A laser sensor for detecting a particle density includes: a laser configured to emit a measurement beam, an optical arrangement being arranged to focus the measurement beam to a measurement volume, the optical arrangement having a numerical aperture with respect to the measurement beam, a detector configured to determine a self-mixing interference signal of a optical wave within a laser cavity of the laser, and an evaluator. The evaluator is configured to: receive detection signals generated by the detector in reaction to the determined self-mixing interference signal, determine an average transition time of particles passing the measurement volume in a predetermined time period based on a duration of the self-mixing interference signals generated by the particles, determine a number of particles based on the self-mixing interference signals in the predetermined time period, and determine the particle density based on the average transition time and the number of particles.

A system and method for dispense characterization is disclosed. According to particular embodiments of the dispense characterization system and method, volumes of dispensed liquids can be determined. In more particular embodiments, additional characteristics and combinations of characteristics of a liquid dispensing event can be determined. Examples of additional characteristics that can be determined include the shape of the dispensing event, the velocity of the dispensing event, and the trajectory of the dispensing event. The dispense characterization system and method can be employed in automated biological sample analysis systems, and are particularly suited for monitoring liquid reagent dispensing events that deliver liquid reagents to a surface of a microscope slide holding a biological sample.

Stationary devices employing quadrature phase analysis light scattering are provided, to aid in the determination of the magnitude and polarity of electrophoretic mobility and zeta potential of particles in colloids. The devices use an optical quadrature interferometer with an electrophoresis sample chamber containing sample particles undergoing electrophoresis, the optical quadrature interferometer being configured to generate a quadrature signal. The phase of the quadrature signal may be analyzed at the frequency of the sample chamber electric field to estimate displacements and directions of the particles. The estimates can be used to determine a central value of the magnitude of the electrophoretic mobility, as well as its polarity. Particles having low electrophoretic mobility, or that may be adversely affected by high electric fields, can be analyzed, and constraints on vibration and light source coherence length may be relaxed. A phase modulator or frequency shifter is not required.

Measurement device for the detection and/or characterization of fluid-borne particles (9), the measurement device comprising means (1, 10) for producing a flow of fluid along a fluid flow path, a laser (2) positioned for emitting pulses of laser light polarized in a first direction of polarization, in a measurement volume of the fluid flow path, each pulse having a pulse duration, means (3) for directing pulses of laser light polarized in a second direction of polarization in the measurement volume, wherein the second direction of polarization is different from the first direction of polarization, a first optical spectrometer for capturing fluorescent light emitted by individual fluid-borne particles (9) in the measurement volume and measuring intensity of the captured fluorescent light at at least one determined wavelength at a sampling rate of at least three samples per pulse duration, wherein the means (3) for directing are configured such that they direct a pulse of laser light polarized in the second direction of polarization in the measurement volume each time a pulse of laser light emitted by the laser (2) and polarized in the first direction has crossed the measurement volume, the time delay between the moment of crossing the measurement volume by the pulse emitted by the laser and the moment of crossing the measurement volume by the pulse directed by the means (3) for directing is longer than the pulse duration and shorter than a travel time of the fluid in the measurement volume. Measurement method for the detection and/or characterization of fluid-borne particles (9) using the measurement device of the invention.

An apparatus to provide multi-beam imaging of particles includes a plurality of vertical cavity surface emitting lasers (VCSELs) configured to generate a plurality of light beams that converge with each other to form a measurement volume within a particle field. The plurality of the VCSELs are configured to provide uniformity in a background illumination of the measurement volume. An imaging optics is coupled to at least one of the plurality of VCSELs. A digital camera is coupled to the imaging optics to obtain a shadow image of a particle passing through the measurement volume at a focal plane of the digital camera. A processor is coupled to the digital camera.

A system, method, and apparatus are provided for flow cytometry. In one example, the flow cytometry system includes dual laser devices and dual scatter channels to measure velocity of particles in a core stream of sample fluid. The total flow rate of the sample fluid and the sheath fluid around the sample fluid is controlled, and thus held constant, by a feedback control system controlling a vacuum pump based on differential pressure across ends of a flow channel in the flow cell.

Embodiments disclose a device for testing biological specimen. The device includes a receiving mechanism to receive a carrier. The carrier includes a holding area that carries or has been exposed to the biological specimen. The device includes a camera module arranged to capture imagery of the holding area. The camera module includes an focusing motor operable to adjust a focal point of the camera. The device also includes a processor that is configured to utilize the camera module to determine, based on operations of the focusing motor, a volumetric property of the holding area and perform a set of analytic processes on at least a portion of the captured imagery of the holding area to determine one or more properties of the biological specimen.

A method of determining a charge of at least one test particle (as herein defined), comprising: applying one of an electric current or a voltage across an aperture connecting two chambers, whereby the chambers are at least partially filled with electrolyte and whereby the at least one test particle is suspended in the electrolyte of at least one of the chambers; measuring a value indicative of the other of the electric current or voltage across the aperture; determining a time interval between a first and a second point in time, the second point in time corresponding to a point in time when the measured current or voltage has reached a specific proportion of the measured current or voltage at the first point in time; and determining the charge of the at least one test particle by: determining a value indicative of an electrical velocity component of a total velocity of at least one calibration particle having a known charge, taking into account that the total velocity of the at least one calibration particle comprises a non zero-convective velocity component and the electrical velocity component; determining a value indicative of an electrical velocity component of a total velocity of the at least one test particle, taking into account that the total velocity of the at least one test particle comprises a non-zero convective-velocity component and the electrical velocity component; and using the determined values indicative of the electrical velocity components of the test particle and the calibration particle to calibrate the quantitative relationship between the charge of the at least one test particle and the determined time interval.

The present invention relates to a method and an apparatus for measuring the properties of a liquid that exploit the power modulation a laser light beam undergoes due to the retro-reflection of the laser light beam itself towards the laser cavity from which the laser is generated when this laser light is directed towards a transparent conduit through which the liquid for which the properties are to be measured flows.

According to the invention this power modulation is detected by at least one photodiode arranged downstream of the transparent conduit.

A method for testing includes capturing a sequence of video images of a sample comprising semen. The sequence of video images is analyzed by a processor so as to compute and output a motile sperm concentration of the sample.