Patent Description:
Optical measuring devices are used within a plurality of technical fields where a solution is allowed to flow across an optical flow cell that serves to determine the presence of a substance and/or a concentration of a substance within the solution. Examples of such technical fields are fluid chromatography and filtering, among others.

The flow cells used in the measuring devices are generally optical flow cells, having a first light guide, such as an optical fiber, with an exit surface where light is emitted and a second light guide with an entrance surface where light is received. The path length or distance between the exit surface and entrance surface can be relatively long for solutions of lower concentration, but in order to achieve reliable detection also for solutions of high concentration the distance should be smaller, typically in the range of <NUM>-<NUM>. To achieve satisfactory quality of measurements, the distance must be kept constant and is typically not allowed to deviate from a set value more than <NUM>%.

A common problem within this area is that cleaning or service operations, of the measuring device, is cumbersome, complex and time consuming. Cleaning or service operations are typically is required when changing from one substance to another to avoid contamination. A further problem is that after cleaning or service operations corrections or adjustments involving cumbersome calibration operations before normal operation can resume. A further problem is that various cleaning or service operations affects the environment the optical flow cell is exposed to and may alter the path length or distance between the exit surface and entrance surface of the device, e.g. after being exposed to high/low temperatures, radiation or air pressure. A further problem is that the dimension path length or distance between the exit surface and entrance surface variability is greater when optical flow cells made from polymers are used. A further problem is that the sensitivity to the path length or distance variability is higher when the path length is short.

Some existing systems with one or more of the above stated problem are disclosed in <CIT><CIT> and <CIT>).

<CIT>) discloses an optical flow cell detector comprising a sample inlet and outlet in fluidic communication through a flow cell channel of cross-sectional area A, an input light guide with a light exit surface arranged adjacent and in optical alignment with a light entrance surface of an output light guide.

<CIT> discloses an optical flow cell capable of use in high temperature and high-pressure environment.

) discloses a probe comprising a plurality of optical fiber sensors containing colorimetric chemical indicators in gaps in the fibers and a method of producing the same.

There is therefore a need for an improved optical flow cell for measuring devices to overcome this drawback.

An objective of embodiments of the present invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

The above and further objectives are achieved by the subject matter of the independent claims. Further advantageous implementation forms of the invention are defined by the dependent claims.

An "or" in this description and the corresponding claims is to be understood as a mathematical OR which covers" and" and "or", and is not to be understand as an XOR (exclusive OR). The indefinite article "a" in this disclosure and claims is not limited to "one" and can also be understood as "one or more", i.e., plural.

The above objectives are solved by the subject matter of the independent claims. Further advantageous implementation forms of the present invention can be found in the dependent claims.

In an embodiment, the housing may be a single use and/or disposable optical flow cell <NUM> made from polymer and/or metal. An advantage of this embodiment is that optical flow cell measurement complexity can be reduced and setup times for measurements can be reduced by using a single use and/or disposable optical flow cell <NUM>, thus eliminating the need for cleaning or service operations.

An advantage of this embodiment is that optical flow cell measurement complexity can be reduced and setup times for measurements can be reduced by using a single use and/or disposable optical flow cell, thus eliminating the need for cleaning or service operations.

At least one advantage is that the measurement quality of the flow cell is improved.

Further applications and advantages of embodiments of the invention will be apparent from the following detailed description.

The scope of the invention is defined by the claims, which are incorporated into this section by reference. A more complete understanding of embodiments of the applications and advantages of the invention will be afforded to those skilled in the art, as well as a realization of additional advantages thereof, by a consideration of the following detailed description of one or more embodiments. Reference will be made to the appended sheets of drawings that will first be described briefly.

<FIG> shows plan view of an optical flow cell <NUM> according to an embodiment of the present invention. The optical flow cell may comprise a housing <NUM> forming an enclosed and elongated fluid channel <NUM> arranged along a first axis <NUM>. An advantage of the enclosed and elongated fluid channel is that it allows for cutting a continuous light guide along the first axis <NUM> to form a first and second light guide and/or cutting the continuous light guide in a motion perpendicular to the first axis <NUM> to form a first and second light guide, such that the first and second light guide are separated by a path length and/or distance.

In an example not falling under the scope of the claims, when manufacturing the optical flow cell <NUM> a continuous light guide may be arranged across the elongated fluid channel <NUM>, e.g. when molding the housing or by making a through hole crossing the first axis <NUM> through the housing and feeding the continuous light guide through the through hole. A diamond saw, e.g. a linear saw with diamond impregnated wire blade or a rotational/wheel saw with diamond wheel and/or laser ablation, can then be used to cut and/or remove a portion of the continuous light guide to form a first and second light guide.

<FIG> shows a vertical section side view of an optical flow cell <NUM> according to an embodiment of the present invention. The optical flow cell <NUM> may further comprise an inlet <NUM> arranged and/or configured to connect a first outer surface area of the housing <NUM> to a first end <NUM> of the fluid channel and an outlet <NUM> arranged to connect a second outer surface area to a second end <NUM> of the fluid channel. The first and second outer surface area may be formed as connectors configured for receiving a matching connector comprising a fluid tube for leading fluid to/from the optical flow cell <NUM>.

An advantage of this embodiment is that the optical flow cell measurement complexity can be further reduced and setup times for measurements can further be reduced as the inlet <NUM> and outlet <NUM> forms a part of the housing <NUM> and will be disposed together with the housing. Thus, the means for leading fluid to and from the optical flow cell <NUM> will not require cleaning or service operations.

<FIG> shows a vertical section end view of an optical flow cell <NUM> according to an embodiment of the present invention. The optical flow cell <NUM> comprises a first light guide <NUM>, e.g. an optical fiber, and a second light guide <NUM> concentrically arranged along a second axis <NUM> and on opposite side walls of the fluid channel. In an example not falling under the scope of the claims, the first and second light guide, e.g. optical fibers, are formed by inserting a continuous light guide into the optical flow cell housing along a second axis. A portion of the continuous light guide is then cut and/or removed by using a diamond saw and/or laser ablation, in a nominal environment, adjacent to a first side wall of the fluid channel to form a first light guide, e.g. having an exit surface where light is emitted, and cut adjacent to a second opposing side wall of the fluid channel to form a second light guide having an entrance surface where the emitted light is received. In a further example not falling under the scope of the claims, the portion of the continuous light guide may be cut and/or removed in a single step, e.g. by using a diamond saw and/or laser ablation device with a cutting width corresponding to the path length or distance d. In one or more embodiments, additional steps of grinding or polishing the exit and entrance surface may further be performed. After cutting is performed, the exit surface and the entrance surface are separated by a path length and/or distance. The first light guide <NUM> may be configured for receiving emitted light within a bandwidth, e.g. extreme ultraviolet, ultraviolet, near ultraviolet, visible light, near Infrared, mid infrared, far infrared, from a light generator <NUM>. The second light guide <NUM> may be configured for receiving the emitted light from the first light guide <NUM>, after it has traversed the fluid channel, and emitting the received emitted light to an absorption value generator <NUM> configured to receive reference light directly from the light generator <NUM>, e.g. via a third light guide, and received light from the optical flow cell <NUM>, i.e. from the second light guide <NUM>. In an embodiment, the first axis <NUM> and the second axis <NUM> intersect each other. In a further embodiment, the first axis <NUM> and the second axis <NUM> are arranged perpendicular to each other. In an embodiment, the first light guide comprises an exit surface, where light is emitted. The exit surface may be arranged adjacent to a first side wall <NUM> of the fluid channel, e.g. protruding from the first side wall of the fluid channel. The first side wall <NUM> may be one of the opposite side walls of the fluid channel described above, as further described in relation to <FIG>. The second light guide may comprise an entrance surface, where the emitted light is received, i.e. from the exit surface. The entrance surface may be arranged adjacent to a second opposing side wall <NUM> of the fluid channel. The second side wall <NUM> may be the other one of the opposite side walls of the fluid channel described above. In one embodiment, the exit surface and the entrance surface may be separated by a path length and/or distance d. The path length and/or distance d may be equal to a nominal distance when the optical flow cell <NUM> is subjected to a nominal environment, e.g. an average temperature of <NUM>° C and average pressure at <NUM> millibars. In an example, the path length and/or distance d is <NUM> at a temperature of the optical flow cell <NUM> of <NUM> degrees Celsius. In an example a nominal light absorption value may be calculated for a fluid at <NUM>° C. It is understood that, when the temperature of the optical flow cell <NUM> changes, the path length and/or distance d and the corresponding absorption value will change accordingly due to thermal expansion.

In an embodiment, the first light guide <NUM> is enclosed in a first connector part <NUM> and/or the second light guide <NUM> is enclosed in a second connector part <NUM>. The first and/or second connector part may comprise a body having an outer end configured to receive an optical connector, a through bore and/or through channel configured for receiving the first/second light guide.

An advantage of this embodiment is at least that the complexity of and time required to setup a measurement is reduced as the the optical flow cell may be connected to the light generator <NUM> and/or the absorption value generator <NUM> using standard optical connectors.

In an embodiment, the optical flow cell may also be connected directly to the light generator <NUM> and/or the absorption value generator <NUM>.

In an embodiment, the optical flow cell <NUM> further comprises a first fastener arranged to fasten or secure the first connector part <NUM> to the housing <NUM> and a second fastener arranged to fasten or securethe second connector part <NUM> to the housing <NUM>, e.g. in the form of locking screws, an adhesive or a welding. The first and/or second fastener is/are preferably a releasable fastener/s. An advantage of this embodiment is that cost, complexity of and time required of manufacturing the optical flow cell <NUM> may be reduced.

<FIG> shows a side view of an optical flow cell <NUM> according to an embodiment of the present invention. In an embodiment, the housing comprises at least a first part <NUM>, a second part <NUM> and a seal <NUM> located between the first and the second part <NUM>, <NUM>. In an embodiment, the first part <NUM> and/or the second part <NUM> is/are configured to form the enclosed and elongated fluid channel <NUM> arranged along the first axis <NUM>, the fluid channel <NUM> having an open side, and the corresponding first part <NUM> and/or the second part <NUM> is configured to close the open side of the fluid channel <NUM>. In an embodiment, the the fluid channel <NUM> is configured with an arcuate channel wall opposite the open side. In an embodiment, the first part <NUM> and/or the second part <NUM> comprises the inlet <NUM> and/or the outlet <NUM> further described in relation to <FIG>.

In an embodiment, the first part <NUM> and/or the second part <NUM> comprise/s the first light guide <NUM> and/or the second light guide <NUM> as further described in relation to <FIG>. An advantage of this embodiment is that complexity of forming the first and second light guide by cutting of the continuous light guide is reduced as the first and second part may be separated before performing cutting.

Optionally, the optical flow cell <NUM> may further comprise one or more fastening means <NUM>, <NUM> configured to mount and/or secure and/or hold and/or secure the at least first part <NUM>, second part <NUM> and the seal <NUM> to each other. An advantage of this embodiment is that complexity of assembly of the optical flow cell <NUM> is reduced.

In an embodiment, the first part <NUM> and/or the second part <NUM> are single unitary pieces. An advantage of this embodiment is that probability of fluid leakage is reduced. A further advantage is that the first and second parts may be moulded for low cost. The single unitary pieces are affected, for example by thermal influences, more than more expensive materials used in some conventional optical flow cells, which may be made from titanium. The computer implemented method for measurement compensation/absorption value compensation further described in relation to <FIG> may be employed to counter these environmental effects and to account for possible manufacturing variances in the path length d.

<FIG> shows a perspective view of the seal <NUM> according to an embodiment of the present invention. The seal <NUM> may be made from an elastomer. The seal <NUM> may enclose edges of opposing surfaces of the first and second parts <NUM>, <NUM>. The seal <NUM> may comprise a saddle shaped surface <NUM>, where the length direction of the saddle shaped surface is perpendicular to the first axis <NUM>. The advantage of the saddle shape is that the seal is centered in relation to the first and second part <NUM>, <NUM>.

The first and second parts <NUM>, <NUM> may further have a saddle shape and/or comprise a saddle shaped surface, where the length direction of the saddle shape and/or saddle shaped surface is perpendicular to the first axis <NUM>. The saddle shape and/or saddle shaped surface of the first part <NUM> may further be configured to fit and/or closely match the saddle shape and/or saddle shaped surface of the second part <NUM> when the second part <NUM> is received by the first part.

<FIG> shows an exploded view of an optical flow cell <NUM> according to an embodiment of the present invention. In this embodiment, an optical flow cell <NUM> is provided that comprises a fluid flow path and/or a fluid channel <NUM> formed in a housing part and/or a second part <NUM> and extending along an axis and/or the first axis <NUM>. The housing part <NUM> is further supporting opposed light guides <NUM>, <NUM> on opposed walls <NUM>, <NUM> of the fluid flow path and/or the fluid channel <NUM>. The fluid flow path and/or the fluid channel <NUM> may be open at least on a side generally parallel with the axis and/or the first axis <NUM> for exposing said light guides. The fluid flow path and/or a fluid channel <NUM> may preferably have open ends, which allow access to removing a portion of a continuous light guide to form the opposed light guides <NUM>, <NUM>, e.g. to a cutting wheel or laser cutter during manufacture. The open side of the flow path and/or the fluid channel <NUM> may be closeable by a further housing part and/or a first part <NUM> to form the flow cell. In an example, the housing part and/or second part <NUM> is configured to form the fluid flow path and/or a fluid channel <NUM> extending along the first axis <NUM>, the fluid channel <NUM> having an open side. The corresponding further housing part and/or first part <NUM> is configured to close the open side of the fluid flow path and/or a fluid channel <NUM>. In an embodiment, the the fluid flow path and/or a fluid channel <NUM> is configured with an arcuate channel wall opposite the open side.

<FIG> shows detailed plan view of the seal <NUM> according to an embodiment of the present invention. The seal <NUM> may further comprise a first and second bore <NUM>, <NUM> arranged on the second axis <NUM>, wherein the first bore <NUM> is arranged to allow the first light guide <NUM> to protrude through the first bore <NUM> and the second light guide <NUM> is arranged to protrude through the second bore <NUM> such that the exit surface of the first light guide <NUM> and the entrance surface of the second light guide <NUM> is separated by a path length and/or distance d. The first light guide <NUM> and the second light guide <NUM> may be arranged to protrude into the fluid channel <NUM>. The advantage of this embodiment is that the seal prevents fluid from leaking out along the the first light guide <NUM> and/or the second light guide <NUM>.

<FIG> shows detailed front view of the first bore <NUM> comprised in the seal <NUM>. <FIG> shows detailed plan view of the fluid channel <NUM> according to an embodiment of the present invention. The fluid channel <NUM> comprises a first side wall <NUM> and a second side wall <NUM> of the opposite side walls previously described. The exit surface of the first light guide <NUM> is arranged adjacent to the first side wall <NUM> of the fluid channel <NUM>, e.g. protruding from the first side wall of the fluid channel. The entrance surface of the second light guide <NUM> is arranged adjacent to the second opposing side wall <NUM> of the fluid channel <NUM>. The exit surface and the entrance surface are separated by a path length and/or distance d. <FIG> also schematically illustrates the location of the first end <NUM> of the fluid channel where the inlet <NUM> connects to and the second end <NUM> of the fluid channel where the outlet <NUM> connects to.

<FIG> shows a method of producing the optical flow cell according to an example not falling under the scope of the claims.

In an example, removing <NUM> the portion of the continuous light guide is performed by cutting the continuous light guide adjacent to the first side wall <NUM> of the fluid channel <NUM> and cutting the continuous light guide adjacent to the second opposing side wall <NUM> of the fluid channel <NUM>.

In an example, removing <NUM> the portion of the continuous light guide is performed in a motion along the first axis <NUM> and perpendicular to the second axis <NUM>. In a further embodiment, removing <NUM> the portion of the continuous light guide is performed in a motion perpendicular to the first axis <NUM> and perpendicular to the second axis <NUM>.

In an embodiment, the method further comprises assembling the first part <NUM>, the second part <NUM> and the seal <NUM> located between the first and the second part <NUM>, <NUM> to an optical flow cell housing <NUM>.

<FIG> shows a method <NUM> performed by a measuring device <NUM> comprising the optical flow cell <NUM> according to any of the embodiments described herein. The method comprising:.

In an embodiment, the compensation function compensates for variations of the path length and/or distance d dependent on the environment data. The environment data may be indicative of one or more of:.

In one example, the optical flow cell <NUM> is operating in <NUM>° C of ambient temperature, resulting in a reduced path length and/or distance d. The above described method compensates the light absorption value for the reduced path length and/or distance d, thus resulting in an improved compensated light absorption value and improved measurement quality. In yet an example, the compensation function is obtained by measuring light absorption value at different temperatures. The measured light absorption values at different temperatures may then be used to and generate a compensation table and/or compensation function based on the obtained result.

In yet an example, the optical flow cell <NUM> has been subjected to gamma irradiation and/or autoclaving, resulting in an altered thermal expansion coefficient and/or reduced path length and/or distance d. The above described method compensates the light absorption value for the altered thermal expansion coefficient and/or the reduced path length and/or distance d, thus resulting in an improved compensated light absorption value and improved measurement quality.

The advantage of this embodiment is that the quality of measurements obtained using the optical flow cell <NUM> is improved. In particular with regards to the environment the optical flow cell <NUM> has been subjected to, such as ambient temperature, having been subjected to gamma irradiation and/or autoclaving.

<FIG> shows a measuring device <NUM> according to an embodiment of the present invention. The measuring device <NUM> may be configured for compensating a light absorption value measured in the optical flow cell <NUM> according to any of the embodiments described herein. The measuring device <NUM> may comprise a light generator <NUM>, e.g. one or more Light Emitting Diodes (LED), Organic Light-Emitting Diodes, Polymer Light-Emitting Diodes, Active-Matrix Organic Light-Emitting Diodes, Light-emitting electrochemical cell, Electroluminescent wires, Field-induced polymer electroluminescent or Lasers, configured to emit light within a bandwidth to the first light guide. The measuring device <NUM> may further comprise an absorption value generator <NUM> configured to receive reference light from the light generator <NUM> and received light from the optical flow cell <NUM> and generate a light absorption value. The measuring device <NUM> may further comprise a flow cell control unit <NUM>, the unit comprising a processor <NUM> and a memory <NUM>, said memory containing instructions executable by said processor, whereby said flow cell control unit <NUM> is operative and/ or configured to perform the method of any of the corresponding methods described herein.

The absorption value generator <NUM> may comprise a first photodiode and/or light sensor configured to receive reference light from the light generator <NUM> and to generate a first signal indicative of the amplitude of the reference light. The absorption value generator <NUM> may further comprise a second photodiode and/or light sensor configured received light from the optical flow cell <NUM>, e.g. from the entrance surface and to generate a second signal indicative of the amplitude of the received light from the optical flow cell <NUM>. The absorption value generator <NUM> may further comprise a differentiator configured to receive the first and second signal and generate a light absorption value. The absorption value generator <NUM> may further be configured to send the light absorption value to the flow cell control unit <NUM>. The measuring device <NUM> may be in the form of a server, an on-board computer, an digital information display, a stationary computing device, a laptop computer, a tablet computer, a handheld computer, a wrist-worn computer, a smart watch, a PDA, a Smartphone, a smart TV, a telephone, a media player, a game console, a vehicle mounted computer system or a navigation device.

The processor <NUM> may be communicatively coupled to a transceiver <NUM> for wired or wireless communication. Further, the measuring device <NUM> may further comprise at least one optional antenna (not shown in the figure). The antenna may be coupled to the transceiver <NUM> and is configured to transmit and/or emit and/or receive a wireless signals in a wireless communication system. In one example, the processor <NUM> may be any of processing circuitry and/or a central processing unit and/or processor modules and/or multiple processors configured to cooperate with each-other. Further, the measuring device <NUM> may further comprise a memory <NUM>. The memory <NUM> may contain instructions executable by the processor to perform the methods described herein. The processor <NUM> may be communicatively coupled to a selection of any of the transceiver <NUM> and the memory <NUM>. The measuring device <NUM> may be configured to receive the absorption value/s directly from the absorption value generator <NUM> or via a wired and/or wireless communications network (not shown in the figure).

In one or more embodiments the measuring device <NUM> may further comprise an input device <NUM>, configured to receive input or indications from a user and send a user-input signal indicative of the user input or indications to the processing means <NUM>. In one or more embodiments the measuring device <NUM> further comprises a display <NUM> configured to receive a display signal indicative of rendered objects, such as text or graphical user input objects, from the processing means <NUM> and to display the received signal as objects, such as text or graphical user input objects. In one embodiment the display <NUM> is integrated with the user input device <NUM> and is configured to receive a display signal indicative of rendered objects, such as text or graphical user input objects, from the processing means <NUM> and to display the received signal as objects, such as text or graphical user input objects, and/or configured to receive input or indications from a user and send a user-input signal indicative of the user input or indications to the processing means <NUM>. In embodiments, the processor/processing means <NUM> is communicatively coupled to the memory <NUM> and/or the transceiver and/or the input device <NUM> and/or the display <NUM>. In embodiments, the transceiver <NUM> communicates using any wired and/or wireless communication techniques known in the art, as further described below.

In embodiments, the one or more memory <NUM> may comprise any of a selection of a hard RAM, disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a CD or DVD drive (R or RW), or other removable or fixed media drive.

In an embodiment, a computer program is provided comprising computer-executable instructions for causing a measuring device <NUM> when the computer-executable instructions are executed on a processor/processing unit comprised in the measuring device <NUM>, to perform any of the methods described herein.

In an embodiment, a computer program product comprising a memory and/or a computer-readable storage medium, the computer-readable storage medium having the computer program described above embodied therein. The memory and/or computer-readable storage medium referred to herein may comprise of essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.

In embodiments, the communications network communicate uses wired or wireless communication techniques that may include at least one of a Local Area Network (LAN), Metropolitan Area Network (MAN), Global System for Mobile Network (GSM), Enhanced Data GSM Environment (EDGE), Universal Mobile Telecommunications System, Long term evolution, High Speed Downlink Packet Access (HSDPA), Wideband Code Division Multiple Access (W-CDMA), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Bluetooth®, Zigbee®, Wi-Fi, Voice over Internet Protocol (VoIP), LTE Advanced, IEEE802. <NUM>, WirelessMAN-Advanced, Evolved High-Speed Packet Access (HSPA+), 3GPP Long Term Evolution (LTE), Mobile WiMAX (IEEE <NUM>. 16e), Ultra Mobile Broadband (UMB) (formerly Evolution-Data Optimized (EV-DO) Rev. C), Fast Low-latency Access with Seamless Handoff Orthogonal Frequency Division Multiplexing (Flash-OFDM), High Capacity Spatial Division Multiple Access (iBurst®) and Mobile Broadband Wireless Access (MBWA) (IEEE <NUM>) systems, High Performance Radio Metropolitan Area Network (HIPERMAN), Beam-Division Multiple Access (BDMA), World Interoperability for Microwave Access (Wi-MAX) and ultrasonic communication, etc., but is not limited thereto.

Moreover, it is realized by the skilled person that the measuring device <NUM> may comprise the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the present solution. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, MSDs, TCM encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the present solution.

Especially, the processor of the present measuring device <NUM> may comprise a processor and/or processing circuitry and/or processing means, e.g., one or more instances of processing circuitry, processor modules and multiple processors configured to cooperate with each-other, Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, a Field-Programmable Gate Array (FPGA) or other processing logic that may interpret and execute instructions. The expression "processor" may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The processing means may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

<FIG> shows a method of producing an optical flow cell, according to the invention, as shown in <FIG>.

In an example not falling under the scope of the invention, removing <NUM> the portion of the continuous light guide is performed by cutting one or more, preferable both ends of the light guides, for example in the manner described above, with any of the modifications described above.

In embodiments of optical flow cells, according to the invention incorporating the arrangement of <FIG>, the optical fiber light guides <NUM> and <NUM> are different diameters, because it has been found that some light diffusion occurs when, in this case, the light emitter <NUM> has been cut with a diamond wheel or the like, and so the light collector (<NUM> in this case) is made larger in diameter to capture the more diffuse light. Whilst a larger diameter is the preferred way to capture more light, it would additionally be possible to use a larger surface area on the surface which capture the light. Other features of this embodiment are as described above in relation to the other embodiments.

Claim 1:
An optical flow cell (<NUM>, <NUM>') comprising:
a housing (<NUM>, <NUM>) comprising at least a first housing part (<NUM>, <NUM>), a second housing part (<NUM>, <NUM>) and a seal (<NUM>) located between the first housing part (<NUM>, <NUM>) and the second housing part (<NUM>, <NUM>), wherein the first housing part (<NUM>, <NUM>) and/or the second housing part (<NUM>, <NUM>) is/are configured to form an enclosed and elongated fluid channel (<NUM>, <NUM>) therebetween arranged along a first axis (<NUM>, <NUM>), and wherein the fluid channel (<NUM>, <NUM>) comprises at least one open side on the first housing part (<NUM>, <NUM>) and/or the second housing part (<NUM>, <NUM>), wherein the corresponding first housing part (<NUM>, <NUM>) and/or the corresponding second housing part (<NUM>, <NUM>) is/are configured to close the at least one open side of the fluid channel (<NUM>, <NUM>); and
a first light guide (<NUM>, <NUM>) and a second light guide (<NUM>, <NUM>) generally concentrically arranged along a second axis (<NUM>, <NUM>) and on opposite side walls (<NUM>, <NUM>) of the fluid channel (<NUM>, <NUM>), wherein the second axis (<NUM>, <NUM>) and the first axis (<NUM>, <NUM>) intersect each other, such as the first axis (<NUM>, <NUM>) and the second axis (<NUM>, <NUM>) are arranged perpendicular to each other; characterised in that:
the first light guide (<NUM>, <NUM>) and the second light guide (<NUM>, <NUM>) are optical fiber light guides of different diameters, and wherein the first light guide (<NUM>, <NUM>) has been cut with a diamond saw and has a surface thereof that is configured to produce diffuse light, and wherein the second light guide (<NUM>, <NUM>) is a light collector light guide that is of a larger diameter than the first light guide (<NUM>, <NUM>) for capturing the diffuse light.