The present disclosure is directed toward optical elements, such as sample cuvettes, lenses, prisms, and the like, whose transmissivity is increased by the addition of a geometric anti-reflection layer disposed on at least one surface of the optical element, where the geometric anti-reflection layer includes a plurality of geometric features that collectively reduce the reflectivity of the interface between the surface and another medium. As a result, more of an optical signal incident on the surface passes through the interface. In some embodiments, every surface through which an optical signal passes includes a geometric anti-reflection layer. Due to the increased transmissivity of the optical element, in some embodiments, the use of low-cost, high-refractive-index materials, such as conventional silicon, is enabled.

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.

Systems and methods are provided for thermal inspection of tape layup. One embodiment is a method for performing inspection of a tape layup. The method comprises laying up tape onto a surface of a laminate, applying heat to tack the tape to the surface, and generating thermographic images of the tape as applied to the surface.

A photo-thermal interferometer for measuring the light absorption of an aerosol or gas comprises a first laser source emitting a laser beam and a beam splitter adapted to divide the laser beam into a probe beam and a reference beam. The interferometer further comprises first optical elements which are adapted to direct the probe beam such that it passes through the aerosol and interferes with the reference beam thereafter thereby causing interference patterns. A detector detects the interference patterns. The interferometer further comprises a second laser source configured to emit a pump beam for transferring energy to the aerosol. Second optical elements are adapted to direct the pump beam such that it overlaps with the probe beam at least partially in the aerosol or gas. At least one of the second optical elements modifying the pump beam is an axicon.

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.

Assays used in conjunction with a thermal contrast reader are disclosed. In the assay, the test strip includes materials that can develop a thermal response if a target analyte is present in a sample. Linear flow assays include nanoparticles with high affinity binding to the analyte. Binding of the nanoparticles with an analyte in the sample is detected using thermal contrast. Analytes over a broad range of concentrations are detected in the linear flow assays. Methods of detecting target analytes and kits comprising lateral flow assays and thermal contrast reader are also disclosed.

The present disclosure is directed toward a cuvette for holding a test sample during optical interrogation with a light signal. The transmissivity of the cuvette is increased by a geometric anti-reflection layer disposed on at least one surface of the cuvette, where the geometric anti-reflection layer includes a plurality of geometric features that collectively reduce the reflectivity of the interface between the surface and another medium. As a result, more of the interrogation signal passes through the interface. In some embodiments, every surface through which the interrogation signal passes includes a geometric anti-reflection layer. Due to the increased transmissivity of the cuvette, light detected after passing through it can have an improved signal-to-noise ratio and/or the light signal used to interrogate the sample can have lower intensity. In addition, the reduction of the reflectivity of each surface enables the use of low-cost, high-refractive-index materials, such as conventional silicon.

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 photothermal deflection measuring system includes a substrate, a detecting light source, a detecting unit, and a processor. The substrate includes a plurality of positioning structures, on each of which supports a cell emitting heat outside a surface thereof. The detecting light source is utilized to project a detecting light passing through a specific position outside the surface whereby the detecting light is deflected due to a thermal gradient caused by the emitted heat. The detecting unit is arranged at a side of the cell for receiving the deflected detecting light thereby generating an optical deflection signal corresponding to a deflection of the deflected detecting light. The processor is configured to receive the optical deflection signal, analyze the optical deflection signal and determine a heat value corresponding to the specific position out side the surface of the cell according to the optical deflection signal.

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.