Disclosed herein is an apparatus (10) for analyzing a material (12) comprising at least one analyte, said apparatus (10) comprising a measurement body (16) having a contact surface (14) suitable to be brought in thermal contact or pressure-transmitting contact with said material (12), an excitation radiation source configured for irradiating excitation radiation into the material (12) to be absorbed therein, and a detection light source for generating a detection light beam (22) travelling through at least a portion of said measurement body (16) or a component included in said measurement body, wherein said detection light beam is directed to be totally or partially reflected at said contact surface (14), wherein said contact surface (14) of the measurement body is curved in at least one principal direction in the area where the detection light beam (22) is reflected.

A method for measuring a refractive index of a medium includes exciting a first antisymmetric resonance of a first metasurface, including a first periodic array of resonators formed on a substrate surface, with illumination incident on the first metasurface at a non-normal incidence angle with respect to the substrate surface, the first metasurface including the medium encapsulating the first periodic array of resonators. The method also includes determining a refractive index of the medium from a first amplitude of a first transmitted signal that includes a portion of the illumination transmitted through the first metasurface.

A device for determining a refractive index may be provided. The device including at least one waveguide having a core and a cladding surrounding the core, the cladding being at least partly removed in at least one first longitudinal portion and the core including at least one fiber Bragg grating in at least one second longitudinal portion. A method for determining a refractive index or a pressure change in a fluid may also provided. The method may include at least one waveguide having a core and a cladding surrounding the core, the cladding being at least partly removed in at least one longitudinal portion. A method for producing such a device may also be provided.

A planar waveguide device (PWD) for interacting with a fluid (FLD) is disclosed, the planar waveguide device (PWD) comprising a waveguide layer (WGL) for supporting optical confinement, a coupling arrangement (CPA) for in-coupling and out-coupling of light into and from the waveguide layer (WGL), a fluid zone (FZN) for accommodating the fluid (FLD), a filter layer (FTL) arranged between the fluid zone (FZN) and the waveguide layer (WGL) in an interaction region (IAR) of the waveguide layer (WGL),
wherein the filter layer (FTL) comprises filter openings (FOP) arranged to allow the fluid (FLD) to interact with an evanescent field of light guided by the waveguide layer (WGL),
wherein the filter openings (FOP) are adapted to prevent particles (PAR) larger than a predefined size from interacting with said evanescent field,
wherein the filter openings (FOP) are arranged as line openings having their longitudinal direction in parallel with the direction of propagation (DOP) of light guided by the waveguide layer (WGL).

A method and apparatus for measuring a refractive index in a model-free manner are disclosed. The method includes: emitting a light to a surface plasmon generation layer that includes a nanoslot antenna and is disposed adjacent to a sample, to convert the light into surface plasmon; measuring a transmission of the sample from the light that is emitted onto the surface plasmon generation layer and passes through the sample; repeating the measuring the transmission while changing a length of the nanoslot antenna; and determining, based on a machine learning scheme, a restoration refractive index of the sample that is close to a graph of transmissions measured while changing the length of the nanoslot antenna from a library including a refractive index, a length of the nanoslot antenna, and a transmission at a specific wavelength.

A liquid chromatograph comprising a column coupled to a microring resonator array and methods of using the same are disclosed. The microring resonator array measures the bulk refractive index of the mobile phase and any sample injected onto and separated in the column. While carrying out the methods, the composition of a mobile phase passing through the chromatography column may remain substantially constant (isocratic elution) or it may vary (gradient elution). One or more microrings may comprise a covering to act as a thermal control. In addition, the sensor surface may be modified with some type of capture agent that can interact with one or more components in the sample.

An aircraft fuel tank, which includes a water sensor, arranged at the bottom of the tank and connected to a calculation and processing mechanism in order to receive a presence of water signal sent by the sensor, and to return information regarding the need, or not, to perform a fuel tank drainage operation.

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.

In one aspect, an apparatus for determining a property of a fluid is disclosed that in one embodiment may include a transparent member having an axis and a first end substantially perpendicular to the axis and a second end having an outer surface at a first angle to the axis, a light source directing light at the first end, a detector placed spaced from the second end, the space between the second end and the detector containing a fluid, wherein the detector detects light exiting from the outer surface at a second angle to the axis and passing through the fluid, and a controller for determining the second angle from the light detected by the detector. A processor determines the bulk fluid refractive index from the light detected by the detector and a property of the fluid therefrom.

The purpose of the present invention is to achieve an in-situ observation of structural change in a shear field of slurry, i.e. an evaluation of a rheology property of slurry containing raw materials of a ceramic as a fluid sample, together with an in-situ observation of internal structure of the fluid sample in an evaluation process, and a clarification of internal structural change. An observation of an internal structure of a fluid sample 1 in an evaluation process of a rheology property by a rheometer 10 is achieved by generating an optical coherence tomographic image by performing an optical coherence tomography by irradiating a light in infrared region from outside of the rheometer 10 to the fluid sample 1, by inclining an optical axis of light in infrared region irradiating the fluid sample 1 for a predetermined angle within an angular range of 1 to 10 degrees with respect to a normal direction of an observation surface 1A of the fluid sample 1 by the optical coherence tomography imaging device 20, together with an evaluation of a rheology property of the fluid sample 1 containing components different in a refractive index by the rheometer 10.