A molecular nanotag is disclosed that includes a core nanoparticle with a diameter of less than about 100 nm, with an optional shell surrounding the core, and an armor bound to the surface of the core nanoparticle, or if present, to the surface of the shell. The molecular nanotag also includes a functionalized end with a fixed number of binding sites that can selectively bind to a molecular targeting ligand. Any one of, or any combination of, the core, the shell and the armor contribute to fluorescence, light scattering and/or ligand binding properties of the molecular tag that are detectable by microscopy or in a devices that measures intensity or power of fluorescence and light scattering. The light scattering intensity or power of the assembled structure is detectable above the specific level of the reference noise of a device detecting the light scattering intensity or power, its fluorescence intensity or power has sufficient brightness for detection above the limit of detection for the instrument, and ligand specificity is conferred by the ligand binding component. Methods of biomarker and biosignature detection using the molecular tags are also disclosed.

Particulate sensing systems or processes identify particulates suspended in an air sample by irradiating the air sample with UV light and measuring light from individual particles in the air sample. Two photodiodes having different wavelength sensitivity may be used to measure the fluorescent light emitted from a single particle, and a type of the particle may be identified using outputs from photodiodes. Repeating the process for multiple particles may produces distributions that further distinguish or identify particulate types.

A nephelometric turbidimeter for measuring a turbidity of a liquid sample in a sample cuvette. The nephelometric turbidimeter includes a measurement light source configured to emit an axial parallel light beam directed to the sample cuvette, a scattering light detector arranged to receive a scattered light from the sample cuvette, and a diffuser comprising a diffuser body and a diffuser actuator. The diffuser actuator is configured to move the diffuser body between a parking position in which the diffuser body does not interfere with the axial parallel light beam and a test position where the diffuser body is arranged between the measurement light source and the sample cuvette so that the diffuser body interferes with the axial parallel light beam and generates a diffuse test light entering the sample cuvette.

A nephelometer that measures turbidity of low volume suspensions using measurements of light transmitted through and/or scattered by the sample. The sample suspension is placed in a tiered cuvette adapted to facilitate measuring the turbidity of low volume samples. The lower portion of the cuvette has smaller dimensions, in horizontal cross section, than the top portion. Both lower and upper portions have angled surfaces. The lower, smaller portion of the cuvette is interrogated by the nephelometer.

A turbidity sensor or an arrangement for optically measuring one or more physical, chemical and/or biological, process variables of a medium. The medium is located in a pipe. The arrangement includes a housing and the housing is embodied for securement in the pipe. The housing is embodied for accommodating at least one light source for sending light through a window region into the medium and at least one light receiver for receiving light through the window region from the medium. The light is scattered by the medium and the light intensity received by the light receiver is a measure for the physical, chemical and/or biological, process variable, characterized in that the light source is so arranged that the light propagates in the medium in the longitudinal direction of the pipe.

Various turbidimeters are described that can detect light directly in a substantially circular, e.g., encompassing, manner such that an increased amount of scattered light from a sample vial may be detected by a light detector, e.g., a photodiode or photodiode array. In an embodiment, a substantially circular photodiode array is provided to directly detect scattered light in an arc about the sample vial. In other embodiments, light guides are provided in an arc element that guides light to a detector or detectors. Other aspects are described and claimed.

A measuring apparatus is provided with: an irradiator configured to irradiate fluid with light; a first light receiver configured to receive a forward scatter component of scattered light scattered by the fluid; a second light receiver configured to receive a backscatter component of the scattered light; a third light receiver configured to receive a side scatter component of the scattered light; and an outputting device configured to output fluid information about the fluid, which is obtained on the basis of light receiving signals of the first light receiver, the second light receiver, and the third light receiver. According to this measuring apparatus, it is possible to output accurate fluid information because of the use of the forward scatter component, the backscatter component, and the side scatter component of the scattered light.

A method for characterizing particle objects comprises generating a radiation beam, illuminating with the radiation beam an observation region transited by a particle object, collecting an interference image determined by an interference between a transmitted fraction and a part of the scattered fraction of the radiation beam that propagates around the direction of the optical axis, collecting a part of the scattered fraction that propagates at the scattering angle, and measuring at least one scattered radiation intensity value determined by the part of the scattered fraction, calculating, from the interference image, a pair of independent quantities that define the complex field of the first part of the scattered fraction, calculating, starting from the pair of independent quantities, a theoretical value of scattered radiation intensity, and comparing the measured value with the theoretical scattered radiation intensity value.

Provided are a light scattering measuring apparatus. The light scattering measuring apparatus includes: light sources; a single light receiver; a sample holder including a cell, a frame body, a first opening formed in an incident portion of a first optical path used for forward measurement or side measurement, and a second opening formed in an incident portion of a second optical path used for back measurement, and an optical element; and a moving mechanism. The first optical path and the second optical path are separated from each other in vertical direction. The moving mechanism moves the first opening to a position of the incident portion of the first optical path when the forward or side measurement is to be performed, and to move the second opening to a position of the incident portion of the second optical path when the back measurement is to be performed.

Techniques for quantitative colorimetric liquid analysis with color and turbidity correction are provided. In one aspect, an optical detector includes: a vessel for containing a liquid sample; a light source on a first side of the vessel; a first sensor on a second side of the vessel opposite the first side and along a light path of the light source; and a second sensor on a third side of the vessel at an angle θ with respect to the light path. A method for quantitative measurement of an analyte is also provided, as is a method for color and turbidity analysis.