A fluorometer may be used to measure ultralow concentrations of fluorescing species, such as ultralow concentrations of fluorescent tracer passing through a reverse osmosis membrane into a permeate stream. In some examples, the fluorometer may be recalibrated by resetting some but not all of the calibration parameters used to determine the concentration of fluorescent tracer in the permeate based on the measured fluorescent response of the fluorometer. For example, an intercept of a calibration curve may be reset or recalibrated for the fluorometer in situ, potentially providing significant accuracy improvements even though the fluorometer has not undergone a full recalibration.

Embodiments are directed to controlling a flow of a mixture of gas at a plurality of concentrations, controlling a temperature of a chamber over a temperature range, reading, by a computing device comprising a processor, gas absorbance values from a first detector included in the chamber over the plurality of concentrations and over the temperature range, generating at least one of a look-up table and a mathematical formula for the first detector based on the gas absorbance values, and causing the at least one of the look-up table and the mathematical formula to be stored in a second detector.

An optical apparatus according to the present embodiment includes a detector for detecting detection light of illumination light reflected by a sample, an optical system for illuminating the sample with the illumination light and guiding the detection light reflected by the sample to the detector, a displacement measurement unit for measuring a displacement drift indicating the amount of drift in the position of an optical element included in the optical system, a storage unit for storing the correlation between the displacement drift and a focus drift indicating the amount of drift in the distance between the sample and the optical system when the detection light detected by the detector is brought into focus, and a prediction unit for predicting a focus drift from the measured displacement drift by using the correlation.

A luminometer (400) includes a light detector (630) configured to sense photons (135). The luminometer (400) includes an analog circuit (915a) configured to provide an analog signal (965) based on the photons (135) emitted from assay reactions over a time period and a counter circuit (915b) configured to provide a photon count (970) based on the photons (135) emitted from the assay reactions over the time period. The luminometer (400) includes a luminometer controller (905) configured to, in response to an analog signal value of the analog signal (965) being greater than a predetermined value, determine and report a measurement value of the photons (135) emitted from the assay reactions over the time period based on the analog signal value of the analog signal (965) and a linear function (1010). Optionally, the linear function (1010) is derived from a relationship between the analog signal (965) and the photon count (970).

An optical measurement device inputs excitation light to an integrating sphere in which a sample is disposed, irradiates the sample with the excitation light having a predetermined beam cross-section, detects measurement light output from the integrating sphere by a photodetector, and acquires intensity data of the sample. The optical measurement device includes a storage unit in which correction data is stored and an optical characteristic calculation unit for calculating optical characteristics of the sample based on the intensity data of the sample and the correction data. The correction data is calculated based on first corrective intensity data and second corrective intensity data. The predetermined beam cross-section is covered with the first light absorbing member and covers the second light absorbing member.

Disclosed herein is a method for improving the precision of a test result from an instrument with an optical system that detects a signal. The method comprises including in the instrument a normalization target disposed directly or indirectly in the optical path of the optical system. Also disclosed are instruments comprising a normalization target, and systems comprising such an instrument and a test device that receives a sample suspected of containing an analyte.

An article is presented configured for controlling a multiple patterning process, such as a spacer self-aligned multiple patterning, to produce a target pattern. The article comprises a test site carrying a test structure comprising at least one pair of gratings, wherein first and second gratings of the pair are in the form of first and second patterns of alternating features and spaces and differ from the target pattern by respectively different first and second values which are selected to provide together a total difference such that a differential optical response from the test structure is indicative of a pitch walking effect.

Disclosed herein is a method for improving the precision of a test result from an instrument with an optical system that detects a signal. The method comprises including in the instrument a normalization target disposed directly or indirectly in the optical path of the optical system. Also disclosed are instruments comprising a normalization target, and systems comprising such an instrument and a test device that receives a sample suspected of containing an analyte.

Technology is provided for an aqueous solution constituent analyzer. The analyzer includes an ultraviolet light emitting diode (LED) with a current source providing variable current thereto. A spectrometer is positioned for receiving light from the LED transmitted through an aqueous solution. A controller receives radiant flux data for a plurality of wavelengths and determines, based on the radiant flux data, a usable number of the plurality of wavelengths that satisfies a relative uncertainty threshold. The controller can increase the current to the LED if the usable number of wavelengths is less than a minimum threshold and calculate a concentration of a constituent of interest in the solution. The controller can also determine a peak wavelength of the plurality of wavelengths having the greatest intensity value, and decrease the current level to the LED if the peak wavelength has an intensity value greater than a saturation value for the spectrometer.

A device for measuring wafers includes an optical coherence tomograph, which generates a measuring light beam and directs it onto the wafer via an optical system. A scanning device deflects the measuring light beam in two spatial directions. A control unit controls the scanning device so that the measuring light beam scans the surface of the wafer successively at several measuring points. Two measuring points have a distance d.sub.max of 140 mmd.sub.max600 mm. An evaluation unit calculates distance values and/or thickness values from the interference signals provided by the optical coherence tomograph and, based on the distance values and/or thickness values, at least one characteristic quantity of the wafer such as TTV, warp or bow.