This application relates to an optical refractometer. In one aspect, the optical refractometer includes a prism, a light source and a sensor. The prism includes a first surface to which light is incident, a second surface to which the incident light is refracted when it contacts a substance, and a third surface reflecting the light refracted at the second surface toward the first surface. The light source emits light onto the first surface of the prism to be refracted toward the second surface. The sensor receives the light reflected from the third surface and output from the first surface. The light projected from the light source travels an optical path that directs the light to pass through the first surface of the prism, refract on the second surface, reflect on the third surface, and emit and condense to the first surface.

Methodology of characterizing surface properties and determining refractive index and extinction coefficient of a prism shaped material, including simultaneously for a multiplicity of wavelengths, using an easy to practice technique.

A method for optical inspection includes illuminating a patterned polymer layer on a semiconductor wafer with optical radiation over a range of infrared wavelengths, measuring spectral properties of the optical radiation reflected from multiple points on the patterned polymer layer over the range of infrared wavelengths, and based on the measured spectral properties, computing a complex refractive index of the patterned polymer layer.

The present invention provides a tapered side-polished fiber-optic biosensor (FOBS) and a method for preparing a tapered side-polished fiber (SPF). The biosensor includes a broadband light source, a first single-mode fiber, a tapered SPF, a second single-mode fiber, and a spectrometer. The broadband light source is connected to the tapered SPF through the first single-mode fiber, and the tapered SPF is connected to the spectrometer through the second single-mode fiber. The broadband light source is configured to emit a light wave. The spectrometer is configured to display a spectrum corresponding to a light wave passing through the first single-mode fiber, the tapered SPF, and the second single-mode fiber successively. In the present invention, a fiber side-polishing technology is combined with a fiber tapering technology to construct a tapered SPF, and a spectrum changes by changing a refractive index around a side-polished tapered region, thereby measuring the refractive index. In addition, the tapered SPF provided in the present invention can generate a Vernier effect, thereby improving the sensor's anti-electromagnetic interference and sensitivity to refractive index measurement.

Apparatus, methods and are disclosed for measuring refractive index of a material film. The method and apparatus utilize a reference measurement and as series of reflectance measurements at a range of wavelengths and thickness values for the material film to determine the refractive index of the material film.

Provided is a method and apparatus for monitoring quality and determining contamination of a space, the method including measuring a plurality of quality parameter actual values in a space with a sensor system, wherein the actual value of at least one quality parameter is measured at a plurality of measuring locations, wherein the sensor system includes a plurality of sensors, comparing the quality parameter actual values with target values for the respective measuring locations, moving the at least one mobile sensor with a control system to a measuring location spaced apart from the previous measuring location of the at least one mobile sensor, wherein in the event of an incident at least one mobile sensor is moved with the control system deviating from the stored movement plan, wherein the data processing system determines the spatial spread, type of contamination and/or concentration of the respective contamination of the space.

Apparatus, methods and are disclosed for measuring refractive index of a material film. The method and apparatus utilize a reference measurement and as series of reflectance measurements at a range of wavelengths and thickness values for the material film to determine the refractive index of the material film.

A method of reducing noise in an output signal of a differential refractive index detection part (RI detection part) of a dual-flow type with an analysis device having the RI detection part includes sending a sample liquid to a sample cell with a sample pump, sending a reference liquid to a reference cell with a reference pump, and detecting a change in direction of travel of light sequentially transmitted through the two cells with a light detector. Before starting RI measurement, a phase difference between the sample pump and the reference pump is adjusted so that a noise that occurs in an output signal of the light detector by propagation of pulsation from the sample pump within the sample cell and a noise that occurs in the output signal of the light detector by propagation of pulsation from the reference pump within the reference cell cancel each other.

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.

A method of determining a refractive index of a material sample comprises removably mounting the material sample into a sample holder having a thermal control mechanism, a thermal expansion compensation mechanism, and a rotation mechanism; projecting a laser beam into the material sample, wherein the material sample has a predetermined orientation and temperature, wherein the material sample has parallel sides defining parallel planes for entry and exit of the laser beam into and out of the material sample; collecting a refracted laser beam from the material sample, and determining the refractive index for the material sample at the predetermined temperature. The laser beam may be a visible laser and/or an infrared laser. The thermal control mechanism comprises a thermal controller coupled to an induction coil apparatus and a temperature sensor. The sample holder comprises a refractory metal consisting of one or more of a niobium/molybdenum alloy and a tantalum/tungsten alloy.