The prism-coupling systems and methods include using a prism-coupling system to collect initial TM and TE mode spectra of a chemically strengthened article having a refractive index profile with a near-surface spike region and a deep region. The initial TM and TE mode spectra are examined to see if they fall within a preferred measurement window that can produce an accurate estimate of the knee stress to within a select tolerance. If not, then measurement configuration of the prism-coupling system is changed and new TM and TE mode spectra are collected. This process is repeated until the new TM and TE mode spectra fall within the preferred measurement window. The new TM and TE mode spectra are then used to determine the knee stress. Changing the measurement configuration can include changing at least one of the measurement wavelength, interfacing fluid thickness and interfacing fluid refractive index.

The prism-coupling systems and methods include using a prism-coupling system to collect initial TM and TE mode spectra of a chemically strengthened article having a refractive index profile with a near-surface spike region and a deep region. The initial TM and TE mode spectra are examined to see if they fall within a preferred measurement window that can produce an accurate estimate of the knee stress to within a select tolerance. If not, then measurement configuration of the prism-coupling system is changed and new TM and TE mode spectra are collected. This process is repeated until the new TM and TE mode spectra fall within the preferred measurement window. The new TM and TE mode spectra are then used to determine the knee stress. Changing the measurement configuration can include changing at least one of the measurement wavelength, interfacing fluid thickness and interfacing fluid refractive index.

Apparatus and methods for measuring mode spectra for ion-exchanged glass substrates having a steep index region are disclosed. An interfacing fluid is provided between the coupling prism and the glass substrate. The interfacing fluid thickness is selected so that the variation in modal birefringence with fluid thickness is reduced to an acceptable level. The coupling prism can include a prism coating on the coupling surface so that the substrate-prism interface includes the prism coating. The coupling prism can also include stand-off members that serve to define the thickness of the interfacing fluid.

An optical sensor has a body including a transparent interface wall having an outer surface in contact with a liquid, to define therewith a reflection interface. An optical module is coupled at an inner surface of the interface wall, to detect a characteristic of the liquid substance via light reflection. The optical module includes a light emitter and a light receiver facing respective inclined surfaces of the interface wall. The optical module also includes a supporting structure which is elastically flexible, to enable the light emitter and the light receiver of the optical module to vary a relative position thereof and with respect to the inclined surfaces of the interface wall, when the supporting structure is secured to the inner surface of the interface wall.

An optical sensor has a body including a transparent interface wall having an outer surface in contact with a liquid, to define therewith a reflection interface. An optical module is coupled at an inner surface of the interface wall, to detect a characteristic of the liquid substance via light reflection. The optical module includes a light emitter and a light receiver facing respective inclined surfaces of the interface wall. The optical module also includes a supporting structure which is elastically flexible, to enable the light emitter and the light receiver of the optical module to vary a relative position thereof and with respect to the inclined surfaces of the interface wall, when the supporting structure is secured to the inner surface of the interface wall.

An optical sensor device (1) for a fluid substance (LS) comprises a device body (2) having a detection portion (14), associated to which is a sensitive optical part that comprises at least one of an emitter (20) and a receiver (21) of an optical radiation (R.sub.e, R.sub.r). The detection portion (14) is made of a material transparent to the optical radiation (R.sub.e, R.sub.r) and has an inner surface (23a, 23b) and an outer surface (15), the outer surface (15) being designed to be in contact with the fluid substance (LS) and the inner surface (23a, 23b) being designed to be isolated from the fluid substance. The at least one of the emitter (20) and the receiver (21) of the sensitive optical part is optically coupled to the inner surface (23a, 23b) of the detection portion (14), in such a way that the optical radiation (R.sub.e, R.sub.r) is at least in part propagated through the detection portion (14), in particular with an angle and/or an intensity that is variable as a function of a characteristic of the fluid substance. The optical sensor device (1) comprises a protection arrangement, configured for preventing possible deformation of the detection portion (14) caused by an increase in volume of the fluid substance (LS), in particular deformation of at least one of its inner surface (23a, 23b) and its outer surface (15). The protection arrangement comprises at least one compensation element (13) having an elastically deformable body, which is able to contract, for compensating thereby a possible increase in volume of the fluid substance (LS) or else for enabling a reversible displacement of the detection portion (14) following upon a possible increase in volume of the fluid substance (LS).

An optical sensor device (1) for a fluid substance (LS) comprises a device body (2) having a detection portion (14), associated to which is a sensitive optical part that comprises at least one of an emitter (20) and a receiver (21) of an optical radiation (R.sub.e, R.sub.r). The detection portion (14) is made of a material transparent to the optical radiation (R.sub.e, R.sub.r) and has an inner surface (23a, 23b) and an outer surface (15), the outer surface (15) being designed to be in contact with the fluid substance (LS) and the inner surface (23a, 23b) being designed to be isolated from the fluid substance. The at least one of the emitter (20) and the receiver (21) of the sensitive optical part is optically coupled to the inner surface (23a, 23b) of the detection portion (14), in such a way that the optical radiation (R.sub.e, R.sub.r) is at least in part propagated through the detection portion (14), in particular with an angle and/or an intensity that is variable as a function of a characteristic of the fluid substance. The optical sensor device (1) comprises a protection arrangement, configured for preventing possible deformation of the detection portion (14) caused by an increase in volume of the fluid substance (LS), in particular deformation of at least one of its inner surface (23a, 23b) and its outer surface (15). The protection arrangement comprises at least one compensation element (13) having an elastically deformable body, which is able to contract, for compensating thereby a possible increase in volume of the fluid substance (LS) or else for enabling a reversible displacement of the detection portion (14) following upon a possible increase in volume of the fluid substance (LS).

Provided are an optical sensor and an analyzer, including an optical sensor section in which a cladding layer of an optical fiber is removed so as to expose a core layer by a predetermined optical path length, and a protective material is added to a surface of the exposed core layer, the protective material having higher resistance to an organic solvent, base, or acid than that of the cladding layer; a light source device that causes light to enter one end of the optical fiber; a light receiving device that receives transmitted light emitted from another end of the optical fiber; and a control device that controls the light source device and the light receiving device to measure optical transmittance in the optical sensor based on a ratio of intensity of the light emitted from the light source device to intensity of the light received by the light receiving device.

A method is provided that allows the sulfur component concentration in gasoline to be estimated to high precision. The measuring method of the disclosure is a method of measuring the concentration of sulfur components in gasoline that contains sulfur components and aromatic components. The measuring method of the disclosure comprises: (A1) removing a portion of the gasoline by gasification to lower the proportion of the aromatic component concentration with respect to the sulfur component concentration in the gasoline, (A2) measuring values related to the refractive index of the gasoline, and (A3) measuring the sulfur component concentration in the gasoline based on the values related to the refractive index.

The prism-coupling systems and methods include using a prism-coupling system to collect initial TM and TE mode spectra of a chemically strengthened article having a refractive index profile with a near-surface spike region and a deep region. The prism-coupling system has a light source configured to generate sequential measurement light beams or reflected light beams having different measurement wavelengths. The different measurement wavelengths generate different TM and TE mode spectra. The light source can include multiple light-emitting elements and optical filters or a broadband light source and optical filters. The optical filters can be sequentially inserted into either the input optical path or the output optical path of the prism-coupling system.