An arrangement for measuring gas concentrations in a gas absorption method, wherein the arrangement includes a plurality of light sources, a measuring cell, at least one measuring receiver and an evaluation apparatus. The measuring cell has a narrow, longitudinally-extended beam path with an entrance-side opening diameter B and an absorption length L with L>B, wherein the measuring cell has a gas inlet and a gas outlet wherein a plurality of light sources of different wavelength spectra is grouped into a first light source group wherein an optical homogeniser is interposed between the first light source group and the measuring cell, wherein, in particular, the homogeniser is coupled to the light source group directly or via a common optical assembly.

A method and instrument for determining optical density of a solution is disclosed. A flow cell 1 having at least three light paths (4a, 4b, 4c) is provided (100), wherein each light path has a respective predetermined path length, l. Absorbance readings are taken (400), A, of the solution at the at least three light paths (4a, 4b, 4c). For each pair of light paths, a slope, αc, is calculated (500) by dividing a difference in absorbance reading, ΔA, with a difference in path length, Δl. The calculated slopes, αc, are compared (600), and a) if the calculated slopes, αc, are the same, the slope is used for determining (700) optical density of the solution, or b) if he calculated slopes, αc, are not the same, the steepest slope of the calculated slopes is used for determining (701a) optical density of the solution, or the slope of the calculated slopes being in the range of an absorbance reading of 0.01 to 2 is used for determining (701b) optical density of the solution

Devices, systems, and methods described herein relate to determining a concentration of a species of interest in a sample by using a spectrometer. For example, a concentration of a species of interest may be determined by passing a first feed of a sample with a species of interest through a flow-through variable pathlength spectrophotometer and reading a first absorbance value. A change in the concentration of the species of interest may be effected in the sample, and a second feed of the sample may be passed through a flow through variable pathlength spectrophotometer. A second absorbance value may be read. The difference between the first absorbance value and the second absorbance value may be used to determine the concentration of the species of interest.

An apparatus for measuring the absorbance of a substance in a solution, includes at least one sample cell arranged to contain the solution that is at least partially transparent to light of a predefined wavelength spectrum, at least two light passages through the at least one sample cell, each of the light passages having a known path length, an LED light source arrangement including at least two LEDs, each arranged to emit a light output with a wavelength within the predefined wavelength spectrum. A plurality of optical fibers, one for each light passage, is arranged at each LED for receiving the light output and guiding it to the light passages. A method for measuring the absorbance of a substance in a solution includes providing the LED light source arrangement with an associate fiber bundle for each LED.

A sensor is disclosed, comprising: a first optical reflector provided on a first support element; a second optical reflector provided on a second support element and arranged opposed to the first optical reflector along an optical axis, the opposed first and second optical reflectors being spaced from each other forming a sample space for containing a sample between the first and second optical reflectors; wherein the second optical reflector comprises a recess to provide an optical cavity with stable resonance in at least one mode and having an optical cavity length of at most 50 μm and/or an optical mode volume of 100 μm.sup.3 or less; at least one electromagnetic (EM) radiation source configured to illuminate the optical cavity with EM radiation; and a detector configured to detect EM radiation from the optical cavity; wherein the first support element and the second support element are bonded to each other and form a unitary structure.

An apparatus for measuring the absorbance of a substance in a solution includes at least one sample cell arranged to contain the solution that is at least partially transparent to light of a predefined wavelength spectrum, at least two light passages through the at least one sample cell, each of the light passages having a known path length, an LED light source arrangement including at least two LEDs, each arranged to emit a light output with a wavelength within the predefined wavelength spectrum. A plurality of optical fibers, one for each light passage, is arranged at each LED for receiving the light output and guiding it to the light passages. A method for measuring the absorbance of a substance in a solution includes providing the LED light source arrangement with an associate fiber bundle for each LED.

Sensor systems, and flow cells for use with them, which can provide for a universal sensor housing. The senor housing includes a first section which is designed to remain statically in position and a selectable sensor head that may be swapped out as necessary. The specific head is selected based on the types of measurement to be performed at the sensor location and the sensor head can integrate with the housing so only a single wire connection needs to be made to obtain all data from the housing.

Device for improving an optical detecting smoke apparatus and implementing thereof. Apparatus and methods for detecting the presence of smoke in a small, long-lasting smoke detector are (disclosed. Specifically, the present disclosure shows how to build one or more optimized blocking members in a smoke detector to augment signal to noise ratio. This is performed while keeping the reflections from the housing structure to a very low value while satisfying all the other peripheral needs of fast response to smoke and preventing ambient light. This allows very small measurements of light scattering of the smoke particles to be reliable in a device resistant to the negative effects of dust. In particular, geometrical optical elements, e.g., cap and optical defection elements, are disclosed.

An optical blood monitoring system and corresponding method avoid the need to obtain a precise intensity value of the light impinging upon the measured blood layer during the analysis. The system is operated to determine at least two optical measurements through blood layers of different thickness but otherwise substantially identical systems. Due to the equivalence of the systems, the two measurements can be compared so that the bulk extinction coefficient of the blood can be calculated based only on the known blood layer thicknesses and the two measurements. Reliable measurements of various blood parameters can thereby be determined without certain calibration steps.

A sample cell apparatus for use in spectroscopic determination of an analyte in a body fluid sample includes a first plate member and a second plate member made from an optically clear material. A channel extending into a surface of the first plate member and an opposing surface of the second plate member houses a floating seal, which surrounds a fluid sample chamber. The fluid chamber is closed to define a repeatable optical path-length therethrough by urging the first plate member against the second plate member without compressing the floating seal between the first plate member and the second plate member. The seal channel is vented to prevent fluid pressure from flexing the first plate member or the second plate member. An actuator having an extended foot portion extends over the fluid chamber to help prevent flexing of the first plate member or the second plate member.