A sensor device including a sensor element, a cover panel, and a detection device detecting contaminants on the cover panel. The detection device includes an emitter emitting light, a coupling-in device coupling light into the cover panel, a decoupling device decoupling light from the cover panel, and a detector. The emitter and the coupling-in device couple light into the cover panel at a plurality of angles, and due to total reflection within the cover panel, the light propagates to the decoupling device and reaches the detector. If contaminants are on the cover panel, the total reflection for light coupled in at an angle within an extinction range is at least partially extinguished, and the detector is configured to detect the extinguishing of the total reflection for these angles. The detection device is configured to deduce the type of contaminant from the angles for which the total reflection has been extinguished.

A method includes: transmitting an incident light to an object located on a stage, in which a first light and a second light are reflected; receiving the first light and the second light by an imaging lens group to obtain a third pattern corresponding to the first pattern and a fourth pattern corresponding to the second pattern; transmitting the third pattern and the fourth pattern to an image sensor, in which a center point of the third pattern and a center point of the fourth pattern are separated by a first distance on the image sensor; calculating a tilted angle between an optical axis of the imaging lens group and a normal direction of the stage according to the first distance; and adjusting the stage according to the tilted angle such that the normal direction is parallel to the optical axis.

Provide herein is a refractometer, optically transmissive structure, and method of making. The structure has a first surface disposing a light source. A second surface is configured and disposed to provide an angular light reflective interface at, or proximate therewith, a fluid being sensed. A third surface disposes an optical sensor. The optically transmissive structure has at least one of the light source and the optical sensor directly incorporated, bonded, or adhered therewith or has at least one light blocker configured and disposed to block a portion of light being directed or reflected toward the third surface.

Provide herein is a refractometer, optically transmissive structure, and method of making. The structure has a first surface disposing a light source. A second surface is configured and disposed to provide an angular light reflective interface at, or proximate therewith, a fluid being sensed. A third surface disposes an optical sensor. The optically transmissive structure has at least one of the light source and the optical sensor directly incorporated, bonded, or adhered therewith or has at least one light blocker configured and disposed to block a portion of light being directed or reflected toward the third surface.

An apparatus for detecting one or more properties of a downhole fluid includes a housing. The apparatus also includes a location-sensitive optical detector, arranged within a chamber formed by the housing. The apparatus further includes a light source, arranged within the chamber. The apparatus also includes a lens, positioned at an end of the housing, the lens preferably having a flat side and a curved side, the flat side positioned proximate the chamber to position the flat side closer to the light source than the curved side. The apparatus further includes a mirror, arranged outside the housing.

A method includes: transmitting an incident light to an object located on a stage, in which a first light and a second light are reflected; receiving the first light and the second light by an imaging lens group to obtain a third pattern corresponding to the first pattern and a fourth pattern corresponding to the second pattern; transmitting the third pattern and the fourth pattern to an image sensor, in which a center point of the third pattern and a center point of the fourth pattern are separated by a first distance on the image sensor; calculating a tilted angle between an optical axis of the imaging lens group and a normal direction of the stage according to the first distance; and adjusting the stage according to the tilted angle such that the normal direction is parallel to the optical axis.

A prism for measuring liquid concentration includes: an accommodating space for accommodating a liquid; an interface formed on a bottom surface of the accommodating space; a first light transmission surface and a second light transmission surface respectively formed on two side surfaces of the accommodating space; a third light transmission surface and a light emitting surface respectively formed relative to the interface. When a first incident light beam enters the prism, the first incident light beam is reflected to the light emitting surface by the interface, and exits the prism from the light emitting surface. When a second incident light beam enters the prism to the first light transmission surface, the second incident light beam exits the prism to the accommodating space from the second incident light beam, passes through the liquid and the second light to the prism, and exits the prism from the third light transmission surface.

A prism for measuring liquid concentration includes: an accommodating space for accommodating a liquid; an interface formed on a bottom surface of the accommodating space; a first light transmission surface and a second light transmission surface respectively formed on two side surfaces of the accommodating space; a third light transmission surface and a light emitting surface respectively formed relative to the interface. When a first incident light beam enters the prism, the first incident light beam is reflected to the light emitting surface by the interface, and exits the prism from the light emitting surface. When a second incident light beam enters the prism to the first light transmission surface, the second incident light beam exits the prism to the accommodating space from the second incident light beam, passes through the liquid and the second light to the prism, and exits the prism from the third light transmission surface.

Optical sensors, systems and methods of use thereof are provided. Aspects of the subject systems include a sensor having a sensing surface and a configuration that directs a first optical signal to interact with the sensing surface at a first incident angle, and directs a second optical signal to interact with the sensing surface at a second incident angle. The subject sensors, systems and methods find use, e.g., in the diagnosis of dry eye disease.

Optical sensors, systems and methods of use thereof are provided. Aspects of the subject systems include a sensor having a sensing surface and a configuration that directs a first optical signal to interact with the sensing surface at a first incident angle, and directs a second optical signal to interact with the sensing surface at a second incident angle. The subject sensors, systems and methods find use, e.g., in the diagnosis of dry eye disease.