An optical element includes a main body formed of a light transmissive material and including an arc-shaped optical path, and a gap formed on the arc-shaped optical path in the main body. The gap may have a notch shape. The main body may have a semicircular plate shape. The main body may have a hemispherical shape.

The present invention relates to an optical flow cell for a measuring device, having an input light guide with a light exit surface, an output light guide with a light entrance surface, said input light guide and output light guide being integrated with a holder to form an optical flow cell, and wherein the holder extends along a first axis and has a through hole for receiving a flow of a sample fluid, said through hole being transversal to said first axis, and the input light guide and output light guide further are arranged in said holder so that the light exit surface and the light entrance surface extend into said through hole and are arranged to be in optical alignment with each other and at a first distance from each other. The invention also relates to a measuring device having at least one optical flow cell.

An in-situ gas-measuring system (1) includes an IR photon source (10) and an IR photon detector (11). The in-situ gas-measuring system (1) has an expansion chamber (12), at which an optical element (16, 16, 16) is arranged. A connection element (13) provides a detachable fluid-communicating connection of the expansion chamber (12) to a gas reaction chamber (2). The IR-photon source (10), the optical element (16, 16, 16) and the IR photon detector (11) define an optical measuring path, which extends through the expansion chamber (12). The installation and maintenance of the in-situ gas-measuring system (1) are reduced by the features of the in-situ gas-measuring system (1).

The present invention relates to an optical flow cell (1) for a measuring device, having an input light guide with a light exit surface, an output light guide with a light entrance surface, said input light guide and output light guide being integrated with a holder (30) to form optical flow cell (1), and wherein the holder (30) extends along a first axis (A) and has a through hole (31) for receiving a flow of a sample fluid, said through hole (31) being transversal to said first axis (A), and the input light guide and output light guide further are arranged in said holder (30) so that the light exit surface and the light entrance surface extend into said through hole (31) and are arranged to be in optical alignment with each other and at a first distance from each other. The invention also relates to a measuring device having at least one optical flow cell (1).

The present invention discloses a flow cell optical detection system comprising a light source, a flow cell and a light detector, wherein the light detector is arranged in a separate detector unit that is arranged to be releasably attached to a detector interface, the detector interface being in optical communication with the light source and comprises optical connectors for optically connecting the flow cell and the detector unit in the light path from the light source, and wherein the flow cell is an interchangeable unit arranged to be held in position by the detector unit when attached to the detector interface.

A sensor positioning device, having a holding module, with a sensor receptacle, fastening element and spring element, the sensor receptacle being mounted movably relative to the fastening element along a compensating axis. The spring is arranged between the fastening element and the sensor receptacle to cooperate therewith, to create a restoring force during movement of the receptacle relative to the fastening element. A measurement connector with an abutment is configured for arrangement onto a process container, and is configured for releasable arrangement on the holding module. The sensor positioning device is configured such that, when the measurement connector is arranged on the holding module, the sensor receptacle is movable relative to the fastening element along the axis, and a pressing force of the sensor receptacle onto the abutment of the measurement connector is created by the spring. A sensor unit, for turbidity measurement, is provided having the sensor positioning device.