An illuminator/collector assembly can deliver incident light to a sample and collect return light returning from the sample. A sensor can measure ray intensities as a function of ray position and ray angle for the collected return light. A ray selector can select a first subset of rays from the collected return light at the sensor that meet a first selection criterion. In some examples, the ray selector can aggregate ray intensities into bins, each bin corresponding to rays in the collected return light that traverse within the sample an estimated optical path length within a respective range of optical path lengths. A characterizer can determine a physical property of the sample, such as absorptivity, based on the ray intensities, ray positions, and ray angles for the first subset of rays. Accounting for variations in optical path length traversed within the sample can improve accuracy.

A method for measuring hemoglobin concentration in a whole blood sample is disclosed. The method may include mixing a whole blood sample with a lysing agent, followed by manual agitation, flowing the whole blood or mixture into a reservoir of a sensor, the sensor comprising a transparent portion configured to allow an optical measurement of an absorbance or reflectance of the whole blood sample in the reservoir of the sensor; detecting, using an analyzer into which at least a portion of the sensor has been inserted, the whole blood sample in the reservoir of the sensor; upon detecting the liquid whole blood sample in the reservoir, optically measuring an absorbance or reflectance of the whole blood sample using a light source and a detector in the analyzer; and determining a concentration of hemoglobin in the whole blood sample based on the measured absorbance or reflectance and a calibration curve that relates the absorbance or reflectance to the concentration of hemoglobin in the whole blood sample.

A gas sensor for measuring concentration of a predetermined gas includes a light source (2) arranged to emit pulses of light, a measurement volume (10), a detector (4) arranged to receive light that has passed through the measurement volume (10), and an adaptable filter (6) disposed between the light source (2) and the detector (4). The gas sensor has a measurement state in which it passes at least one wavelength band which is absorbed by the gas and a reference state in which said wavelength band is attenuated relative to the measurement state. A controller is connected to each of the light source, the detector and the adaptable filter to change the adaptable filter between one of said measurement state and said reference state to the other at least once during a gas sensor operation period.

A sensor for monitoring CO.sub.2 in a fluid regardless of the phase properties of the fluid, i.e., regardless of whether the fluid contacting the window is a liquid water-based phase, a liquid oil-based phase, a mixture of liquid water and liquid oil-based phases, or a gas phase. The sensor includes an internal reflection window for contacting with the fluid. A mid-infrared light source directs a beam of mid-infrared radiation into the window and the beam is internal reflected at an interface between the window and the fluid. The reflected beam is passed through three narrow bandpass filters which preferentially transmit mid-infrared radiation over bands of wavelengths corresponding to absorbance peaks of water, oil and CO.sub.2. The amount of CO.sub.2 is determined from the intensities of the mid-infrared radiation passing through the three filters.

A multi-point detection system includes one or more light sources, one or more light sensors, and a controller. The light sources are configured to emit an array of collimated light beams, and the light sensors define an array of lines of view. Each of the lines of view intersect different ones of the collimated light beams at respective detection nodes. The light sensors are operable to emit sensor signals responsive to received scattered light from interaction of the collimated light beams with an analyte at the detection nodes. The controller is connected to receive the sensor signals and configured to determine from the scattered light whether the analyte contains a contaminant.

An apparatus and methods for high-speed non-linear spectrally encoded multi-photon imaging that are particularly suited for use in two photon fluorescence and fluorescence lifetime imaging. The system is capable of optical image compression and scale invariant digital zoom. A wavelength agile laser with digitally synthesized electro-optic modulation in a master oscillator-power amplifier configuration is combined with spectral encoding to eliminate the speed limitations of inertial scanning. The technique for fast two photon fluorescent imaging with simultaneous lifetime imaging independently detects the location, amplitude and lifetime of fluorescent emission by synthesizing a sequential excitation beam via digital electro-optic modulation of a quasi-CW swept source followed by time encoded detection. For fluorescent imaging, spectral and temporal mappings are employed separately, with quasi-CW spectral encoding used for pumping and time encoding for constructing the image at fluorescence wavelength.

A sensor for monitoring CO.sub.2 in a fluid regardless of the phase properties of the fluid, i.e., regardless of whether the fluid contacting the window is a liquid water-based phase, a liquid oil-based phase, a mixture of liquid water and liquid oil-based phases, or a gas phase. The sensor includes an internal reflection window for contacting with the fluid. A mid-infrared light source directs a beam of mid-infrared radiation into the window and the beam is internal reflected at an interface between the window and the fluid. The reflected beam is passed through three narrow bandpass filters which preferentially transmit mid-infrared radiation over bands of wavelengths corresponding to absorbance peaks of water, oil and CO.sub.2. The amount of CO.sub.2 is determined from the intensities of the mid-infrared radiation passing through the three filters

A device for torque measurement of friction includes a cylindrical core and a cap with a central cavity for receiving the cylindrical core. The cap includes at least one protrusion or indent on an inner surface, and the cylindrical core includes at least one protrusion or indent on an exterior surface. The device includes at least one protrusion to provide a pulsed interference contact with a second protrusion or indent on the cylindrical core or cap as the protrusion moves into and out of contact with the at least one second protrusion or indent when the cap is rotated about the cylindrical core. The device may be connected to a test apparatus configured to measure rotational torque between the cap and cylindrical core as they rotate with respect to one another.

Naphthalene, benzene, toluene, xylene, and other volatile organic compounds VOCs have been identified as serious health hazards. Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter badges to be worn by personnel potentially exposed to hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined.

For tracking a plurality of objects in a three-dimensional space two-dimensional pictures objects are recorded with two black and white cameras out of two different imaging directions. Both first pictures and second pictures of the two cameras are simultaneously exposed at two points in time in equal ways, a point in time at which the second pictures are exposed for a first time following to a point in time at which the first pictures are exposed for a last time at a much shorter interval than the two points in time of exposure of both the first and second pictures. First and second distributions of real positions of the individual objects are determined from their images in the first and second pictures, respectively; and temporally resolved trajectories of the individual objects in the three-dimensional space are determined from the first and second distributions of real positions.