure, and a first light source operable to produce a probe beam having a first wavelength, wherein the probe beam is coupled into a first end of the waveguide structure. A second light source is operable to produce an excitation beam with having a second wavelength to excite gas molecules in close proximity to a path of the probe beam. A light detector is coupled to a second end of the integrated waveguide structure and is operable to detect the probe beam after it passes through the waveguide structure. The apparatus is operable such that excitation of the gas molecules results in a temperature increase of the gas molecules that induces a change in the probe beam that is measurable by the light detector.

System for performing chemical spectroscopy on samples from the scale of nanometers to millimeters or more with a multifunctional platform combining analytical and imaging techniques including dual beam photo-thermal spectroscopy with confocal microscopy, Raman spectroscopy, fluorescence detection, various vacuum analytical techniques and/or mass spectrometry. In embodiments described herein, the light beams of a dual-beam system are used for heating and sensing.

A screening system includes a modulated light source, a wavelength-shifting filter, and a photosensor. The light source is operable to emit light into a screening region through which people or objects move. The photosensor is adjacent the screening region and is operable to emit sensor signals from scattered light received through the wavelength-shifting filter from interaction of the light with the people or objects in the screening region.

System for performing chemical spectroscopy on samples from the scale of nanometers to millimeters or more with a multifunctional platform combining analytical and imaging techniques including dual beam photo-thermal spectroscopy with confocal microscopy, Raman spectroscopy, fluorescence detection, various vacuum analytical techniques and/or mass spectrometry. In embodiments described herein, the light beams of a dual-beam system are used for heating and sensing.

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.

A system and method for photo-thermal imaging of a lateral flow immunoassay (LFA) device are provided. The system includes an intensity modulated heat source directed at a surface of the LFA device to selectively excite chromophore particles of interest and a thermal capture device configured to capture thermal waves emitted from the surface of the LFA device as a radiometric signal. A computing device, in communication with the thermal capture device, receives the radiometric signal and executes lock-in demodulation to detect surface or subsurface inhomogeneities of the LFA device.

An absorption sheet for absorbing power from an electromagnetic wave generated by a device under test includes a substrate and an array of absorption elements. Each absorption element includes a conductive portion and a resistive portion. A system for performing a radiation characterization includes the absorption sheet. A method of measuring a radiative near field of a device under test and a method of characterizing a radiative near field of a device under test are also disclosed.