An optical device configured to pass an input light signal through a medium under test, for example, a fluid, and to retrieve an output light signal. A comparison of the output light signal to the input light signal is indicative of the medium and can be used to determine if another unknown medium is the same. Another optical device passes an input signal through a known medium and an unknown medium and corresponding output light signals are received. A comparison of the output light signal corresponding to the unknown medium with the output light signal of the known medium can be used to characterize the unknown medium as against other mediums.

A method can include transmitting, from a light source, light through a fuel tank ullage, and determining, by a processing device, an amount of absorption of at least one wavelength of the transmitted light. The method can further include determining, by the processing device based on the amount of absorption of the at least one wavelength of the transmitted light, a chemical composition of the fuel tank ullage.

For comparing first optical properties of a first fluid with second optical properties of a second fluid a first transparent grating having a grating constant is made of the first liquid, and a second transparent grating also having the grating constant is made of the second liquid. The second transparent grating is arranged at a lateral offset of less than 45% of the grating constant with regard to the first transparent grating such that grating bars of the first and second transparent gratings are arranged side by side. Coherent light is directed onto the first and second transparent gratings such that light which passed through the grating bars of the first and second transparent gratings forms a diffraction pattern comprising intensity maxima. Two light intensities of two intensity maxima of a same order higher than zero are measured and compared to each other.

An observation apparatus includes a case having a transmissive window, an image sensor, an optical system, and a light source housed in the case, and an optical deflection unit. The optical system is configured to condense light incident inside the case to form an image of a sample inside a container. The light source is configured to emit light to the outside of the case without passing through the optical system. The optical deflection unit is configured to deflect light emitted to the outside of the case from the light source to a first direction proceeding toward the transmissive window. An angle of exit between the first direction and an optical axis of the optical system is different from an angle of incidence between a second direction in which light emitted to the outside of the case is incident on the optical deflection unit, and the optical axis.

An optical refraction barometer measures pressure based on refractivity changes and includes: an optical light source; an optical frequency controller; a first optical phase controller; a first polarization controller; an electronic reference arm in optical communication with the first polarization controller; a second optical phase controller in optical communication with the optical frequency controller; a second polarization controller in optical communication with the second optical phase controller; an electronic sample arm in optical communication with the second polarization controller and in electrical communication with the second optical phase controller; a second sideband frequency generator; a mixer in electrical communication with the detector and the second sideband frequency generator; and a first sideband frequency generator in electrical communication with the mixer; and a dual fixed length optical cavity refractometer.

A material application and analysis device may comprise at least one analysis device for optically monitoring at least a first material application and a second material application, and a material application element for applying the second material application to a substrate provided with the first material application at least in sections. The material application element is arranged between a first radiation source and detection device assembly and a second radiation source and detection device assembly, wherein by the first radiation source and detection device assembly the first material application is detectable and wherein by the second radiation source and detection device assembly the second material application is detectable. Furthermore, first image data are processed and second image data are processed, and the processed first image data are evaluated with respect to a physical parameter and the processed second image data are evaluated with respect to a geometrical parameter.

Methods, systems, and devices for wearing detection are described. A method may include directing light from a light source to a detector using an optical light guide of the wearable device, where the optical light guide includes an optical interface configured to allow at least a portion of the directed light to escape the optical light guide based on a refractive property of a material contacting the optical interface. The method may include measuring, via the detector, an amount of escaped light which escaped the optical light guide, where the amount of escaped light is indicative of a level of surface contact at the optical interface of the optical light guide. The method may further include controlling an activation of one or more sensors of the wearable device based on the amount of escaped light.

This invention this invention is a device and method for validating the identity of a liquid in a container that is transparent to light, while the liquid is in the container, without physically invading container. The liquid is particularly suited for validating vaccines such as the vaccine for COVID-19. The invention uses light from a refractometer and/or nephelometer, passing into and reflected out of the transparent wall of the container, to characterize the liquid.

The hybrid measurement system includes an evanescent prism coupling spectroscopy (EPCS) sub-system and a light-scattering polarimetry (LSP) sub-system. The EPCS sub-system includes an EPCS light source system optically coupled to an EPCS detector system through an EPCS coupling prism. The LSP sub-system includes an LSP light source optically coupled to an optical compensator, which in turn is optically coupled to a LSP detector system via a LSP coupling prism. A support structure supports the EPCS and LSP coupling prisms to define a coupling prism assembly, which supports the two prisms at a measurement location. Stress measurements made using the EPCS and LSP sub-systems are combined to fully characterize the stress properties of a transparent chemically strengthened substrate. Methods of processing the EPCS and LSP measurements and enhanced configurations of the EPCS and LPS sub-systems to improve measurement accuracy are also disclosed.

A refractometer includes an enclosure, a single use prism, a light source, and an index of refraction (IoR) sensor. The single use prism is removably disposed within the enclosure. The light source and IoR sensor are disposed within the housing and are configured to be repeatably used with a series of single use prisms of similar construction. One single use prism can be removed after being used, and a new single use prism can be installed in the enclosure for use with the same light source and IoR sensor as were used with the first prism.