A label-free optical device for near real time quantification of the multifractal micro-optical properties of a sample includes a source of broadband light; a tunable filter that receives at least a portion of the broadband light and then transmits narrowband light, whereby a specific band of light is selected to avoid unwanted absorption of light by the sample; where the narrowband light is configured to illuminate a selected area of the sample, and in response elastically-scattered light is dispersed from the sample; a light collection device configured to collect at least some of the elastically-scattered light; where at least some of the collected elastically-scattered light is configured to be transmitted to a detector by the light collection device, and the detector is configured to record a light scattering signal; and where the detector is configured to perform light scattering signal measurements at multiple angles or wavelengths to determine a refractive index multifractality of the sample.

There is provided detecting modification of optically active cellulose-based film. A method comprises split refracting or split reflecting light received by a surface pattern of an optically active cellulose-based film into a plurality of output light patterns, wherein an output light pattern is determined from the plurality of output light patterns on the basis of a modification applied to the optically active cellulose-based film.

A droplet sensor includes an optical cover that forms part of a spheroid, a major axis of the spheroid being a vertical axis, a light emitting/receiving device disposed at a position offset from a first focal point of the spheroid along the major axis, and a reflector disposed in vicinity of a second focal point of the spheroid. The optical cover has an effective detection area between the light emitting/receiving device and the reflector. The effective detection area satisfies a total internal reflection condition at an interface with a gas, and does not satisfy the total internal reflection condition at an interface with a liquid. The reflector reflects, towards a light receiving surface of the light emitting/receiving device, light totally reflected by the effective detection area, or reflects, towards the effective detection area, light directly incident on the reflector from the light emitting/receiving device.

A droplet sensor includes an optical cover that forms part of a spheroid, a major axis of the spheroid being a vertical axis, a light emitting/receiving device disposed at a position offset from a first focal point of the spheroid along the major axis, and a reflector disposed in vicinity of a second focal point of the spheroid. The optical cover has an effective detection area between the light emitting/receiving device and the reflector. The effective detection area satisfies a total internal reflection condition at an interface with a gas, and does not satisfy the total internal reflection condition at an interface with a liquid. The reflector reflects, towards a light receiving surface of the light emitting/receiving device, light totally reflected by the effective detection area, or reflects, towards the effective detection area, light directly incident on the reflector from the light emitting/receiving device.

Described embodiments include a system for inspecting a tubular device that includes an outer surface and a spatially-periodic supporting structure beneath the outer surface. The system includes an imaging device, configured to acquire an image of a reflection of light from the outer surface, and a processor, configured to ascertain a spatial frequency of the supporting structure by processing the image. Other embodiments are also described.

Described embodiments include a system for inspecting a tubular device that includes an outer surface and a spatially-periodic supporting structure beneath the outer surface. The system includes an imaging device, configured to acquire an image of a reflection of light from the outer surface, and a processor, configured to ascertain a spatial frequency of the supporting structure by processing the image. Other embodiments are also described.

A monitoring system and method are presented for use in monitoring a target. The monitoring system comprises: an input utility for receiving input data comprising measured data indicative of optical response of the target measured under predetermined conditions and comprising phase data indicative of a two-dimensional profile of full phase of the optical response of the target in a predetermined two-dimensional parametric space including a two-dimensional range in which said target exhibits phase singularity; an analyzer module for processing said measured data and extracting at least one phase singularity signature of the target characterizing the target status, the phase singularity signature being formed by a number N of phase singularity points, each corresponding to a condition that the physical phase continuously accumulates a nonzero integer multiple m of 2π around said point.

A testing apparatus for dynamic characterization of a sample of a material under test. A terahertz (THz) time-domain spectroscopy system is configured and arranged to generate and detect terahertz waves to interrogate the sample. A shock wave loading system is configured and arranged to produce a shock wave in the sample concurrently with said THz spectroscopy device interrogating the sample. The sample undergoes changes in an index of refraction in response to the produced ultrafast shock wave in the sample that are detected by the terahertz spectroscopy system.

A testing apparatus for dynamic characterization of a sample of a material under test. A terahertz (THz) time-domain spectroscopy system is configured and arranged to generate and detect terahertz waves to interrogate the sample. A shock wave loading system is configured and arranged to produce a shock wave in the sample concurrently with said THz spectroscopy device interrogating the sample. The sample undergoes changes in an index of refraction in response to the produced ultrafast shock wave in the sample that are detected by the terahertz spectroscopy system.

An apparatus includes a measurement chamber configured to retain one or more sample substances. The apparatus includes an entrance window mounted on a side of the measurement chamber. The apparatus includes a light source configured to generate an incident light beam. The apparatus includes a Raman sensor configured to collect inelastically scattered light from the chamber, and measure an intensity of a Raman peak of a first substance from the one or more sample substances based on the collected inelastically scattered light. The apparatus further includes a processor configured to (i) calculate a concentration of the first substance based on at least the measured intensity of the Raman peak of the first substance, (ii) determine the end point of a wafer cleaning process based on a calculated concentration of the first substance, and (iii) terminate the wafer cleaning process based on the determined end point.