A stretchable strain sensor may exhibit wavelength selectivity according to a thickness change of a thickness of the stretchable strain sensor, in a thickness direction extending parallel to the thickness of the stretchable strain sensor, due to elongation of the stretchable strain sensor in an elongation direction extending perpendicular to the thickness direction. The stretchable strain sensor may have an emission spectrum that changes according to strain variation of a strain on the stretchable strain sensor.

Methods of improving the measurement of knee stress in an ion-exchanged chemically strengthened Li-containing glass sample that includes a knee are disclosed. One of the methods includes compensating for a shift in the location of the TIR-PR transition location associated with the critical angle location, wherein the shift is due to the presence of a leaky mode. Another method includes applying select criteria to the captured mode spectra image to ensure a high-quality image is used for the knee stress calculation. Another method combines direct and indirect measurements of the knee stress using the mode spectra from multiple samples to obtain greater accuracy and precision as compared to using either the direct measurement method or the indirect measurement method alone. Quality control methods of forming the glass samples using measured mode spectra and related techniques for ensuring an accurate measurement of the knee stress are also disclosed.

A tactile sensor including a camera positioned to capture images of marks. An elastically deformable skin including an outer surface having attributes and an undersurface having pins, ridges, or both. Each undersurface pin or ridge includes a mark. A processor detects displacement of the marks in captured images and compares the displaced positions of the marks in the captured images to stored sets of prelearned positions of marks, based on a distance function, to determine a quality of match value for each set of the prelearned positions of marks. A best quality matched prelearned pattern of forces is determined using a user selected function, to calculate a best matching set of the prelearned positions of marks. Identify a pattern of forces acting on the elastically deformable skin based on the determined best matched prelearned pattern of forces.

An optical sensor according to an embodiment of the present disclosure includes a light emitting substrate and a circuit board. The light emitting substrate includes a light emitting device. The circuit board is provided at a position opposing the light emitting device. The circuit board includes a light transmitting section and one or multiple light receiving devices. The light transmitting section transmits light of the light emitting device. The one or multiple light receiving devices receive light reflected by a reflective layer of the light of the light emitting device exiting through the light transmitting section. For example, the one or multiple light receiving devices are formed on a first major surface of the circuit board. For example, the light emitting substrate is disposed at a position opposing a second major surface, of the circuit board, on an opposite side to the first major surface, and is stacked on the circuit board with a first bump interposed therebetween.

A method for measuring interfacial stress and residual stress in multilayer thin films coated on a substrate is disclosed. First of all, a residual stress measurement process is applied to each thin film of a multi-layered structure. Subsequently, after two kinds of interfacial stress (F.sub.HL, F.sub.LH) are calculated, a mathematical formula for estimating at least one adjusting parameter is derived based on the two interfacial stresses. As a result, a modified Ennos formula is obtained by involving the adjusting parameters into the Ennos formula, such that a residual stress in the multi-layered structure (i.e., multilayer thin films) is therefore calculated by using the modified Ennos formula.

A method and system for stress engineering of a transparent material can include an imaging system that can visualize a spatial distribution of an internal stress in a transparent material, an actuator system that can induce stress in the transparent material, the actuator system comprising one or more actuator elements, and a feedback system that can communicate with the imaging system and the actuator system, and which can guide an internal stress distribution in the transparent material toward a preferred final state.

Methods and systems for measuring optical properties of transistor channel structures and linking the optical properties to the state of strain are presented herein. Optical scatterometry measurements of strain are performed on metrology targets that closely mimic partially manufactured, real device structures. In one aspect, optical scatterometry is employed to measure uniaxial strain in a semiconductor channel based on differences in measured spectra along and across the semiconductor channel. In a further aspect, the effect of strain on measured spectra is decorrelated from other contributors, such as the geometry and material properties of structures captured in the measurement. In another aspect, measurements are performed on a metrology target pair including a strained metrology target and a corresponding unstrained metrology target to resolve the geometry of the metrology target under measurement and to provide a reference for the estimation of the absolute value of strain.

Apparatus can comprise a cavity at least partially defined by a first major surface of a reference block and configured to receive a sample. The apparatus can comprise a first polarization-switching light source configured to emit a first polarization-switched light beam toward the cavity and a first detector configured to detect a corresponding signal. The apparatus can comprise a second polarization-switching light source configured to emit a second polarization-switched light beam toward the cavity and a second detector configured to detect a corresponding signal. The first reference block can be positioned between the second detector and the second reference block. Methods of determining an estimated stress profile can comprise determining a central tension from a measured retardation profile of the sample. Methods can comprise determining an initial stress profile from a refractive index profile of the sample. Methods can comprise scaling and adjusting stress profiles.

A stretchable strain sensor may exhibit wavelength selectivity according to a thickness change of a thickness of the stretchable strain sensor, in a thickness direction extending parallel to the thickness of the stretchable strain sensor, due to elongation of the stretchable strain sensor in an elongation direction extending perpendicular to the thickness direction. The stretchable strain sensor may have an emission spectrum that changes according to strain variation of a strain on the stretchable strain sensor.

Provided is a displacement measurement system including: a sensor that is contactable with a measurement target object and includes a first spacer that has at least a one-dimensional spread, and two or more types of light emitting particles that are distributed over the spread of the first spacer and emit light at different wavelengths by an excitation energy; an excitation energy source that causes the two or more types of light emitting particles included in the sensor to emit light; and a light receiver that receives light emitted from the sensor.