Patent Publication Number: US-2023152227-A1

Title: Light energy fluorescence excitation

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Pat. Application No. 16/206,574, filed Nov. 30, 2018, entitled, “LIGHT ENERGY FLUORESCENCE EXCITATION,” which is incorporated herein by reference in its entirety, which U.S. Pat. Application No. 16/206,574 claims priority to U.S. Pat. Application No. 62/611,448, filed Dec. 28, 2017, entitled, “LIGHT ENERGY FLUORESCENCE EXCITATION,” which is incorporated herein by reference in its entirety, which U.S. Pat. Application No. 16/206,574 also claims priority to U.S. Pat. Application No. 62/644,805, filed Mar. 19, 2018, entitled, “LIGHT ENERGY FLUORESCENCE EXCITATION,” which is incorporated herein by reference in its entirety, which U.S. Pat. Application No. 16/206,574 also claims priority to Dutch Patent Application No. 2020636, filed Mar. 20, 2018, entitled, “LIGHT ENERGY FLUORESCENCE EXCITATION,” which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Various protocols in biological or chemical research involve performing controlled reactions. The designated reactions can then be observed or detected and subsequent analysis can help identify or reveal properties of chemicals involved in the reaction. 
     In some multiplex assays, an unknown analyte having an identifiable label (e.g., fluorescent label) can be exposed to thousands of known probes under controlled conditions. Each known probe can be deposited into a corresponding well of a microplate. Observing any chemical reactions that occur between the known probes and the unknown analyte within the wells can help identify or reveal properties of the analyte. Other examples of such protocols include known DNA sequencing processes, such as sequencing-by-synthesis (SBS) or cyclic-array sequencing. 
     In some fluorescent-detection protocols, an optical system is used to direct excitation light onto fluorophores, e.g. fluorescently-labeled analytes and to also detect the fluorescent emissions signal light that can emit from the analytes having attached fluorophores. However, such optical systems can be relatively expensive and require a larger benchtop footprint. For example, the optical system can include an arrangement of lenses, filters, and light sources. 
     In other proposed detection systems, the controlled reactions in a flow cell define by a solid-state light sensor array (e.g. a complementary metal oxide semiconductor (CMOS) detector or a charge coupled device (CCD) detector). These systems do not involve a large optical assembly to detect the fluorescent emissions. 
     BRIEF DESCRIPTION 
     There is set forth herein a light energy exciter that can include one or more light sources. A light energy exciter can emit excitation light directed toward a detector surface that can support biological or chemical samples. 
     There is set forth herein a method comprising: emitting with a light energy exciter excitation light, wherein the light energy exciter comprises a first light source and a second light source, the first light source to emit excitation light rays in a first wavelength emission band, the second light source to emit excitation light rays in a second wavelength emission band; and receiving with a detector the excitation light and emissions signal light resulting from excitation by the excitation light, the detector comprising a detector surface for supporting biological or chemical samples and a sensor array spaced apart from the detector surface, the detector blocking the excitation light and permitting the emissions signal light to propagate toward light sensors of the sensor array; and transmitting with circuitry of the detector data signals in dependence on photons sensed by the light sensors of the sensor array. 
     There is set forth herein a light energy exciter comprising: at least one light source to emit excitation light rays; and a light pipe homogenizing the excitation light and directing the excitation light toward a distal end of the light energy exciter, the light pipe comprising a light entrance surface and a light exit surface, the light pipe receiving the excitation light rays from the at least one light source; wherein the distal end of the light energy exciter is adapted for coupling with a detector assembly that comprises a detector surface for supporting biological or chemical samples. 
     There is set forth herein a system comprising: a light energy exciter comprising at least one light source to emit excitation light rays, and a light pipe to homogenize the excitation light rays and to direct the excitation light rays, the light pipe comprising a light entrance surface to receive the excitation light rays from the at least one light source; and a detector comprising a detector surface for supporting biological or chemical samples and a sensor array comprising light sensors spaced apart from the detector surface, wherein the detector receives excitation light from the exciter and emissions signal light, wherein the detector comprises circuitry to transmit data signals in dependence on photons detected by light sensors of the sensor array, wherein the detector blocks the excitation light and permits the emissions signal light to propagate toward the light sensors. 
     It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages set forth herein will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG.  1    is a schematic block diagram of a system for performance of biological or chemical tests, the system having a light energy exciter and a detector assembly having a detector according to one example; 
         FIG.  2    is a cutaway side view of a light energy exciter according to one example; 
         FIG.  3    is a ray trace diagram illustrating light ray propagation in the light energy exciter of  FIG.  2    according to one example; 
         FIG.  4    depicts a light source bank including light sources provided by a plurality of LEDs disposed on a printed circuit board according to one example; 
         FIG.  5    is a side view of light sources provided by a plurality of LEDs surface coupled onto a light entry surface of a light pipe according to one example; 
         FIG.  6    is a perspective schematic view of a light energy exciter according to one example; 
         FIG.  7    is a schematic diagram of a light energy exciter according to one example; 
         FIG.  8    is a ray trace diagram illustrating operation of a light energy exciter having first and second light pipes according to one example; 
         FIG.  9    is a perspective cutaway side view showing a light energy exciter according to one example; 
         FIG.  10    is a perspective view of a system having a light energy exciter coupled with a detector assembly according to one example; 
         FIG.  11    is an assembly perspective view of a flow cell frame defining a flow cell according to one example; 
         FIG.  12    is an internal view of a detector assembly cartridge defining registration features for alignment of a light energy exciter that can be coupled and aligned thereon according to one example; 
         FIG.  13    is a top view of the flow cell defined with respect to a detector provided by an integrated circuit according to one example; 
         FIG.  14    is a light energy exciter provided by a single piece of material defining a light pipe and a lens according to one example; 
         FIG.  15    is a perspective view of a light energy exciter having a single piece of material that commonly defines a light pipe and a lens, wherein the lens is provided by a Fresnel lens according to one example; 
         FIG.  16    is a cutaway side view of a portion of a detector provided by an integrated circuit having a light sensor array and an aligned light guide array according to one example; 
         FIG.  17    is a cutaway side view of a portion of a detector provided by an integrated circuit having a light sensor and an aligned light guide according to one example; 
         FIG.  18    is a schematic diagram of a process control system according to one example, 
         FIG.  19    is a spectral profile coordination diagram depicting spectral profiles of a plurality of light energy exciter light sources and a plurality of fluorophores that may be excited with use of the excitation light sources; and 
         FIG.  20    is a flowchart depicting process that can be used in support of a DNA sequencing process for DNA sequence reconstruction. 
     
    
    
     DETAILED DESCRIPTION 
     In  FIG.  1    there is set forth a light energy exciter  10  for use in a system  100 . System  100  can be used to perform biological or chemical tests. System  100  can include light energy exciter  10  and detector assembly  20 . Detector assembly  20  can include detector  200  and flow cell  282 . Detector  200  can include a plurality of light sensors  202  and detector surface  206  for supporting samples  502  e.g. analytes which can be provided by DNA fragments. Detector surface  206  according to one example can define a plurality of reaction recesses  210  and samples  502  such as biological or chemical samples can be supported within such reaction recesses  210 . 
     Detector  200  can include a plurality of light guides  214  that receive excitation light and emissions signal light from detector surface  206  resulting from excitation by the excitation light. The light guides  214  can guide light from detector surface  206 . The light guides  214  extend toward respective light sensors  102  and can include filter material that blocks the excitation light and permits the emissions signal light to propagate toward the respective light sensors. 
     According to one example, detector  200  can be provided by a solid-state integrated circuit detector such as a complementary metal oxide semiconductor (CMOS) integrated circuit detector or a charge coupled device (CCD) integrated circuit detector. 
     According to one example, each light sensor  202  can be aligned to a respective light guide  214  and a respective reaction recess  210  so that longitudinal axis  268  extends through a cross sectional geometric center of a light sensor  202 , light guide  214  and reaction recess  210 . Flow cell  282  can be defined by detector surface  206 , sidewalls  284 , and flow cover  288 . Flow cover  288  can be a light transmissive cover to transmit excitation light provided by light energy exciter  10 . 
     In another aspect, detector  200  can include dielectric stack areas  218 , intermediate of the light guides  214 . Dielectric stack areas  218  can have formed therein circuitry, e.g. for read out of signals from light sensors  202  digitization storage and processing. 
     System  100  can include inlet portal  289  through which fluid can enter flow cell  282  and outlet portal  290  through which fluid can exit flow cell  282 . Inlet portal  289  and outlet portal  290  can be defined by flow cover  288 . 
     According to one example, system  100  can be used for performance of biological or chemical testing with use of fluorophores. For example, a fluid having one or more fluorophore can be caused to flow into and out of flow cell  282  through inlet port using inlet portal  289  and outlet portal  290 . Fluorophores can attract to various samples  502  and thus, by their detection fluorophores can act as markers for the samples  502  e.g. biological or chemical analytes to which they attract. 
     To detect the presence of a fluorophore within flow cell  282 , light energy exciter  10  can be energized so that excitation light  101  in an excitation wavelength range is emitted by light energy exciter  10 . On receipt of excitation light fluorophores attached to samples  502  can radiate emissions signal light  501  which is the signal of interest for detection by light sensors  202 . Emissions signal light  501  owing to fluorescence of a fluorophore attached to a sample  502  will have a wavelength range red shifted relative to a wavelength range of excitation light  101 . 
     Light energy exciter  10  can be activated to emit excitation light  101  to excite fluorophores that have attached to samples  502 . On being excited by excitation light  101  fluorophores attached to samples 5102 can fluoresce to radiate emissions signal light  501  at a wavelength range having longer wavelengths than a wavelength range of excitation light  101 . The presence or absence of emissions signal light  501  can indicate a characteristic of a sample  502 . Light guides  214  according to one example can filter light in the wavelength range of excitation light  101  transmitted by light energy exciter  10  so that light sensors  202  do not detect excitation light  101  as emissions signal light  501 . 
     System  100  in test support systems area  300  can include process control system  310 , fluid control system  320 , fluid storage system  330 , and user interface  340  which permits an operator to enter inputs for control of system  100 . Process control system  310  according to one example can be provided by processor based system. Process control system  310  can run various biological or chemical processes such as DNA sequence reconstruction processes. According to one example, for running of a biological or chemical process, process control system  310  can send coordinated control signals e.g. to light energy exciter  10 , detector  200  and/or fluid control system  320 . Fluid storage system  330  can store fluids that flow through flow cell  282 . 
     According to one example, light energy exciter  10  can include one or more light sources. According to one example, light energy exciter  10  can include one or more light shaping element. Light energy exciter  10  can include one or more optical component for shaping light emissions directing light emitted from the one or more light sources. The one or more light sources can include, e.g. one or more light pipe, lens, wedge, prism, reflector, filter, grating, collimator, or any combination of the above. 
       FIG.  2    illustrates a light energy exciter  10  according to one example. Light energy exciter  10  can include a light source bank  102  having one or more light sources, e.g. light source  102 A- 102 Z and various optical elements for directing light along optical axis  106 , which in the example shown is a folded axis. 
     Light energy exciter  10  can include light pipe  110  and lens  114  for shaping excitation light rays transmitted through light pipe  110 . Light pipe  110  and lens  114  can have cross sectional geometric centers centered on optical axis  106 . 
     Light pipe  110  can include light entry surface  109  and light exit surface  111 . Excitation light  101  emitted from light source bank  102  can enter light entry surface  109  and can exit light exit surface  111  of light pipe  110 . Light pipe  110  by having an index of refraction selected for providing internal reflections can reflect received light rays received from light source bank  102  in various directions to homogenize light so that exit light rays transmitted through light pipe  110  are homogenous. Thus, even where a light source of light source bank  102  may have “hot spots” or is asymmetrically disposed with respect to light pipe  110  or have other irregularities, homogenous light can be produced at the light exit surface  111  of light pipe  110 . 
     Light pipe  110  by having an index of refraction selected for providing internal reflections can confine excitation light rays that it receives and transmits to the volumetric area delimited by sidewall surfaces defining light pipe  110 . Light pipe  110  can be formed of homogenous light transmissive material, e.g. polycarbonate or silica glass. 
     According to one example, light pipe  110  can be of tapered construction defined by an increasing diameter throughout its length in a direction from the light entry surface  109  to the light exit surface  111  of light pipe  110 . According to one example, light pipe  110  can be of tapered construction defined by a linearly increasing diameter throughout its length in a direction from the light entry surface  109  to the light exit surface  111  of light pipe  110 . 
     According to one example, light energy exciter  10  can be configured so that lens  114  images light exit surface  111  of light pipe  110  onto image plane  130  and according to one example system  100  can be configured so that image plane  130  coincides with detector surface  206  which can be configured to support a sample  502  such as a DNA fragment. Lens  114  by imaging an object plane onto an image plane can project an image of homogenized light present at light exit surface  111  of light pipe  110  onto sample supporting detector surface  206  of detector  200  ( FIG.  1   ). 
     Examples herein recognize that while light source bank  102  can be selected so that excitation light rays emitted from light source bank  102  do not include fluorescence range light rays, fluorescence range light rays can nevertheless radiate within light energy exciter  10  as a result of autofluorescence. In another aspect, light energy exciter  10  can include a short pass filter  122  to filter fluorescence range wavelengths radiating as a result of autofluorescence from within light energy exciter  10 , e.g. radiating from lens  114 , light pipe  110 , and reflector  118  as well as other surfaces of light energy exciter  10   
     Light energy exciter  10  can include light reflector  118  for folding optical axis  106  so that optical axis  106  changes direction from a first direction in which optical axis  106  extends parallel to the reference Y axis shown to a second direction in which optical axis  106  extends parallel to the reference Z axis shown. Light energy exciter  10  can include window  126  having a cross sectional center centered on optical axis  106  as well as housing  134  and other supporting components for supporting the various optical components in certain spatial relation such as the certain spatial relation depicted in  FIG.  1   . 
     A ray trace diagram for light energy exciter  10  in the example of  FIG.  2    is shown in  FIG.  3   . Referring to the ray trace diagram of  FIG.  3   , lens  114  can image an object plane  112  which can be defined at the light exit surface  111  of light pipe  110  onto an image plane  130  which can be located at detector surface  206  that can be adapted to support biological or chemical samples. As seen from the ray trace diagram of  FIG.  3   , light rays exiting light exit surface  111  of light pipe  110  can be diverging light rays that diverge at a divergence angle that is sufficiently restricted so that a majority of light rays exiting light exit surface  111  of light pipe  110  are received by light entry surface of lens  114 . Examples herein recognize that while light pipes are useful for purposes of homogenizing light, they are capable of transmitting exit light rays that exit at large maximum divergence angles, e.g. approaching 90°. 
     Examples herein recognize for example that in the case that light pipe  110  is constructed alternatively to have a uniform diameter, i.e. a non-tapered diameter, a substantial percentage of exit light rays exiting light pipe  110  may exit light exit surface  111  at a divergence angle that is sufficiently large that a light entry surface  113  of lens  114  may not collect the exit light rays. Examples herein recognize that providing light pipe  110  to be of tapered construction, tapered along its length and having a geometric cross sectional center centered on optical axis  106  and including an appropriate index of refraction provides reflections within light pipe  110  so that light exiting light rays exiting light exit surface  111  of light pipe  110  exit light exit surface  111  of light pipe  110  at an angle that is reduced relative to a 90° angle of maximum divergence. 
     In the example described in reference to  FIGS.  2  and  3   , exit light rays exiting light exit surface  111  of light pipe  110  can define a diverging cone of light  1100  having light rays that diverge at angles ranging from zero degrees to a maximum divergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 . The defined diverging cone of light  1100  can diverge at the maximum divergence angle with respect to optical axis  106 . According to one example, the maximum divergence angle is a divergence angle designed so that the majority of exit light rays exiting light exit surface  111  are collected by a light entry surface of lens  114 . According to one example, the light energy exciter  10  is configured so that light excitation light rays exiting exit surface  111  diverge at a maximum divergence angle respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106  that is sufficiently small so as to ensure collection by light entry surface  113  of lens  114 . 
     According to one example, light energy exciter  10  can be configured so that exit light rays exiting light exit surface  111  of light pipe  110  define a diverging cone of light  1100  having light rays that diverge at angles ranging from zero degrees to a maximum divergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the light pipe  110  is configured so that the maximum divergence angle is about 60 degrees or less. According to one example, light energy exciter  10  is configured so that exit light rays exiting light exit surface  111  of light pipe  110  define a diverging cone of light  1100  having light rays that diverge at angles ranging from zero degrees to a maximum divergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the light pipe  110  is configured so that the maximum divergence angle is about 50 degrees or less. According to one example, light energy exciter  10  is configured so that exit light rays exiting light exit surface  111  of light pipe  110  define a diverging cone of light  1100  having light rays that diverge at angles ranging from zero degrees to a maximum divergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the light pipe  110  is configured so that the maximum divergence angle is about 40 degrees or less. According to one example, light energy exciter  10  is configured so that exit light rays exiting light exit surface  111  of light pipe  110  define a diverging cone of light  1100  having light rays that diverge at angles ranging from zero degrees to a maximum divergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the light pipe  110  is configured so that the maximum divergence angle is about 35 degrees or less. According to one example, light energy exciter  10  is configured so that exit light rays exiting light exit surface  111  of light pipe  110  define a diverging cone of light  1100  having light rays that diverge at angles ranging from zero degrees to a maximum divergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the light pipe  110  is configured so that the maximum divergence angle is about 30 degrees or less. 
     For providing imaging functionality, lens  114  can converge received excitation light rays transmitted through light pipe  110 . In the example described in reference to  FIGS.  2  and  3   , exit light rays exiting light exit surface  115  of lens  114  can define a converging cone of light  1400  having light rays that converge at angles ranging from zero degrees to a maximum convergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the lens  114  is configured so that the maximum convergence angle is about 60 degrees or less. The defined converging cone of light  1400  can converge at the maximum convergence angle with respect to optical axis  106 . In the example described in reference to  FIGS.  2  and  3   , exit light rays exiting light exit surface  115  of lens  114  can define a converging cone of light  1400  having light rays that converge at angles ranging from zero degrees to a maximum convergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the lens  114  is configured so that the maximum convergence angle is about 50 degrees or less. In the example described in reference to  FIGS.  2  and  3   , exit light rays exiting light exit surface  115  of lens  114  can define a converging cone of light  1400  having light rays that converge at angles ranging from zero degrees to a maximum convergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the lens  114  is configured so that the maximum convergence angle is about 40 degrees or less. In the example described in reference to  FIGS.  2  and  3   , exit light rays exiting light exit surface  115  of lens  114  can define a converging cone of light  1400  having light rays that converge at angles ranging from zero degrees to a maximum convergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the lens  114  is configured so that the maximum convergence angle is about 35 degrees or less. In the example described in reference to  FIGS.  2  and  3   , exit light rays exiting light exit surface  115  of lens  114  can define a converging cone of light  1400  having light rays that converge at angles ranging from zero degrees to a maximum convergence angle in respect to a reference light ray extending from the light exit surface in a direction parallel to optical axis  106 , wherein the lens  114  is configured so that the maximum convergence angle is about 30 degrees or less. 
       FIG.  4    illustrates light source bank  102  according to one example. Light source bank  102  can include one or more light sources. According to one example, one or more light sources can be provided by one or more electroluminescence based light sources, e.g. a light emitting diode, a light emitting electrochemical cell, an electroluminescent wire, or a laser, or any combination of the above. In the example described in  FIG.  4   , light source bank  102  can include a plurality of light sources  102 A- 102 J provided by a plurality of light emitting diodes (LEDs). Light sources  102 A- 102 G in the example described can be green LEDs emitting excitation light rays in the green wavelength band and light sources  102 H- 102 J can be blue LEDs emitting excitation light rays in the blue wavelength band. Light sources  102 A- 102 J provided by LEDs can be disposed on printed circuit board  1020  according to one example. In operation of system  100 , process control system  310  can control energization of light sources  102 A- 102 J provided by LEDs so that one or more LEDs of a certain emission band is selectively activated at a certain time. Light sources  102 A- 102 J according to one example can be provided by surface emitting LEDs. LEDs such as surface emitting LEDs can have emissions patterns that correlate ray angles with light intensity. LED emissions patterns can be a function of such parameters as a die geometry, a die window, indices of and refraction of light shaping materials. Emissions patterns can be Lambertian according to one example i.e. specifying that intensity is proportional to the cosine of the emission angle relative to the normal. 
     Process control system  310  for example can energize only light sources  102 A- 102 G provided by green LEDs during a first exposure period of detector  200  in which light sensors  202  are exposed and can energize only light sources  102 H- 102 J provided by blue LEDs during a second exposure period of detector  200  in which light sensors  202  are exposed. Providing light source bank  102  to emit at two independently selectable peak wavelengths facilities a dye chemistry process that can use both green (532 nm) and blue (470 nm) excitation. According to one example, light source bank  102  can include a light source e.g. a red LED disposed on printed circuit board  1020  that emits at a red band center wavelength (e.g. red: 630 nm). Providing red illumination facilitates additional test and calibration procedures according to one example. 
     It is seen in reference to  FIG.  4    that light sources defining light source bank  102  need not be arranged symmetrically uniformly or according to any ordered configuration. For example, it is seen that according to the particular configuration shown in  FIG.  4   , wherein light sources  102 A- 102 G provided by green LEDs are selectively energized with light sources  102 H- 102 J provided by blue LEDs maintained in a deenergized state, a larger percentage of excitation light rays will enter light pipe  110  through a left side of light entry surface  109  of light pipe  110 , and when light sources  102 H- 102 J provided by blue LEDs are selectively energized with green LEDs maintained in a deenergized state, a larger percentage of excitation light rays will enter light pipe through a right side of light entry surface  109  of light pipe  110 . Notwithstanding, light pipe  110  by its light reflective properties homogenizes the imbalanced incoming received light to produce homogenized light at the light exit surface  111  of light pipe  110  irrespective of the arrangement of light sources of light source bank  102 . The refractive index of light pipe  110  can be chosen such that the light rays from light source bank  102  exhibit total internal reflection (TIR) within light pipe  110  such that at light exit surface  111  of light pipe  110 , homogeneous (uniform) illumination is achieved. 
     As shown in  FIG.  5   , light source bank  102  can be coupled to light pipe  110  in a manner to assure reduced light loss. In the arrangement depicted in  FIG.  5   , there is a side view of the LEDs shown as being disposed on printed circuit board  1020  in  FIG.  4   . In the side view depicted in  FIG.  5   , light sources  102 A,  102 C, and  102 E provided by LEDs are shown to correspond to light sources  102 A,  102 C, and  102 E, as depicted in  FIG.  4   . Light sources  102 A- 102 J can be provided by LEDs having flat planar light emission faces depicted as depicted in in  FIG.  5   . Referring to  FIG.  5    the flat planar light emission faces of light sources  102 A- 102 J provided by LEDs (of which light sources  102 A,  102 C, and  102 E are shown in the side view) are surface coupled (butt coupled) onto light entry surface  109  of light pipe  110 . Light entry surface  109  like the emission surfaces of light sources  102 A- 102 J provided by LEDs, can be flat and planar to assure low light loss when light sources  102 A- 102 J provided by LEDs are surface coupled onto light entry surface  109 . With use of the surface coupling depicted in  FIG.  5   , coupling efficiency specifying the efficiency of LED light transmission through light pipe  110  of 90 percent or greater can be achieved, and according to one example 98 percent or higher, which compares favorably to coupling efficiency of light sources into a lens where coupling efficiency is in dependence on the numerical aperture of the lens. 
     Further in reference to  FIG.  5   , it is seen that an entirety of the front face of each respective light source  102 A- 102 J provided by LEDs is opposed by light entry surface  109  of light pipe  110 , thus assuring that a majority of excitation light rays emitted by light sources  102 A- 102 J provided by LEDs are received by light entry surface  109  of light pipe  110 . 
     Light energy exciter  10  can emit excitation light  101  ( FIG.  1   ) at a first lower wavelength range, e.g. below about 560 nm to excite fluorophores which, in response to the excitation light fluoresce to radiate emissions signal light 501 second wavelength range having longer wavelengths, e.g. including wavelengths longer than about 560 nm. Detector  200  can be configured so that these wavelength range emissions at longer wavelengths are detected by light sensors  202 . Detector  200  can include light guides  214  that can be formed of filtering material to block light in the wavelength range of excitation light  101  so that that emissions signal light  501  attributable to fluorescing fluorophores is selectively received by light sensors  202 . 
     Examples herein recognize that if light energy exciter  10  emits light in a fluorescence emission band (fluorescence range) such emitted light can be undesirably be sensed as emissions signal light by light sensors  202 . Examples herein include features to reduce the emission of fluorescence range wavelengths by light energy exciter  10 . 
     As noted, light energy exciter  10  can include short pass filter  122 . Short pass filter  122  permits transmission of excitation light rays in the emission energy band of light source bank  102  but which blocks light at a fluorescence range within flow cell  282  attributable to autofluorescing components within light energy exciter  110 . Short pass filter  122  can be disposed at a distal end of light energy exciter  10  so that-short pass filter  122  can reject autofluorescence range wavelengths attributable to autofluorescing materials within light energy exciter  10 . To facilitate filtering of autofluorescence range radiation radiating from lens  112  and from components disposed before lens  114  in the direction of light propagation short pass filter  122  can be disposed after lens  114  in a light propagation direction at a distal end of light energy exciter  10 . Short pass filter  122  according to one example can include a substrate having deposited thereon alternating layers of materials having higher and lower indices of refraction. Higher index of refraction material can include e.g. titanium dioxide (TiO 2 ) or tantalum pentoxide (Ta 2 O 5 ) and lower index of refraction material can include e.g. silicon dioxide (SiO 2 ). Material layers can be hard coated e.g. using ion beam sputtering, according to one example. 
     To further reduce fluorescence range light, materials of light energy exciter  10  can be selected for reduced autofluorescence. Examples herein recognize that silicate glass autofluoresces less than polycarbonate materials commonly used in optical systems. According to one example one or more optical components of light energy exciter  10  can be selected to be formed of silicate glass. Examples herein recognize that silicate glass can produce reduced autofluorescence relative to an alternative material for optical components and accordingly in accordance with one example one or more of light pipe  110 , lens  114 , short pass filter  122  (substrate thereof), and window  126  can be selected to be formed of silicate glass for reduction of autofluorescence. According to one example one or more of light pipe  110 , lens  114 , short pass filter  122  (substrate thereof), and window  126  is selected to be formed of homogeneous silicate glass for reduction of autofluorescence. According to one example each of light pipe  110 , lens  114 , short pass filter  122  (substrate thereof), and window  126  is selected to be formed of homogeneous silicate glass for reduction of autofluorescence. 
     In  FIG.  6    a three-dimensional schematic diagram of light energy exciter  10  is shown. As shown in  FIG.  6   , object plane  112  can be imaged by lens  114  onto image plane  130 . As set forth herein, object plane  112  can be defined at light exit surface  111  of light pipe  110 , so that the image of the light at light exit surface  111  is projected onto image plane  130 , which as noted can be located at detector surface  206  ( FIG.  1   ) of detector  200  for supporting a sample. It will be understood that because lens  114  can image the light exit surface  111  of light pipe  110 , the shape of the light exit surface  111  can be imaged onto and according projected onto image plane  130 . According to one example, the shape of light exit surface  111  is selected to correspond to the shape and size of detector surface  206 , and light energy exciter  110  is configured to image the shape of light exit surface  111  onto image plane  130  so that lens  114  projects an illumination pattern  107  ( FIG.  3   ) onto detector surface  206  that matches a shape and size of detector surface  206 . 
     Configuring light energy exciter  10  to project a light pattern  107  ( FIG.  3   ) onto detector surface  206  that matches a shape and size of detector surface  206  provides various advantages. By such configuring the projected illumination pattern does not illuminate areas outside of a perimeter of detector  200  which is wasteful of light energy and also does not under-illuminate areas that are areas of interest. 
     In the example described with reference to  FIG.  6   , both light exit surface  111  and detector surface  206  for supporting a sample can be rectilinear in shape. As seen in  FIG.  6   , light pipe  110  can include a rectilinear cross section (taken along  6 - 6  transverse to optical axis  106 ) throughout its length. Further, as noted, light pipe  110  can be of tapered construction and can have an increasing diameter throughout its length from light entry surface  109  to light exit surface  111  thereof. Where light pipe  110  has a rectilinear cross section, it will be understood that diverging cone of light  1100  defined by excitation light rays exiting light exit surface  111  of light pipe  110  can have a rectilinear cross section with corners becoming softer and more diffuse in the direction of light propagation toward light entry surface  113  of lens  114 . 
     According to one example, light energy exciter  10  can be configured so that light pipe  110  has a rectilinear light exit surface  111 , an image of which can be projected by lens  114  onto detector surface  206  for supporting a sample which can have a rectilinear shaped perimeter corresponding to a shape of light exit surface  111 . 
     A specification for components of light energy exciter  10  according to one example are set forth  FIG.  7    illustrating various optical parameter values for light energy exciter  10  according to one example. In the example illustrated in  FIG.  7    lens  114  has a 1:1 magnification so that a size of the projected image at the image plane  130  is in common with the size of the object (the light exit surface  111 ) at the object plane  112 . Light energy exciter  10  according to one example can produce green illumination intensity of about 5 W/cm^2 at 2A drive current per LED die and blue illumination intensity of about 7 W/cm^2 at 2A drive current per LED die. An illumination uniformity of about &gt; 75% can be achieved within the whole illumination area. Materials for use in light energy exciter  10  are set forth in Table 1 hereinbelow.  
     
       
         
          TABLE 1
           
               
               
               
             
               
                 Item 
                 Description 
                 Property 
               
             
            
               
                 102 
                 Light source bank provided by LEDs 
                 SemiLed® Version 40 mil chips: Proto; Green: 7 dies; 0.6 W/die; 1 x 1 mm 2 ; 525 nm, (±5 nm) 
               
               
                   
                   
                 Proto; Blue: 3 dies; 1.3 W/die; 1 x 1 mm 2 ; 460 nm, (±5 nm) (SemiLed is a trademark of SemiLEDs Optoelectronics Co., Ltd.) 
               
               
                 110 
                 Light pipe 
                 Material: N-BK7® (N-BK7 is a registered trademark of SCHOTT Corporation) Length = 35 mm Entrance: 3.3 mm x 4.4 mm; Exit: 7.2 mm x 9.1 mm 
               
               
                 114 
                 Lens provided by a lens pair 
                 Material: Zeonor® 330R feff = 20 mm (Zeonor is a registered trademark of Zeon Corporation) 
               
               
                 122 
                 Filter 
                 Semrock ® short pass filter; (Semrock is a registered trademark of Semrock, Inc.) Substrate Material: Fused Silica; short pass filter λ &lt; 540 nm 
               
               
                 126 
                 Window 
                 Substrate Material: fused silica Coating: Broadband Dielectric Thickness; 1 mm 
               
               
                 118 
                 Reflector provided by a fold mirror 
                 Substrate Material: N-BK7® (N-BK7 is a registered trademark of SCHOTT Corporation) Coating: Broadband Dielectric 
               
            
           
         
       
     
     In another example, light pipe  110  can be shaped so that a light exit surface  111  of light pipe  110  can have a shape other than a rectilinear shape, e.g. can have a circular cross section taken along  6 - 6  transverse to optical axis  106 ). Such an example can be advantageous where sample supporting detector surface  206  has a perimeter that is of a shape other than a rectilinear shape and corresponds to the shape of light exit surface  111 . 
     A design for light energy exciter  10  can be readily be modified for optimization with different detectors according to detector  200  having different detector surfaces  206  with different shapes. For example, a first detector according to detector  200  can have a rectangular shaped (from a top view along Z axis) detector surface  206 , a second detector according to detector  200  can have a square shaped detector surface  206 , and a third detector according to detector  200  can have a circle shaped detector surface  206 . Because lens  114  is configured to image object plane  112  coinciding with light exit surface  111  onto detector surface  206 , light energy exciter  10  can be optimized for use with any of the differently shaped detectors simply by changing light pipe  110  to be a different configuration. According to one example, as indicated by dashed line  132  of  FIG.  2    which indicates a holder for holding an interchangeable module light energy exciter  10  can be of modular construction with a light pipe module  133  being removably exchangeable and light energy exciter  10  can be provided with multiple of such light pipe blocks modules each with a differently configured one or more light pipe  110 . Optimizing light energy exciter  10  for use with a differently shaped detector  200  having a differently shaped detector surface  206  can include simply switching out a first currently installed light pipe module  133  having a first light pipe  110  and first pipe light exit surface  111  of a first shape with a second light pipe module  133  having a second light pipe  110  and light pipe exit surface  111  of a second shape that matches the shape the differently shaped detector  200  having a differently shaped detector surface  206 . Light energy exciter  10  can be configured so that when a different module is installed into a holder of housing  114  as indicated by dashed line  132 , the light exit surface  111  of a light pipe  110  of the newly installed module  133  is located on the object plane  112  so that the light exit surface  111  of light pipe  110  can be imaged onto image plane located on detector surface  206 . 
     In the example of  FIG.  8    light energy exciter  10  can include light pipe  110  as set forth herein and second light pipe  110 B. Light pipe  110  can be surface coupled to a first light source  102 A, e.g. provided by an LED and light pipe  110 B can be surface coupled to a second light source  102 B, e.g. provided by second LED. Light source  102 A and light source  102 B can be configured to emit light in the same wavelength band or different wavelength bands. Lens  114  can be configured to image object plane  112  defined at light exit surface  111  of light pipe  110  and second light pipe  110 B onto image plane  130  which can be defined on detector surface  206 . Thus, light energy exciter  10  can project two separate illumination patterns  107 A and  107 B onto detector surface  206 , which can be advantageous in the case a biological or chemical test designer wishes to separate a detector surface  206  into separate test areas. According to one example, a test designer can specify that a test is to be performed using a first detector according to detector  200  and a second detector according to detector  200  and system  100  can be configured so that light energy exciter  10  projects the illumination areas  107 B and  107 B onto separate detector surfaces  206  respectively of the first and second different detectors  200 . 
     There is set forth herein a light energy exciter  10 , having a light source  102 A and a second light source  102 B, wherein the light pipe  110  receives excitation light from the light source  102 A, and wherein the exciter comprises a second light pipe  110 B housed in a common housing  134  with the light pipe  110 , wherein the second light pipe  110 B receive the excitation light from the second light source  102 B, wherein the light pipe  110  and the second light pipe  110 B propagate the excitation light emitted from the first light source  102 A and the second light source  102 B, respectively, and wherein the light energy exciter  10  shapes the excitation light propagating, respectively, through the light pipe  110  and the second light pipe  110 B to define first and second separate illumination areas  107  and  107 B. 
     The configuration as shown in  FIG.  8    can define an optical axis  106  and a second optical axis  106 B. In the single channel system as set forth in  FIGS.  2 - 7   , optical axis  106  can be co-located with a central axis  1060  of lens  114 . In the example of  FIG.  8    each of optical axis  106  and optical axis  106 B can be offset and parallel to central axis  1060  of lens  114 . Each of light pipe  110  and light pipe  110 B can define a diverging cone of light  1100  and 1100B respectively having the divergence angle characteristics of diverging cone of light  1100  described with reference to the ray trace diagram (single channel system) described with reference to  FIG.  3   . Lens  114  can define respective converging cones of light  1400  and 1400B having the convergence angle characteristics of converging cone of light  1400  described with reference to the ray trace diagram (single channel system) described with reference to  FIG.  3   . 
     According to one example, light pipe  110  and light pipe  110 B for defining first and second illumination channels can be included in a set of interchangeable modules  133  as set forth herein that can be interchangeably installed into a defined holder of housing  134  of light energy exciter  10  indicated by dashed line  132  described in connection with  FIG.  2   . 
       FIG.  9    illustrates a cutaway physical form view of light energy exciter  10 . As shown in  FIG.  9   , light energy exciter  10  can be mounted on a heat sink  702  for drawing heat away from light energy exciter  10  to improve the performance of light energy exciter  10 .  FIG.  10    is a perspective physical form view of system  100  having light energy exciter  10  coupled to detector assembly  20 . As shown in  FIG.  10    detector assembly  20  can include cartridge  802  that houses flow cell  282 . Flow cell  282  can be defined by flow cell frame  902 , as shown in  FIG.  11   , illustrating a perspective assembly physical form view of flow cell frame  902  defining flow cell  282 . Flow cell frame  902  for example can include sidewalls  284  and flow cover  288  as depicted in the schematic view of  FIG.  1   . 
       FIG.  12    illustrates construction detail illustrating internal components of cartridge  802  of detector assembly  20 . Cartridge  802  as shown in  FIG.  12    can be configured to include physical registration features  806  which aid in the alignment of light energy exciter  10  to detector  200 . As shown in  FIG.  2   , detector  200  is shown as being located in a location that is established by flow cell frame  902  having detector  200  and flow cell  282  received into slot  814  of cartridge  802 . Physical registration features  806  can be provided to catch corresponding features of light energy exciter  10  that are defined by a distal end portion of housing  134  of light energy exciter  10 . For coupling light energy exciter  10  to detector assembly  20  and detector  200 , a distal end portion of housing  134  of light energy exciter  10  can be inserted into receptacle  826  of cartridge  802  of detector assembly  20  and arranged so that at a distal end of housing  134  of light energy exciter  10  is registered with corresponding registration features  806  as shown in  FIG.  12    so that light energy exciter  10  is properly aligned with flow cell  282  and detector  200  as shown in  FIG.  1   . 
       FIG.  13    illustrates a top view of a flow cell  282  disposed over detector  200 . According to one example as shown in  FIG.  13    flow cell  282  can include sidewalls  283  that shape flow cell  282  so that less than all light sensors  202  are active during a biological or chemical test. Detector  200  according to one example can include an array of 14M of light sensors which can be regarded as pixels and flow cell  282  can be configured by flow cell walls  283  so that about 8M of light sensors  202  are active during a biological or chemical test. 
     Alternative examples of light energy exciter  10  are described with reference to  FIGS.  14  and  15   . According to one example as shown in  FIG.  14   , lens  114  can be formed integral with light pipe  110 .  FIG.  14    illustrates light pipe  110  and lens  114  integrally formed by a single piece of material defining both light pipe  110  and lens  114 . Light energy exciter  10  can be configured so that lens  114  integrally formed with light pipe  110  projects homogenized light onto an image plane  130  which can be defined at detector surface  206  for supporting a sample ( FIG.  1   ). 
       FIG.  15    illustrates another example of light energy exciter  10  having an integrated lens  114  that is integrally formed with light pipe  110  and defined with a single piece of material that commonly defines both lens  114  and light pipe  110 . In the example of  FIG.  15    lens  114  is shown as being provided by a Fresnel lens. Fresnel lenses can produce converging light rays with reduced lens thicknesses and therefore can provide space saving advantages. Lens  114  in the example of  FIG.  13    can project homogenized light reflected within light pipe  110  onto image plane  130  which can be defined at sample supporting detector surface  206 . In any example herein, including the example of  FIGS.  14  and  15    a filter coating can be directly deposited at the light exit surface  115  of lens  114  to remove a discrete filter 22 of light energy exciter  10 . 
       FIGS.  16  and  17    illustrate further details of detector assembly  20  and detector  200  according to one example that can be used with light energy exciter  10 . 
     In the illustrated example shown in  FIG.  16   , flow cell  282  is defined by detector surface  206  sidewall  284  and a flow cover  288  that is supported by the sidewall  284  and other sidewalls (not shown). The sidewalls can be coupled to the detector surface  206  and can extend between the flow cover  288  and the detector surface  206 . In some examples, the sidewalls are formed from a curable adhesive layer that bonds the flow cover  288  to detector  200 . 
     The flow cell  282  can include a height H1. By way of example only, the height H1 can be between about 50 µm to about 400 µm or, more particularly, about 80 µm to about 200 µm. The flow cover  288  can include a material that is light transmissive to excitation light  101  propagating from an exterior of the detector assembly  20  into the flow cell  282 . 
     Also shown, the flow cover  288  can define inlet portal  289  and outlet portal  290  that are configured to fluidically engage other ports (not shown). For example, the other portals can be from a cartridge (not shown) or a workstation (not shown). 
     Detector  200  can include a sensor array  201  of light sensors  202 , a guide array  213  of light guides  214 , and a reaction array  209  of reaction recesses  210 . In certain examples, the components are arranged such that each light sensor  202  aligns with a single light guide  214  and a single reaction recess  210 . However, in other examples, a single light sensor  202  can receive photons through more than one light guide  214 . In some examples there can be provided more than one light guide and/or reaction recess for each light sensor of a light sensor array. 
     In some examples there can be provided more than one light guide and/or light sensors aligned to a reaction recess of a reaction recess array. The term “array” does not necessarily include each and every item of a certain type that the detector  200  can have. For example, the sensor array  201  of light sensors  202  may not include each and every light sensor of detector  200 . As another example, the guide array  213  may not include each and every light guide  214  of detector  200 . As another example, the reaction array  209  may not include each and every reaction recess  210  of detector  200 . As such, unless explicitly recited otherwise, the term “array” may or may not include all such items of detector  200 . 
     Detector  200  has a detector surface  206  that can be functionalized (e.g., chemically or physically modified in a suitable manner for conducting designated reactions). For example, the detector surface  206  can be functionalized and can include a plurality of reaction sites having one or more biomolecules immobilized thereto. The detector surface  206  can have a reaction array  209  of reaction recesses  210 . Each of the reaction recesses  210  can include one or more of the reaction sites. The reaction recesses  210  can be defined by, for example, an indent or change in depth along the detector surface  206 . In other examples, the detector surface  206  can be substantially planar. 
       FIG.  17    is an enlarged cross-section of detector  200  showing various features in greater detail. More specifically,  FIG.  17    shows a single light sensor  202 , a single light guide  214  for directing emissions signal light  501  toward the light sensor  202 , and associated circuitry  246  for transmitting signals based on emissions signal light  501  (e.g., photons) detected by the light sensor  202 . It is understood that the other light sensors  202  of the sensor array  201  ( FIG.  16   ) and associated components can be configured in an identical or similar manner. It is also understood, however, the detector  200  is not required to be manufactured identically or uniformly throughout. Instead, one or more light sensors  202  and/or associated components can be manufactured differently or have different relationships with respect to one another. 
     The circuitry  246  can include interconnected conductive elements (e.g., conductors, traces, vias, interconnects, etc.) that are capable of conducting electrical current, such as the transmission of data signals that are based on detected photons. Detector  200  comprises an integrated circuit having a planar array of the light sensors  202 . The circuitry  246  formed within detector  200  can be configured for at least one of read out signals from light sensors  202  exposed during an exposure period (integration period) in which charge accumulates on light sensors  202  in dependence on emission signal light  501  received by light sensors  202 , signal amplification, digitization, storage, and processing. The circuitry  246  can collect and analyze the detected emissions signal light  501  and generate data signals for communicating detection data to a bioassay system. The circuitry  246  can also perform additional analog and/or digital signal processing in detector  200 . Light sensors  202  can be electrically coupled to circuitry  246  through gates  241 - 243 . 
     Detector  200  according to one example can be provided by a solid-state integrated circuit detector such as a CMOS integrated circuit detector or a CCD integrated circuit detector. Detector  200  according to one example can be an integrated circuit chip manufactured using integrated circuit manufacturing processes such as complementary metal oxide semiconductor (CMOS) fabrication processes. 
     The resolution of the sensor array  201  defined by light sensors  202  can be greater than about 0.5 megapixels (Mpixels). In more specific examples, the resolution can be greater than about 5 Mpixels and, more particularly, greater than about 14 Mpixels. 
     Detector  200  can include a plurality of stacked layers  231 - 237  including a sensor layer  231  which sensor layer  231  can be a silicon layer. The stacked layers can include a plurality of dielectric layers  232 - 237 . In the illustrated example, each of the dielectric layers  232 - 237  includes metallic elements (e.g., W (tungsten), Cu (copper), or Al (aluminum)) and dielectric material, e.g. SiO 2 . Various metallic elements and dielectric material can be used, such as those suitable for integrated circuit manufacturing. However, in other examples, one or more of the dielectric layers  232 - 237  can include only dielectric material, such as one or more layers of SiO 2 . 
     With respect to the specific example of  FIG.  17   , the dielectric layers  232 - 237  can include metallization layers that are labeled as layers M 1 -M 5  in  FIG.  17   . As shown, the metallization layers, M 1 -M 5 , can be configured to form at least a portion of the circuitry  246 . 
     In some examples, detector  200  can include a shield structure  250  having one or more layers that extends throughout an area above metallization layer M 5 . In the illustrated example, the shield structure  250  can include a material that is configured to block the light signals that are propagating from the flow cell  282 . The light signals can be the excitation light  101  and/or emissions signal light  501 . By way of example only, the shield structure  250  can comprise tungsten (W). By way of specific example only, the excitation light may have a peak wavelength of about 523 nm (green light) or 456 nm (blue light) and emissions signal light  501  can include wavelengths of about 570 nm and longer ( FIG.  4   ). 
     As shown in  FIG.  17   , shield structure  250  can include an aperture  252  therethrough. The shield structure  250  can include an array of such apertures  252 . Aperture  252  can be dimensioned to allow signal emission light to propagate to light guide  214 . Detector  200  can also include a passivation layer  256  that extends along the shield structure  250  and across the apertures  252 . Detector  200  can also include a passivation layer  258  comprising detector surface  206  that extends along passivation layer  256  and across the apertures  252 . Shield structure  250  can extend over the apertures  252  thereby directly or indirectly covering the apertures  252 . Passivation layer  256  and passivation layer  258  can be configured to protect lower elevation layers and the shield structure  250  from the fluidic environment of the flow cell  282 . According to one example, passivation layer  256  is formed of SiN or similar. According to one example, passivation layer  258  is formed of tantalum pentoxide (Ta 2 O 5 ) or similar. Structure  260  having passivation layer  256  and passivation layer  258  can define detector surface  206  having reaction recesses  210 . Structure  260  defining detector surface  206  can have any number of layers such as one to N layer. 
     Structure  260  can define a solid surface (i.e., the detector surface  206 ) that permits biomolecules or other analytes-of-interest to be immobilized thereon. For example, each of the reaction sites of a reaction recess  210  can include a cluster of biomolecules that are immobilized to the detector surface  206  of the passivation layer  258 . Thus, the passivation layer  258  can be formed from a material that permits the reaction sites of reaction recesses  210  to be immobilized thereto. The passivation layer  258  can also comprise a material that is at least transparent to a desired fluorescent light. Passivation layer  258  can be physically or chemically modified to facilitate immobilizing the biomolecules and/or to facilitate detection of the emissions signal light  501 . 
     In the illustrated example, a portion of the passivation layer  256  extends along the shield structure  250  and a portion of the passivation layer  256  extends directly along filter material defining light guide  214 . The reaction recess  210  can be aligned with and formed directly over light guide  214 . According to one example each of reaction recess  210  and light guide  214  can have cross sectional geometric centers centered on longitudinal axis  268 . Filter material can be deposited in a cavity defined by sidewalls  254  formed in a dielectric stack having stacked layers  232 - 237 . 
     The light guide  214  can be configured relative to surrounding material of the dielectric stack defined by dielectric layers  231 - 237  to form a light-guiding structure. For example, the light guide  214  can have a refractive index of at least about 1.6 according to one example so that light energy propagating through light guide  214  is substantially reflected at an interface at sidewalls  254  between light guide  214  and the surrounding dielectric stack defined by dielectric layers  231 - 237 . In certain examples, the light guide  214  can be configured such that the optical density (OD) or absorbance of the excitation light is at least about 4 OD. More specifically, the filter material can be selected and the light guide  214  can be dimensioned to achieve at least 4 OD. In more particular examples, the light guide  214  can be configured to achieve at least about 5 OD or at least about 6 OD. In more particular examples, the light guide  214  can be configured to achieve at least about 7 OD or at least about 8 OD. Other features of the detector  200  can be configured to reduce electrical and optical crosstalk. 
     In reference to  FIG.  18   , further details of process control system  310  are described. Process control system  310  can include according to one example one or more processors  3101 , memory  3102 , and one or more input/output interface  3103 . One or more processors  3101 , memory  3102  and one or more input/output interface can be connected via system bus  3104 . According to one example process control system  3110  can be provided by a computer system as set forth in  FIG.  18   . Memory  3102  can include a combination of system memory and storage memory. Memory  3102  according to one example can store one or more programs for facilitating processes that are set forth herein. One or more processors  3101  can run one or more programs stored in memory  3102  to facilitate processes as is set forth herein. Memory  3102  can define a computer readable medium. 
     A DNA sequencing process facilitated by light energy exciter  10  is described with reference to  FIGS.  19  and  20   . Referring to  FIG.  19   , there is shown a spectral profile coordination diagram illustrating aspects of the operation of system  100 . According to one example light source bank  102  can include light sources that emit light at first and second different wavelengths. Providing light source bank  102  to include light sources that emit excitation light at first and second different wavelength ranges facilitates dye chemistry DNA sequence reconstruction processes in which first and second dyes can be disposed in fluid within flow cell  282 . 
     Spectral profile  1702  shown in  FIG.  19    illustrates an excitation wavelength emission band of a green emitting light source of light energy exciter  10 , e.g. such as light source  102 A as shown in  FIG.  4   . Spectral profile  1712  is the wavelength emission band of a blue emitting light source of light energy exciter  10  such as light source  102 H as shown in  FIG.  4   . Spectral profile  1704  is the absorption band spectral profile of a first fluorophore sensitive to green light that can be disposed with fluid into flow cell  282 . Spectral profile  1714  is the absorption band spectral profile of a second fluorophore sensitive to blue light that can be disposed with fluid into flow cell  282 . Spectral profile  1707  is the absorption band spectral profile of a third fluorophore sensitive to green light and blue light that can be disposed with fluid into flow cell  282 . 
     Spectral profile  1706  is the partial spectral profile of emissions signal light  501  attributable to the first fluorophore fluorescing when excited by green light having spectral profile  1702 . Spectral profile  1716  is the partial spectral profile of emissions signal light  501  attributable to the second fluorophore fluorescing when excited by blue light having spectral profile  1712 . Spectral profile  1708  is the partial spectral profile of emissions signal light  501  attributable to the third fluorophore fluorescing when excited by green light having spectral profile  1702 . Spectral profile  1709  is the partial spectral profile of emissions signal light  501  attributable to the third fluorophore fluorescing when excited by blue light having spectral profile  1712 . 
     Spectral profile  1730  is the transmission spectral profile of light sensors  202  defining light sensor array  201  indicating the detection band of light sensor array  201 . 
     Examples herein recognize in reference to the spectral profile coordination diagram of  FIG.  19    that process control system  310  can be configured to (a) determine that the first fluorophore is attached to a sample  502  based on fluorescence being sensed by a light sensor  202  under excitation restricted to excitation by one or more green emitting light sources and fluorescence not being sensed by the light sensor  202  under excitation restricted to excitation by one or more blue emitting light source; (b) determine that the second fluorophore is attached to a sample  502  based on fluorescence being sensed by a light sensor  202  under excitation restricted to excitation by one or more blue emitting light sources and fluorescence not being sensed by the light sensor  202  under excitation restricted to excitation by one or more green emitting light sources; and (c) determine that the third fluorophore is attached to a sample  502  based on fluorescence being sensed by a light sensor  202  under excitation restricted to excitation by one or more green emitting light sources and fluorescence also being sensed by the light sensor  202  under excitation restricted to excitation by one or more blue emitting light sources. Process control system  310  can discriminate which fluorophores have attached to samples, and can determine nucleotide types, e.g. A, C, T, and G that are present in a fragment of a DNA strand providing a sample  502  e.g. using a decision logic data structure indicated by the decision logic table of Table 2 mapping fluorophore presence to nucleotide type, where discriminated nucleotides Nucleotide-Nucleotide4 are nucleotides of the nucleotide types A, C, T and G (the particular mapping based on the test setup parameters).  
     
       
         
          TABLE 2
           
               
               
               
               
            
               
                 Detected fluorescence under excitation restricted to excitation by one or more green emitting light sources 
                 Detected fluorescence under excitation restricted to excitation by one or more blue emitting light sources 
                 Fluorophore presence indicated 
                 Nucleotide indicated 
               
               
                 YES 
                 NO 
                 first Fluorophore 
                 Nucleotide 1 
               
               
                 NO 
                 YES 
                 second Fluorophore 
                 Nucleotide2 
               
               
                 YES 
                 YES 
                 third Fluorophore 
                 Nucleotide3 
               
               
                 NO 
                 NO 
                 -- 
                 Nucleotide4 
               
            
           
         
       
     
     Process control system  310  can run a process in support of DNA sequence reconstruction in a plurality of cycles. In each cycle, a different portion of a DNA fragment can be subject to sequencing processing to determine a nucleotide type, e.g. A, C, T, or G, associated to the fragment, e.g. using a decision data structure such as a decision data structure as set forth in Table 2. Aspects of a process which can be run by process control system  310  for use in performing DNA sequence reconstruction using light energy exciter  10  is described in the flowchart of  FIG.  20   . 
     At block  1802  process control system  310  can clear flow cell  282 , meaning process control system  310  can remove fluid from flow cell  282  used during a prior cycle. At block  1804 , process control system  310  can input into flow cell  282  fluid having multiple fluorophores, e.g. first and second fluorophores, or first, second and third fluorophores. The first and second fluorophores can include, e.g. the absorption characteristics described with reference to absorption band spectral profile  1704  and absorption band spectral profile  1714  respectively as described in reference to the spectral profile diagram of  FIG.  19   . First second and third fluorophores can include, e.g. the absorption characteristics described with reference to absorption band spectral profile  1704  and absorption band spectral profile  1714  and absorption band spectral profile  1707  respectively as described in reference to the spectral profile diagram of  FIG.  19   . 
     At block  1806 , process control system  310  can read out signals from light sensors  202  exposed with a first wavelength range excitation active. At block  1806 , process control system  310  can control light energy exciter  10  so that during an exposure period of light sensors  202  light energy exciter  10  emits excitation light restricted excitation by one or more green light sources. At block  1806 , process control system  310  can during an exposure period of light sensors  202  energize each one or more green emitting light sources of light source bank  102 , e.g. light sources  102 A- 102 G as set forth in  FIG.  4   , while maintaining in a deenergized state each one or more blue emitting light sources of light bank, e.g. light sources  102 H- 102 J as set forth in  FIG.  4   . With the light source bank  102  being controlled as described so that green light sources are on and blue light sources are off during an exposure period of light sensors  202 , process control system  310  at block  1806  can read out first signals from light sensors  202  exposed with excitation restricted to excitation by one or more green light sources as set forth herein. 
     At block  1808 , process control system  310  can read out signals from light sensors  202  exposed with a second wavelength range excitation active. At block  1808 , process control system  310  can control light energy exciter  10  so that during an exposure period of light sensors  202  light energy exciter  10  emits excitation light restricted to excitation by one or more blue light sources of light energy exciter  10 . At block  1808 , process control system  310  can during an exposure period of light sensors  202  energize each of one or more blue emitting light sources of light source bank  102 , e.g. light sources  102 H- 102 J as set forth in  FIG.  4   , while maintaining in a deenergized state each one or more green emitting light sources of light bank, e.g. light sources  102 A- 102 G as set forth in  FIG.  4   . With the light source bank  102  being controlled as described so that blue light sources are on and green light sources are off during an exposure period of light sensors  202 , process control system  310  at block  1808  can read out second signals from light sensors  202  exposed with excitation restricted to excitation by one or more blue light sources as set forth herein. 
     At block  1810  process control system  310  for the current cycle can process the first signals read out at block  1806  and the second signals read out at block  1808  to determine a nucleotide type of the DNA fragment being subject to testing during the current cycle, e.g. using a decision data structure as set forth in Table 2 according to one example. Process control system  310  can perform the described nucleotide identification process described with reference to the flowchart of  FIG.  20    for each cycle of the DNA sequencing process until nucleotide identification is performed for each scheduled cycle. 
     Process control system  310  can be configured to perform a wide range of tests for testing operation of the system  100 . Process control system  310  can perform a calibration test in which operation of light energy exciter  10  and detector  200  is tested. In such an example process control system  310  can be configured to selectively energize different lights sources during exposure periods of sensor array  201  and can examine signals read out of sensor array  201  during the exposure periods. A method can include selectively energizing a first light source (e.g. green emitting) during a first exposure period of the light sensors with second (blue emitting) and third (e.g. red emitting) light sources maintained in a deenergized state, selectively energizing the second light source during a second exposure period of the light sensors with the first and third light sources maintained in a deenergized state, and selectively energizing the third light source during a third exposure period of the light sensors with the first and second light sources maintained in a deenergized state. 
     It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the subject matter disclosed herein. In particular, all combinations of claims subject matter appearing at the end of this disclosure are contemplated as being part of the subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein. 
     This written description uses examples to disclose the subject matter, and also to enable any person skilled in the art to practice the subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described examples (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various examples without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various examples, they are by no means limiting and are merely exemplary. Many other examples will be apparent to those of skill in the art upon reviewing the above description. The scope of the various examples should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Forms of term “based on” herein encompass relationships where an element is partially based on as well as relationships where an element is entirely based on. Forms of the term “defined” encompass relationships where an element is partially defined as well as relationships where an element is entirely defined. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular example. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. 
     While the subject matter has been described in detail in connection with only a limited number of examples, it should be readily understood that the subject matter is not limited to such disclosed examples. Rather, the subject matter can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the subject matter. Additionally, while various examples of the subject matter have been described, it is to be understood that aspects of the disclosure may include only some of the described examples. Also, while some examples are described as having a certain number of elements it will be understood that the subject matter can be practiced with less than or greater than the certain number of elements. Accordingly, the subject matter is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.