Patent Description:
This disclosure relates to optical measuring devices and, more particularly, to fluorometers for monitoring the concentration of one or more substances in a sample.

In cleaning and antimicrobial operations, commercial users (e.g., restaurants, hotels, food and beverage plants, grocery stores, etc.) rely upon the concentration of a cleaning or antimicrobial product to make the product work effectively. Failure of a cleaning or antimicrobial product to work effectively (for example due to concentration issues) can cause a commercial user to perceive the product as lower quality. End consumers may also perceive the commercial provider of such products as providing inferior services. In addition, commercial users may be investigated and/or sanctioned by government regulatory and health agencies. Accordingly, there is a need for a system that can monitor the characteristics of fluid solutions, e.g., to determine if the concentration of a product is within a specified concentration range. The same may be true for other applications, such as commercial and industrial water treatment, pest control, beverage and bottling operations, oil and gas refining and processing operations, and the like.

One method of monitoring the concentration of a product relies on monitoring the fluorescence of the product that occurs when the sample (and the product within the sample) is exposed to a predetermined wavelength of light. For example, compounds within the product or a fluorescent tracer added to the product may fluoresce when exposed to certain wavelengths of light. The concentration of the product can then be determined using a fluorometer that measures the fluorescence of the compounds and calculates the concentration of the chemical based on the measured fluorescence.

Generally, fluorometric spectroscopy requires directing light from a source of radiant light to a sample and then receiving light from the sample at a detector. In order to do so, the source and detector must be in optical communication with the sample. In existing systems, providing optical access to the sample can be a costly process requiring significant modification to the system and significant downtime to perform such modification.

<CIT> describes a method of detecting particles in a fluid sample by illuminating the fluid sample with light at two different wavelengths emitted by two respective light sources into a common light path and detecting, by a common detector array, fluorescent light and scattered light resulting from the illumination.

The invention is directed to a method as defined in claim <NUM>.

The following detailed description is exemplary in nature and is not intended to limit the scope of the invention, which is defined by the appended claims.

Optical sensors are used in a variety of applications, including monitoring industrial processes. An optical sensor can be implemented as a portable, handheld device that is used to periodically analyze the optical characteristics of a fluid in an industrial process. Alternatively, an optical sensor can be installed online to continuously analyze the optical characteristics of a fluid in an industrial process. In either case, the optical sensor may optically analyze the fluid sample and determine different characteristics of the fluid, such as the concentration of one or more chemical species in the fluid.

As one example, optical sensors are often used in industrial cleaning and sanitizing applications. During an industrial cleaning and sanitizing process, water is typically pumped through an industrial piping system to flush the piping system of product residing in pipes and any contamination build-up inside the pipes. The water may also contain a sanitizing agent that functions to sanitize and disinfect the piping system. The cleaning and sanitizing process can prepare the piping system to receive new product and/or a different product than was previously processed on the system.

An optical sensor can be used to monitor the characteristics of flushing and/or sanitizing water flowing through a piping system during an industrial cleaning and sanitizing process. Either continuously or on an intermittent basis, samples of water are extracted from the piping system and delivered to the optical sensor. Within the optical sensor, light is emitted into the water sample and used to evaluate the characteristics of the water sample. The optical sensor may determine whether residual product in the piping system has been sufficiently flushed out of the pipes, for example, by determining that there is little or no residual product in the water sample. The optical sensor may also determine the concentration of sanitizer in the water sample, for example, by measuring a fluorescent signal emitted by the sanitizer in response to the light emitted into the water sample. If it is determined that there is an insufficient amount of sanitizer in the water sample to properly sanitize the piping system, the amount of sanitizer is increased to ensure proper sanitizing of the system.

While the optical sensor can have a variety of different configurations, in some examples, the optical sensor is designed to have a single optical lens through which light is emitted into a fluid sample and also received from the fluid sample. The optical sensor may include a housing that contains various electronic components of the sensor and also has optical pathways to control light movement to and from the single optical lens. Such an arrangement may facilitate design of a compact optical sensor that can be readily installed through a variety of mechanical pipe and process fittings to optically analyze a desired process fluid.

<FIG> is a conceptual diagram illustrating an example fluid system <NUM>, which may be used to produce a chemical solution having fluorescent properties, such as a sanitizer solution exhibiting fluorescent properties. Fluid system <NUM> includes optical sensor <NUM>, a reservoir <NUM>, a controller <NUM>, and a pump <NUM>. Reservoir <NUM> may store a concentrated chemical agent that can be blended with a diluent, such as water, to generate the chemical solution, or can be any other source for the sample to be characterized. Optical sensor <NUM> is optically connected to fluid pathway <NUM> and is configured to determine one or more characteristics of the solution traveling through the fluid pathway.

The fluid pathway <NUM> can be a single fluid vessel or combination of vessels which carry a fluid sample through the fluid system <NUM> including, but not limited to, pipes, tanks, valves, pipe tees and junctions, and the like. In some instances, one or more components of the fluid pathway <NUM> can define an interface or opening sized to receive or otherwise engage with the optical sensor <NUM>. In operation, optical sensor <NUM> can communicate with controller <NUM>, and controller <NUM> can control fluid system <NUM> based on the fluid characteristic information generated by the optical sensor.

Controller <NUM> is communicatively connected to optical sensor <NUM> and pump <NUM>. Controller <NUM> includes processor <NUM> and memory <NUM>. Controller <NUM> communicates with pump <NUM> via a connection <NUM>. Signals generated by optical sensor <NUM> are communicated to controller <NUM> via a wired or wireless connection, which in the example of <FIG> is illustrated as wired connection <NUM>. Memory <NUM> stores software for running controller <NUM> and may also store data generated or received by processor <NUM>, e.g., from optical sensor <NUM>. Processor <NUM> runs software stored in memory <NUM> to manage the operation of fluid system <NUM>.

As described in greater detail below, optical sensor <NUM> is configured to optically analyze a sample of fluid flowing through fluid pathway <NUM>. Optical sensor <NUM> may include an optical detector that is positioned and configured to measure fluorescent emissions emitted by the fluid sample. In some configurations, a single optical detector can be used to measure both scattering and fluorescence from a sample and can receive both scattered and fluoresced light via a single optical pathway in the sensor <NUM>. The single optical pathway can additionally be used to direct light to induce scattering and fluorescence to the sample, thereby providing a compact and spatially efficient interface between the sensor <NUM> and the sample. Providing a single optical communication point between the sensor <NUM> and sample also can simplify implementation of the sensor <NUM> into fluid system <NUM>, e.g., by providing a sensor that can easily interface with one or more components of the fluid pathway <NUM> such as a tee configuration in a pipe.

In the example of <FIG>, fluid system <NUM> is configured to generate or otherwise receive a chemical solution having fluorescent properties. Fluid system <NUM> can combine one or more concentrated chemical agents stored within or received from reservoir <NUM> with water or another diluting fluid to produce the chemical solutions. In some instances, dilution is not necessary, as the reservoir immediately provides an appropriate sample. Example chemical solutions that may be produced by fluid system <NUM> include, but are not limited to, cleaning agents, sanitizing agents, cooling water for industrial cooling towers, biocides such as pesticides, anti-corrosion agents, anti-scaling agents, anti-fouling agents, laundry detergents, clean-in-place (CIP) cleaners, floor coatings, vehicle care compositions, water care compositions, bottle washing compositions, and the like.

The chemical solutions generated by or flowing through the fluid system <NUM> may emit fluorescent radiation in response to optical energy directed into the solutions by optical sensor <NUM>. Optical sensor <NUM> can then detect the emitted fluorescent radiation and determine various characteristics of the solution, such as a concentration of one or more chemical compounds in the solution, based on the magnitude of the emitted fluorescent radiation. In some embodiments, the optical sensor <NUM> can direct optical energy to the solution and receive fluorescent radiation from the solution via an optical pathway within the optical sensor <NUM>, allowing for a compact design for the optical sensor <NUM>.

In order to enable optical sensor <NUM> to detect fluorescent emissions, the fluid generated by fluid system <NUM> and received by optical sensor <NUM> may include a molecule that exhibits fluorescent characteristics. In some examples, the fluid includes a polycyclic compound and/or a benzene molecule that has one or more substituent electron donating groups such as, e.g., -OH, -NH<NUM>, and - OCH<NUM>, which may exhibit fluorescent characteristics. Depending on the application, these compounds may be naturally present in the chemical solutions generated by fluid system <NUM> because of the functional properties (e.g., cleaning and sanitizing properties) imparted to the solutions by the compounds.

In addition to or in lieu of a naturally fluorescing compound, the fluid generated by fluid system <NUM> and received by optical sensor <NUM> may include a fluorescent tracer (which may also be referred to as a fluorescent marker). The fluorescent tracer can be incorporated into the fluid specifically to impart fluorescing properties to the fluid. Example fluorescent tracer compounds include, but are not limited to, naphthalene disulfonate (NDSA), <NUM>-naphthalenesulfonic acid, Acid Yellow <NUM>,<NUM>,<NUM>,<NUM>,<NUM>-pyrenetetrasulfonic acid sodium salt, and fluorescein.

Independent of the specific composition of the fluid generated by fluid system <NUM>, the system can generate fluid in any suitable fashion. Under the control of controller <NUM>, pump <NUM> can mechanically pump a defined quantity of concentrated chemical agent out of reservoir <NUM> and combine the chemical agent with water to generate a liquid solution suitable for the intended application. Fluid pathway <NUM> can then convey the liquid solution to an intended discharge location. In some examples, fluid system <NUM> may generate a flow of liquid solution continuously for a period of time such as, e.g., a period of greater than <NUM> minutes, a period of greater than <NUM> minutes, or even a period of greater than <NUM> hours. Fluid system <NUM> may generate solution continuously in that the flow of solution passing through fluid pathway <NUM> may be substantially or entirely uninterrupted over the period of time.

In some examples, monitoring the characteristics of the fluid flowing through fluid pathway <NUM> can help ensure that the fluid is appropriately formulated for an intended downstream application. Monitoring the characteristics of the fluid flowing through fluid pathway <NUM> can also provide feedback information, e.g., for adjusting parameters used to generate new fluid solution. For these and other reasons, fluid system <NUM> can include a sensor to determine various characteristics of the fluid generated by the system. The sensor can engage directly with the fluid pathway <NUM> to monitor fluid characteristics, or can alternatively receive fluid from the fluid system <NUM> separately from the fluid pathway <NUM>.

In the example of <FIG>, fluid system <NUM> includes optical sensor <NUM>. The optical sensor <NUM> can engage the fluid pathway <NUM> in any number of ways, such as interfacing with a tee configuration in a pipe in the fluid pathway <NUM>, being inserted into a port of a tank or other fluid vessel through which fluid periodically flows, or the like. Optical sensor <NUM> may determine one or more characteristics of the fluid flowing through fluid pathway <NUM>. Example characteristics include, but are not limited to, the concentration of one or more chemical compounds within the fluid (e.g., the concentration of one or more active agents added from reservoir <NUM> and/or the concentration of one or more materials being flushed from piping in fluid system <NUM>), the temperature of the fluid, the conductivity of the fluid, the pH of the fluid, the flow rate at which the fluid moves through the optical sensor, and/or other characteristics of the fluid that may help ensure the system from which the fluid sample being analyzed is operating properly. Optical sensor <NUM> may communicate detected characteristic information to controller <NUM> via connection <NUM>.

Optical sensor <NUM> may be controlled by controller <NUM> or one or more other controllers within fluid system <NUM>. For example, optical sensor <NUM> may include a device controller (not illustrated in <FIG>) that controls the optical sensor to emit light into the fluid under analysis and also to detect light received back from the fluid. The device controller may be positioned physically adjacent to the other components of the optical sensor, such as inside a housing that houses a light source and detector of the optical sensor. In such examples, controller <NUM> may function as a system controller that is communicatively coupled to the device controller of optical sensor <NUM>. The system controller <NUM> may control fluid system <NUM> based on optical characteristic data received from and/or generated by the device controller. In other examples, optical sensor <NUM> does not include a separate device controller but instead is controlled by controller <NUM> that also controls fluid system <NUM>. Therefore, although optical sensor <NUM> is generally described as being controlled by controller <NUM>, it should be appreciated that fluid system <NUM> may include one or more controllers (e.g., two, three, or more), working alone or in combination, to perform the functions attributed to optical sensor <NUM> and controller <NUM> in this disclosure. Devices described as controllers may include processors, such as microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components.

In the example illustrated in <FIG>, processor <NUM> of controller <NUM> can receive determined optical characteristic information from optical sensor <NUM> and compare the determined characteristic information to one or more thresholds stored in memory <NUM>, such as one or more concentration thresholds. Based on the comparison, controller <NUM> may adjust fluid system <NUM>, e.g., so that the detected characteristic matches a target value for the characteristic. In some examples, controller <NUM> starts and/or stops pump <NUM> or increases and/or decreases the rate of pump <NUM> to adjust the concentration of a chemical compound flowing through fluid pathway <NUM>. Starting pump <NUM> or increasing the operating rate of pump <NUM> can increase the concentration of the chemical compound in the fluid. Stopping pump <NUM> or decreasing the operating rate of pump <NUM> can decrease the concentration of chemical compound in the fluid. In some additional examples, controller <NUM> may control the flow of water that mixes with a chemical compound in reservoir <NUM> based on determined characteristic information, for example, by starting or stopping a pump that controls the flow of water or by increasing or decreasing the rate at which the pump operates. Although not illustrated in the example fluid system <NUM> of <FIG>, controller <NUM> may also be communicatively coupled to a heat exchanger, heater, and/or cooler to adjust the temperature of fluid flowing through fluid pathway <NUM> based on characteristic information received from optical sensor <NUM>.

In yet other examples, optical sensor <NUM> may be used to determine one or more characteristics of a stationary volume of fluid that does not flow through a flow chamber of the optical sensor. For example, optical sensor <NUM> may be implemented as an offline monitoring tool (e.g., as a handheld sensor), that requires filling the optical sensor with a fluid sample manually extracted from fluid system <NUM>. Alternatively, the optical sensor <NUM> can engage a portion of the fluid system <NUM> configured to receive and hold a stationary volume of the fluid, such as a stop-flow device, or an otherwise external vessel for receiving fluid and engaging the optical sensor <NUM>. In some embodiments, a controller <NUM> can control a system of pumps and/or valves to direct a finite amount of the sample to be measured into such a stationary vessel outfitted with a sensor <NUM>.

Fluid system <NUM> in the example of <FIG> also includes reservoir <NUM>, pump <NUM>, and fluid pathway <NUM>. Reservoir <NUM> may be any type of container that stores a chemical agent for subsequent delivery including, e.g., a tank, a tote, a bottle, and a box. Reservoir <NUM> may store a liquid, a solid (e.g., powder), and/or a gas. Pump <NUM> may be any form of pumping mechanism that supplies fluid from reservoir <NUM>. For example, pump <NUM> may comprise a peristaltic pump or other form of continuous pump, a positive-displacement pump, or any other type of pump appropriate for the particular application. In examples in which reservoir <NUM> stores a solid and/or a gas, pump <NUM> may be replaced with a different type of metering device configured to deliver the gas and/or solid chemical agent to an intended discharge location. Fluid pathway <NUM> in fluid system <NUM> may be any type of flexible or inflexible tubing, piping, or conduit.

In the example of <FIG>, optical sensor <NUM> determines a characteristic of the fluid flowing through fluid pathway <NUM> (e.g., concentration of a chemical compound, temperature or the like) and controller <NUM> controls fluid system <NUM> based on the determined characteristic and, e.g., a target characteristic stored in memory <NUM>. <FIG> is a block diagram of an example optical sensor <NUM> that can be installed in fluid system <NUM> to monitor a characteristic of a fluid flowing through fluid pathway <NUM>. Sensor <NUM> may be used as optical sensor <NUM> in fluid system <NUM>, or sensor <NUM> may be used in other applications beyond fluid system <NUM>.

In the example of <FIG>, the sensor <NUM> includes a housing <NUM>, a first optical emitter <NUM>, a second optical emitter <NUM>, an optical window <NUM>, and an optical detector <NUM>. The housing <NUM> houses the first optical emitter <NUM>, the second optical emitter <NUM>, and the optical detector <NUM>. Optical window <NUM> is positioned on an external surface of the housing <NUM> to provide a fluid-tight, optically transmissive barrier between an interior of the housing and fluid in fluid sample <NUM> that contacts the external surface of the housing. In operation, first optical emitter <NUM> and second optical emitter <NUM> emit light that is directed through optical window <NUM> and into the fluid sample <NUM> under analysis. In response to light emitted by the first optical emitter <NUM> and/or the second optical emitter <NUM> impinging on the fluid adjacent optical window <NUM>, the fluid may scatter light and/or generate fluorescent emissions. The scattered light and/or fluorescent emissions can pass through optical window <NUM> to be detected by optical detector <NUM>.

To control light transmission to and from optical window <NUM>, optical sensor <NUM> includes at least one optical pathway <NUM> optically connecting various components of the optical sensor to the fluid sample <NUM> under analysis. The optical pathway <NUM> may guide light emitted by the first optical emitter <NUM> and second optical emitter <NUM> so the light is guided from the optical emitters, through optical lens <NUM>, and into fluid sample <NUM>. The optical pathway <NUM> may also guide light received from the fluid sample <NUM> through optical window <NUM> so the light is guided to the optical detector <NUM>. When so configured, the first optical emitter <NUM> and the second optical emitter <NUM> may be positioned inside of the housing <NUM> to direct light into the optical pathway <NUM> and the optical detector <NUM> may be positioned inside of the housing to receive light from the optical pathway. Such an arrangement may allow optical sensor <NUM> to be configured with a single optical lens through which multiple light sources emit light and through which light is also received and detected from a fluid sample under analysis. This may help minimize the size of optical sensor <NUM>, for example, so that the sensor is sufficiently compact to be inserted through a mechanical pipe fitting into a piece of process equipment containing fluid for analysis.

Optical sensor <NUM> can include any suitable number of optical pathways optically connecting various emitter and detector components housed inside the housing <NUM> to the fluid sample under analysis via optical window <NUM>. In the example of <FIG>, optical sensor <NUM> is conceptually illustrated as having a first optical pathway <NUM> and a second optical pathway <NUM>. The second optical pathway <NUM> is optically connected to the first optical pathway <NUM> and also optically connected to the first optical emitter <NUM> and the second optical emitter <NUM>. The second optical pathway <NUM> can receive light from the first optical emitter <NUM> and second optical emitter <NUM> and guide the light to the first optical pathway <NUM> which, in turn, guides the light through optical window <NUM> into the fluid sample <NUM> under analysis. In some alternative embodiments, one optical emitter can emit light into the second optical pathway <NUM> while a second optical emitter is configured to emit light directly into the first optical pathway <NUM>. For example, in some embodiments, the first optical emitter <NUM> is configured to emit light into the second optical pathway <NUM> while the second optical emitter <NUM> is configured to emit light directly to the first optical pathway <NUM> by way of optical connection <NUM>. It should be noted that the diagram of <FIG> is intended to show optical connection and does not necessarily illustrate literal optical paths. For example, in some embodiments, the second optical emitter <NUM> is positioned proximate the first optical pathway <NUM>, and optical connection <NUM> need not be a literal bypass of the second optical pathways <NUM>. Rather, optical connection <NUM> merely illustrates that the second optical emitter <NUM> may be optically coupled directly to the first optical pathway <NUM> while the first optical emitter <NUM> is optically coupled to the first optical pathway <NUM> by way of the second optical pathway <NUM>. By configuring optical sensor <NUM> with additional optical pathways, various light emitters and detectors in the optical sensor can be optically connected to the fluid sample under analysis without being positioned directly adjacent the first optical pathway <NUM>.

Optical pathways in optical sensor <NUM> may be channels, segments of optically conductive tubing (e.g., fiber optic lines), or ducts that allow light to be conveyed through the optical sensor. The optical pathways may also be machined or cast into the housing <NUM> of the optical sensor. In different examples, the optical pathways may or may not be surrounded by optically opaque material, e.g., to bound light movement through the optical pathways and to prevent light from escaping through the sides of the optical pathways. When optical sensor <NUM> includes multiple optical pathways, the intersection of one optical pathway with another optical pathway may be defined where light traveling linearly through the one optical pathway is required to change direction to travel through the other optical pathway.

In the example of <FIG>, the optical sensor <NUM> includes at least one light source, and, in the illustrated example, is shown with two light sources: first optical emitter <NUM> and second optical emitter <NUM>. Each of the first optical emitter <NUM> and the second optical emitter <NUM> is a light source and can be implemented using any appropriate light source, such as a laser, a lamp, an LED, or the like. In some embodiments, the first optical emitter <NUM> and/or the second optical emitter <NUM> are configured to emit substantially uncollimated beams of light into the optical pathway <NUM>. In this case, the optical sensor <NUM> can include optical components to collimate the light from the first optical emitter <NUM> and/or the second optical emitter <NUM> in order to achieve a higher optical efficiency during operation.

Configuring the optical sensor <NUM> with multiple light sources may be useful, for example, to emit light at different wavelengths into the fluid sample <NUM>. For example, the first optical emitter <NUM> may be configured to emit light within a first range of wavelengths into the fluid sample <NUM> to generate fluorescent emissions within the fluid. The second optical emitter <NUM> may be configured to emit light within a second range of wavelengths different than the first range of wavelengths to measure the amount of light scattered by fluid sample <NUM>.

Independent of the specific number of light sources included in optical sensor <NUM>, the optical sensor includes an optical window <NUM> through which light is directed into and received from the fluid sample <NUM>. In some examples, optical window <NUM> focuses light directed into and/or received from the fluid sample under analysis. In such examples, optical window <NUM> may be referred to as an optical lens. In other examples, optical window <NUM> passes light directed into and/or received from the fluid sample without focusing the light. Therefore, although optical window <NUM> is also referred to as optical lens <NUM> in this disclosure, it should be appreciated that an optical sensor in accordance with the disclosure can have an optical window that does or does not focus light.

Optical window <NUM> is optically connected to optical pathways <NUM> and, in some examples, physically connected at a terminal end of the optical pathway. In different examples, the optical window <NUM> is formed of a single lens or a system of lenses able to direct light into and receive light from the fluid sample <NUM>. The optical window <NUM> can be integral (permanently attached) to the housing <NUM> or can be removable from the housing. In some examples, optical window <NUM> is an optical lens formed by a ball lens positioned within optical pathway <NUM> to seal the optical pathway and prevent fluid from fluid sample <NUM> from entering the optical pathway. In such examples, the ball lens may extend distally from an external face of the housing <NUM>, e.g., into a moving flow of fluid. The optical lens <NUM> can be fabricated from glass, sapphire, or other suitable optically transparent materials.

As briefly mentioned above, the optical pathway <NUM> is configured to direct light through an optical window <NUM> optically connected to the optical pathway and also to receive light from the fluid sample through the optical window <NUM>. To detect the light received from the fluid sample under analysis, optical sensor <NUM> includes at least one optical detector <NUM> optically connected to optical pathway <NUM>. The optical detector <NUM> can be implemented using any appropriate detector for detecting light, such as a solid-state photodiode or photomultiplier, for example. The optical detector <NUM> may be sensitive to, and therefore detect, only a narrow band of wavelengths. Alternatively, the optical detector <NUM> may be sensitive to, and therefore detect, a wide range of light wavelengths.

During operation, light is emitted into the fluid sample <NUM> via the optical window <NUM> optically connected to the optical pathway <NUM>. The window <NUM> can additionally collect light from the fluid sample <NUM>, such as light scattered off of the sample or emitted by the sample via a mechanism such as fluorescence. Such light can be directed from the fluid sample <NUM> back into the optical pathway <NUM> via the window <NUM> and received by optical detector <NUM>.

To control the wavelengths of light emitted by the optical emitters and/or detected by the optical detector in sensor <NUM>, the optical sensor may include an optical filter. The optical filter can filter wavelengths of light emitted by the optical emitters and/or received by optical detectors, e.g., so that only certain wavelengths of light are emitted into fluid sample <NUM> and/or received from the fluid sample and detected by optical detector <NUM>.

For example, the sensor <NUM> may include an optical filter <NUM> configured to prevent unwanted light received from fluid sample <NUM> from impinging on the optical detector <NUM>. If the detection of a particular wavelength or band of wavelengths is desired but the optical detector <NUM> is sensitive to a wider band or otherwise large number of wavelengths, the filter <NUM> can act to prevent light outside of the desired band from impinging on the optical detector <NUM>. The filter <NUM> can absorb or reflect light that it does not allow to pass through.

According to some embodiments, one of the first optical emitter <NUM> and second optical emitter <NUM> may emit a wider band of wavelengths than is desired or useful for use with the sensor <NUM>, as will be explained in more detail below. Accordingly, sensor <NUM> can include a filter <NUM> disposed between the first <NUM> and/or the second <NUM> optical emitter and the fluid sample <NUM>. The filter <NUM> may be configured to prevent certain wavelengths of light from reaching the fluid sample <NUM> via the optical pathway <NUM>. Such a filter <NUM> can be positioned to at least partially filter light from either one or both of the first optical emitter <NUM> and the second optical emitter <NUM>. For example, in <FIG>, the optical filter <NUM> is shown disposed between the first optical emitter <NUM> and the second optical pathway <NUM>.

During operation, the optical sensor <NUM> can control the first optical emitter <NUM> to emit light at a first wavelength (e.g., range of wavelengths) into the fluid sample <NUM>, control the second optical emitter <NUM> to emit light at a second wavelength (e.g., range of wavelengths) into the fluid sample, and receive light from the fluid sample at optical detector <NUM>. According to some embodiments, the first optical emitter <NUM> is configured to emit light at a wavelength sufficient to cause molecules in the fluid sample <NUM> under analysis to fluoresce. Light fluoresced by the fluid sample <NUM> may be collected by the optical window <NUM> and directed into the optical pathway <NUM> as an emission beam. Additionally, the second optical emitter <NUM> may be configured to emit light at a wavelength sufficient to cause light scattering by the fluid sample <NUM> under analysis. Such light scattering may occur when the fluid sample <NUM> is turbid, e.g., and contains light reflective particles. Light scattered by the fluid sample <NUM> may be collected by optical window <NUM> and directed back into the optical pathway <NUM> as a scattering beam.

Although the wavelengths can vary, in some examples, the first optical emitter <NUM> is configured to emit light within a wavelength ranging from approximately <NUM> nanometers (nm) to approximately <NUM>, such as from approximately <NUM> to approximately <NUM>, or from approximately <NUM> to approximately <NUM>. The second optical emitter <NUM> may emit light at a wavelength ranging from approximately <NUM> to approximately <NUM>, such as from approximately <NUM> to approximately <NUM>. For example, the first optical emitter <NUM> may emit light within the ultraviolet (UV) spectrum while the second optical emitter <NUM> emits light within the infrared (IR) spectrum. Other wavelengths are both contemplated and possible, and it should be appreciated that the disclosure is not limited in this respect.

To detect light emanating from the fluid sample <NUM> under analysis (e.g., fluorescent emissions, light scattering), the sensor <NUM> of <FIG> further includes an optical detector <NUM>. Optical detector <NUM> is optically connected to optical pathway <NUM> and may receive at least a portion of the fluorescent emission beam and the scattered light beam transmitted through the optical window <NUM> from the fluid sample <NUM> under analysis. Upon entering housing <NUM>, the received portions of the fluorescent emission beam and scattered light beam may be directed to the optical detector via the optical pathway <NUM> for measurement and/or analysis. In some embodiments, the intensities of the beams are measured by the optical detector <NUM> and used to determine information about the sample, such as the concentration of a particular component (e.g., a fluorescing compound and/or a non-fluorescing compound) contained therein. Information about the fluid sample under analysis carried by scattered light and fluorescent emissions received from the fluid sample and detected by optical detector <NUM> may provide different channels of information, e.g., for characterizing the fluid sample and/or controlling the system containing the fluid sample.

For example, the optical sensor <NUM> may use light scattering information detected by optical detector <NUM> to adjust or correct the amount of fluorescent emissions detected by the optical sensor and/or calculations based on the measured fluorescent emissions. The turbidity of the fluid sample under analysis may affect the magnitude of the fluorescent emissions generated by the fluid sample and/or received by optical detector <NUM>. Optical sensor <NUM> may compensate for these turbidity effects by measuring the amount of turbidity in the fluid sample, which may be proportional to the amount of light scattered by the fluid sample, and adjusting the magnitude of the measured fluorescent emissions based on the turbidity measurement. In another configuration, the optical sensor <NUM> can adjust the calculation based on the measured fluorescence (e.g., concentration) to incorporate the measured turbidity. In addition, optical detector <NUM> may measure the amount of light scattered by the fluid sample <NUM> in response to light emitted by the second optical emitter <NUM> and determine other characteristics of the fluid sample. For example, the optical sensor <NUM> may determine a concentration of a non-fluorescing species (e.g., a contaminant) in the fluid sample based on the amount of light scattered by the fluid sample and, e.g., calibration data stored in memory. For instance, if the fluid sample <NUM> under analysis has a first concentration of a non-fluorescing chemical compound(s), the optical detector <NUM> may detect a first magnitude of scattered light. However, if the fluid sample has a second concentration of the non-fluorescing chemical compound(s) that is greater than the first concentration, the optical detector <NUM> may detect a second magnitude of scattered light that is greater than the first magnitude.

Optical sensor <NUM> includes at least one, and optionally multiple, optical detectors to detect light received from the fluid sample <NUM> in response to light emitted by the first optical emitter <NUM> and/or the second optical emitter <NUM>. To measure the amount of light emitted by the first optical emitter <NUM> and/or the second optical emitter <NUM> into the fluid sample <NUM> under analysis, optical sensor <NUM> may also include at least one reference optical detector. The reference optical detector may be positioned inside of the housing <NUM> and configured to measure light emitted by the first optical emitter <NUM> and/or the second optical emitter <NUM>. The amount of light received from the fluid sample <NUM> in response to light emitted by the first optical emitter <NUM> and/or the second optical emitter <NUM> may vary based on the amount of light originally emitted by the first and second optical emitters. Accordingly, light measurements made by the reference optical detector can be used to adjust light measurements made by optical detector <NUM>.

In the embodiment of <FIG>, optical sensor <NUM> includes a second optical detector <NUM> that can function as a reference optical detector. Second optical detector <NUM> is in optical communication with the second optical pathway <NUM> and is configured to receive light therefrom. In some embodiments, the second optical detector <NUM> is configured to receive light from both the first optical emitter <NUM> and the second optical emitter <NUM>, e.g., in alternating sequence. Such light can be measured at the second optical detector <NUM> in order to determine operating conditions of the sensor, calibrate the sensor, or to perform any other useful function associated with the sensor. In an exemplary embodiment, the second optical detector <NUM> can detect light received from the first optical emitter <NUM> and then detect light received from the second optical emitter <NUM>. Optical sensor <NUM> may then determine the relative intensities or an intensity ratio between light emitted from the two optical emitters. This information can be used to supplement the information determined about the fluid sample under analysis, such as adjusting a fluid characteristic determined based on light received by the first optical detector <NUM>.

Optical sensor <NUM> is configured to measure at least one optical characteristic of the fluid sample <NUM> under analysis. To supplement optical characteristic information generated by the optical sensor <NUM>, the sensor may include one or more non-optical sensors configured to measure non-optical characteristics of the fluid sample <NUM> under analysis. The non-optical sensor hardware / software may be housed within housing <NUM> and include a contact extending through an external surface of the housing (e.g., adjacent to optical lens <NUM>) for measuring a non-optical property of the fluid sample under analysis. As examples, optical sensor <NUM> may include a temperature sensor, a pH sensor, an electrical conductivity sensor, and/or a flow rate sensor. When used, the temperature sensor may sense a temperature of the fluid adjacent the sensor; the pH sensor may determine a pH of the fluid adjacent the sensor; the conductivity sensor may determine an electrical conductivity of the fluid adjacent the sensor; and the flow sensor may monitor a rate of fluid flowing past the sensor. In one example, optical sensor <NUM> includes both a temperature sensor and an electrical conductivity sensor. Optical sensor <NUM> may include additional or different non-optical sensors, and the disclosure is not limited to an optical sensor that utilizes any particular type of non-optical sensor.

The sensor <NUM> of <FIG> can have a number of different physical configurations. Some such examples are described in <CIT>. <FIG> is a schematic drawing of an example arrangement of components that may be used for the optical sensor of <FIG>. A method using the optical sensor shown in <FIG> is not according to the claimed invention. <FIG> shows a sensor <NUM> for measuring at least one property of a fluid sample. Similar to the sensor of <FIG>, sensor <NUM> comprises a first optical emitter <NUM> and a second optical emitter <NUM>. First <NUM> and second <NUM> optical emitters can include any appropriate light sources, including those discussed above with respect to <FIG>. During operation, the first optical emitter <NUM> can emit light at a first wavelength while the second optical emitter <NUM> can emit light at a second wavelength. The first wavelength may be the same wavelength or range of wavelengths as the second wavelength, or the first wavelength may be a different wavelength or range of wavelengths as the second wavelength. Depending on the application, the first optical emitter <NUM> and second optical emitter <NUM> can emit light within the ultraviolet (UV), infrared (IR), and/or visible light spectrum. In some examples as described above, the first wavelength may cause molecules in the fluid sample under analysis (e.g., fluid sample <NUM>) to excite and fluoresce, while the second wavelength may scatter off the fluid sample under analysis.

Additionally, the first <NUM> and/or second <NUM> optical emitter may be such that one or both emit unnecessary or unwanted light in addition to the first or second wavelengths of light desired to be emitted. To prevent such light from undesirably affecting measurements, sensor <NUM> may include a first optical filter <NUM> configured to limit the light emitted by the first optical emitter <NUM> into the sample under analysis. The embodiment of <FIG> shows a first optical filter <NUM> positioned between the first optical emitter <NUM> and a partially reflective optical window <NUM>. The first optical filter <NUM> can be configured to filter out, for example, substantially all wavelengths of light within a range of fluorescent light emitted by the fluid sample, when the fluid sample emits fluorescence. Such a filter <NUM> can help eliminate false fluorescence detection by detector <NUM> in the sensor due to scattering of light within the same wavelength range as the fluorescent emissions. For example, if the first optical emitter <NUM> were to emit light within the wavelength of the fluorescent emissions generated by the fluid sample under analysis, the optical detector <NUM> may detect both fluorescent emissions generated by the fluid sample and light emitted by the first optical emitter <NUM> and scattered back to the optical detector <NUM>. Optical filter <NUM> can filter out light emitted by the first optical detector <NUM> within the wavelength range of the fluorescent emissions.

The sensor <NUM> in the example of <FIG> also includes a housing <NUM> that houses various hardware /software components of the sensor and controls light movement through the sensor. In some embodiments, the housing <NUM> contains all or some of the first optical emitter <NUM> and/or the second optical emitter <NUM>, while in other embodiments, the emitters are located external to the housing <NUM>.

As was the case with the schematic sensor shown in <FIG>, the embodiment shown in <FIG> includes an optical detector <NUM>, an optical window <NUM> (e.g., optical lens <NUM>) for directing light into and receiving light from a fluid sample, and an optical pathway <NUM>. In the illustrated example, optical lens <NUM> is shown physically separate from but optically connected to optical pathway <NUM>. In other examples, lens <NUM> is physically connected (e.g., attached) at a terminal end of the optical pathway.

To control light movement through optical sensor <NUM>, the optical sensor includes at least one optical pathway which, in the illustrated example is shown as three optical pathways: a first optical pathway <NUM>, a second optical pathway <NUM>, and a third optical pathway <NUM>. The optical pathways may define bounded channels, tubes, conduits, or cavities that control light movement through the sensor. The emitters and detectors of optical sensor <NUM> may be arranged around the optical pathways to direct light into the optical pathways and/or receive light from the optical pathways. For example, the first optical emitter <NUM> and second optical emitter <NUM> in <FIG> are configured to direct light into the first optical pathway <NUM> that is optically connected to the optical lens <NUM> and, subsequently, the fluid sample under analysis. Further, the optical detector <NUM> in <FIG> is configured to receive light from the first optical pathway <NUM> that propagates from the fluid sample under analysis and travels through optical lens <NUM>.

The optical sensor <NUM> can have a number of different optical pathway configurations and the configurations can vary, e.g., based on the number of optical emitters and detectors contained in the sensor. In the example of <FIG>, optical sensor <NUM> includes the first optical pathway <NUM> positioned between optical lens <NUM> and the first optical detector <NUM>. Light traveling linearly through the optical lens <NUM> (e.g., an optical center of the lens) can travel through the first optical pathway <NUM> and impinge on the first optical detector <NUM> (e.g., an optical center of the detector). In such an example, the first optical pathway <NUM> may define a major axis <NUM> extending along the length of the pathway and extending through a center of the optical lens <NUM> (e.g., an optical center) and a center of the first optical detector <NUM> (e.g., an optical center of the detector). The first optical pathway <NUM> may be optically connected to a single optical window of the detector (e.g., optical lens <NUM>) to other components housed within housing <NUM>.

The first optical emitter <NUM> and the second optical emitter <NUM> are configured to emit light into the first optical pathway <NUM> and, subsequently, into the fluid sample under analysis. In some examples, the first optical emitter <NUM> and/or the second optical emitter <NUM> emit light directly into the first optical pathway <NUM>, e.g., without emitting into an intervening optical pathway that intersects the first optical pathway. In other examples, the first optical emitter <NUM> and/or the second optical emitter <NUM> emit light into an intermediate optical pathway that is optically connected to the first optical pathway <NUM>. That is, the first optical emitter <NUM> and/or the second optical emitter <NUM> may indirectly emit light into the first optical pathway <NUM>.

In optical sensor <NUM> in <FIG>, the first optical emitter <NUM> is positioned to emit light into the second optical pathway <NUM> that extends to the first optical pathway <NUM>. Further, in the illustrated embodiment, the second optical emitter <NUM> is positioned to emit light into the third optical pathway <NUM> that extends to the second optical pathway <NUM> which, in turn, extends to the first optical pathway <NUM>. The second optical pathway <NUM> intersects the first optical pathway <NUM>, allowing at least a portion of the light transmitting from the first optical emitter <NUM> and second optical emitter <NUM> to travel through the second optical pathway, into the first optical pathway, and through the optical lens <NUM>. The third optical pathway <NUM> intersects the second optical pathway, allowing at least a portion of the light transmitting from the second optical emitter <NUM> to travel through the third optical pathway, into the second optical pathway, into the first optical pathway, and through the optical lens <NUM>.

Although the configuration can vary, the second optical pathway <NUM> in <FIG> intersects the first optical pathway <NUM> at an approximately <NUM> degree angle. Further, the third optical pathway <NUM> intersects the second optical pathway <NUM> at an approximately <NUM> degree angle. In some examples, the third optical pathway <NUM> extends parallel to the first optical pathway <NUM>, while in other examples, the third optical pathway does not extend parallel to the first optical pathway. By arranging the optical emitters and optical detectors of optical sensor <NUM> around intersecting optical pathways optically connected to a single optical lens <NUM>, the sensor can provide a compact design that is easily installed in a variety of chemical and fluid processes.

In examples in which the optical sensor <NUM> includes intersecting optical pathways to control light movement, the optical sensor may also include optical elements (e.g., reflectors, partially reflective optical windows) that direct light received from one intersecting optical pathway into another intersecting optical pathway. The optical elements can help control the direction of light movement to optical lens <NUM> and/or to optical detectors.

In the illustrated example of <FIG>, the sensor includes a partially reflective optical window <NUM> that is positioned at the intersection of the first <NUM> and second <NUM> optical pathways. The partially reflective optical window <NUM> is configured to reflect at least a portion of light emitted by the first optical emitter <NUM> and the second optical emitter <NUM> from the second optical pathway <NUM> to the first optical pathway <NUM>. In some embodiments, the partially reflective optical window <NUM> is further configured to transmit light from the fluid sample and lens <NUM> to the optical detector <NUM>. Accordingly, the partially reflective optical window can be configured to both transmit and reflect portions of incident light. The angle of the partially reflective optical window <NUM> relative to the direction of light travel through the first optical pathway may vary, e.g., based on the angle at which the first optical pathway <NUM> intersects the second optical pathway <NUM>. However, in <FIG> where the first optical pathway <NUM> intersects the second optical pathway <NUM> at an approximately <NUM> degree angle, the partially reflective optical window <NUM> is oriented at approximately a <NUM> degree angle, e.g., relative to the direction of light travel through both the first optical pathway <NUM> and the second optical pathway <NUM>.

According to various embodiments, the partially reflective optical window <NUM> can be configured to reflect or transmit between <NUM>% and <NUM>% of incident light, with the reflection and transmission percentages being wavelength dependent. Any suitable optical element can be used as partially reflective optical window <NUM>. Such a partially reflective optical window <NUM> can comprise, for example, a dichroic filter, or any other suitable optical component.

In operation, the partially reflective optical window <NUM> of <FIG> is configured to reflect light from the first <NUM> and second <NUM> optical emitters from the second optical pathway <NUM> into the first optical pathway <NUM> (e.g., approximately <NUM> degrees). This can change the direction of light emitted by the first optical emitter <NUM> and the second optical emitter <NUM> from traveling along the length of the second optical pathway <NUM> to traveling along the length of first optical pathway <NUM>. While the partially reflective optical window <NUM> may reflect at least part of the light emitted by the first optical emitter <NUM> and the second optical emitter <NUM>, e.g., into the fluid sample under analysis, the partially reflective optical window may also allow at least a portion of the light received from the fluid sample to pass through the partially reflective optical window. For example, light scattered by the fluid sample under analysis and/or fluorescent emissions generated by the fluid sample may enter into the first optical pathway <NUM> and at least partially transmit through the partially reflective optical window <NUM> (e.g., without being reflected or absorbed by the optical window) to be detected by optical detector <NUM>. In this way, the partially reflective optical window <NUM> can reflect light received from the optical emitters into the fluid sample and transmit light received from the fluid sample to be detected by the optical detector <NUM>.

In some embodiments, the sensor <NUM> further includes a beam dump <NUM>, positioned opposite the partially reflective optical window <NUM> from the first <NUM> optical emitter along the second optical pathway <NUM>. The beam dump <NUM> is configured to absorb or trap any light that is incident thereon. For example, in some embodiments, any light that is transmitted from the second optical pathway <NUM> through the partially reflective optical window <NUM> will be transmitted to the beam dump <NUM> where it will be absorbed and prevented from being detected by optical detector <NUM>.

Optical sensor <NUM> in <FIG> also includes a first reference optical detector <NUM>, which may function as a reference optical detector for first <NUM> and or second <NUM> optical emitters <NUM>, for example. In the illustrated embodiment, the first reference optical detector <NUM> is positioned to receive light emitted by at least one of the first optical emitter <NUM> and the second optical emitter <NUM>. Although the location can vary, in the illustrated example, the second optical detector <NUM> is positioned on an opposite side of the second optical pathway <NUM> from the second optical emitter <NUM>. In particular, the second optical detector <NUM> is positioned at a terminal end of the third optical pathway <NUM>, opposite the second optical emitter <NUM>. In the exemplary embodiment illustrated in <FIG>, the first optical emitter <NUM> and second optical emitter <NUM> are oriented substantially perpendicular to one another, with the first optical emitter <NUM> being approximately coaxial with the second optical pathway <NUM> and the second optical emitter <NUM> being approximately coaxial with a third optical pathway <NUM>. In other examples, the second optical emitter <NUM> can be positioned at other locations within optical sensor <NUM>, and it should be appreciated that the disclosure is not limited to the specific configuration of <FIG>. As one example, the position of the first optical emitter <NUM> and the second optical emitter <NUM> may be switched so that the first optical emitter is in the position occupied by the second optical emitter shown on <FIG> and the second optical emitter is in the position occupied by the first optical emitter.

In examples in which optical sensor <NUM> includes the third optical pathway <NUM> intersecting the second optical pathway <NUM>, the sensor may include a partially reflective optical window <NUM> that is positioned at the intersection of the second <NUM> and third <NUM> optical pathways. The partially reflective optical window <NUM> may be configured to reflect at least a portion of light emitted by the second optical emitter <NUM> from the third optical pathway into the second optical pathway <NUM> and also transmit at least a portion of light emitted by the second optical emitter <NUM> to be received by the second optical detector <NUM>. In addition, the partially reflective optical window <NUM> may be configured to reflect at least a portion of light emitted by the first optical emitter <NUM> from the second optical pathway into the third optical pathway <NUM> to be received by the first reference optical detector <NUM> and also transmit at least a portion of light emitted by the first optical emitter <NUM> to pass through the second optical pathway <NUM> into the first optical pathway <NUM>. Any suitable optical element can be used as partially reflective optical window <NUM>. Such a partially reflective optical window <NUM> can comprise, for example, a dichroic filter, a quartz window, and/or a sapphire window. In some embodiments, the partially reflective optical window <NUM> includes an anti-reflective coating.

The angle of the partially reflective optical window <NUM> relative to the direction of light travel through the second optical pathway <NUM> may vary, e.g., based on the angle at which the second optical pathway <NUM> intersects the third optical pathway <NUM>. However, in <FIG> where the second optical pathway <NUM> intersects the third optical pathway <NUM> at an approximately <NUM> degree angle, the partially reflective optical window <NUM> is oriented at approximately a <NUM> degree angle, e.g., relative to the direction of light travel through the second optical pathway <NUM>. In particular, in the illustrated exemplary embodiment, the partially reflective optical window <NUM> is oriented at substantially <NUM>° relative to the second <NUM> and third <NUM> optical pathways, as well as the first <NUM> and second <NUM> optical emitters. In this arrangement, the partially reflective optical window <NUM> is configured to reflect a portion of the light emitted by the first optical emitter <NUM> from the second optical pathway <NUM> into the third optical pathway <NUM>, and to transmit at least a portion of light emitted by the second optical emitter <NUM> into the third optical pathway <NUM>. The partially reflective optical window <NUM> shown in <FIG> can also act to transmit a portion of the light emitted from the first optical emitter <NUM> into the second optical pathway <NUM> toward the first optical pathway <NUM>, and to reflect a portion of the light emitted from the second optical emitter <NUM> from the third optical pathway <NUM> into the second optical pathway <NUM> and toward the first optical pathway <NUM>.

<FIG> is a conceptual diagram illustrating example light flows through the optical sensor illustrated in <FIG>. For ease of description, <FIG> illustrates light emanating from a first optical emitter <NUM> and a second optical emitter <NUM> simultaneously and also light being received by a first optical detector <NUM> and a reference optical detector <NUM> simultaneously. In practice, the first optical emitter <NUM> and the second optical emitter <NUM> may emit at the same time or at different times. Further, the first optical detector <NUM> and the reference optical detector <NUM> may receive light while one or both of the first optical emitter <NUM> and the second optical emitter <NUM> are emitting or during a time period in which one or both of the emitters are not emitting light into the fluid sample under analysis. Therefore, although <FIG> illustrates various light flows as occurring simultaneously in sensor <NUM>, it should be appreciated that an optical sensor according to the disclosure is not limited to such an example operation.

In the example of optical sensor <NUM>, light is emitted from a first optical emitter <NUM> at a first wavelength into a second optical pathway <NUM>. The light from the first optical emitter <NUM> may be configured to excite fluorescence in a fluid sample and will thus be referred to as generating an excitation beam <NUM> for purposes of illustration. Within sensor <NUM> in the example of <FIG>, the excitation beam <NUM> is emitted into the second optical pathway <NUM> where it encounters a partially reflective optical window <NUM>. A portion of the excitation beam <NUM> may be reflected by the partially reflective optical window <NUM> to be detected by a first reference optical detector <NUM>. Another portion of the excitation beam <NUM> may pass through the partially reflective optical window <NUM> and continue traveling through the second optical pathway <NUM>.

In operation, light is also emitted from a second optical emitter <NUM> at a second wavelength into a third optical pathway <NUM>. The light from the second optical emitter <NUM> may be configured to scatter off the fluid sample and will thus be referred to as generating a scattering beam <NUM> for purposes of illustration. Within sensor <NUM> in the example of <FIG>, the scattering beam <NUM> is emitted into the third optical pathway <NUM> where it encounters the partially reflective optical window <NUM>. A portion of the scattering beam <NUM> may be reflected by the partially reflective optical window <NUM> toward the second optical pathway. Another portion of the scattering beam <NUM> may pass through the partially reflective optical window <NUM> and continue traveling through the third optical pathway <NUM> to be detected by the second optical detector <NUM>, which may function as a reference optical detector.

Portions of the excitation beam <NUM> and the scattering beam <NUM> traveling through the second optical pathway <NUM> in the example of <FIG> encounter partially reflective optical window <NUM>. A portion of the excitation beam <NUM> and the scattering beam <NUM> encountering the partially reflective optical window <NUM> may be reflected by the partially reflective optical window into the first optical pathway optical pathway <NUM>. These beams reflected into the first optical pathway <NUM> are directed to the fluid sample under analysis via an optical lens <NUM> disposed between the first optical pathway and the fluid sample. In some examples, another portion of the excitation beam <NUM> and the scattering beam <NUM> encountering the partially reflective optical window <NUM> may pass through the partially reflective optical window into the beam dump <NUM>. The beam dump <NUM> may be an optically absorbent region of optical sensor <NUM> positioned on an opposite side of the first optical pathway <NUM> from the second optical pathway <NUM>. The beam dump may absorb light directed into the region, e.g., to help prevent the light from reflecting back into first optical pathway <NUM> and being detected by optical detector <NUM>.

As previously described, the excitation beam <NUM> traveling into the fluid sample via optical lens <NUM> may excite fluorescence in the sample while the scattering beam <NUM> traveling into the fluid sample may scatter, e.g., by suspended materials in the sample such as oil or particulates. In some examples, the fluorescent light emitted by the fluid sample in response to the excitation beam <NUM> is at a third wavelength different from the wavelength or wavelengths encompassed by either the excitation beam <NUM> or the scattering beam <NUM>. Depending on the fluid sample under analysis, the third wavelength may be in the UV or near-UV spectrum, such as in a range from approximately <NUM> to approximately <NUM> (e.g., a wavelength greater than <NUM>, such as <NUM>). Fluoresced light and scattered light can be captured by the optical lens <NUM> and directed back into the first optical pathway <NUM> of the sensor <NUM>. In some embodiments, the optical lens <NUM> acts to substantially collimate the fluoresced and scattered light into an emission beam <NUM> and a scattered beam <NUM>, respectively, which travel back through the optical pathway <NUM> toward the partially reflective optical window <NUM>.

In the configuration of <FIG>, the partially reflective optical window <NUM> may transmit at least a portion of the emission beam <NUM> generated by fluorescing molecules in the fluid sample under analysis and also at least a portion of the scattered beam <NUM> generated by light scattering caused by the fluid sample. The emission beam <NUM> and scattered beam <NUM> may enter optical sensor <NUM> via optical lens <NUM> and travel through the first optical pathway <NUM> before encountering partially reflective optical window <NUM>. Upon impinging upon the partially reflective optical window <NUM>, at least a portion of the emission beam <NUM> and scattered beam <NUM> may pass through the partially reflective optical window and be detected by optical detector <NUM>.

In some embodiments, the partially reflective optical window <NUM> may transmit more light or wavelengths of light to the first optical detector <NUM> than is desired to optically characterize the fluid sample under analysis. For example, the partially reflective optical window <NUM> may allow some portion of the excitation beam <NUM> to pass therethrough, such that portions of the excitation beam <NUM> that reach and are scattered by the fluid sample may reach the first optical detector <NUM> and be detected as corresponding to fluorescent emissions emitted by the fluid sample. To help control the light received and detected by the optical detector <NUM>, the optical sensor <NUM> may include an optical filter <NUM> disposed between the optical lens <NUM> and the first optical detector <NUM> to filter out undesired light. In the embodiment of <FIG>, the optical filter <NUM> is positioned between the partially reflective optical window <NUM> and the first optical detector <NUM>. In some embodiments, the optical filter <NUM> is designed to filter out substantially all wavelengths of light (and, in other examples, all wavelengths of light) emitted by the first optical emitter <NUM>. This may help prevent light emitted by the first optical emitter <NUM> that does not generate fluorescent emissions from being detected by the optical detector <NUM> and characterized as fluorescent emissions (e.g., light from the first optical emitter <NUM> that travels toward the optical detector <NUM> rather than toward optical lens <NUM> and/or light from the optical emitter that scatters in the fluid sample rather than generates fluorescent emissions). The optical filter <NUM> may transmit substantially all (and, in other examples, all) wavelengths of fluorescent emissions emitted from the fluid sample in response to the light from the first optical emitter <NUM> and wavelengths of light scattered by the fluid sample in response to light from the second optical emitter <NUM>.

The first optical detector <NUM> can be configured to detect or measure the intensity and/or other properties of incident light thereupon. As described, the first optical detector <NUM> may receive at least a portion of the scattered beam <NUM> and the emission beam <NUM> transmitted from the fluid sample through the partially reflective optical window <NUM>. In some embodiments, such as that shown in <FIG>, the first optical detector <NUM> can comprise a single detector configured to detect light from both the emission beam <NUM> and the scattered beam <NUM>. In such an arrangement, optical sensor <NUM> may control the first optical emitter <NUM> and the second optical emitter <NUM> to alternatingly emit the excitation beam <NUM> and the scattering beam <NUM>. Light detected by the optical detector <NUM> in response to light emitted by the first optical emitter <NUM> (e.g., when the second optical emitter <NUM> is not emitting light) can be attributed to fluorescent emissions generated in the fluid sample. Conversely, light detected by the optical detector <NUM> in response to light emitted by the second optical emitter <NUM> (e.g., when the first optical emitter <NUM> is not emitting light) can be attributed to light scattering caused by the fluid sample. In this way, a single detector can detect and resolve both the emission beam <NUM> and the scattered beam <NUM> propagating from the fluid sample under analysis.

As previously described, the first optical detector can detect light fluoresced from the fluid sample and received as at least one emission beam <NUM>. In some embodiments, the intensity of the emission beam <NUM> can be measured to calculate a characteristic of the sample, for example the concentration of a fluorophore. In one example, the fluoresced light from the sample is measured while light from the first optical emitter <NUM> is emitting and incident on the fluid sample. In another example, the fluoresced light from the sample is received and measured after light from the first optical emitter <NUM> ceases emitting. In these examples, fluorescence emitted by the fluid sample may persist beyond the duration of emission from the first optical emitter <NUM>. Accordingly, the first optical detector <NUM> may receive fluorescent emissions from the fluid sample subsequent to ceasing emission of light from the first optical emitter <NUM>. In some examples, optical sensor <NUM> may determine a characteristic of the fluid sample under analysis based the magnitude of fluorescent emissions detected by the first optical detector <NUM> and the change in that magnitude over time after ceasing light emission by the first optical emitter <NUM>. For example, the optical sensor <NUM> may perform time-resolved fluorescence spectroscopy by measuring a fluorescence decay curve (e.g., fluorescence intensity as a function of time) for the fluid sample. This may involve measuring fluorescent emissions emanation from the fluid sample under analysis from a time when the first optical emitter <NUM> ceases emitting light to a time when the first optical detector <NUM> ceases detecting fluorescent emissions from the fluid. In addition to detecting fluorescent emissions, light scattered off the fluid sample and returned to the sensor in the form of a scattered beam <NUM> can also be detected by optical detector <NUM>.

In some examples, the amount of fluorescence emitted by the fluid sample under analysis is dependent upon the amount of excitation light directed into the sample by the first optical emitter <NUM>. Likewise, the amount of light scattered by the fluid sample may be dependent upon the amount of scattering light directed into the sample by the second optical emitter <NUM>. In such examples, the intensity of light emitted by the first optical emitter <NUM> and/or the second optical emitter <NUM> can be measured, e.g., by second optical detector <NUM>. Optical sensor <NUM> can then adjust the magnitude of the fluorescent emissions and/or scattered light detected by the first optical detector <NUM> based on the magnitude of light emitted by the first optical emitter <NUM> and/or the second optical emitter <NUM>.

In some circumstances, light emitted by the second optical emitter <NUM> in the configuration of <FIG>, for example, can substantially flood optical pathways <NUM>, <NUM>, <NUM>. In some such instances, light of the second wavelength within the housing <NUM> can interfere with the measurement of the light scattered off the fluid sample. That is, light travelling through various optical pathways can result in a measureable background signal at the optical detector <NUM>. Too large of a background signal can obscure measurements within the system. For example, a large detected background signal of light of the second wavelength can make it difficult to accurately detect light scattered from the sample, especially in samples with minimal scattered light. Inaccuracy in measuring the scattered light can lead to a false measurement of the sample turbidity. An error in the turbidity measurement can manifest itself in an error in correcting the fluorometric measurement of a concentration, for example.

In some embodiments, components of the optical sensor can be repositioned to minimize or eliminate background light in the system. <FIG> is a cross-sectional view of an alternative embodiment of an optical sensor. The sensor <NUM> of <FIG> includes a first optical emitter <NUM>, first <NUM>, second <NUM> and third <NUM> optical pathways, partially reflective optical windows <NUM> and <NUM>, first optical detector <NUM> and first reference optical detector <NUM> similar to the illustrated embodiments of <FIG> and <FIG>. Sensor <NUM> of the illustrated embodiment comprises an optical emitter assembly <NUM> disposed in the first optical pathway <NUM>. The optical emitter assembly <NUM> can be configured to emit and/or detect light, and, in some embodiments, is configured to emit light of the second wavelength toward the fluid sample via the first optical pathway <NUM>. The sensor <NUM> of <FIG> further includes a collimating lens between the optical emitter assembly <NUM> and the sensor/sample interface (not shown). The collimating lens can substantially collimate light from the optical emitter assembly <NUM> as the light passes therethrough prior to encountering the optical window and fluid sample (not shown).

In some embodiments, the optical emitter assembly is removably attached to the sensor. <FIG> illustrate a sensor for receiving an optical emitter assembly and the optical emitter assembly, respectively. The sensor <NUM> of <FIG> includes a hole <NUM> in the first optical pathway <NUM>. Hole <NUM> can be configured to receive at least a portion of the optical emitter assembly therethrough. In the illustrated embodiment, the hole <NUM> is positioned between the partially reflective optical window <NUM> and the sensor/sample interface (not shown). The collimating lens <NUM> of the sensor <NUM> of <FIG> is positioned between the hole <NUM> and the sensor/sample interface such that when the optical emitter assembly is positioned through the hole <NUM>, light emitted therefrom can be substantially collimated prior to encountering the fluid sample.

<FIG> is a perspective view of an optical emitter assembly used in a method according to some embodiments of the invention. As shown, optical emitter assembly <NUM> comprises an emitter housing <NUM> including a protrusion <NUM> extending therefrom. In some embodiments, the hole of the sensor is configured to receive protrusion <NUM>. In the illustrated embodiment, assembly <NUM> includes a plurality of fasteners <NUM> for securing the optical emitter assembly <NUM> to the sensor. Fasteners <NUM> can include, for example, screws, bolts, or any other appropriate fastening component. Fasteners <NUM> can secure the optical emitter assembly <NUM> to the sensor housing such that the protrusion <NUM> extends at least partially into the hole in the housing.

<FIG> is an exploded view illustrating the assembly of the optical emitter assembly and housing of the optical sensor. As shown in the exploded view, the optical emitter assembly <NUM> can include the second optical emitter <NUM> and a second reference optical detector <NUM> configured to receive emissions from the second optical emitter <NUM>. The second optical emitter <NUM> and second reference optical detector <NUM> can be positioned in housing 865a of the optical emitter assembly <NUM> as shown. In some embodiments, the housing 865a is closed off by a back plate 865b. Back plate 865b can comprise, for example a circuit board for interfacing with the second optical emitter <NUM> and second reference optical detector <NUM>. In some embodiments, the optical emitter assembly <NUM> can be removably attached to the sensor housing <NUM>.

The optical emitter assembly <NUM> can be held together and to the housing <NUM> of the optical sensor <NUM> via fasteners <NUM>. The optical emitter assembly <NUM> can engage the housing <NUM> proximate a hole <NUM> through which a protrusion <NUM> at least partially extends. As shown, protrusion <NUM> can be configured to receive the second optical emitter <NUM> such that the second optical emitter <NUM> can emit light into the housing <NUM> of the optical sensor <NUM>. In some embodiments, the hole <NUM> can be positioned in a receiving element <NUM> of the optical sensor <NUM> configured to receive the optical emitter assembly <NUM>.

<FIG> is a cross-sectional view of an optical sensor and attached optical emitter assembly taken along the first optical pathway along line <NUM>-<NUM> in <FIG>. As shown, the optical emitter assembly <NUM> is secured to the housing <NUM> of the optical sensor <NUM> via fastener <NUM>. As previously discussed, the optical emitter assembly <NUM> is positioned such that the second optical emitter <NUM> is within the first optical pathway <NUM> of the sensor <NUM> between the partially reflective optical window <NUM> and the collimating lens <NUM>. In the illustrated embodiment, the second optical emitter <NUM> is enclosed within the housing 965a of the optical emitter assembly <NUM>. In some embodiments, the housing 965a of the optical emitter assembly <NUM> defines a plurality of pathways. As shown, the housing 965a defines a second emitter pathway <NUM> designed to direct light from the second optical emitter <NUM> toward the collimating lens <NUM> and subsequently the fluid sample. The housing 965a can define a second emitter reference pathway <NUM> designed to direct light from the second optical emitter <NUM> toward the second reference optical detector <NUM>. In the illustrated embodiment, the housing 965a of the optical emitter assembly <NUM> otherwise encloses the second optical emitter <NUM>, thereby preventing light from the second optical emitter <NUM> from undesirably emitting stray light into the optical pathways of the optical sensor. The housing 965a can additionally reduce the amount of stray light that reaches the second reference optical detector <NUM>, which can result in a more accurate reference measurement of the light emitted from the second optical emitter <NUM>.

It will be appreciated that many configurations which prevent light from the second optical emitter <NUM> from undesirably flooding the sensor. For example, the sensor <NUM> and/or optical emitter assembly <NUM> can include one or more optical shields disposed between the second optical emitter <NUM> and the optical detector (e.g., <NUM> in <FIG>). In some embodiments, the shield(s) can be disposed between the second optical emitter <NUM> and the partially reflective optical window <NUM>. In some instances, the one or more shields comprises the housing 965a of the optical emitter assembly <NUM> acting to prevent light from being emitted from the second optical emitter toward the optical detector. The shield(s) can comprise a substantially enclosed volume such as the housing 965a to prevent light from being emitted from the second optical emitter <NUM> toward the optical detector <NUM>. One or more shields can act to substantially prevent light from being emitted from the second optical emitter toward the first optical detector through the first optical pathway. That is, while a portion of light emitted by the second optical emitter may initially be emitted toward the first optical detector, such a portion of the light prevented from reaching the first optical detector by the one or more shields.

In some embodiments the optical emitter assembly <NUM> includes a back plate 965b which can further act to define the substantially enclosed volume. Back plate 965b can combine with housing 965a to enclose one or both of the second optical emitter <NUM> and the second reference optical detector <NUM>. In some embodiments, the back plate 965b can comprise a circuit board for interfacing with one or both of the second optical emitter <NUM> and the second reference optical detector <NUM>. In the illustrated embodiment, back plate 965b is shown as having conductors <NUM> and <NUM> passing therethrough for electrically interfacing with the second optical emitter <NUM> and the second reference optical detector <NUM>, respectively.

<FIG> and <FIG> are conceptual diagrams illustrating example light flows through the optical sensor of <FIG>. As shown in and described above with reference to <FIG>, a first optical emitter <NUM> is configured to emit light of a first wavelength, also referred to as the excitation beam <NUM>. The excitation beam <NUM> is emitted into the second optical pathway <NUM> where it encounters a partially reflective optical window <NUM> which reflects a portion of the excitation beam <NUM> toward a first reference optical detector <NUM>. Another portion of the excitation beam <NUM> is transmitted through the partially reflective optical window <NUM> to a second partially reflective optical window <NUM>, which reflects a portion of the excitation beam <NUM> into the first optical pathway <NUM> and toward the optical window <NUM> and fluid sample (not shown). In some configurations, while propagating through the first optical pathway <NUM> toward the fluid sample, a portion of the excitation beam can encounter an optical emitter assembly <NUM> in the optical pathway <NUM>. In some embodiments, the optical emitter assembly <NUM> blocks a portion of the excitation beam from reaching the optical window <NUM>.

As discussed elsewhere herein, the excitation beam <NUM> can excite fluorescence in the fluid sample, which can enter the sensor <NUM> via the optical window <NUM> as an emission beam <NUM>. The emission beam <NUM> can travel through the optical pathway <NUM> to the optical detector <NUM> where it can be analyzed. Since the intensity of fluorescent emissions measured as the excitation beam can depend on the intensity of the excitation beam exciting the emissions, the measured emission beam <NUM> can be compared to the measured portion of the excitation beam <NUM> at the first reference optical detector <NUM>. The comparison can be used to provide information about the fluid sample such as the concentration of a fluorophore.

In some embodiments, the optical emitter assembly <NUM> is configured to emit light of a second wavelength, which can be referred to as the scattering beam <NUM>. The scattering beam <NUM> can be directed from the optical emitter assembly <NUM> and toward the fluid sample via the optical pathway <NUM>, collimating lens <NUM> and optical window <NUM>. The scattering beam <NUM> can subsequently scatter off of the sample. A portion of the scattered light can be received by the optical window and directed back into the optical pathway <NUM> as a scattered beam <NUM>. The scattered beam <NUM> can propagate through the optical pathway <NUM> to the detector <NUM> for analysis. The measured scattered beam <NUM> can be used to determine, for example, the turbidity of the fluid sample. The turbidity can have an effect on the fluorescence of the fluid sample, and therefore can be measured and used to correct the fluorometry measurement and thus the concentration measurement based thereon.

The light flow of the scattering beam according to some embodiments is illustrated in <FIG>. According to the illustrated embodiment, the second optical emitter <NUM> is substantially enclosed by housing 1065a of the optical emitter assembly. Substantially enclosed, as used herein, is intended to indicate that the housing encloses the optical emitter such that light emitted therefrom only escapes the housing via preconfigured pathways. The housing defines a second emitter pathway <NUM> and a second emitter reference pathway <NUM> through which light emitted from the second optical emitter <NUM> (i.e., the scattering beam <NUM>) can propagate. For example, the scattering beam can propagate through the second emitter pathway <NUM> out of the housing 1065a and the optical emitter assembly <NUM> and toward the fluid sample as shown in <FIG>. The scattering beam <NUM> can scatter off the sample and back into the sensor <NUM> as a scattered beam <NUM> and detected by detector <NUM> as previously described.

As mentioned, a measurement of the scattered beam can provide information regarding the turbidity of the sample, which can be used to correct a fluorometry measurement. However, in some configurations, the measurement of the scattered beam <NUM> is dependent not only on the turbidity of the sample, but also on the intensity of the scattering beam <NUM>. Accordingly, as shown in <FIG>, the housing 1065a of the optical emitter assembly <NUM> includes a second emitter reference pathway <NUM> via which light from the second optical emitter <NUM> is directed toward a second reference optical detector <NUM>. The second reference optical detector <NUM> can determine the intensity of the light emitted by the second optical emitter <NUM>. Such a measurement can be compared to the detected scattered beam <NUM> to more accurately determine the turbidity of the sample.

Providing the second optical emitter <NUM> and the second reference optical detector <NUM> in the optical emitter assembly <NUM> can act to reduce undesired light from entering the optical pathways of the optical sensor. For example, the housing 1065a of <FIG> allows light emitted from the second optical emitter <NUM> to exit the housing 1065a as a scattering beam <NUM> only via the second emitter pathway <NUM> toward the fluid sample. Additionally, the housing 1065a of <FIG> is configured such that the second reference optical detector <NUM> receives light via only the second emitter reference pathway <NUM>. Accordingly, the second reference optical detector <NUM> receives light from only the second optical emitter <NUM>, reducing the noise received by the second reference optical detector <NUM>.

In addition, emitting light directly from the second optical emitter <NUM> toward the fluid sample via second emitter pathway <NUM> can result in a relatively intense scattering beam <NUM> at the fluid sample. By comparison, in a configuration such as that in <FIG>, the scattering beam <NUM> is potentially split by partially reflective optical windows <NUM> and <NUM> and only a portion of the emitted light is directed to the fluid sample. Thus, in a configuration such as is shown in <FIG>, the relative intensity of the light directed to the fluid sample can be larger when compared to other configurations. In some situations, the relative intensity of the light received.

Accordingly, in some configurations, emitting a scattering beam <NUM> toward the sample from the optical emitter assembly <NUM> disposed in the first optical pathway <NUM> can improve the signal strength of the scattering <NUM> beam to the sample and thus the scattered beam <NUM>. Additionally, positioning the second reference optical detector <NUM> in the housing 1065a of the optical emitter assembly <NUM> can result in a reduction of noise detected at the second reference optical detector <NUM>. In some situations, such a configuration can lead to improved accuracy in determining the turbidity of the fluid sample. An improved measurement of the sample turbidity can increase the accuracy of the turbidity correction in determining a concentration from measured fluorescence as previously discussed.

Optical sensors in accordance with the disclosure can be used as part of a system (e.g., fluid system <NUM> in <FIG>) in which the sensor is communicatively coupled to a controller to receive data from and send data to the sensor. The controller may include an integral component such as a microcontroller, or an external component, such as a computer. The controller can be in communication with the first and second optical emitters, as well as various optical detectors. The controller can be configured to control the first and second optical emitters to emit light at a first wavelength and a second wavelength, respectively. As discussed, the first wavelength may excite fluorescence in a fluid sample, while the second wavelength may scatter off of the fluid sample. The controller can also be configured to control an optical detector to detect fluorescent emissions emitted by the fluid sample and also light scattered by the sample. The controller can be further configured to determine at least one characteristic of the fluid sample based on the detected fluorescent emissions. For example, the controller may determine a characteristic of the fluid sample based on data generated by the optical sensor and information stored in a memory associated with the controller, such as calculating based on an equation, finding in a lookup table, or any other method known in the art.

In some embodiments, the controller can be further configured to adjust the determination of the at least one characteristic based on one or more additional measurements. For example, the controller can adjust the determination of the at least one characteristic based on a measured turbidity of the sample, which can be determined from detected light scattered off the sample. Further, the controller can be configured to detect light emitted from optical emitters via one or more reference optical detectors to establish reference measurements. The controller can compare the detected light from the sample to light detected at the one or more reference optical detectors to determine a relative measurement which can be used in determining the at least one characteristic.

In some examples, a first light source directs light to a first reference optical detector and to the fluid sample, where it causes fluorescence which is detected by a first optical detector. A second light source can be configured to direct light to a second reference optical detector and to the fluid sample, where it at least partially scatters off of the fluid sample and is detected at a second optical detector. The controller can be configured to compare the detected light at the first optical detector and the detected light at the first reference optical detector to determine a relative fluorescence measurement. Similarly, the controller can compare the detected light at the second optical detector and the second reference optical detector to determine a relative turbidity measurement. In such a configuration, the controller can determine the at least one characteristic of the fluid sample based on a combination of the relative fluorescence measurement and the relative turbidity measurement.

In applications where the first and second optical emitters are operated in an alternating sequence of activation, the controller can coordinate the frequency and duration of light emissions from each optical emitter. In addition, in embodiments where the sensor includes one or more reference optical detectors, the controller can detect light from the first and second optical emitters and use this detected light to calibrate light detected by the first optical detector.

In some examples, an optical sensor according to the disclosure also includes one or more non-optical sensors. Exemplary non-optical sensors can include, but are not limited to, pH sensors, conductivity sensors, and temperature sensors. Data from the non-optical sensors can be used determine non-optical characteristics of the sample under analysis. In some embodiments, data from one or more non-optical sensors can be used to adjust a measurement of fluorescent emissions from a fluid sample to determine one or more characteristics of the sample. For example, a temperature sensor can be mounted in a sensor body to correct for temperature effects on fluorescence as well as on electronics and/or detectors. In other examples, data from a non-optical sensor may be used to monitor a fluid sample and/or control a fluid process in addition to or in lieu of using optical sensor data to monitor the fluid sample and/or control the fluid process.

As discussed, in certain embodiments, an optical sensor according to the disclosure may detect light fluoresced from a sample at one or more wavelengths and scattered off of the sample at yet another wavelength. The optical sensor may also detect additional characteristics, such as non-optical characteristics, of the fluid sample. Data generated by the optical sensor can be used to calculate or otherwise determine at least one characteristic of the sample. Such data can be received simultaneously, alternatingly in sequence, or in a combination in which some but not all data can be received simultaneously.

The received data contributing to determining at least one characteristic can be received in a plurality of channels. Channels can be optical channels, comprising one or more fluorescence channels and a scattering channel, but can also include data channels such as data received from one or more non-optical sensors. Optical channels can be defined by wavelength bands, for example. Accordingly, in some embodiments, data is received in the form of a first fluoresced wavelength is data received in the first fluorescent channel, while data received in the form of light scattered off the sample is data received in the scattering channel. Thus, in various embodiments, the optical sensor can receive data in any combination of optical channels via the first optical pathway simultaneously and/or alternatingly, and additionally in non-optical channels from one or more non-optical sensors. In addition, as previously described, the first or second reference optical detectors can receive light from the first or second optical emitters used for calibration of measurements at the first optical detector. Thus, the data received at the reference optical detectors can be received in one or more calibration channels. In some examples, the first and second reference optical detectors can be connected electrically in parallel. In such an embodiment, each of the first and second reference optical detectors can provide reference signals in a single reference channel.

In applications where the optical sensor includes a single optical detector that detects fluorescent emissions received from the fluid sample and also detects scattered light received from the fluid sample, the first and second optical emitters may activate and deactivate in alternating sequence. This may allow data generated by the optical detector to be resolved into fluorescent emission data corresponding to detected fluorescent emissions and scattering data corresponding to detected scattered light. In other examples, the optical sensor can include multiple optical detectors that detect fluorescent emissions received from the fluid sample and detect scattered light received from the fluid sample. For example, the optical sensor may include one optical detector that detects fluorescent emissions received from the fluid sample and another optical detector that detects scattered light received from the fluid sample.

As further described in <CIT>, <FIG> illustrate example alternative optical detector arrangements that can be used in an optical sensor, such as the optical sensors of <FIG>. In general, <FIG> illustrate various configurations for incorporating a plurality of optical detector elements (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) into an optical pathway <NUM>. As described in the above application and similarly to other configurations described elsewhere herein, partially reflective optical widows (e.g., <NUM>, <NUM>, <NUM>) and optical filters (e.g., <NUM>) can be used to filter, separate, and direct light to appropriate optical detector elements. For example, fluoresced light and scattered light may be directed to separate optical detector elements by a partially reflective optical window in order to measure fluoresced and scattered light simultaneously. A method using such an arrangement is not according to the claimed invention. As further described in <CIT>, an optical sensor according to the disclosure can be modified to meet requirements for use in specific applications or configurations. For example, <FIG> (FIGS. 6A-6D of the above application) illustrate a sensor attached to various components for use with a fluid vessel. Such figures also illustrate different sensor components and physical arrangements that can be used by any sensor according to the disclosure. As described in the above application, various sensor arrangements can be implemented and fitted into various fluid containers by way of mounting discs, press-fit inserts, flanges and the like.

Various embodiments and configurations of sensors have been described. <FIG> is a process flow diagram of an optical analysis technique according to the disclosure. <FIG> illustrates a process in which a sensor emits light at a first wavelength <NUM> from a first optical emitter through an optical pathway and into a fluid sample. The optical pathway is defined by a housing of the sensor. The sensor is configured to detect <NUM> light emitted by the first optical emitter at a first reference optical detector. In some embodiments, the fluorescent emissions are excited by the light emitted by the first optical emitter. Thus, in some configurations, the sensor also receives fluorescent emissions <NUM> emitted by the fluid sample through the optical pathway at an optical detector. The sensor can compare <NUM> the light emitted from the first optical emitter to the received fluorescent emissions. The comparison can provide information regarding the amount of fluoresced light relative to the intensity of light of the first wavelength incident on the sample. In some examples, the comparison can be performed in order to determine a relative fluorescence measurement.

The sensor can be configured to emit light at a second wavelength <NUM> from a second optical emitter, through the optical pathway and into the fluid sample. In some configurations, the light of the second wavelength is directed to the sample via the same optical pathway as light of the first wavelength. The sensor can detect <NUM> light emitted at the second wavelength at a second reference optical detector. The sensor can also receive light, scattered by the fluid sample <NUM> through the optical pathway, at the optical detector. Similar to the process referenced above with light of the first wavelength, the sensor can compare <NUM> the light emitted from the second optical emitter to the received scattered light. The comparison can provide information regarding the amount of scattered light relative to the intensity of light of the second wavelength incident on the sample. In some examples, the comparison can be performed in order to determine a relative turbidity measurement.

In some embodiments, the sensor can be configured to determine <NUM> at least one characteristic of the sample based on the compared fluoresced and scattered light. In some examples, the sensor can determine the concentration of a constituent of the fluid sample. For example, in some instances, the relative fluorescence measurement from the fluid sample is indicative of the concentration of a fluorophore in the sample. However, in some situations, the turbidity of the sample can have an effect on the fluorescent properties of the sample. The relative turbidity measurement can be used to determine the turbidity of the sample. Thus, in some examples, the compared scattered light indicative of the turbidity can be used to adjust a determination of a fluorophore concentration based on the compared fluoresced light. In general, the relative fluorescence measurement and the relative turbidity measurement can be combined in order to determine at least one characteristic of the fluid sample.

It will be appreciated that various steps can be added, omitted, permuted or performed simultaneously with regard to the method of <FIG>. For example, as described in the process of <FIG>, light is emitted at the first wavelength and second wavelength into a fluid sample, as well as received from the fluid sample, via a single optical pathway. Received light can be scattered off the sample, and in some embodiments, comprises light of the second wavelength scattered off the sample. Received light can also be in the form of light fluoresced from the sample, which can be caused by the light of the first wavelengths. As discussed previously, in some embodiments, the sensor is unable to resolve the difference in light scattered by the sample and fluoresced from the sample if they are simultaneously incident on the optical detector. Thus, in some embodiments, emitting light at the first wavelength is ceased prior to emitting light at the second wavelength <NUM>. For the same reason, should the process be repeated, in some embodiments, emitting light at the second wavelength is ceased prior to emitting light at the first wavelength <NUM>.

In further embodiments, emitting light at the first wavelength is ceased prior to receiving useful fluorescent emissions at the optical detector. This can be done, for example, if a sample contains multiple fluorescing species that fluoresce for different durations, such that the fluorescence from one species persists longer than that from another species. If fluorescence from the longer persisting species is desired to be measured while fluorescence from the shorter persisting species is extraneous, it can be advantageous to cease emitting light at the first wavelength, wait for the fluorescence excited by the shorter persisting species to subside, and then measure the remaining fluorescent emissions attributable to the longer persisting species. It should be noted that the optical detector may be receiving fluorescent emissions from the sample while light of the first wavelength is being emitted; however, the measurement of fluoresced light may or may not be disregarded until the appropriate time.

It will be appreciated that the process outlined in <FIG> can be performed by a controller in a system comprising a sensor. The controller can include a processor for controlling the timing and duration of emitting light from either the first or second optical emitters, as well as the timing of receiving light from the fluid sample. That is, the controller can be programmed to disregard received light when there is extraneous light present that can disrupt the ability to adequately determine the at least one characteristic of the sample. The controller can utilize data from received fluoresced light, scattered light, and any other data that it receives to calculate or otherwise determine, or adjust the determination of, at least one characteristic of the sample.

Exemplary sensors have been described. Some embodiments comprise multi-channel fluorometric sensors in which fluorescence from a sample is excited and detected in at least one fluorescence channel, and the detected fluorescence is used to determine a characteristic of the sample. Other factors, such as light scattered off the sample, or additional non-optical measurements can be used to supplement the fluorescence detection and account for potential variations in fluorescence of the sample. The sensor can be part of a system comprising a controller to automate the control of emitters and detectors, and calculate or otherwise determine characteristics of the sample from measured data. Sensors can be secured into vessels in which fluid samples to be characterized are present or flow through.

The term "processor" or "controller" may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry.

Claim 1:
A method comprising:
positioning an optical sensor (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) in optical communication with a fluid sample (<NUM>) under analysis, the optical sensor (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising:
a first optical emitter (<NUM>, <NUM>, <NUM>);
a second optical emitter (<NUM>, <NUM>, <NUM>, <NUM>);
a first optical pathway (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>);
an optical detector (<NUM>, <NUM>, <NUM>, <NUM>); and
an optical window (<NUM>, <NUM>) optically coupling the optical sensor (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the fluid sample (<NUM>);
emitting light at a first wavelength (<NUM>) by the first optical emitter (<NUM>, <NUM>, <NUM>) through the first optical pathway (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the optical window (<NUM>, <NUM>) into the fluid sample (<NUM>) to excite fluorescent emissions in the fluid sample (<NUM>);
detecting the fluorescent emissions emitted by the fluid sample (<NUM>) through the first optical pathway (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) by the optical detector (<NUM>, <NUM>, <NUM>, <NUM>);
emitting light at a second wavelength (<NUM>) different than the first wavelength (<NUM>) by the second optical emitter (<NUM>, <NUM>, <NUM>, <NUM>) through the first optical pathway (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the optical window (<NUM>, <NUM>) into the fluid sample (<NUM> under analysis, wherein the light emitted by the second optical emitter is scattered off the fluid sample (<NUM>); and
detecting the light scattered by the fluid sample (<NUM>) through the first optical pathway (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) by the optical detector (<NUM>, <NUM>, <NUM>, <NUM>), wherein the method is characterized in that the second optical emitter (<NUM>, <NUM>, <NUM>, <NUM>) is positioned in the first optical pathway (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>).