Patent Publication Number: US-2021181028-A1

Title: Radiometric modeling for optical identification of sample materials

Description:
TECHNICAL FIELD 
     The disclosure generally relates to the field of optical analysis of materials and more particularly to techniques and structures for implementing and using radiometrically characterized optical modeling. 
     BACKGROUND 
     Real-time estimation of material compositions and properties using downhole optical sensing tools is utilized for well testing and sampling in the oil and gas industry. For petroleum exploration, extraction, and processing applications, optical sensors may be utilized in situ (underground or otherwise in the field) to identify various materials including fluid components within oil or gas samples. To improve accuracy of in-situ sample material analysis, radiometry testing is utilized to characterize optical sensors and individual components within the sensors prior to field deployment. The radiometric characterization is utilized to calibrate the sensors and sensor output data processing tools such as sensor output modeling tools. Such radiometric characterization typically requires a controlled environment in which reference characterizations are determined using specialized equipment including reference components and optical diffusers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure may be better understood by referencing the accompanying drawings. 
         FIG. 1  is a block diagram depicting a system for optically determining material properties in accordance with some embodiments; 
         FIG. 2  is a block diagram illustrating a radiometry system in accordance with some embodiments; 
         FIGS. 3A and 3B  depict transmissive diffusers that may be utilized in a radiometry system in accordance with some embodiments; 
         FIGS. 4A and 4B  illustrate transmissive diffusers that may be utilized in a radiometry system in accordance with some embodiments; 
         FIG. 5  is a flow diagram depicting operations and functions for radiometrically characterizing components of an optical sensor and utilizing the radiometric characterization for downhole fluid sampling; 
         FIG. 6  is a flow diagram depicting operations and functions for utilizing radiometric characterization of an optical sensor to re-characterize the optical sensor using reference sample material response data; 
         FIG. 7  illustrates a drilling system in accordance with some embodiments; 
         FIG. 8  depicts a wireline logging system in accordance with some embodiments; and 
         FIG. 9  is a block diagram of an example computer system configured to implement operations and functions described with reference to  FIGS. 1-8 . 
     
    
    
     DESCRIPTION 
     The description that follows includes example systems, methods, techniques, and program flows that embody aspects of the disclosure. However, it is understood that this disclosure may be practiced without one or more of these specific details. In other instances, well-known instruction instances, protocols, structures and techniques have not been shown in detail in order not to obfuscate the description. 
     Overview 
     Disclosed embodiments include methods and systems for radiometrically characterizing optical sensors for downhole optical fluid analysis. In some embodiments, the characterization of optical sensors using either transmissive or reflective light diffusion is utilized to accurately and comprehensively correct optical sensor responses during fluid analysis. Embodiments further include methods and systems for defining models for optical sensors and utilizing the radiometric characterizations to parameterize the model based on radiometric optical responses. The parameters determined to be variable parameters of optical system components such as light source parameters are fitted to the optical responses. The characterized optical sensors are field deployed to measure optical properties of downhole material samples such as fluid samples. The parameterized models may be utilized to process optical sensor output data to more accurately determine properties of downhole material samples. 
     Disclosed embodiments include a field re-characterization system that includes operations and components for re-fitting a model using one or more reference material responses from the optical sensor. For example, the field deployed optical sensor having a sample cell may generate an optical response to a sample material such as a sample fluid within the sample cell. The response is measured and utilized to generate a re-parameterized model by refitting a subset of the parameters of the optical sensor that were used to parameterize the model using the radiometric responses. 
     Example Illustrations 
       FIG. 1  is a block diagram depicting a system  100  for optically determining material properties in accordance with some embodiments. System  100  includes a radiometric characterization system  102  that may be incorporated in part or in whole within a field test facility or a remote laboratory facility. Radiometric characterization system  102  includes a radiometry system  104  that is configured for performing radiometric characterization and calibration operations. Radiometry system  104  includes optical sensor components  106 , such as a sensor light source and an optical detector. To implement reference testing of the optical sensor components  106 , radiometry system  104  also includes reference components  107 , such as a reference light source and a reference optical detector. For example, and as depicted and described in further detail with reference to  FIG. 2 , various combinations of optical sensor components  106  and reference components  107  are installed and operated in an optical measurement path to collect optical component and reference optical response information. 
     The optical response information collected by radiometry system  104  is transmitted to and processed by a processing system  108  that is configured to determine parameter characterizations for optical sensor models. Processing system  108  includes a characterization application  109  that is configure using any combination of data and program logic to determine optical component characterization values such as calibration coefficients based on the optical responses from radiometry system  104 . The optical components that are characterized may include discrete physical components such as light sources, optical detectors, and optical transform devices. The optical “components” for which the characterization values are determined may also or alternatively include optical properties of such physical components such as reflection, refraction, and diffusion values for or more optical components. 
     Processing system  108  further includes a model generator  111  that is configured to define a model for an optical sensor by selecting a model type and populating the model with components corresponding to the components characterized by characterization application  109 . Model generator  111  generates a model in part by defining the components and in some embodiments defining parameters associated with the components. The parameters may include, for example, light emission parameters such as the voltage, current, or frequency of the light source supply, filament temperature, thickness of source containment, etc. The parameters may also include optical interaction parameters such as sample cell thickness, sample cell length, angular offset from nominal values of incidence/transmission/reflection angles. The parameters may further include parameters associated with optical detection such as angular offset, detector sensitivity with respect to radiation wavelength, etc. 
     Processing system  108  generates and outputs the characterization data and corresponding component model data in the form of component characterization records  110  and corresponding sensor configuration records  112  to a parameterization tool  114 . Characterization records  110  contain the characterization values determined by characterization application  109  for a given optical sensor under test within radiometry system  104 . Sensor configuration records  112  contain the component identification data and parameter definitions for the corresponding components of the optical sensor model. The characterization records  110 , sensor configuration records  112 , and optical responses measured by radiometry system  104  are transmitted to or accessed or otherwise received and processed by parameterization tool  114 . Based on the component characterization records  110 , parameterization tool  114  may determine parameters values and also a variability characteristic of the parameters in terms of being variable (e.g., light source temperature) or relatively fixed in and therefore substantially non-variable (e.g., lens refraction). 
     Parameterization tool  114  is configured using any combination of data and program logic to generate a parameterized model  116 . Parameterized model  116  is generated, in part, by fitting a number (e.g., an integer, n, greater than zero) of variable parameters of the model components with the optical response data measured by radiometry system  104 . A number of fitting algorithms such as curve fitting may be implemented. Parameterization tool  114  fits the number of variable parameters using optical responses, such as those collected by radiometry system  104 , that are associated with optical sensor components to which the model components correspond. The parameterization by parameterization tool  114  may also include determining a number of parameters having a lower variability in terms of rate of variation (e.g., temporal or by usage) and/or range of variation. Parameterization tool  114  may fix a value for each of these lower variability parameters within parameterized model  116  based, for example, on an average of the optical responses. Parameterized model  116  may be transmitted to or otherwise retrieved by a models database  118  that records models corresponding to optical sensors that have been parameterized using reference type radiometric characterization. 
     System  100  further includes a measurement processing system  120  that is configured to process field measured optical response data collected by optical sensors and is communicatively coupled with database  118 . Measurement processing system  120  may be incorporated within electronics and processing equipment within or proximate a well head apparatus (not expressly depicted). Such a well head apparatus may include mechanical, electrical, and electronic systems, subsystems, devices, and components for drilling a borehole  133  and subsequently retrieving hydrocarbon fluid from or injecting fluid into a subterranean region  125 . Subterranean region  125  may include sedimentary layers, rock layers, sand layers, or combinations of these and other types of subsurface layers. One or more of the subsurface layers may contain fluids, such as water and liquid and/or gaseous hydrocarbon fluids. 
     Measurement processing system  120  is configured to interoperate with a downhole logging tool  130  in part by receiving and processing measurement information collected and generated by logging tool  130 . In some embodiments, all or part of measurement processing system  120  may be implemented as a component of or may be fully or partially integrated with one or more components of logging tool  130 . For instance, one or more components of a processing node  160  within measurement processing system  120  may be embedded within logging tool  130  and operate concurrently with ongoing downhole measurement operations within borehole  133 . 
     Processing node  160  includes processing and storage components configured to receive and process detected downhole information such as temperature, pressure, fluid properties, etc. During logging operations, logging tool  130  is disposed at various depths within borehole  133  via a conveyance mechanism such as a wireline  156 . Logging tool  130  is communicatively coupled to measurement processing system  120  and processing node  160  via a telemetry link within wireline  156 . In alternate embodiments such as depicted in  FIG. 7 , a telemetry link for a logging tool such as logging tool  130  may comprise components and connectivity media for establishing acoustic, optical, electronic, and/or electromagnetic communications links between logging tool  130  and processing node  160 . 
     Logging tool  130  may include multiple sampling and measurement devices and associated control and communication electronics. In the depicted embodiment, logging tool  130  comprises a logging sonde  134  and an electronics assembly  135 . Logging sonde  134  includes an optical sensor  136 , a fluid density detector  138 , and a controller  140 . Fluid density detector  138  includes components configured to measure the density of fluids that are sampled within logging sonde  134 . Optical sensor  136  includes components such as a light source  142 , a sample cell  144 , one or more optical transform components  146 , and an optical detector  148 . The components within optical sensor  136  interoperate to enable optical analysis of sampled materials such as sampled downhole fluids within borehole  133  such as formation fluids contained within subterranean region  125 . Controller  140  may be a microcontroller configured to actuate, coordinate, and otherwise control operations of measurement components within logging sonde  134 . 
     During a fluid sampling and measurement sequence, controller  140  actuates fluid intake and flow components such as valve to intake fluid from within borehole  133  into sample cell  144  of optical sensor  136 . During an optical measurement interval, light source  142  transmits light toward and through the sample fluid within sample cell  144  to generate sample-interacted light. The sample-interacted light from sample cell  144  propagates to the optical transform components  146  that may comprise any combination of lenses, refractory components, scattering components, filters, etc. In some embodiments optical transform components  146  may include an optically reactive optical sensor configured to perform a spectral processing function. For example, optical transform components  146  may include an optical band-pass filter or a multivariate optical sensing element. 
     Having been optically interacted via optical transform components  146 , the optically interacted light is received and measured by optical detector  148 , resulting in an optical response signal generated by optical detector  148 . Attributes of the received optically interacted light, such as wavelength, amplitude, and phase, are represented in the optical response signal that is processed by optical receiver components within the electronics assembly  135  of logging tool  130 . Electronics assembly  135  includes, in part, a measurement sequence controller  150  configured to implement measurement cycles such as implemented by density detector  138  and optical sensor  136 . Electronics assembly  135  further includes a log unit  152  that is configured to process and record measurement data based on the detected response signals from density detector  138  and optical sensor  136 . 
     Logging tool  130  may collect the downhole measurement data including densities and optical responses from fluid samples at various positions along the length of borehole  133 . For example, logging tool  130  may be incrementally moved upwardly or downwardly to each logging position at a series of depths within borehole  133 . At each logging position, instruments in logging tool  130  implement measurements on materials and/or environment conditions within borehole  133  and/or the subterranean region  125  surrounding the borehole. The measurement data is communicated to processing node  160  within measurement processing system  120  for storage, processing, and post-processing analysis. While collection of data using a wireline deployment is depicted in  FIG. 1 , such data may be gathered and analyzed during drilling operations (e.g., during logging while drilling (LWD) operations), during wireline logging operations, or during other types of downhole operations. Processing node  160  is configured to receive and analyze the optical response data and other measurement data from logging tool  130  to determine downhole and formation properties and conditions. For example, processing node  160  may be configured to identify fluid composition and physical properties such as density and viscosity, as well as material (e.g., chemical) composition of sample downhole fluids. 
     The optical response data comprising signal attributes such as frequency and amplitude that are collected during optical measurement sequences may be recorded by logging unit  152  in defined data structures such as records within a log file  155 . Log file  155  is transmitted from electronics assembly  135  to a communication interface (not depicted) within measurement processing system  120  from which is may be transferred to and recorded by processing node  160 . Log file  155  may also or alternatively be provided directly as streamed data or otherwise real-time formatted data to processing node  160 . Processing node  160  is configured, using any combination of hardware and software devices and program components, to generate fluid analysis results based on the optical responses in combination with parameterized or re-paremeterized models that may be retrieved or otherwise operably accessed from models database  118 . 
     The hardware within processing node  160  incudes a processor  162  configured to execute instructions corresponding to program instructions loaded into an associated memory device  164 . The software stored or retrieved by or otherwise accessible for loading into memory  164  includes a fluid analysis tool  166 , which is configured to implement fluid composition detection. Fluid analysis tool  166  implements fluid composition detection, including chemical identification of sample fluids, by selecting a parameterized model from database  118  that corresponds to the optical sensor  136 , or more components of optical sensor  136 , from which the optical response data is received. The parameterized model is executed by fluid analysis tool  166  with the optical response data as input to determine properties of the downhole material samples to which the optical responses correspond. 
     The accuracy of the parameterized model in terms of optical response processing depends on how closely the parameterization (i.e., the fitting of the variable parameters) matches the optical properties of the optical sensor components. Some optical sensor components such as a light source or filament of a light source may undergo significant physical transformation over time and usage cycles resulting in substantial performance drift. Re-characterizing optical sensors in a controlled laboratory environment or even in the field may be relatively expensive in terms of radiometric test equipment such as within characterization system  102 . Radiometric re-characterization is also costly in terms of formation test delays and may result in longer re-characterization intervals that may compromise fluid test results. 
     Disclosed embodiments include operations, functions, and components for reducing the cost of radiometric re-characterization and reducing the requisite frequency of such re-characterization. In one aspect, disclosed embodiments include a substantially portable and flexibly configured radiometry system that utilizes a transmissive type light diffuser instead of, for example, a reflective type diffuser. In a second aspect, disclosed embodiments utilize optical measurements of reference materials in combination with the radiometrically parameterized models to re-parameterize the models to maintain accuracy of fluid analysis results such as from fluid analysis tool  166 . 
     System  100  may be configured to implement one or both aspects of the disclosed embodiments that address inefficiencies associated with radiometric characterization and re-characterization. Regarding the first aspect, and as depicted and described in further detail with reference to  FIGS. 2-5 , radiometry system  104  may be further configured to implement optical measurement paths that utilize transmissive optical diffusers that are configured to maximize source light propagation intensity and also are far less expensive and more portably that reflective-type diffusers. Regarding the second aspect, system  100  is further configured to implement reference material measurements that may be utilized to adjust the parameterization (i.e., re-parameterize) the models such as those recorded in database  118 . 
     In some embodiments, a determination is made based on expiration of a re-characterization period or otherwise that optical sensor  136  requires re-characterization. To implement re-characterization, a reference material such as a reference sample fluid is deposited within sample cell  144  to be measured by optical sensor  136 . For example, the reference material may be a pre-selected fluid maintained in storage and having multiple known physical properties such as material composition and variations in density and viscosity based on temperature. In addition or alternatively, the reference material may be a downhole fluid sample for which one or more physical and optically significant properties such as density and viscosity are determined and therefore known in real-time. Such properties may be determined by downhole operation of logging tool  130  such as measurements by density detector  138 . 
     To support the re-characterization, fluid analysis tool  166  includes components configured to interoperate with parameterization tool  114  to re-parameterize a previously parameterized model using one or more reference material measurements. For example, fluid analysis tool  166  and parameterization tool  114  may re-parameterize model  116  corresponding to optical sensor  136  using a reference sample stored within logging sonde  134  in a reference fluid cell  149 . In some embodiments, several optically significant properties such as chemical composition and variation in density and/or viscosity with temperature are pre-determined or otherwise known and are specified by records within processing node  160 . An optical sensor re-characterization (e.g., re-calibration) cycle may begin with controller  140  actuating flow control mechanisms within logging sonde  134  to deposit the reference fluid within cell  149  into the sample cell  144  of optical sensor  136 . Optical sensor  136  is activated to obtain/measure an optical response of the reference fluid via optical detector  148 . 
     The optical response and other information relating to the condition of the fluid that may affect its optical properties such as downhole temperature measured by another sensor (not depicted) are transmitted to processing node  160 . Processing node  160  is configured to retrieve the recorded optically significant property information regarding the reference fluid. Processing node  160  may be further configured via programmed constructs such as fluid analysis tool  166  to determining some of the optical property information based on downhole measurements such as temperature and/or density of the reference fluid as may also be measured downhole. Fluid analysis tool  166  determines a reference fluid composition result based on the reference sample optical response. Fluid analysis tool  166  is further configured to determine optical component characterizations for optical sensor  136  based on comparing the reference fluid composition result with the known fluid composition and other measured fluid properties that affect the measured optical response. Based on the comparison, fluid analysis tool  166  generates a reference fluid characterization file  170  comprising re-characterization of one or more of the variable optical sensor parameters based on the comparison/correlation between the measured reference response and known reference fluid properties. 
     Measurement processing system  120  transmits characterization file  170  to a local or remote data processing system in which parameterization tool  114  executes and that will receive and process the file. In addition to the parameter re-characterization, characterization file  170  includes an identifier associated with the optical sensor model (e.g., model  116 ) that is being re-characterized. Parameterization tool  114  is configured to retrieve the parameterized model (e.g., model  116 ) from models database  118  and re-parameterize the retrieved model by re-fitting a subset of the original set of fitted parameters (e.g., subset, m, of the n originally fitted parameters). The refitting of the subset of variable parameters is based, at least in part, on the parameter re-characterization information in file  170  that was determined based on the reference material optical response. The re-parameterized model may then be transmitted to and recorded in models database  118  from which it may be accessible by measurement processing system  120  for further field measurements. 
     Accuracy and efficiency of the radiometric characterization utilized as the foundation of the parameterization model may be enhanced by embodiments such as disclosed in  FIGS. 2-5 .  FIG. 2  is a block diagram depicting a radiometry system  200  in accordance with some embodiments. The sub-systems, devices, components, operations, and functions depicted and described with reference to radiometry system  200  may be implemented by the radiometric characterization system  104  in  FIG. 1 . Radiometry system  200  includes sub-systems, devices, and components configured to implement characterization and related calibration techniques applicable to components and systems that implement electromagnetic (EM) radiation measurement operations. EM radiation measurement operations performed by components tested by radiometry system  200  may include spectroscopic analysis of how EM radiation interacts with various types of matter. Spectroscopic analysis may be performed on formation materials and fluids by deploying an optical measurement system downhole and/or may be implemented in a surface field test site in which the optical measurement system measures spectral transformation properties of solids and/or fluids sampled downhole and transported to the surface field test site. The range of EM radiation included in optical measurements used for spectroscopic analysis is typically EM “light” radiation, including visible, infrared, and ultraviolet spectra, collectively referred to as light energy, light waves, light, optical waves, optical energy, etc. 
     Radiometry system  200  is configured to determine and compare performance metrics for one or more test components (i.e., components to be deployed in an optical measurement system) and one or more corresponding reference components (i.e., components having known operational parameters). As utilized herein a test component may be referred to as an “uncharacterized” component and a reference component as a “characterized” component. Radiometry system  200  may be configured to measure performance values for a component under test (e.g., a test optical detector) that correspond to input from a reference component (e.g., a reference light source) and input from another test component (e.g., a test light source). The sequence of measurements performed by radiometry system  200  are utilized to quantify performance degradation of the test components over periods of usage in the field. 
     An optical train within radiometry system  200  includes an interchangeable light source  202  that generates and transmits EM light radiation that is detected by an optical detector  204 . Light source  202  may comprise a broad-spectrum or narrow-spectrum source that generates light  226  in the visible, infrared, or ultraviolet spectra ranges. Light, such as light  226 , generally refers to non-scattered/non-diffused light transmitted from a point source such as light source  202 . Example implementations of light source  202  include electroluminescence sources such as an electroluminescent lamp, laser, LED, etc. Light source  202  is interchangeable in terms of comprising either a test light source or a reference light source, depending on the optical measurement cycle within an overall characterization sequence. 
     Optical detector  204  is configured to generate response signals corresponding to metrics such as intensity and/or frequency of light energy originating from light source  202  and propagating through the optical train until being received by optical detector  204 . Like light source  202 , optical detector  204  is interchangeable in terms of comprising either a test optical detector or a reference optical detector, depending on the optical measurement cycle within an overall calibration sequence. In some embodiments, optical detector  204  may include a photoreactive component such as a photodiode that converts light energy into electrical current. Optical detector  204  may also or alternatively include other types of optical transducer components such as a photo-acoustic detector, a piezo-electric detector, a charge coupled device detector, a photon detector, and any combination thereof. In response to receiving/detecting light energy, optical detector  204  generates corresponding response signals that are transmitted to a data processing system  206  such as via a controller  220 . 
     During and/or following optical measurement cycles, detector response information from optical detector  204  is processed by data processing system  206  to determine and compare performance metrics of one or more of the components, including light source  202  and optical detector  204  within the optical measurement path. For instance, data processing system  206  may comprise processing components configured to derive characterization values such as calibration coefficients from the raw and/or pre-processed detector response data. 
     Data processing system  206  includes a memory device  210  into which components of a characterization application  216  are loaded and a processor  208  for executing instructions to implement operations and functions encoded in characterization application  216 . 
     Characterization application  216  includes program instructions configured to determine characterization values such as calibration coefficients based on response information received from optical detector  204  over one or more optical measurement cycles. Data processing system  206  may further include a user input device  214  that may be used individually or in conjunction with a display device  212  to input instructions and provide intermediary results data from the measurement and characterization processes. 
     Some field optical measurement systems are configured to detect spectral results that may be determined, at least in part, by the use of optical filter components that selectively remove particular spectral components. Therefore, the information required to determine optimally comprehensive characterization values may require responses generated by optical detector  204  having a similar spectral selectivity. In the depicted embodiment, the optical train includes a wavelength selection device  222  positioned at the input of optical detector  204 . Wavelength selection device  222  is configured to selectively pass/reject one or more wavelength components of light energy received by wavelength selection device  222 . In some embodiments, wavelength selection device  222  may be a monochromator that includes a wavelength/frequency selective filter that filters the light energy to provide a monochromatic spectral output to optical detector  204 . The spectral output comprises light energy components within a spectral range determined in accordance with the design, configuration, and settings of wavelength selection device  222 . 
     Radiometry system  200  is configured to characterize, such as by measuring performance values for, a test optical sensor that includes one or more optical sensor components including a light source and an optical detector. Characterizing an optical sensor and/or components within the optical sensor may entail measuring field/test component performance based on optical responses generated by detector  204 . For some measurement cycles in which the performance of one or more components of the optical sensor is measured, a test light source (i.e., uncharacterized light source) may be utilized as light source  202  and a reference detector (i.e., characterized detector) may be utilized as optical detector  204 . For other measurement cycles in which the performance of one or more components of the optical sensor is measured, a reference (i.e., characterized) light source is utilized as light source  202  and a test (i.e., uncharacterized) detector is utilized as optical detector  204 . 
     In addition to the light source and optical detector the optical sensor components under radiometric test may include one or more optical sensor components  207  that form an intermediary portion of an overall optical train that begins with light source  202  and ends with detector  204 . For example, optical components  207  may comprise optical components such as lenses, filters, and other types of optical components through which light propagates in a field optical system. In this manner, light  226  may be modified in some ways to become a light  227  from the end of the series of optical system components  207 . Radiometry system  200  may perform a sequence of optical response and other measurements that are utilized to quantify individual and/or combined performance of one or more test components. During and/or following optical measurement cycles, detector response information from optical detector  104  is processed by data processing system  206  to determine and compare performance metrics of various subsets of an overall optical system comprising optical system components  207  as well as light source  202  and optical detector  204 . 
     Optical system component performance metrics are compared across measurement cycles to determine characterization values such as calibration coefficients. To determine the test component performance metrics in a manner that the results may be utilized for calibration, the performance metrics may be normalized such as by comparing test component performance with performance metrics of reference components. For instance, radiometry system  200  may be configured to implement sequences of optical measurement cycles using corresponding combinations of test and/or reference components in the optical train. 
     Externally induced variations in optical characterization metrics are minimized by utilizing a consistently configured optical measurement path between measurement cycles. The absolute and relative positioning of the optical components within an optical train are substantially (to the extent practicable) the same between measurement cycles. However, between measurement cycles one or more optical train components such as light source  202 , optical detector  204 , and/or other components not depicted may be replaced. For example, light source  202  may be a reference light source that is replaced with a test light source and similarly for optical detector  204 . Since replacing even a single component in the optical train may alter alignment of portions of the measurement path, a transmissive diffuser may be included in the optical train to at least partially negate the effects of differing alignments on light energy such as generated by light source  202 . 
     In the depicted embodiment, the optical train of radiometry system  200  includes an in-line, transmission-based diffusion component in the form of a transmissive diffuser  224 . Transmissive diffuser  224  is configured to include one or more transmissive scattering boundaries through which light  226  is diffused as it propagates toward optical detector  204 . The diffusion path is in alignment with the original propagation direction of the light  126  in the depicted configuration in which light source  202 , transmissive diffuser  224 , and optical detector  204  are axially aligned. In some embodiments, such as during operation of radiometry system  200 , substantial diffusion of light  226  may be achieved by material composition and other structural aspects of transmissive diffuser  224  that results in light  226  being scattered while propagating through transmissive diffuser  224 . The transmissive diffusion may result in substantially lower energy losses that may occur for reflective type light scattering devices such as integrating spheres. For example, the lossy reflections within an integrating sphere results in a total attenuation factor on the order of the ratio of the exit aperture area divided by the total internal sphere area. 
     The transmissive, in-line configuration of transmissive diffuser  224  provides lower and adjustably lower light energy attenuation as well as a more flexibly configurable overall optical measurement path. As shown, transmissive diffuser  224  comprises multiple translucent elements, such as translucent plates, including a translucent element  228 . The translucent elements within transmissive diffuser  224  are axially aligned with the propagation path of light  226  generated by light source  202 . Each of the translucent elements may be comprised of a non-crystalline amorphous solid material such as glass. Also, or alternatively the translucent elements of transmissive diffuser  224  may comprise polymers, liquid crystals, silicon, or other materials through which at least a portion of light  226  may propagate. 
     In addition to enabling light propagation via translucence, the translucent elements also include material composition and/or structural features that scatter the light  226  as it propagates through transmissive diffuser  224  to become diffused light  232 . In some embodiments, the structural features that scatter the propagating light, also referred to as diffusion structures, comprises one or more scattering layers formed on one or both surfaces of each of the translucent elements. For instance, translucent element  228  may comprise a plate-like body having a substantially planar front side surface  229  and a substantially planar back side surface  230 . As depicted and described in further detail with reference to  FIGS. 3A and 3B , front side surface  229  and/or back side surface  230  may include diffusion structures comprising roughened surfaces that implement the light scattering function of translucent element  228 . Each of the other translucent elements within transmissive diffuser  224  may similarly include roughened surfaces, such as roughened front side and/or back side surfaces, that individually and cumulatively result in diffused light  232  exiting transmissive diffuser  224 . A lens  234  may be deployed at or proximate to an input port of wavelength selection device  222  to focus or otherwise intensify the light energy within diffused light  232 . 
       FIG. 3A  illustrates a transmission-based optical diffuser in the form of a transmissive diffuser  300  that may be implemented as transmissive diffuser  124  in one or more of the radiometry systems depicted in  FIGS. 1 and 2  in accordance with some embodiments. Transmissive diffuser  300  comprises a first translucent element  302  and a second translucent element  304  that each comprise material, such as glass, formed as substantially plate-like material layers. Translucent element  302  includes a front side surface  306  and a back side surface  308  each of which are substantially planar. The front side surface  306  is substantially smooth and therefore a light  314 , while possibly moderately refracted, is not substantially scattered as it propagates into and through front side surface  306 . The back side surface  308  is a diffusion structure comprising a substantially planar surface that is roughened, comprising relatively small surface irregularities such as may be implemented by mechanical and/or chemical roughening procedures. 
     The light  314  continues propagating through translucent element  302  until reaching back side surface  308  at which the light is scattered by surface irregularities, resulting in release of initially diffused light  316 . The initially diffused light  316  radiates in a diffused manner over a distance  315  to a front side surface  310  of translucent element  304 . In some embodiments, distance  315  comprises a distance of between and including 0.5 and 1.5 inches. Front side surface  310 , like the front side surface  306  of translucent element  302  is substantially smooth. Therefore, the incident initially diffused light  316  is not substantially scattered as it reaches and passes through front side surface  310 . The initially diffused light  316  continues propagating through translucent element  304  until reaching a back side surface  312 , that like back side surface  308  is a diffusion structure comprising a substantially planar surface having a roughness level sufficient to substantially scatter the initially diffused light  316 , resulting in release of secondarily diffused light  318 . 
       FIG. 3B  depicts a transmission-based transmissive diffuser  330  that may be utilized in radiometry systems such as the radiometry systems depicted in  FIGS. 1 and 2  in accordance with some embodiments. Transmissive diffuser  330  comprises a first translucent element  332  and a second translucent element  334  that each comprise material, such as glass, formed as substantially plate-like material layers. Translucent element  332  includes a front side surface  336  and a back side surface  338  each of which are substantially planar. Both the front side surface  336  and back side surface  338  of translucent element  332  comprise substantially roughened planar surfaces such as may be produced by applying mechanical and/or chemical roughening procedures to produce surface irregularities. An incident light  344  is therefore scattered as it reaches and passes through each of the roughened surface boundaries formed by front side surface  336  and back side surface  338 , resulting in diffused light  346  radiating in a diffused manner across a distance  345  to translucent element  334 . In some embodiments, distance  345  comprises a distance of between and including 0.5 and 1.5 inches. Both a front side surface  340  and a back side surface  342  of translucent element  334  comprise substantially roughened planar surfaces. Therefore, the incident diffused light  346  is substantially scattered as it reaches and passes through each of the roughened surface boundaries formed by front side surface  340  and back side surface  342 , resulting in further diffused light  348  radiating from transmissive diffuser  330 . 
     In some embodiments, a radiometry system may include a transmissive diffuser having alternative surface diffusion structures such as surface coating of translucent or semi-translucent material. A radiometry system may also or alternatively implement a transmissive diffuser having internal diffusion structures. For example,  FIG. 4A  illustrates a transmission-based optical diffuser in the form of a transmissive diffuser  400  that may be utilized in radiometry systems such as the radiometry systems depicted in  FIGS. 1 and 2  in accordance with some embodiments. Transmissive diffuser  400  comprises a first translucent element  402  and a second translucent element  404  that each comprise material, such as glass, formed as substantially plate-like material layers. In contrast to the translucent element configurations shown in  FIGS. 3A and 3B , translucent element  402  includes an internal diffusion structure in the form of a diffusion material layer  409  within the body of translucent element  402 . A light  414 , while possibly moderately refracted, is not substantially scattered as it propagates into and through a front side surface  406 . 
     The light  414  continues propagating through translucent element  402  until reaching diffusion material layer  409  at which the light is scattered, resulting in release of initially diffused light  416  through the back side  408 . The initially diffused light  416  radiates in a diffused manner over a distance  415  to a front side surface  410  of translucent element  404 . In some embodiments, a distance  415  between back side  408  and a front side  410  of translucent element  404  comprises a distance of between and including 0.5 and 1.5 inches. Front side surface  410 , like the front side surface  406  of translucent element  402  is substantially smooth. Therefore, the incident initially diffused light  416  is not substantially scattered as it reaches and passes through front side surface  410 . The initially diffused light  416  continues propagating through translucent element  404  until reaching a roughened back side surface  412  that scatters the initially diffused light  416 , resulting in release of secondarily diffused light  418 . 
       FIG. 4B  illustrates a transmission-based optical diffuser in the form of a transmissive diffuser  430  that may be utilized in radiometry systems such as the radiometry systems depicted in  FIGS. 1 and 2  in accordance with some embodiments. Transmissive diffuser  430  comprises a single translucent element that like translucent element  402  includes an internal diffusion structure. The translucent element comprises a first matrix material, such as glass, formed as substantially plate-like body member. An internal diffusion structure is disposed within the translucent element in the form of multiple particulates  439  that may be randomly distributed throughout the matrix material volume of transmissive diffuser  430 . In some embodiments, particulates  439  may comprise differently sized particulates comprising a material that is translucent to the wavelengths of light to be detected and having a different index of refraction than the matrix material of translucent element  430  in which particulates  439  are suspended. A light  444 , while possibly moderately refracted, is not substantially scattered as it propagates into and through a front side surface  436 . As light  444  propagates into and through transmissive diffuser  430 , light  444  is scattered, resulting in release of diffused light  446  through the back side  408 . 
       FIG. 5  is a flow diagram illustrating operations and functions for characterizing optical components and utilizing the characterized optical components for downhole fluid sampling and measurements in accordance with some embodiments. The process begins as shown at block  502  with the selection of an optical diffuser design based on the types of optical components to be included in an optical measurement path. For example, variations in the optical diffuser type/design that may be selected are illustrated and described with reference to  FIGS. 1, 2, 3A, 3B, 4A, and 4B . The optical diffuser design may be selected such that the level of diffusion provided by the selected design varies inversely with the level of light attenuation of the optical components in the measurement path. In some embodiments, the optical diffuser design is selected based on the light attenuation characteristics of optical components that operate as spectral filter elements. The selection of an optical diffuser design may be implemented by programmed elements such as those stored and executed on data processing system  206  depicted in  FIG. 2 . 
     At block  504 , an optical measurement path that includes an optical diffuser having the selected design is configured. As depicted in  FIG. 2 , the optical measurement path may include various combinations of optical and measurement components. The combinations of possible optical and measurement components include, among other possible components, a light source, an optical detector and the optical diffuser positioned between the light source and the optical detector. At block  506 , an optical response for the optical measurement path is measured or otherwise determined using the optical detector among other possible components. 
     At block  508 , the optical measurement path is reconfigured in terms of replacing at least one of the optical or measurement components in the measurement path. For example, if the initial measurement path configured as shown at block  504  included a reference light source, the reconfiguration at block  508  may include replacing the reference light source with a field light source (i.e., a light source to be deployed in a downhole optical sensor). As shown at block  510 , an optical response for the reconfigured optical measurement path is measured or otherwise determined using the optical detector among other possible components. At inquiry block  512  control passes back to block  508  if additional radiometry cycles remain to be performed. 
     When all radiometry cycles have been performed using one or more reconfigured optical measurement paths, control passes to block  514  that illustrates characterization of the optical field components included in one or more of the optical measurement paths. The characterizations may be used for various purposes including calibration of an optical sensor that incorporates one or more of the optical components. Such characterization and calibration operations may be implemented by programmed elements such as those stored and executed on data processing system  108  in  FIG. 1  and data processing system  206  in  FIG. 2 . 
     At block  516 , an optical sensor is assembled to include one or more of the optical devices that were characterized at blocks  502 - 514  and the optical sensor is deployed downhole within a downhole sampling tool. At block  518 , the downhole tool collects a fluid sample, such as may be a formation fluid, to be measured or otherwise characterized at least in terms of optical properties by the optical sensor. At block  520 , the optical sensor is utilized to detect the optical characteristics, such as may relate to spectral responses, of the collected downhole fluid. Programmed elements includes with the optical sensor or executed by another information processing system may be used to compute, calculate, or otherwise determine the material/chemical composition of the collected downhole fluid based on the determined optical responses/characteristics. The collection and processing of downhole fluid samples may continue with control passing from block  520  back to block  518  until the downhole fluid sampling cycle terminates. 
       FIG. 6  is a flow diagram depicting operations and functions for utilizing radiometric characterization of an optical sensor to re-characterize the optical sensor using reference sample material response data. The operations and function depicted and described with reference to  FIG. 6  may be implemented for radiometric characterization and reference material re-characterization by one or more of the systems, devices, and components depicted and described with reference to  FIGS. 1-5 and 7-8 . The process begins as shown at block  602  with a model generator, such as model generator  111 , generating an optical sensor model comprising model components of a particularly configured optical sensor. The model generator may be deployed as a programmed processing element that receives via user input or otherwise information describing a type of optical sensor including optical components that may comprise descriptions of optical characteristics (e.g., reflection) within the optical sensor. The model may be constructed using a selected one or more model types such as grey body emission, fluorescence, stimulated emission, etc. 
     Whether prior to or following model generation, a radiometric characterization phase begins as shown at block  604  with configuration of an optical measurement path that includes optical components of an optical sensor. An example of such optical measurement path is depicted and described with reference to  FIG. 2  as including light source components, optical detector components, and intermediary optical transform components. As indicated at block  604  the measurement path may be configured, particularly in terms of the type of optical diffuser utilized, based on optical characteristics of components in the optical train. At block  606 , a characterization application such as depicted and described with reference to  FIGS. 1 and 2  is utilized to determine characterization data for one or more of the optical components being characterized. The characterization application determines the characterization data based, at least in part, on the optical responses obtained and measured by the radiometry system. 
     The process continues as shown at block  608  with a parameterization tool, such as parameterization tool  114 , generating a parameterized model by fitting a number of variable and optically significant parameters of the model based on the characterization data. Having been otherwise characterized via the characterization data and calibrated via the parameterized model, the optical sensor may be field deployed to implement optical analysis of sample materials (block  610 ). Such a sensor is depicted as optical sensor  136  in  FIG. 1 . The optical sensor may have an assigned re-calibration period that may be defined as a sensor usage time period or number of measurement cycles. Upon expiration of the re-calibration period at block  612 , control passes to block  614  at which a reference material re-characterization cycle begins. As shown at block  614 , the re-characterization of the optical sensor begins with the optical sensor obtaining/measuring an optical response to a reference material for which at least one, and typically several, optically significant material properties are known and recorded in the re-characterization system. 
     Reference re-characterization continues at block  616  with a programmed components such as fluid analysis tool  166  and parameterization tool  114  interoperating to generate a re-parameterized model by refitting a number of the variable parameters fitted at block  608  based, at least in part, on the measurement optical response to the reference materials. In some embodiments, the number of parameters refit at block  616  is less that the number radiometrically fit at block  608  with additional parameter information determined or derived from the known properties information for the reference material. The optical sensor measurement processing system, such as system  120 , may be re-programmed in terms of retrieving, loading, and executing the updated (i.e., re-characterized) model (block  618 ) for subsequent optical measurements by the optical sensor (control returning to block  610 ). 
       FIG. 7  illustrates a drilling system  700  in accordance with some embodiments. Drilling system  700  is configured to including and use optical components for measuring properties of downhole material such as downhole fluids for example to determine the chemical composition or other composition aspects of the downhole materials. The resultant downhole material properties information may be utilized for various purposes such as for modifying a drilling parameter or configuration, such as penetration rate or drilling direction, in a measurement-while-drilling (MWD) and a logging-while-drilling (LWD) operation. Drilling system  700  may be configured to drive a bottom hole assembly (BHA)  704  positioned or otherwise arranged at the bottom of a drill string  706  extended into the earth  702  from a derrick  708  arranged at the surface  710 . Derrick  708  may include a kelly  712  and a traveling block  713  used to lower and raise kelly  712  and drill string  706 . 
     BHA  704  may include a drill bit  714  operatively coupled to a tool string  716  that may be moved axially within a drilled wellbore  718  as attached to the drill string  706 . During operation, drill bit  714  penetrates the earth  702  and thereby creates wellbore  718 . BHA  704  may provide directional control of drill bit  714  as it advances into the earth  702 . Tool string  716  can be semi-permanently mounted with various measurement tools (not shown) such as, but not limited to, MWD and LWD tools, that may be configured to perform downhole measurements of downhole conditions. In some embodiments, the measurement tools may be self-contained within tool string  716 , as shown in  FIG. 7 . 
     Drilling fluid from a drilling fluid tank  720  may be pumped downhole using a pump  722  powered by an adjacent power source, such as a prime mover or motor  724 . The drilling fluid may be pumped from the tank  720 , through a stand pipe  726 , which feeds the drilling fluid into drill string  706  and conveys the same to drill bit  714 . The drilling fluid exits one or more nozzles arranged in drill bit  714  and in the process cools drill bit  714 . After exiting drill bit  714 , the drilling fluid circulates back to the surface  710  via the annulus defined between wellbore  718  and drill string  706 , and in the process, returns drill cuttings and debris to the surface. The cuttings and mud mixture are passed through a flow line  728  and are processed such that a cleaned drilling fluid is returned down hole through stand pipe  726 . 
     Tool string  716  may further include a downhole tool  730  similar to the downhole tools described herein. More particularly, downhole tool  730  may have a calibrated optical sensor comprising optical components arranged therein, and the downhole tool  730  may have been calibrated or otherwise characterized prior to being introduced into the wellbore  718  using the radiometric characterization testing described herein. Moreover, prior to being introduced into the wellbore  718 , downhole tool  730  may have been optimized by the steps described with reference to  FIG. 6 . Downhole tool  730  may be controlled from the surface  710  by a computer  740  having a memory  742  and a processor  744 . Accordingly, memory  742  may store commands that, when executed by processor  744 , cause computer  740  to perform at least some steps in methods consistent with the present disclosure. 
       FIG. 8  illustrates a wireline system  800  that may employ one or more principles of the present disclosure. In some embodiments, wireline system  800  may be configured to use a formation tester and calibrated optical tool. After drilling of wellbore  718  is complete, it may be desirable to determine details regarding composition of formation fluids and associated properties through wireline sampling. Wireline system  800  may include a downhole tool  802  that forms part of a wireline logging operation that can include one or more optical measurement components  804 , as described herein, as part of a downhole measurement tool. Wireline system  800  may include the derrick  708  that supports the traveling block  713 . Wireline logging tool  802 , such as a probe or sonde, may be lowered by a wireline cable  806  into wellbore  718 . 
     Downhole tool  802  may be lowered to potential production zone or other region of interest within wellbore  718  and used in conjunction with other components such as packers and pumps to perform well testing and sampling. More particularly, downhole tool  802  may include a calibrated optical sensor  804  comprising optical components arranged therein, and the optical sensor  804  may have been calibrated, including characterizing one or more of the optical components using the radiometric characterization testing described herein prior to being introduced into the wellbore  718 . Moreover, prior to being introduced into the wellbore  718 , downhole tool  802  including optical sensor  804  may have been optimized by the steps described below with reference to  FIG. 8 . Optical sensor  804  may be configured to measure optical responses of the formation fluids, and any measurement data generated by downhole tool  802  and its associated optical sensor  804  can be real-time processed for decision-making, or communicated to a surface logging facility  808  for storage, processing, and/or analysis. Logging facility  808  may be provided with electronic equipment  810 , including processors for various types of data and signal processing including perform at least some steps in methods consistent with the present disclosure. 
       FIG. 9  depicts an example computer system, according to some embodiments. The computer system includes a processor  901  (possibly including multiple processors, multiple cores, multiple nodes, and/or implementing multi-threading, etc.). The computer system includes a memory  907 . The memory  907  may be system memory (e.g., one or more of cache, SRAM, DRAM, eDRAM, EEPROM, NRAM, etc.) or any one or more of the above already described possible realizations of machine-readable media. The computer system also includes a bus  903  (e.g., PCI, ISA) and a network interface  905 . 
     The computer system includes a model generation and parameterization system  911 , which may be hardware, software, firmware, or a combination thereof. For example, the model generation and parameterization system  911  may comprise instructions executable by the processor  901 . Any one of the previously described functionalities may be partially (or entirely) implemented in hardware and/or on the processor  901 . For example, the functionality may be implemented with an application specific integrated circuit, in logic implemented in the processor  901 , in a co-processor on a peripheral device or card, etc. Additional realizations may include fewer or more components not expressly illustrated in  FIG. 9  (e.g., video cards, audio cards, additional network interfaces, peripheral devices, etc.). The processor  901  and the network interface  905  are coupled to the bus  903 . Although illustrated as being coupled to the bus  903 , the memory  907  may be coupled to the processor  901 . 
     VARIATIONS 
     While the aspects of the disclosure are described with reference to various implementations, these aspects are illustrative and the scope of the claims is not limited thereto. Plural instances may be provided for components, operations or structures described herein as a single instance. Finally, boundaries between various components, operations and data stores can vary, and particular operations are illustrated in the context of specific illustrative configurations. Other allocations of functionality are envisioned and may fall within the scope of the disclosure. In general, structures and functionality presented as separate components in the example configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. 
     The flowcharts are provided to aid in understanding the illustrations and are not to be used to limit scope of the claims. The flowcharts depict example operations that can vary within the scope of the claims. The operations may be performed in parallel and/or in a different order. Each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by program code provided to a processor of a general-purpose computer, special purpose computer, or other programmable machine or apparatus. 
     Aspects of the disclosure may be embodied as a system, method or program code/instructions stored in one or more machine-readable media. Aspects may take the form of hardware, software (including firmware, resident software, micro-code, etc.), or a combination of software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable storage medium may be, for example, but not limited to, a system, apparatus, or device, that employs any one of or combination of electronic, magnetic, optical, electromagnetic, infrared, or semiconductor technology to store program code. More specific examples (a non-exhaustive list) of the machine readable storage medium would include the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a machine-readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A machine-readable storage medium is not a machine-readable signal medium. Use of the phrase “at least one of” preceding a list with the conjunction “and” should not be treated as an exclusive list and should not be construed as a list of categories with one item from each category, unless specifically stated otherwise. 
     EXAMPLE EMBODIMENTS 
     Embodiment 1: A method for optically measuring material properties comprising: radiometrically characterizing an optical sensor based on measured optical responses; generating a model comprising model components of the optical sensor; generating a parameterized model by fitting n variable parameters of the model components using the optical responses; measuring, by the optical sensor, an optical response to a reference material; and generating a re-parameterized model by re-fitting m of the n variable parameters of the model components based, at least in part, on the measured optical response to the reference material, wherein m is less than n. The method may further include measuring, utilizing the optical sensor, an optical response to a material sample; processing, by the re-parameterized model, the optical response to the material sample; and determining properties of the material sample based on the processed optical response to the material sample. Said processing the optical response to the material sample may comprise adjusting the optical response to the material sample based on the re-parameterized model. The m parameters may include at least one of a light source temperature parameter and a light source energy supply parameter. Said re-fitting the m variable parameters may comprise re-fitting the m variable parameters based, at least in part, on pre-determined values for at least one of the n-m of the n variable parameters that are not among the m variable parameters. Said re-fitting the m variable parameters may include refitting the m variable parameters based on one or more pre-determined optical interactive properties of the reference material. Said radiometrically characterizing the optical sensor may comprise: measuring a first set of one or more optical responses of an optical measurement path including one or more optical sensor components; measuring a second set of one or more optical responses of a reconfigured optical measurement path including one or more reference components; and determining parameters of the optical sensor components based on the first set of one or more optical responses and the second set of one or more optical responses. The optical measurement path and the reconfigured optical measurement path may include a light source that generates light, an optical detector, and a transmissive diffuser having a diffusion structure that scatters the light, wherein the transmissive diffuser is positioned between the light source and the optical detector. Said generating the model may comprise generating the model components to represent a light source and optical components that modify light from the light source. Said generating the model components may comprise generating a physical component representation or a data construct representation of optical components within the optical sensor. Said generating the parameterized model may include determining p parameters of the model components having lower variability in terms of rate of variation or range of variation than the n variable parameters, and fixing a value of at least one of the p parameters based on an average of the optical responses. 
     Embodiment 2: A system for optically measuring material properties comprising: a radiometry system configured to radiometrically characterize an optical sensor based on measured optical responses; processing means configured to generate a model comprising model components of the optical sensor; processing means configured to generate a parameterized model by fitting n variable parameters of the model components using the optical responses; the optical sensor configured to measure an optical response to a reference material; and processing means configured to generate a re-parameterized model by re-fitting m of the n variable parameters of the model components based, at least in part, on the measured optical response to the reference material, wherein m is less than n. The system may further comprise: the optical sensor configured to measure an optical response to a material sample; the re-parameterized model configured to process the optical response to the material sample; and processing means configured to determine properties of the material sample based on the processed optical response to the material sample. Said processing the optical response to the material sample may comprise adjusting the optical response to the material sample based on the re-parameterized model. The m parameters may include at least one of a light source temperature parameter and a light source energy supply parameter. Said re-fitting the m variable parameters may comprise re-fitting the m variable parameters based, at least in part, on pre-determined values for at least one of the n-m of the n variable parameters that are not among the m variable parameters. Said re-fitting the m variable parameters may include refitting the m variable parameters based on one or more pre-determined optical interactive properties of the reference material. Said radiometrically characterizing the optical sensor may comprise: measuring a first set of one or more optical responses of an optical measurement path including one or more optical sensor components; measuring a second set of one or more optical responses of a reconfigured optical measurement path including one or more reference components; and determining parameters of the optical sensor components based on the first set of one or more optical responses and the second set of one or more optical responses. The optical measurement path and the reconfigured optical measurement path may include a light source that generates light, an optical detector, and a transmissive diffuser having a diffusion structure that scatters the light, wherein the transmissive diffuser is positioned between the light source and the optical detector. Said generating the model may comprise generating the model components to represent a light source and optical components that modify light from the light source, and wherein said generating the model components comprises generating a physical component representation or a data construct representation of optical components within the optical sensor.