Patent Publication Number: US-10309613-B2

Title: Method and apparatus for horticultural lighting and associated optic systems

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to horticultural lighting, and more particularly to horticultural lighting that better simulates the sun. 
     BACKGROUND 
     Light emitting diodes (LEDs) have been utilized since about the 1960s. However, for the first few decades of use, the relatively low light output and narrow range of colored illumination limited the LED utilization role to specialized applications (e.g., indicator lamps). As light output improved, LED utilization within other lighting systems, such as within LED “EXIT” signs and LED traffic signals, began to increase. Over the last several years, the white light output capacity of LEDs has more than tripled, thereby allowing the LED to become the lighting solution of choice for a wide range of lighting solutions. 
     LEDs exhibit significantly optimized characteristics, such as source efficacy, optical control and extremely long operating life, which make them excellent choices for general lighting applications. LED efficiencies, for example, may provide light output magnitudes up to 200 lumens per watt of power. Energy savings may, therefore, be realized when utilizing LED-based lighting systems as compared to the energy usage of, for example, incandescent, halogen, compact fluorescent and high-intensity discharge (HID) lighting systems. As per an example, an LED-based lighting fixture may utilize a small percentage (e.g., 15-20%) of the power utilized by a halogen-based lighting system, but may still produce an equivalent magnitude of light. 
     While HID lighting systems have been the predominant choice for conventional horticultural lighting applications, LED technologies are gaining attraction due to their high luminous efficacy and their ability to produce narrow-band spectral distributions. Current LED-based horticultural lighting systems, however, fail to produce adequate light uniformity for indoor horticulture facility applications where natural light is not present nor do they produce adaptable spectral tuning. In addition, conventional LED-based horticultural lighting systems produce light rays exhibiting decreased intensity with increasing emission angle relative to the optical axis. Accordingly, none of the control systems used to effect adequate light distribution characteristics, spectral tuning and power efficiency are in existence either. 
     Efforts continue, therefore, to develop an LED lighting system and associated controls that exceed the performance parameters of conventional horticultural lighting systems. 
     SUMMARY 
     To overcome limitations in the prior art, and to overcome other limitations that will become apparent upon reading and understanding the present specification, various embodiments of the present invention disclose methods and apparatus for the control and production of LED-based lighting for indoor horticultural systems that may exhibit specific light distribution having increased intensity as the beam angle increases with respect to the optical axis. 
     In accordance with one embodiment of the invention, a light fixture comprises means for producing a first light distribution having a first beam width, means for modifying the first light distribution into a second light distribution having a second beam width. The means for modifying produces the second light distribution with a maximum intensity at a beam angle substantially equal to the second beam width. 
     In accordance with an alternate embodiment of the invention, a method of producing light comprises producing a first light distribution having a first beam width, modifying the first light distribution into a second light distribution having a second beam width. An intensity of the second light distribution is substantially maximized at the second beam width and an intensity of the second light distribution is substantially minimized at center beam. 
     In accordance with an alternate embodiment of the invention, a light fixture comprises at least one light source configured to produce a first light distribution having a first optical axis and a first beam width, at least one refractor disposed in proximity to the at least one light source and configured to modify the first light distribution into a second light distribution having a second optical axis parallel to the first optical axis and a second beam width. The refractor is configured to produce the second light distribution with a light intensity that increases from a minimum intensity at a beam angle that is substantially parallel to the second optical axis to a maximum intensity at a beam angle that is substantially equal to the second beam width. 
     In accordance with an alternate embodiment of the invention, a lens array comprises a mechanical framework configured to mount to a printed circuit board, a plurality of lenses disposed within the mechanical framework. Each of the plurality of lenses includes an indented portion to accommodate the insertion of at least a portion of at least one LED that is mounted to the printed circuit board. The mechanical framework establishes an optimal separation distance between each lens of the plurality of lenses and each associated LED. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects and advantages of the invention will become apparent upon review of the following detailed description and upon reference to the drawings in which: 
         FIG. 1  illustrates an LED-based horticultural light in accordance with one embodiment of the present invention; 
         FIGS. 2A and 2B  illustrate a lens array in accordance with one embodiment of the present invention; 
         FIG. 3  illustrates a cross-section of an LED/lens pair in accordance with one embodiment of the present invention; 
         FIGS. 4A and 4B  illustrate an intensity distribution and shaded illuminance plot in accordance with one embodiment of the present invention; 
         FIGS. 5A and 5B  illustrate a conventional intensity distribution and shaded illuminance plot resulting from a bare LED without a lens or an LED with a standard Lambertian optic; 
         FIG. 6  illustrates a cross-section of an LED/lens pair in accordance with an alternate embodiment of the present invention; 
         FIGS. 7A and 7B  illustrate an intensity distribution and shaded illuminance plot in accordance with an alternate embodiment of the present invention; 
         FIG. 8  illustrates a horticulture system in accordance with one embodiment of the present invention; 
         FIG. 9  illustrates an LED-based horticultural light in accordance with an alternate embodiment of the present invention; 
         FIG. 10  illustrates a block diagram of a power supply that may be used with the LED-based horticultural light of  FIG. 9 ; 
         FIG. 11  illustrates a lighting system in accordance with one embodiment of the present invention; 
         FIG. 12  illustrates flow diagrams in accordance with several embodiments of the present invention; 
         FIG. 13  illustrates a lighting system in accordance with an alternate embodiment of the present invention; 
         FIG. 14  illustrates flow diagrams in accordance with several alternate embodiments of the present invention; 
         FIGS. 15A, 15B and 15C  illustrate timing diagrams in accordance with several embodiments of the present invention; 
         FIG. 16  illustrates an indoor horticultural system in accordance with one embodiment of the present invention; 
         FIG. 17  illustrates a schematic diagram that extracts power from a portion of an LED string to implement an auxiliary function in accordance with one embodiment of the present invention; 
         FIG. 18  illustrates an LED-based horticultural light in accordance with an alternate embodiment of the present invention; 
         FIG. 19A  illustrates internal portions of the LED-based horticultural light of  FIG. 18 ; 
         FIGS. 19B-19C  illustrate top and bottom orthographic views of the optical pucks of the LED-based horticultural light of  FIG. 18 ; 
         FIG. 20  illustrates light distributions from horticultural lighting fixtures that do not include optical lenses in accordance with an alternate embodiment of the present invention; 
         FIG. 21  illustrates cooling features of the LED-based horticultural lighting fixtures in accordance with various embodiments of the present invention; and 
         FIG. 22  illustrates cooling features of the LED-based horticultural lighting fixtures in accordance with various embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Generally, the various embodiments of the present invention are applied to a light emitting diode (LED) based lighting system that may contain an array of LEDs and an array of associated lenses. The LED array may be mechanically and electrically mounted to a PCB having control and bias circuitry that allows specific sets (e.g., channels or strings) of LEDs to be illuminated on command. Any set of one or more LEDs may be grouped into one or more channels, such that specific rows, columns or other arrangements of LEDs in the LED array may be illuminated independently depending upon the specific channel within which the LED or LEDs are grouped. A channel of LEDs may include non-linear arrangements, such as square, circular, rectangular, zig-zag or star-shaped arrangements to name only a few. An associated lens array may be mounted in proximity to the LED array in such a way that the lens array may perform more than one function. For example, the lens array may mechanically impose a uniform pressure onto the PCB against the associated heat sink to optimize heat transfer from the PCB to the heat sink. Further, the lens array may contain individual lenses with mechanical standoffs so as to maintain an optimal separation distance between the LED and associated lens so that light rays generated by each individual LED may be optically varied before projection onto a target. 
     The mechanical standoffs may, for example, exhibit a shape (e.g., circular) having a dimension (e.g., circumference) that is slightly larger than a dimension (e.g., a circumference) of the LED&#39;s footprint as mounted on its associated PCB. Accordingly, as the lens array is pressed against the PCB, each mechanical standoff of each lens of the lens array may impose a substantially uniform pressure along a circular perimeter surrounding the LED to further enhance heat transfer from the LED to the heat sink. 
     Each lens of the lens array may, for example, be placed in such proximity to its corresponding LED so as to collect substantially all of the light generated by its associated LED and virtually none of the light generated by neighboring LEDs. Each lens may optically vary (e.g., refract) the light distributed by its associated LED into an optically varied light distribution, such that the light distributed by the lens may exhibit a modified intensity distribution as compared to the intensity distribution of light generated by a bare LED. In alternate embodiments, multiple LEDs may be associated with a single lens such that the intensity of light generated by each of the multiple LEDs may be modified by the single lens. 
     The Full Width Half Maximum (FWHM) beam angle may be defined as the beam angle where the light distribution exhibits an intensity equal to half the peak intensity. A conventional LED may exhibit an FWHM beam angle of about 120 degrees, where the peak intensity of light distribution may exist at a zero-degree offset from the optical axis of the LED (e.g., centerbeam). Each lens of the lens array may, however, modify the intensity distribution, such that the FWHM beam angle may either be less than, or substantially the same as, the FWHM beam angle produced by a bare LED, but the intensity distribution may be modified by the lens such that the peak intensity may not exist at centerbeam, but rather may be offset from centerbeam. 
     In one example, the intensity distribution of a bare LED may exhibit a relatively wide FWHM beam angle (e.g., a 120-degree FWHM beam angle) having a peak intensity at centerbeam. A lens of the lens array may, for example, be used to substantially refract the FWHM beam angle of the bare LED between about 100 degrees and 140 degrees (e.g., between approximately 115 degrees and 128 degrees), but may alter the intensity distribution such that the peak intensity may not exist at centerbeam, but instead may exist at an offset between about 40 and 60 degrees (e.g., between approximately 50 and 55 degrees) half angle from centerbeam. 
     As per another example, a lens of the lens array may be used to substantially reduce the FWHM beam angle of the bare LED from about 120 degrees to between about 50 degrees and 90 degrees (e.g., between approximately 65 degrees and 75 degrees) and may further alter the intensity distribution such that the peak intensity may not exist at centerbeam, but instead may exist at an offset between about 15 and 35 degrees (e.g., between approximately 20 and 28 degrees) half angle from centerbeam. 
     Generally, each lens of the lens array may distribute light into a ray set that exhibits varying intensity depending upon the angle that each light ray of the projected ray set exhibits relative to a reference axis. For example, a reference axis of the LED may be defined as the axis that is orthogonal to the surface of the PCB to which the LED is mounted and each light ray emitted by the LED may be refracted by the lens to exhibit an intensity that is proportional to the angle that the refracted light ray forms with respect to the reference axis. In one embodiment, refracted light rays at lower angles relative to the reference axis may exhibit lower intensities while refracted light rays at higher angles relative to the reference axis may exhibit relatively larger intensities. 
     Refracted light rays incident upon a target surface may similarly be defined with respect to the reference axis. For example, light rays refracted by the lens that exhibit a zero-degree offset from the reference axis may be described as exhibiting a zero-degree incidence angle. Similarly, light rays refracted by the lens that exhibit non-zero-degree offsets from the reference axis may be described as exhibiting incidence angles greater than zero as measured relative to the reference axis. 
     A lens may be configured to refract light rays emitted by the LED to exhibit intensities that are proportional to their respective incidence angles. For example, refracted light rays with lower incidence angles may exhibit lower intensities as compared to refracted light rays with higher incidence angles. The lens may be further configured to substantially prohibit refraction of light rays exhibiting incidence angles greater than a reference angle. 
     The lens, therefore, may produce lower intensity light rays having lower incidence angles as compared to the intensity of light rays having relatively higher incidence angles. Such a lens may be particularly useful when the beam is to be projected onto a flat surface target with a substantially uniform illuminance across the entire illuminated surface regardless of the angle of incidence, or when the beam is to be projected onto a flat surface target with an increasing illuminance across the entire illuminated surface as the angle of incidence increases. Such a lens may be further useful when the beam is to be projected not only onto a flat surface below the light, but also onto objects that are adjacent to the flat surface at higher incidence angles with respect to the light. 
     Stated differently, since target illuminance is proportional to the intensity of the projected light ray and inversely proportional to the square of the distance between the target and the lens that is producing the projected light ray, a lens that produces light rays having intensities that are proportional to the angle of incidence up to a threshold angle may be used to produce substantially even or uniform illuminance on a flat plane across the full beam width. That is to say in other words, that as the angle of incidence of light rays projected by the lens increase, so does their intensity. Furthermore, by increasing the intensity of the light rays in proportion to the square of the distance between the lens and the target, a substantially even target illuminance may be projected across the entire illuminated flat surface regardless of the angle of incidence of light rays onto the target, or an illuminance may be projected onto a flat surface that increases with the angle of incidence. Adjacent targets may also be illuminated by light rays that do not illuminate the flat surface due to their higher angles of incidence, but due to the higher intensity of such light rays, may illuminate such adjacent targets with substantially equal illuminance, or with substantially increasing illuminance, as compared to those light rays that are incident on the flat surface. 
     It should be noted that the advantages obtained by using the horticultural lights in accordance with the present invention do not exist with conventional horticultural lights, which may include LED-based horticultural lights as well. For example, conventional horticultural lights typically use a very small, yet high power light source with a secondary reflector in order to obtain a particular distribution of light onto a typical grow bed. Such a light source, however, produces non-reflected light rays directly from the light source having increased intensity at centerbeam, which in turn requires increased vertical distance between the horticultural light and the canopy of plants below the horticultural light. 
     Alternately, smaller LED-based horticultural lights may be used, but are used in very large numbers so as to obtain a projection area substantially equal to that of the larger conventional horticultural lights. While reduced vertical distance between the smaller LED-based horticultural lights and the plant canopy may be achieved, cross-lighting becomes virtually non-existent and the amount of light projecting throughout the depth of the plant canopy is significantly reduced. 
     Accordingly, even when a particular coverage area is achieved, the illuminance projected onto the grow bed lacks uniformity and, therefore, includes “hot spots” and “dim spots” and generally provides uneven projected illuminance due to the inverse square law as discussed in more detail below. As discussed above, for example, conventional horticultural lights generally project maximum intensity at zero to low angles of incidence, which requires relatively large vertical distances to be established between the conventional horticultural light and the underlying plant. As a result, vertical distances between the conventional horticultural light and the corresponding plant must be maximized to, for example, prevent plant burn. 
     Horticultural lights in accordance with the present invention, on the other hand, utilize a dense array of lenses that optically vary the intensity of the light distributed by an associated array of LEDs to project a uniform illuminance across a large surface area of a flat plane, or to project an increasing illuminance as the angle of incidence increases from centerbeam, despite the effects of the inverse square law (e.g., regardless of the increased distances that the light travels to the target due to the increased angles of incidence). Accordingly, not only may the light projection area from each horticultural light fixture in accordance with the present invention be increased as compared to conventional horticultural lights, but the illuminance within the illuminated area may be made substantially uniform, or substantially increasing as incidence angles increase from centerbeam outward, as well. In addition, the illuminance projected onto secondary targets that are adjacent to the primary target may also be made to be substantially uniform, or substantially increasing as incidence angles increase from centerbeam outward, due to the increased intensity of light rays projected by the horticultural light fixture at angles that are incident upon the secondary targets. 
     In other embodiments, horticultural lights in accordance with the present invention may utilize other techniques, with or without optics, to vary light intensity. Variability of the light output (e.g., spectral variability) may be controlled, for example, using any number of wired protocols including 0-10V, I2C, digital multiplex (DMX), ethernet or digital addressable lighting interface (DALI) to name only a few. In addition, spectral variability may be achieved via wireless protocols, such as via ZigBee, Wi-Fi, Bluetooth or a thread-based mesh network, along with other wireless protocols. Furthermore, by combining broad-spectrum white LEDs with a combination of other LEDs may allow the horticultural light to produce photosynthetically active radiation (PAR). 
     For example, two or more sets of broad-spectrum LEDs may be utilized along with one or more sets of fixed-color LEDs (e.g., one set of blue LEDs and one set of red LEDs) in order to implement broad-spectrum illumination that may better simulate sun light. In addition, the two or more sets of broad-spectrum LEDs may exhibit different correlated color temperatures (CCT), such that once varying intensities of the light generated by both sets of broad-spectrum LEDs is mixed, a tunable CCT composite spectrum may result that may better simulate the various phases of the sun, may better simulate sunlight at the various latitudes that the sun may assume and may better simulate sun light across each of the four seasons. 
     In addition, the intensities of multiple horticultural lighting fixtures may be controlled within an indoor grow facility to better simulate the position of the sun throughout the daylight hours. For example, by increasing the intensity of easterly-positioned horticultural lighting fixtures in the morning hours may better simulate the rising sun, by increasing the intensity of centrally-positioned horticultural lighting fixtures during the mid-day hours may better simulate the mid-morning/mid-afternoon sun and by increasing the intensity of westerly-positioned horticultural lighting fixtures in the late afternoon/evening hours may better simulate the setting sun. 
     In one embodiment, each set of the multiple sets of LEDs may be arranged as independent channels of LEDs, where each channel of LEDs may be independently operated at a selected intensity based upon a magnitude of current that may be conducted by each channel of LEDs. The control circuitry that may be used to select the magnitude of current that may be conducted by each channel of LEDs may be integrated within the power supply that may also contain the bulk power conversion (e.g., alternating current (AC) to direct current (DC) and/or DC to DC power conversion electronics) and regulation (e.g., constant current regulation or constant voltage regulation) electronics. 
     Turning to  FIG. 1 , horticultural light  100  is exemplified, which may include one or more lens arrays (e.g., lens array  118  and  126 ). Each lens array may include one or more rows of lenses (e.g., four rows of lenses) and one or more columns of lenses (e.g., 12 columns of lenses). One or more LEDs (not shown) may be included behind each lens (e.g., lens  102 ) so that in one example, the number of LEDs included within horticultural light  100  may be equal to the number of lenses included in each lens array (e.g., 48 LEDs per lens array for a total of 96 LEDs per horticultural light  100 ). As per another example, multiple LEDs (e.g., one red, one green, one blue and one white LED from each RGBW channel of LEDs) may be included behind each lens and may further be rotated with respect to one another so as to smooth the light distribution projected by each multiple LED/single lens combination. In one embodiment, for example, each of 4 LEDs combined under a single lens may be attached to the underlying PCB at 0 degree, 45 degree, 90 degree and 135 degree offsets, respectively, whereby the magnitude of angle offset may be inversely proportional to the number of LEDs combined under a single lens (e.g., 180 degrees/4 equals a rotation offset of 45 degrees from one LED to the next). 
     Bezel  134  may, for example, provide a substantially constant pressure around a perimeter of horticultural light  100  to, for example, seal a substantially transparent media to horticultural light  100  thereby maintaining horticultural light  100  in a water proof/water resistant state. The transparent media may also press the lens array against the PCB behind the lens array, such that substantially 100% of the light generated by each LED may be directed through its respective lens and through the transparent media to prohibit virtually any of the light from being redirected back into horticultural light  100 . While the dimensions (e.g., 4.5 inches wide×22 inches long) of horticultural light  100  may be significantly smaller than conventional LED horticultural lights (e.g., 4 feet wide×4 feet long), horticultural light  100  via its dense array of LEDs and associated lenses may nevertheless project a substantially equivalent amount of light onto a conventional grow bed, but may do so with substantially uniform illuminance, or substantially increasing illuminance from centerbeam outward, across the entire grow bed and adjacent grow beds unlike the substantially non-uniform illuminance, or substantially decreasing illuminance from centerbeam outward, as projected by conventional horticultural lights. 
     Horticultural light  100  may further include control circuitry (e.g., controllers  110 ,  112 ,  114  and  116 ) and associated circuitry (e.g., bias circuitry  124 ) such that any one or more LEDs (not shown) may be independently transitioned into conductive and non-conductive states on command. Alternately, LED control and bias circuitry (e.g., controllers  110 ,  112 ,  114 ,  116  and associated bias control circuitry  124 ) may not be co-located on the same PCB to which the associated LEDs are mounted, but may instead be located remotely to the PCB (e.g., on a modular control and bias circuit that may be interchangeably introduced into horticultural light  100  or into a bias and control bus that connects two or more horticultural lights  100  together). 
     In one embodiment, the conductive state of any multiple of LEDs (e.g., the LEDs, not shown, behind each row of lenses  126 ,  128 ,  130  and  132 ) may be independently controlled. In other embodiments, the conductive state of any multiple of LEDs (e.g., the LEDs, not shown, behind each column of each array of lenses  118  and  126 ) may be independently controlled. Once an LED (not shown) is transitioned to its conductive state, the associated lens (e.g., lens  102 ) may produce a light distribution that may exhibit a particular intensity profile, which may produce a substantially uniform target illuminance, or a substantially increasing target illuminance from centerbeam to the edge of the beam pattern, across a flat surface as discussed in more detail below. 
     Multiple horticultural lights  100  may be employed for use as horticultural lighting in a greenhouse, small indoor grow room, or in a commercial production facility as part of an integrated horticultural system. Horticultural light  100  may, for example, replicate natural light that may be absent in an indoor grow facility and may be controlled (e.g., via bias controller  124  and controllers  110 ,  112 ,  114  and  116 ) to deliver virtually any wavelength of light that may be produced by an LED, at virtually any intensity, at virtually any duty cycle that may be useful in a horticultural facility. Furthermore, virtually any mixture of LEDs may be utilized within horticultural light  100  to produce a wide range of color temperature, spectrum and color rendering index (CRI). 
     As an example, each channel of LEDs (e.g., rows of LEDs, not shown, behind rows of lenses  126 ,  128 ,  130  and  132 , respectively) may each include a selection of LEDs that may produce a range of color temperature and CRI attributes. For example, the rows of LEDs (not shown) behind lens rows  126  and  128  may include LEDs exhibiting a color temperature of approximately 3000° K and a CRI greater than 90. As another example, the row of LEDs (not shown) behind lens row  130  may include LEDs exhibiting a color temperature of approximately between 5700° K and 6500° K and may exhibit a CRI less than 80. As per another example, the row of LEDs (not shown) behind lens row  132  may include LEDs exhibiting a narrow-bandwidth red color spectrum (e.g., at or below 1800° K or between 580 nm and 750 nm). It should be noted that virtually any combination of wavelength, color temperature, spectrum and CRI may be used to match the particular photosynthetic and photomorphogenic requirements of the crop of interest. 
     It should be further noted that the LEDs (not shown) may include a percentage (e.g., 75%) of phosphor converted white LEDs and a percentage (e.g., 25%) of narrow band red or blue spectrum LEDs, such as aluminum gallium indium phosphide (AlGaInP) LEDs. Alternately, for example, phosphor converted red LEDs may also be used, which may facilitate the use of indium gallium nitride (InGaN) LEDs exclusively, both for the phosphor converted white LEDs and the phosphor converted red LEDs. Such an arrangement of matched InGaN LEDs may, for example, provide a very broad spectrum white light with an emphasis on the blue and red spectra while also providing uniform thermal performance and degradation as well as the advantage of facilitating the implementation of strings of multiple LEDs (e.g., the string of LEDs, not shown, behind lens rows  126 ,  128 ,  130  and  132 ) that may be arranged serially with a substantially constant forward voltage. 
     As discussed in more detail below, bias controller  124  may include wired and/or wireless access control systems, such as Bluetooth, Wi-Fi, thread-based mesh, digital multiplex (DMX), I2C, ethernet or telecommunications-based control systems that may allow horticultural light  100  to be controlled remotely, either within the same facility, or via a regional or national control room. Accordingly, the lighting of one or more unmanned horticultural facilities may be centrally controlled by a single control station. Such a control station, for example, may also control other aspects of the horticultural facility. Air filtration and circulation systems, for example, may require remote access control for heat and exhaust mitigation. Various irrigation systems, such as drip irrigation, hydroponic flood benches and trough benches along with a nutrient management system may also be controlled by the control station. In general, the control station may not only control the one or more horticultural lights  100  of the horticultural facility, but also the nutrients, air circulation, irrigation, dehumidification, carbon dioxide (CO 2 ) injection and other facilities that may be required to maintain the exact environment needed by the various growing rooms, cloning rooms and flowering rooms of the horticultural facility. 
     Turning to  FIGS. 2A and 2B , a front view and a rear view, respectively, of a lens array (e.g., lens array  118  of  FIG. 1 ) are exemplified. Mechanical portions  202  and  204 , for example, of the lens array may not include any optical attributes, but may instead provide a framework within which optical portions (e.g., lenses  206 ) may be configured into an array (e.g., multiple rows and columns of lenses  206 ). Mechanical portions  202  and  204  may, for example, include mounting features (e.g., apertures  208 ) that may facilitate the insertion of mounting hardware (e.g., screws) that may be used to mount the lens array to the underlying PCB and lighting fixture housing/heat sink (not shown). By utilizing such mounting hardware, mechanical portion  204  may be pressed against the underlying PCB and LEDs (not shown), which may in turn press the underlying PCB against the housing/heat sink (not shown) of the horticultural light (e.g., horticultural light  100 ) so as to promote effective conduction of heat away from the LEDs. 
     Mechanical portion  204  may further include raised portions  210  that may be used to create an optimal separation distance between the lens array and the underlying LED array (not shown). Indented portions  212  may, for example, accommodate the insertion of at least a portion of an LED package (e.g., the dome portion of an LED package). The height of raised portions  210  may be selected to create an optimal separation distance between the optical input portion of the lens (e.g., lens  206 ) and the associated LED (not shown) that is inserted into the corresponding indented portion  212  of lens  206  as discussed in more detail below. Raised portions  210  may exhibit a particular geometric shape (e.g., circular) so as to match a particular foot print of each LED (not shown) of the LED array. As such, raised portions  210  may impose a substantially uniform pressure surrounding, and in close proximity to, each associated LED (not shown) so as to create a uniform conduction path so that heat may be conducted away from the LED through the associated PCB and heat sink, thereby improving the performance of the LED. 
     In one embodiment, the array of lenses  206  may be arranged as an array of rows and columns of lenses, where each lens may exhibit a circular shape having a diameter (e.g., 13 mm diameter) and a separation distance from each neighboring lens (e.g., a separation distance of 16 mm center to center). The composition of the array of lenses  206  may be that of an optical grade polymer (e.g., acrylic) that may exhibit an index of refraction of between about 1.48 and 1.5 (e.g., approximately 1.491) or that of an optical grade polycarbonate that may exhibit an index of refraction of between about 1.5 and 1.7 (e.g., approximately 1.58). 
     Turning to  FIG. 3 , a cross-sectional view is exemplified in which LED package  306 , having hemispherical dome portion  312 , may protrude into indented portion  304  of lens  314 . It should be noted that indented portion  304  may exemplify a cross-section of a lens array (e.g., a cross-section of indented portion  212  of the lens array of  FIG. 2 ) where indented portion  304  may include optical input  308  to lens  314  that may accept the light distribution from LED package  306  into lens  314 . Protrusion  302  may exemplify a cross-section of a lens array (e.g., a cross-section of mechanical portion  210  of the lens array of  FIG. 2 ) where protrusion  302  includes surface area  316  that may be in communication with a PCB (not shown) to select an optimal separation distance (e.g., separation distance  318 ) between the LED deck (e.g., PCB  326  of LED package  306 ) and optical input  308  to lens  314 . In one embodiment, separation distance  318  may be between about 0.3 mm and about 0.4 mm (e.g., approximately 0.35 mm). 
     Portion  310  may exemplify a cross-section of a lens array (e.g., a cross-section of lens  206  of  FIG. 2 ) where portion  310  may be the optical output of lens  314  that produces the optically varied (e.g., refracted) light distribution. Light distribution from lens  314  may exhibit an optical axis (e.g., axis  320 ) that may be orthogonal to the mounting surface of the PCB (not shown) to which LED package  306  is mounted. In addition, the projected light distribution from lens  314  may be described in terms of the intensity of each ray and its geometric orientation with respect to axis  320  as well as the projected illuminance onto a flat plane and projected illuminance onto targets adjacent to the flat plane. 
     It should be noted that the lens array is configured such that a projected light distribution from an individual lens (e.g., lens  314 ) of the lens array may not be incident upon adjacent lenses (e.g., lenses  326  and  328 ) of the lens array. In one embodiment, for example, lens  314  may refract the light distribution of LED  306  into a half-beam angle between about 50 degrees and 90 degrees (e.g., between approximately 65 degrees and 75 degrees) having full-beam width  322  that is not incident on any adjacent lenses (e.g., lenses  326  and  328 ). 
     Turning to  FIG. 4A , a light distribution is exemplified that may be produced by an LED/lens combination in accordance with one embodiment that may include an LED (e.g., LED package  306  of  FIG. 3 ) and a lens (e.g., lens  314  of  FIG. 3 ) to produce a light distribution as exemplified in  FIG. 4A . As illustrated, for example, the light distribution from lens  314  may exhibit a center beam intensity (e.g., about 77 candela) at a zero-degree offset from the optical axis (e.g., axis  320  of  FIG. 3 ). The light distribution from lens  314  may exhibit a peak intensity (e.g., 84 candela) offset from the center beam by an angle of about 22.5 degrees to about 27.5 degrees. 
     It can be seen, therefore, that if the light distribution of  FIG. 4A  is projected onto a target having a flat surface by a lens (e.g., lens  314  of  FIG. 3 ), the distance between the lens and the target changes depending upon the angle of incidence of the light distribution onto the target. As an example, if the angle subtended by a light ray is offset from the optical axis (e.g., axis  320  of  FIG. 3 ) by zero degrees, then the distance traveled by the light ray to the target is at its minimal value. As the angle subtended by a light ray referenced to the optical axis increases, so does the distance that the light ray must travel before being incident onto the target&#39;s surface. 
     According to the inverse square law, therefore, the target illuminance decreases in proportion to the inverse square of the distance between the lens and the target, thereby causing the target illuminance to decrease with increasing beam width. However, since the intensity of the light distribution of  FIG. 4A  increases with increasing beam angle up to a reference beam angle (e.g., between about 22.5 degrees to about 27.5 degrees), the target illuminance may nevertheless remain substantially uniform, or may substantially increase with increasing beam angle, despite the effects of the inverse square law as exemplified, for example, in the associated shaded illuminance plot of  FIG. 4B . In addition, for example, since the intensity of light distribution is maximum at maximum beam angle, the effective distance of the illuminance onto targets adjacent to the main target may be extended, such as may be the case when projecting light through side portions of the canopies of adjacent plants. 
     As a comparison,  FIG. 5A  exemplifies an intensity distribution from a bare LED (e.g., an LED without an optically varied distribution found on conventional horticultural lights) and  FIG. 5B  exemplifies the associated shaded illuminance plot. As can be seen from  FIG. 5A , the intensity peaks at centerbeam (e.g., zero-degree offset from the LED&#39;s optical axis) and then decreases with increasing beam angle, which causes the illuminance, as exemplified by the shaded illuminance plot of  FIG. 5B , to be non-uniform and decreasing in proportion to the inverse of the square of the increasing distance between the LED and its illumination target. It can be seen, therefore, that without the optical distribution of a lens in accordance with the various embodiments of the present invention, uniform illuminance onto a flat target is not possible. Rather, decreasing illuminance with increasing angles of incidence is produced. 
     Turning to  FIG. 6 , a cross-sectional view of an alternate LED/lens embodiment exhibiting a wider beam angle is exemplified in which LED package  606 , having hemispherical dome portion  612 , may protrude into indented portion  604  of lens  614 . It should be noted that indented portion  604  may exemplify a cross-section of a lens array (e.g., a cross-section of indented portion  212  of the lens array of  FIG. 2 ) where indented portion  604  includes optical input  608  to lens  614  that accepts the light distribution from LED  606  into lens  614 . Protrusion  602  may exemplify a cross-section of a lens array (e.g., a cross-section of mechanical portion  210  of the lens array of  FIG. 2 ) where protrusion  602  includes surface area  616  that may be in communication with a PCB (not shown) to select an optimal separation distance (e.g., separation distance  618 ) between the LED deck (e.g., PCB  626  of LED package  606 ) and optical input  608  to lens  614 . In one embodiment, separation distance  618  may be between about 0.3 mm and about 0.4 mm (e.g., approximately 0.35 mm). 
     Portion  610  may exemplify a cross-section of a lens array (e.g., a cross-section of lens  206  of  FIG. 2 ) where portion  610  may be the optical output of lens  614  that produces the optically varied (e.g., refracted) light distribution. Light distribution from lens  614  may exhibit an optical axis (e.g., axis  620 ) that may be orthogonal to the mounting surface of the PCB (not shown) to which LED package  606  is mounted. In addition, the projected light distribution from lens  614  may be described in terms of the intensity of each ray and its geometric orientation with respect to axis  620  as well as the projected illuminance onto a flat plane and the projected illuminance onto targets adjacent to the flat plane. 
     It should be noted that the lens array is configured such that a projected light distribution from an individual lens (e.g., lens  614 ) of the lens array may not be incident upon adjacent lenses (e.g., lenses  626  and  628 ) of the lens array. In one embodiment, for example, lens  614  may refract the light distribution of LED  606  into a beam angle between about 100 degrees and 140 degrees (e.g., between approximately 115 degrees and 128 degrees) having beam width  624  that is not incident on adjacent lenses  626  and  628 . 
     Turning to  FIG. 7A , a light distribution is exemplified that may be produced by an LED/lens combination in accordance with an alternate embodiment that may include an LED (e.g., LED package  606  of  FIG. 6 ) and a lens (e.g., lens  614  of  FIG. 6 ) to produce a light distribution as exemplified in  FIG. 7A . As illustrated, for example, the light distribution from lens  614  may exhibit a center beam intensity (e.g., about 20 candela) at a zero-degree offset from the optical axis (e.g., axis  620  of  FIG. 6 ). The light distribution from lens  614  may exhibit a peak intensity (e.g., 59 candela) offset from the center beam by an angle of about 50 degrees to about 55 degrees (e.g., approximately 54 degrees). 
     It can be seen, therefore, that if the light distribution of  FIG. 7A  is projected onto a target having a flat surface by a lens (e.g., lens  614  of  FIG. 6 ), the distance between the lens and the target changes depending upon the angle of incidence of the light distribution onto the target. As an example, if the angle subtended by a light ray is offset from the optical axis (e.g., axis  620  of  FIG. 6 ) by zero degrees, then the distance traveled by the light ray to the target is at its minimal value. As the angle subtended by a light ray referenced to the optical axis increases, so does the distance that the light ray must travel before being incident onto the target&#39;s surface. 
     According to the inverse square law, therefore, the target illuminance decreases in proportion to the inverse square of the distance between the lens and the target, thereby causing the target illuminance to decrease with increasing beam width. However, since the intensity of the light distribution of  FIG. 7A  increases with increasing beam angle up to a reference beam angle (e.g., about 54 degrees), the target illuminance may nevertheless remain substantially uniform, or may substantially increase with increasing beam angle, despite the effects of the inverse square law as exemplified, for example, in the associated shaded illuminance plot of  FIG. 7B . In addition, for example, since the intensity of light distribution is maximum at maximum beam angle, the effective distance of the illuminance onto targets adjacent to the main target may be extended, such as may be the case when projecting light through side portions of the canopies of adjacent plants. 
     In comparing the intensity distribution plots of  FIGS. 4A and 7A , it can be seen that lens  314  of  FIG. 3  produces a greater peak intensity than the peak intensity produced by lens  614  of  FIG. 6 . Furthermore, since the beam angle produced by lens  614  of  FIG. 6  is wider than that produced by lens  314  of  FIG. 3 , the area illuminated by lens  614  may be greater than the area illuminated by lens  314 , but the illuminance produced by lens  614  may be less than that produced by lens  314  given the same distance to target. Accordingly, while the number of horticultural lights (e.g., horticultural lights  100  of  FIG. 1 ) utilizing lens  614  needed to illuminate a given target area may be less than the number of horticultural lights utilizing lens  314  needed to illuminate the same target area, horticultural lights utilizing lens  614  may be mounted closer to the target area to achieve the same illuminance generated by horticultural lights utilizing lens  314  that are mounted further away from the target area. Accordingly, less vertical distance between the horticultural light and the associated grow bed may be needed when utilizing lens  614 , thereby allowing multiple levels of grow beds to be established floor to ceiling within the indoor horticultural facility. 
     Turning to  FIG. 8 , horticultural system  800  is exemplified including horticulture light  804 , which may include a lens array (e.g., lens array  118  and  126  as exemplified by horticulture light  100  of  FIG. 1 ). In alternate embodiments, horticulture light  804  may not include a lens array, or may use a different lens array layout. In addition, horticultural system  800  may include grow beds  808 ,  808 A and  808 B that may be used to cultivate virtually any crop that may be grown within a horticulture facility. Horticultural lighting system  800  may further include, for example, quantum sensor  806 , which may include a photosynthetically active radiation (PAR) sensor having a uniform sensitivity to PAR light, a light meter to measure instantaneous light intensity and/or a data logger to measure cumulative light intensity. Quantum sensor  806  may, for example, provide spectrographic data, which may include correlated color temperature (CCT), CRI, chromaticity and photosynthetic photon flux (PPF) associated with horticulture light  804 , among other spectrographic data. 
     In one embodiment, controller  802  may access a database (e.g., light prescription database  814 ), which may include predetermined light prescriptions for controlling the light output from horticulture light  804  and may then utilize interface  810  to tune horticulture light  804  in accordance with the predetermined light prescriptions (e.g., prescribed light intensity, CCT and color spectrum). Controller  802  and interface  810  may, for example, be used by an operator to either manually tune horticulture light  804  to manual settings or tune horticulture light  804  to predetermined light prescriptions  814 . Alternately, controller  802  may automatically update horticulture light  804  based upon comparisons between quantum sensor measurements  812  and light prescriptions  814  using closed-loop feedback control so as to maintain horticulture light  804  within operational constraints as defined by light prescriptions  814 . For example, the temperature of horticulture light  804  may increase, thereby increasing the temperature of the LEDs contained within horticulture light  804 , which may in turn decrease an intensity of light generated by horticulture light  804 . As a result of closed-loop feedback, the decreased intensity due to increased temperature may be detected by quantum sensor  806  and reported to controller  802 , whereby controller  802  may responsively increase the intensity of the light distributed by horticulture light  804 . Conversely, as discussed in more detail below, controller  802  may instead invoke other measures (e.g., increased air flow), which may then lower the temperature of horticulture light  804 , thereby resulting in an increased intensity light distribution. 
     Controller  802  may provide command and control signals to horticulture light  804  via interface  810  (e.g., via a wired protocol such as 0-10V, I2C, DALI or DMX, or via a wireless protocol, such as ZigBee, Wi-Fi, thread-based mesh network or Bluetooth). Controller  802  may receive all measurement data from quantum sensor  806  and may provide such results via human-machine interface (HMI)  816  to an operator of horticultural system  800  so that the operator may ascertain the performance characteristics of horticulture light  804 . It should be noted that HMI  816  may either be located within the same facility as controller  802 , or may be located remotely within a regional or national control room, so that multiple controllers  802  in multiple grow facilities may be centrally managed remotely. 
     As discussed above in relation to  FIG. 1 , horticulture light  804  may implement multiple arrays of LEDs, whereby each LED array may be arranged into channels (e.g., along rows and/or columns) and each channel of LEDs may be controlled separately and independently. In one embodiment, horticulture light  804  (e.g., as discussed above in relation to horticulture light  100  of  FIG. 1 ) may implement multiple channels (e.g., 4 channels) whereby each row of LEDs (e.g., rows  126 ,  128 ,  130  and  132  of  FIG. 1 ) may represent a separately and independently controllable LED channel. 
     Horticulture light  804  may be utilized to produce broad-spectrum white light (e.g., between about 420 nm and about 750 nm) with variable CCT so that the light spectrum may be tuned to better simulate various aspects of sun light. For example, multiple phases of the sun, simulation of sun light in all four seasons (e.g., fall, winter, spring, summer) and latitude of the sun may be better simulated using CCT control. Furthermore, no matter what CCT value may be selected, the intensity of light produced may be selectable as well, such that in one example, multiple CCT values may be obtained while maintaining a constant intensity. 
     As discussed above, horticultural light  804  may include appropriate lens/LED combinations to provide illuminance  818 , where illuminance  818  may be substantially uniform or may substantially increase as the angle of incidence increases with respect to optical axis  824 . In addition, through increased intensity at increased beam angles as compared to optical axis  824 , light rays  820  and  822  may illuminate adjacent grow beds  808 A and  808 B, respectively, with increased illuminance from the sides of the respective grow beds to better simulate light received from the sun. Stated differently, by increasing the intensity at increasing angles of incidence as compared to optical axis  824 , light generated by horticulture light  804  may not only be effective as to grow bed  808 , but also to grow beds  808 A and  808 B even though grow beds  808 A and  808 B are further away from horticulture light  804  as compared to grow bed  808 . 
     In one embodiment, horticulture light  804  may include multiple channels (e.g., two rows) of broad-spectrum white LEDs, whereby the intensity of each row of LEDs may be controlled by a separate channel (e.g., 1 of N channels  810 ) of controller  802 . The first set of broad-spectrum white LEDs may, for example, exhibit a first CCT (e.g., a CCT equal to about 2700K) and the second set of broad-spectrum white LEDs may exhibit a second CCT (e.g., a CCT equal to about 5700K). Through operation of controller  802 , the intensity of each set of broad-spectrum white LEDs may be controlled to create an averaged mix of light exhibiting a CCT between about 2700K and 5700K as may be required (e.g., as required by light prescription  814 ). Alternately, each channel of broad-spectrum white LEDs may include mixed CCT values (e.g., both 2700K and 5700K). 
     In alternate embodiments, the number of channels of broad-spectrum white LEDs may, for example, be increased (e.g., increased to 3 channels) each channel exhibiting a different CCT value (e.g., 2700K, 4000K and 6000K). In such an instance, the averaged CCT value of the 3-channel combination may be variable between about 2700K and 6000K, but with an emphasis of mid-range energy due to the addition of the 3 rd  channel (e.g., the 4000K channel) of broad-spectrum white LEDs. Alternately, each channel of broad-spectrum white LEDs may include mixed CCT values (e.g., all three of 2700K, 4000K and 5700K). 
     In yet other embodiments, horticulture light  804  may include one or more channels of fixed color LEDs (e.g., one channel of red LEDs and/or one channel of blue LEDs) in addition to one or more channels of broad-spectrum white LEDs. In such an instance, even wider ranging mixed CCT values may be obtained, since the averaged CCT values produced by the broad-spectrum white LEDs may be pushed to lower values (e.g., through the use of the variable intensity red channel) and/or pushed to higher values (e.g., through the use of the variable intensity blue channel). 
     Even broader spectrums may be achieved, for example, when the one or more channels of fixed color LEDs may themselves be implemented using multiple wavelengths. For example, a channel of red LEDs may be implemented through use of a first proportion of red LEDs (e.g., 50% of the red LEDs producing light with a 660 nm wavelength) and a second proportion of red LEDs (e.g., 50% of the red LEDs producing light with a 625 nm wavelength). Additionally, a channel of blue LEDs may be implemented through use of a first proportion of blue LEDs (e.g., 50% of the blue LEDs producing light with a 440 nm wavelength) and a second proportion of blue LEDs (e.g., 50% of the blue LEDs producing light with a 460 nm wavelength). Accordingly, even broader spectrum red and blue channels may be combined with broad-spectrum white channels to create the broadest spectrum light possible all while also providing variable CCT. 
     Turning to  FIG. 9 , an alternate embodiment of horticulture light  900  is exemplified, in which substantially none of the bias and control circuitry that may be associated with each channel of LEDs is co-located on the same PCB as each LED. Instead, the bias and control circuitry for each channel of LEDs (e.g., 4 channels  810  of  FIG. 8 ) may be integrated within the bulk power conversion (e.g., power supply  904 ) that may be mounted to horticulture light  900 . In addition, power supply  904  may convert the AC voltage (e.g., 110 VAC at 60 Hz applied via power cord  902 ) to a wide ranging DC potential between approximately 10 VDC and 300 VDC (e.g., approximately between about 12 VDC and 48 VDC). Buck, boost and/or buck/boost converters (not shown) also contained within power supply  904  may form at least a portion of the bias and control circuitry that may be required to illuminate each channel of LEDs contained within horticulture light  900  at specified intensities as may be selected via a wired or wireless control interface (e.g., a wired DMX interface). 
     Horticulture light  900  may exhibit a longer length profile as compared, for example, to horticulture light  100  of  FIG. 1 . For example, a longer profile may be obtained by concatenating two horticulture lights  910  and  912  (e.g., two horticulture lights  100  of  FIG. 1  end to end for twice the length). It should be noted that the circuitry of controller areas (e.g., areas  908 ) that may otherwise exist within other horticulture lights (e.g., horticulture light  100  of  FIG. 1 ) may instead be contained within power supply  904 . 
     Turning to  FIG. 10 , a block diagram of power supply  904  of  FIG. 9  is illustrated, which may include AC/DC bulk conversion block  1002  to bulk convert an alternating current (AC) input to a direct current (DC) voltage, power management block  1004  to provide operational power for miscellaneous devices (e.g., CPU  1018  and DMX  1010 ) and one or more DC-DC converters (e.g., buck, boost and/or buck/boost converters  1006 - 1008 ) to, for example, provide sufficient power to vary the intensity of the one or more arrays of LEDs contained within the horticulture light (e.g., horticulture light  900  of  FIG. 9 ). 
     In one embodiment, for example, converters  1006 - 1008  may generate a voltage substantially equal to the forward voltage of their respective LED arrays and may vary the drive current according to a constant current topology to achieve a desired intensity of each LED array (e.g., as may be determined by light prescription  814  or HMI  816  of  FIG. 8 ). The desired intensity of each LED array may, for example, be controlled via DMX  1010  and/or I2C  1020 , where each LED array may exist within the same DMX universe and may be responsive to an 8-bit intensity control word received within its designated DMX slot. DMX  1010  may facilitate remote device management (RDM) data handling, whereby full duplex communications may be accommodated to, for example, define DMX slot numbers and to correlate those DMX slot numbers to each of the respective LED arrays. 
     Firmware executed by CPU  1018  may reside, for example, within memory (e.g., flash memory), which may be local to CPU  1018  or remotely located with respect to CPU  1018 . Firmware may, for example, be changed or updated (e.g., boot loaded) via universal serial bus (USB)  1012  (e.g., USB port  906  of  FIG. 9 ). Such firmware may control, for example, power management to the LED arrays as provided by converters  1006 - 1008 . In one embodiment, for example, firmware executed by CPU  1018  may operate DC-DC converters  1006 - 1008  according to a fixed-frequency, constant current topology that may select a minimum and a maximum current to be conducted by each LED array through analog control. Furthermore, firmware executed by CPU  1018  may operate DC-DC converters  1006 - 1008  (e.g., via pulse width modulated (PWM) control signals) to select any number (e.g., 255) of intensity levels that may be generated by each LED array at any current setting. In one example, current magnitudes between 1% and 25% of the maximum current magnitude may be PWM modulated so as to provide precision dimming at the lowest levels of dimming (e.g., 255 levels of dimming may be implemented via PWM modulation to achieve approximately 0.1% dimming granularity between 1% and 25% of maximum current). 
     Firmware executed by CPU  1018  may, for example, receive telemetry data (e.g., thermal data via temperature sensors  1016 ) relative to, for example, the operating temperature of the horticulture light (e.g., horticulture light  900  of  FIG. 9 ). In response, CPU  1018  may issue fan control signals (e.g., fan RPM control signals) to fan  1014  so as to maintain horticulture light  900  within a specified temperature range. In addition, CPU  1018  may limit the maximum current conducted by each LED array as discussed above to maintain the operating temperature of horticulture light  900  below a maximum temperature range. For example, if the maximum temperature range is exceeded by horticulture light  900 , CPU  1018  may first increase the speed at which one or more fans  1014  may be operating, thereby providing increased air flow to horticulture light  900  in an effort to lower the operating temperature of horticulture light  900  below its maximum operating temperature. If the operating temperature is not reduced below the maximum temperature range, then CPU  1018  may decrease the magnitude of current conducted by each LED array in a linear rollback fashion until the operating temperature is reduced below the maximum temperature range. As discussed above in relation to  FIG. 8 , for example, CPU  1018  may be operating in response to quantum sensor input data (e.g., quantum sensor input data that may be received via I2C interface  1020 ), whereby intensity variations of light measured by the quantum sensor may be compared to light prescriptions contained within a database and through closed-loop feedback, CPU  1018  may counteract such intensity variations any number of ways. For example, an amount of current generated by DC-DC converters  1006 - 1008  may be changed to effect an intensity variation in the LED arrays. Alternately, for example, adjusting the speed by which fan  1014  is spinning may control the temperature of the one or more LED arrays, which may then effectuate a change in intensity of light generated by the LED arrays, since light intensity generated by the LED arrays may be inversely proportional to the temperature of the LED arrays. 
     As discussed above, firmware received via USB  1012  may be used to control certain parameters of operation of horticulture light  900  via a computer (not shown) that may be communicating with USB  1012 . For example, any number of DC-DC converters  1006 - 1008  may be activated depending upon the number of LED arrays or channels that may exist within horticulture light  900 . For example, if eight DC-DC converters exist within power supply  904 , but only four LED arrays or channels exist within a particular horticulture light, then half of the DC-DC converters may be activated for operation via firmware loaded via USB  1012  while the other half remain in a deactivated state. In operation, each activated DC-DC converter may receive a unique DMX address, such that DMX control words may be correctly addressed to the corresponding DC-DC converter to correctly control the intensity of the associated LED array. 
     In addition, firmware loaded via USB  1012  may be used to select the temperature trigger value, such that either fan RPM may be increased or LED array current drive may be decreased (as discussed above) once the temperature trigger value (e.g., as detected by temperature sensors  1016 ) is exceeded. Dim control may also be selected via firmware loaded via USB  1012  to, for example, select the rate at which the LED array(s) may be dimmed. For example, each DMX control word (e.g., 256 control words per DMX slot total) may correspond to a particular LED array intensity as may be controlled by a corresponding PWM signal as generated by CPU  1018 . User controllable dimming as defined by firmware loaded via USB  1012  may, for example, be used to select the rate at which such intensity variation occurs. 
     Turning to  FIG. 11 , a schematic diagram of lighting system  1100  is illustrated, which may include AC/DC converter  1102  (e.g., power supply  904  of  FIG. 9 ), which may include one or more constant current and/or constant voltage DC output stages (e.g., DC stages  1110 ,  1112  and/or  1140 ) and an auxiliary low voltage output (e.g., 5 VDC not shown) with which components (e.g., processor  1104 , wireless node  1106  and wired node  1108  of lighting system  1100 ) may derive their operational power. Any one or more of DC output stages  1110 ,  1112  and  1140  may provide power via any one or more switched-mode conversion techniques (e.g., buck, boost, buck/boost or flyback). 
     AC/DC converter  1102  may be configured to provide sufficient power to, for example, vary the intensity of the one or more arrays of LEDs contained within one or more horticulture lights (e.g., one or more horticulture lights as exemplified in  FIG. 9 ). It should be noted that while only two LED arrays  1122  and  1124  are exemplified, any number of LED arrays  1138  and associated bias control circuitry may be accommodated by any number of DC stages within AC/DC converter  1102 . Furthermore, each LED array  1122  and  1124  may include virtually any number (e.g., one or more) of LEDs  1144  and  1146 , respectively. 
     As discussed in more detail below, the magnitude of DC voltage available from any one DC stage  1110 ,  1112  or  1140  may be adjusted as needed (e.g., via control  1148  from processor  1104 ) to be substantially equal to the combined forward voltage of any one associated LED string  1122 ,  1124  or  1138 . In one embodiment, for example, processor  1104  may empirically deduce the magnitude of forward voltage required to forward bias each LED in each string LED string  1122 ,  1124  and/or  1138 . Once the magnitude of forward voltage needed to forward bias each LED in each LED string  1122 ,  1124  and/or  1138  is known, processor  1104  may then command one or more associated DC stages  1110 ,  1112  and/or  1140  (e.g., via control  1148 ) to the determined magnitude of forward voltage so that each LED string may be operated as efficiently as possible. In alternate embodiments, DC stages  1110 ,  1112  and/or  1140  may automatically determine the magnitude of forward voltage needed to forward bias each LED in each LED string  1122 ,  1124  and/or  1138  and may communicate that voltage to processor  1104  (e.g., via control  1148 ). 
     In one embodiment, each LED array may be configured to operate in accordance with one or more bias topologies. As per one example, LED array  1122  and  1124  may be configured in parallel to operate using a single voltage rail (e.g., a single voltage rail generated by one of DC stages  1110 ,  1112  or  1140 ) such that switches  1118  and/or  1120  may be configured as shown (e.g., via control  1148  from processor  1104 ) to produce a forward voltage across each LED array and a forward current through each LED array as may be modulated by a power switch (e.g., field effect transistors (FETs)  1150  and/or  1152 ) via control signals  1154  and/or  1156 , respectively, as may be appropriately level shifted by level shifters  1180  and  1182 , respectively, whereby the current conducted by each LED array may be stabilized via ballast elements (e.g., resistors  1126  and  1128 ). Other power switching elements, such as insulated gate bipolar transistors (IGBTs) or vertical MOSFETs, may be used instead of FETs  1150  and  1152  as well. 
     As per another example, each LED array may be configured in parallel to operate using a single voltage rail (e.g., a single voltage rail generated by DC stage  1110  or DC stage  1112 ) whereby switches  1118  and  1120  may be configured in the opposite configuration as shown to produce a forward voltage across each LED array and a forward current through each LED array as may be modulated by a power switch (e.g., FETs  1150  and  1152 ) via control signals  1154  and/or  1156 , respectively, as may be appropriately level shifted by level shifters  1180  and  1182 , respectively, whereby the average current conducted by each LED array may be stabilized via a current stabilization network (e.g., inductor  1130 /diode  1132  and inductor  1134 /diode  1136 , respectively). 
     Still other examples include configurations whereby each LED array (e.g., LED array  1122  and  1124 ) may be operated independently using a dedicated DC stage (e.g., DC stage  1112  and DC stage  1110 , respectively) in either of a constant voltage or constant current configuration using either ballast or inductor-based current stabilization techniques as may be selected by switches  1118  and  1120 . 
     As discussed in more detail below, wired node  1108  may include any wired interface (e.g., DMX, I2C, Ethernet, USB, DALI, etc.) that may be used to configure lighting system  1100  (e.g., via processor  1104 ) for operation and/or allow processor  1104  to communicate the status and operational capability of lighting system  1100  to wired network  1158  (e.g., BACnet-enabled wired network  1158 ). Similarly, wireless node  1106  may include any wireless interface (e.g., Wi-Fi, thread-based mesh, Bluetooth, ZigBee, etc.) that may similarly be used to configure lighting system  1100  (e.g., via processor  1104 ) for operation and/or allow processor  1104  to communicate the status and operational capability of lighting system  1100  to wireless network  1160  (e.g., BACnet-enabled wireless network  1160 ). 
     As discussed above, processor  1104  may be configured to deduce the number of LED strings that may be under its control as well as the number of LEDs in each LED string. Such deduction, for example, may occur each time lighting system  1100  is provisioned with LEDs, either at initial deployment or after reconfiguration. Processor  1104  may then configure the operation of AC/DC converter  1102  for optimal performance in response to the number of LED strings found and/or the number of LEDs in each LED string subsequent to such deduction. Accordingly, the number of LED strings and the number of LEDs in each LED string contained within lighting system  1100  may not necessarily be fixed at initial deployment or after each reconfiguration, but rather may be dynamic such that processor  1104  may intelligently determine the lighting capability of lighting system  1100  (e.g., the number of LED strings and the number of LEDs in each LED string after initial deployment and/or after each reconfiguration) and may, therefore, intelligently select the most efficient mode of operation of each DC stage (e.g., constant current, constant voltage or a mixture of both), the most efficient magnitude of voltage and/or current to be generated by each DC stage and may also intelligently select the most efficient current stabilization mode for each LED string (e.g., ballast or inductor-based current stabilization). 
     It should be noted that the mode of operation of DC stages  1110 ,  1112  and  1140  may be programmable (e.g., via control  1148  of processor  1104 ) to either a constant-voltage or a constant-current mode of operation. Conversely, the mode of operation of DC stages  1110 ,  1112  and  1140  may be fixed such that a mixture of both constant-voltage and constant-current DC stages may exist within AC/DC converter  1102  and may be individually selected for operation (e.g., via control  1148  of processor  1104 ) and individually connected to respective LED strings  1122 ,  1124  and/or  1138  via a multiplexer (not shown) within AC/DC converter  1102 . 
     In alternate embodiments, each DC stage of AC/DC converter  1102  may be paired with either a ballast-based current stabilization network or an inductor-based current stabilization network, such that switches  1118  and  1120  may no longer be necessary. In addition, the operational mode of each DC stage (e.g., constant-current or constant-voltage) may be predetermined, such that upon configuration of lighting system  1100 , LED strings  1122 ,  1124  and/or  1138  may be statically paired with a ballast-based current stabilization network, an inductor-based current stabilization network, or both, and each pairing may include constant-voltage and/or constant-current topologies. 
     Turning to  FIG. 12 , flow diagrams are exemplified whereby processor  1104  may first discover the number of LED strings initially provisioned and/or reconfigured within lighting system  1100 . Next, processor  1104  may then configure the bias and stabilization networks of lighting system  1100  that may be necessary for the most efficient mode of operation of each detected LED string. 
     In step  1202 , for example, processor  1104  may first select a continuity mode, whereby AC/DC converter  1102  may be selected to perform a continuity test to determine the number of LED strings that may exist within lighting system  1100 . Initially, a first DC stage of AC/DC converter  1102  (e.g., DC stage  1112 ) may be configured by processor  1104  via control  1148  to provide a maximum output voltage (e.g., 250 VDC) as in step  1204 , which may then be applied to a first LED string (e.g., LED string  1122  in a current-limited fashion). In one embodiment, for example, processor  1104  may select switch  1118  to the position shown via control  1148  and FET  1150  may be momentarily rendered conductive by processor  1104  via control  1154  (e.g., as in step  1206 ). In response, a current may or may not be conducted by resistor  1126 , as may be sensed by current sensor  1162  of processor  1104 , to determine whether or not LED string  1122  exists within lighting system  1100 . A voltage developed across resistor  1126 , for example, may lead to the determination that a particular magnitude of current is being conducted by LED string  1122 , which may then lead processor  1104  to deduce that LED string  1122  exists within lighting system  1100 . Steps  1202 - 1206  may then be repeated as above (e.g., with the same DC stage or a different DC stage within AC/DC converter  1102 ) to determine the number of LED strings that may or may not exist within lighting system  1100 , the result may then be logged as in step  1208 . 
     For the one or more LED strings that may be detected through execution of steps  1202 - 1208  by processor  1104 , a substantially minimum magnitude of forward voltage may then be empirically determined such that each LED string may be operated at maximum efficiency using the determined minimum magnitude of forward voltage. For example, processor  1104  may first select a continuity mode (as in step  1210 ), whereby AC/DC converter  1102  may be selected to perform a continuity test to determine the forward voltage required to illuminate all of the LEDs that may exist within a previously detected LED string. A first DC stage of AC/DC converter  1102  (e.g., DC stage  1112 ) that may correspond to the first detected LED string may first be configured by processor  1104  via control  1148  to provide a maximum output voltage (e.g., 250 VDC) as in step  1212 , which may then be applied to the first detected LED string (e.g., LED string  1122  in a current-limited fashion) as discussed above, for example, in relation to step  1206 . 
     In step  1214 , the applied voltage may be modulated (e.g., decreased from 250 VDC) by processor  1104  via control  1148  in coarse voltage steps (e.g., 10V steps) until current stops flowing (e.g., as detected by current sense  1162  as the applied voltage is decreased from 250 VDC). The coarse voltage obtained in step  1214  may then be logged by processor  1104  as the minimum coarse voltage magnitude required to illuminate the LED string. 
     In step  1216 , the DC stage may be programmed to the minimum coarse voltage from step  1214  increased by one coarse voltage step and then modulated (e.g., decreased) by processor  1104  via control  1148  in medium voltage steps (e.g., 1V steps) until current stops flowing (e.g., as detected by current sense  1162 ). The medium voltage obtained in step  1216  may then be logged by processor  1104  as the minimum medium voltage magnitude required to illuminate the LED string. 
     In step  1218 , the DC stage may be programmed to the sum of the minimum coarse voltage from step  1214  and the minimum medium voltage from step  1216  increased by one medium voltage step and then modulated (e.g., decreased) by processor  1104  via control  1148  in fine voltage steps (e.g., 0.1V steps) until current stops flowing (e.g., as detected by current sense  1162 ). The voltage may then be increased in fine voltage steps (e.g., 0.1 VDC steps) until the current begins to flow again. The fine voltage obtained in step  1218  may then be logged by processor  1104  as the minimum fine voltage magnitude required to illuminate the LED string. 
     Once steps  1214 - 1218  have been completed, the minimum forward voltage required to most efficiently illuminate the LED string may have been determined within a minimum voltage resolution (e.g., 0.1 VDC). For example, if the LED string under test contains 72 LEDs where each LED exhibits a forward voltage of 3.1 volts and assuming that the on-resistance of FET  1150  and the resistance of resistor  1126  adds an additional overhead voltage (e.g., 0.5 VDC) to the magnitude of forward voltage required to illuminate LED string  1122 , then a minimum forward voltage of approximately 72*3.1+0.5=223.7 VDC (e.g., constituting a coarse voltage magnitude of 220 VDC, a medium voltage magnitude of 3 VDC and a fine voltage magnitude of 0.7 VDC) would be required to illuminate the LED string under test. In such an instance, the first DC stage of AC/DC converter  1102  (e.g., DC stage  1112 ) corresponding to the first detected LED string of lighting system  1100  may be programmed by processor  1104  via control  1148  to provide approximately 223.7 VDC (perhaps rounding up to 225-230 volts for increased headroom), instead of the maximum output voltage (e.g., 250 VDC), such that the first detected LED string of lighting system  1100  may be operated at the most efficient voltage rail possible (e.g., substantially equal to the sum of forward voltages (V f ) of all LEDs in the LED string plus the FET, current sense and miscellaneous voltage overhead) and the current magnitude corresponding to such voltage may be measured (e.g., via current sense  1162 ) and logged by processor  1104  (e.g., as in step  1220 ). It should be noted that reduced resolution may be obtained when determining the minimum forward voltage required to most efficiently illuminate the LED string by simply eliminating step  1218  or steps  1218  and  1216 . 
     In an alternate embodiment (e.g., as in step  1224 ), the applied voltage may be modulated (e.g., increased from 0 VDC) by processor  1104  via control  1148  in coarse voltage steps (e.g., 10V steps) until current begins to flow (e.g., as detected by current sense  1162  as the applied voltage is increased from 0 VDC). The coarse voltage obtained in step  1224  may then be decreased by one coarse voltage step and then logged by processor  1104  as the minimum coarse voltage magnitude required to illuminate the LED string. 
     In step  1226 , the DC stage may be programmed to the minimum coarse voltage from step  1224  and then modulated (e.g., increased) by processor  1104  via control  1148  in medium voltage steps (e.g., 1V steps) until current begins to flow (e.g., as detected by current sense  1162 ). The medium voltage obtained in step  1226  may be decreased by one medium voltage step and then logged by processor  1104  as the minimum medium voltage magnitude required to illuminate the LED string. 
     In step  1228 , the DC stage may be programmed to the sum of the minimum coarse voltage from step  1224  and the minimum medium voltage from step  1226  and then modulated (e.g., increased) by processor  1104  via control  1148  in fine voltage steps (e.g., 0.1V steps) until current begins to flow (e.g., as detected by current sense  1162 ). The fine voltage obtained in step  1228  may then be logged by processor  1104  as the minimum fine voltage magnitude required to illuminate the LED string. Once steps  1224 - 1228  have been completed, the minimum forward voltage required to most efficiently illuminate the LED string may have been determined within a minimum voltage resolution (e.g., 0.1 VDC) similarly as discussed above in relation to steps  1214  to  1218  and the current magnitude corresponding to such voltage may be measured (e.g., via current sense  1162 ) and logged by processor  1104  (e.g., as in step  1220 ). It should be noted that reduced resolution may be obtained when determining the minimum forward voltage required to most efficiently illuminate the LED string by simply eliminating step  1228  or steps  1228  and  1226 . 
     In one embodiment, processor  1104  may determine which current stabilization mode to utilize depending upon the results of steps  1210 - 1220  or steps  1210 - 1212 , steps  1224 - 1228  and step  1220 . For example in step  1230 , processor  1104  may compare the optimal forward voltage for each detected LED string. In step  1234 , comparison of the optimal forward voltage deduced for each detected LED string may lead to a determination that each optimal forward voltage may be approximately equal and in such an instance, a ballast-based stabilization technique may be selected as in step  1236 , whereby each LED string may be operated from the same DC stage of AC/DC converter  1102  and the current in each LED string may be appropriately stabilized by its associated ballast resistor and modulated (e.g., increased or decreased on average over time) by analog control and/or appropriate control of the duty cycle of each power switch associated with each LED string (e.g., FET  1150 /duty cycle control  1154  for LED string  1122  and FET  1152 /duty cycle control  1156  for LED string  1124 ). 
     If, on the other hand, the deduced optimal forward voltages for each detected LED string are not substantially equal, inductor-based current stabilization may instead be selected (e.g., as in step  1238 ), whereby each LED string may be operated from independent DC stages of AC/DC converter  1102  (e.g., constant current DC stages each set at the optimal forward voltage associated with each LED string) and the current in each LED string may be appropriately stabilized by its associated inductor/diode pair and modulated (e.g., increased or decreased on average over time) by analog control and/or appropriate control of the duty cycle of each power switch associated with each LED string (e.g., FET  1150 /duty cycle control  1154  for LED string  1122  and FET  1152 /duty cycle control  1156  for LED string  1124 ). 
     It should be noted that the inductor (e.g., inductor  1130  or inductor  1134 ) of an inductor-based current stabilization network may add an additional forward voltage component to the minimum voltage required to operate an LED string. However, since the voltage magnitude of each DC stage of AC/DC converter  1102  may be optimally controlled (e.g., minimized), the magnitude of inductance required by each inductor may be minimized as well (thereby minimizing the physical size of the inductor), since the required inductance magnitude is directly proportional to the voltage developed across the inductor. 
     In one embodiment, a capacitor (e.g., capacitor  1168  and  1170 ) may be optionally placed across LED strings  1122  and  1124 , respectively, to a reference potential (e.g., ground) in either of a ballast-based or inductor-based current stabilization mode of operation. In a ballast-based mode of operation, for example, the capacitor may be selected for a specific output voltage ripple to maintain a substantially constant output voltage under load transient conditions. 
     In an inductor-based current stabilization mode of operation, on the other hand, capacitors (e.g., capacitors  1168  and  1170 ) may interact with inductors (e.g., inductors  1130  and  1134 , respectively) to provide AC current filtering, thereby allowing the capacitor to control the ripple current to acceptable levels as required by each LED string while at the same time decreasing the required inductance magnitude, thereby further minimizing the physical size and cost of the inductor. For example, by allowing smaller inductance magnitudes to be selected, the resulting increase in peak-to-peak current ripple may be conducted by each capacitor (e.g., capacitor  1168  and  1170 ), thereby maintaining the magnitude of current ripple experienced by each LED string (e.g., LED string  1122  and  1124 , respectively) to within acceptable limits (e.g., 10% of the DC forward current conducted by each LED string). 
     It should also be noted that other algorithms may be used to determine the current stabilization technique other than those algorithms depicted in steps  1230 - 1238 . For example, inductor-based current stabilization may be selected by processor  1104  even though the optimal forward voltage for each detected LED string may be approximately equal and operated from the same or different DC stages of AC/DC converter  1102 . Conversely, ballast-based current stabilization may be selected by processor  1104  even though the optimal forward voltage for each detected LED string may be substantially unequal and operated from the same or different DC stages of AC/DC converter  1102 . 
     Algorithms defining the operation of lighting system  1100  (e.g., algorithms described by the execution steps of  FIG. 12 ) may, for example, fully reside within processor  1104  (e.g., flash memory that is local to processor  1104 ). Alternately, such algorithms may fully reside within a network (e.g., wired network  1158  and/or wireless network  1160 ) whereby execution instructions associated with such algorithms may be received by processor  1104  via wired node  1108  and/or wireless node  1106 . Conversely, algorithms defining the operation of lighting system  1100  (e.g., algorithms described by the execution steps of  FIG. 12 ) may be distributed to partially reside within processor  1104  and partially reside within a network (e.g., wired network  1158  and/or wireless network  1160 ) whereby a portion of execution instructions may be received by processor  1104  via wired node  1108  and/or wireless node  1106 . 
     In operation, the status of lighting system  1100  may be continuously monitored and such status may be relayed to wired network  1158  and/or wireless network  1160  via wired node  1108  and/or wireless node  1106 , respectively. As per one example, processor  1104  may continuously monitor the current conducted by each LED string (e.g., LED strings  1122 ,  1124  and/or  1138  as may be measured by current sense  1162 ,  1164  and/or  1166 , respectively) to determine whether each LED string is operating in accordance with the logged current magnitudes for each LED string (e.g., as logged by step  1220  of  FIG. 12 ). A detected fault (e.g., zero conducted current) in one LED string, for example, may result in the deactivation of at least the faulted LED string and perhaps the remaining LED strings by causing the associated voltage and current regulation devices (e.g., FETs  1150  and/or  1152 ) to remain non-conductive (e.g., via control signals  1154  and  1156 , respectively). Such detected faults and subsequent actions taken by processor  1104  may then be reported (e.g., via wired network  1158  and/or wireless network  1160 ) to allow maintenance personnel to react to the reported fault (e.g., decommissioning of the faulted lighting system and the subsequent commissioning of a replacement lighting system). 
     In alternate embodiments, trends of each LED string may be tracked to predict, for example, efficiency, maximum light output, peak wavelength and spectral wavelength variations due to increased junction temperature. Increased junction temperatures, for example, may be related to a forward voltage decrease of a particular LED string due to a reduction in the bandgap energy of the active region of each LED in the LED string as well as a decrease in the series resistance of each LED occurring at high temperatures. Accordingly, for example, by tracking a reduced forward voltage of a particular LED string over time, predictions may be made and reported by processor  1104  (e.g., via wired network  1158  and/or wireless network  1160 ) as to certain performance parameters of each LED string so that maintenance personnel may respond accordingly. 
     Turning to  FIG. 13 , an alternate embodiment of lighting system  1300  is exemplified, such that the current stabilization topologies may not be selectable and may instead be provided as ballast-based current stabilization networks for each LED string utilized within lighting system  1300 . In addition, a single DC stage  1340  may be utilized within AC/DC converter  1302 , which may provide a single-rail voltage magnitude (e.g., via voltage signal  1390  at node  1310 ) in a constant-current mode of operation to multiple LED strings connected in a parallel configuration (e.g., LED strings  1322 ,  1324  and  1380 ). 
     Similarly as discussed above in relation to  FIG. 11 , wired node  1308  may include any wired interface (e.g., DMX, I2C, Ethernet, USB, DALI, etc.) that may be used to configure lighting system  1300  (e.g., via processor  1304 ) for operation and/or allow processor  1304  to communicate the status and operational capability of lighting system  1300  to wired network  1358  (e.g., BACnet-enabled wired network  1358 ). Similarly, wireless node  1306  may include any wireless interface (e.g., Wi-Fi, thread-based mesh, Bluetooth, ZigBee, etc.) that may similarly be used to configure lighting system  1300  (e.g., via processor  1304 ) for operation and/or allow processor  1304  to communicate the status and operational capability of lighting system  1300  to wireless network  1360  (e.g., BACnet-enabled wireless network  1360 ). 
     The number of series-connected LEDs (e.g., one or more) in each LED string (e.g.,  1322 ,  1324  and  1380 ) may be selected based upon the sum of forward voltage (V f ) of each series-connected LED, where the forward voltage of each LED string may be selected to be substantially equal. In one embodiment, for example, an LED string may be selected to contain about 45 to 50 (e.g., 46) LEDs each having a V f  between about 2.5V and 3.5V (e.g., 3V) for a cumulative forward voltage of 46*3=138V for the LED string. In an alternate embodiment, for example, an LED string may be selected to contain about 60 to 75 (e.g., 69) LEDs each having a V f  between about 1.5V and 2.5V (e.g., 2V) for a cumulative forward voltage of 69*2=138V for the LED string. 
     In alternate embodiments, each LED string may have the same or a different number of LEDs, but due to differences in V f  for each LED type in each LED string, each LED string may exhibit a forward voltage that is substantially equal to the forward voltage of each of the other LED strings. Furthermore, while only three LED strings are depicted, any number of LED strings (e.g., 4) may be utilized. Still further, each of LED strings  1322 ,  1324  and  1380  may reside within a single lighting fixture or may reside within multiple lighting fixtures. 
     Due to slight deviations in the Vf for each LED of each LED string (e.g., due to forward current deviations in each LED string), the cumulative forward voltage for each LED string may not necessarily conform to the calculations above, which may necessitate the existence of ballast elements (e.g., resistor  1326 ,  1328  and  1382 ) such that the voltage magnitude at node  1310  may be allowed to remain substantially equal under all load conditions for each LED string. Furthermore, each ballast element may facilitate current stabilization as well as current sense measurements by processor  1304  as discussed in more detail below. 
     Processor  1304  may be configured to deduce the number of LED strings that may be under its control as well as the forward current requirements (e.g., minimum and maximum forward current) in each LED string. Such deduction, for example, may occur each time lighting system  1300  is provisioned with LEDs, either at initial deployment or after reconfiguration. 
     Turning to  FIG. 14 , flow diagrams are exemplified whereby processor  1304  may first discover the number of LED strings initially provisioned and/or reconfigured within lighting system  1300 . Next, processor  1304  may then configure the current provisioning for each LED string of lighting system  1300 . 
     In a first embodiment, processor  1304  may have control of both the voltage and current magnitude output of DC stage  1340  via control  1348 . In such an instance, processor  1304  may configure DC stage  1340  to its minimum voltage output (e.g., as in step  1402 ) and its maximum current output (e.g., as in step  1404 ). Processor  1304  may then configure lighting system  1300  for a continuity check (e.g., as in step  1406 ) whereby, for example, processor  1304  may render one of LED strings  1322 ,  1380  and  1324  conductive by transitioning one of power switches (e.g., FETs  1350 ,  1352  or  1386 , respectively), into a conductive state. In step  1408 , the output voltage magnitude of DC stage  1340  may be increased (e.g., as in steps  1224  through  1228  of  FIG. 12 ) until current is conducted through the LED string under test (e.g., as may be detected by current sense  1362 ,  1366  or  1364 , respectively). Processor  1304  may then decrease the current conducted by the LED string under test via control  1348  by programming the current output of DC stage  1340  to decreasingly lower magnitudes (e.g., in 1 mA steps decreasing from the maximum current set in step  1404 ) until current ceases to flow (e.g., as in step  1410 ). In step  1412 , for example, processor  1304  may then log the minimum voltage and current magnitudes as measured by steps  1408  and  1410  into a memory location (e.g., as located on-board processor  1304  and/or as may be located in memory locations of wired network  1358  and/or wireless network  1360 ). 
     In an alternate embodiment, processor  1304  may program the current magnitude output of DC stage  1340  via control  1348 , but DC stage  1340  may internally adjust the output voltage as required to produce the programmed current magnitude output of DC stage  1348 . In such an instance, processor  1304  may configure DC stage  1340  to its maximum current output (e.g., as in step  1414 ). Processor  1304  may then configure lighting system  1300  for a continuity check (e.g., as in step  1416 ) whereby, for example, processor  1304  may render one of LED strings  1322 ,  1380  and  1324  conductive by transitioning one of power switches (e.g., FETs  1350 ,  1352  or  1386 , respectively), into a conductive state. The output voltage magnitude of DC stage  1340  may then be internally increased (e.g., increased by circuitry located internal to DC stage  1340 ) until current is conducted through the LED string under test (e.g., as may be detected by current sense  1362 ,  1366  or  1364 , respectively). Processor  1304  may then decrease the current conducted by the LED string under test via control  1348  by programming the current output of DC stage  1340  to decreasingly lower magnitudes (e.g., in 1 mA steps decreasing from the maximum current set in step  1414 ) until current ceases to flow (e.g., as in step  1418 ). In step  1420 , for example, processor  1304  may then log the minimum voltage (e.g., as may be reported by DC stage  1340  to processor  1304  via control  1348 ) and current magnitudes (e.g., minimum and maximum current magnitudes) as measured by step  1418  into a memory location (e.g., local to processor  1304  and/or as may be located in memory locations of wired network  1358  and/or wireless network  1360 ). 
     Once the initial configuration of each LED string is complete and lighting system  1300  is operational, each subsystem of lighting system  1300  may be monitored (e.g., as in step  1422 ) to, for example, continuously determine the operational status of lighting system  1300 . For example, each LED string of lighting system confirmed to be operational (e.g., as in steps  1402 - 1412  or steps  1414 - 1420 ) may be continuously monitored (e.g., the forward current of each LED string may be continuously monitored) for normal operation. If the measured forward current substantially equals the current magnitudes as logged in steps  1412  or  1420  taking into account any digital current modulation performed by power switches (e.g., FETs  1350 ,  1352  and/or  1386 ), such as reduced forward current through less than 100% duty cycle modulation of the power switches, then normal status of lighting system  1300  may be reported (e.g., as in step  1426 ). If, on the other hand, the modulated forward current does not meet previously verified current magnitudes, then abnormal status of lighting system  1300  may be reported (e.g., as in step  1428 ) and reported to, for example, wired network  1358  and/or wireless network  1360  to alert maintenance personnel of the abnormal status. 
     Other operational aspects of lighting system  1300  may be monitored as well. For example, temperature sensors and fans (e.g., temperature sensors  1016  and fans  1014  as exemplified in  FIG. 10 ) may be utilized by lighting system  1300  to ensure that, for example, the temperature of each LED string is operating within specification. If not, the abnormal temperature and/or fan malfunction may be reported as in step  1428 ; otherwise, normal fan and temperature status may be reported as in step  1426 . 
     Processor  1304  may implement a hybrid dimming scheme, whereby both digital modulation of LED string current (e.g., via PWM control of the power switches) and analog modulation of LED string bias current may be used to provide deep dimming control of the LED string intensity while minimizing audible and radiated noise. In step  1430 , for example, the minimum and maximum current magnitudes (e.g., as determined in steps  1414  and  1418 ) may be accessed by processor  1304  to determine the full range of DC bias current magnitudes (e.g., as produced by DC stage  1340 ) that may be utilized to illuminate a particular LED string (e.g., LED string  1322 ) across a range of intensity. As per one example, the maximum current for an LED string (e.g., LED string  1322 ) may be determined to be equal to an upper current limit (e.g., 1.25 A as determined in step  1414  so that LED string  1322  may produce full intensity), whereas the minimum current for the LED string may be determined to be equal to a percentage of the upper current limit (e.g., 30% of 1.25 A or 0.375 A). 
     In step  1432 , processor  1304  may determine the range over which analog control of the current magnitude may be used to select a particular intensity of light emission from a particular LED string. In one embodiment, for example, processor  1304  may determine that for all current magnitudes conducted by an LED string (e.g., LED string  1322 ) between a maximum current magnitude and a minimum threshold current magnitude (e.g., 30% of the maximum current magnitude), analog control (e.g., the continuous bias current magnitude provided by DC stage  1340  as commanded by control  1348 ) may be used. That is to say for example, that for light intensities produced by LED string  1322  between a maximum intensity and a lower threshold intensity (e.g., 30% of maximum intensity), processor  1304  may command DC stage  1340  to the desired bias current magnitude via control  1348  as required to produce the desired intensity range (e.g.,  1 . 25 A of continuous DC bias current for maximum intensity and 0.375 A of continuous DC bias current for 30% intensity). Variation between maximum intensity and the lower threshold intensity may be accomplished through variation of the continuous DC bias current generated by DC stage  1340  via control  1348  from processor  1304  in programmable steps (e.g., 1 mA steps). In each instance, the averaged current conducted by LED string  1322  may be equal to the continuous DC bias current generated by DC stage  1340  as delivered to LED string  1322  via node  1310 , as may be controlled by FET  1350  in accordance with an appropriate DC control signal  1354  applied to the gate terminal of FET  1350 . 
     In step  1434 , processor  1304  may determine the range over which digital control of the current magnitude may be used to select a particular intensity (e.g., below the lower threshold intensity) of light emission from a particular LED string. In one embodiment, for example, processor  1304  may determine that for all current magnitudes conducted by an LED string (e.g., LED string  1322 ) between the lower threshold intensity (e.g., 30% of maximum intensity) and a minimum intensity (e.g., 1% of maximum intensity), digital control (e.g., PWM modulation of FET  1350  to produce a discontinuous current signal where the current signal is reduced from a non-zero magnitude to a zero magnitude according to the duty cycle of the PWM modulation over multiple periods) may be used. In particular, any number (e.g., 256) of PWM duty cycle variations may be used to modulate the minimum bias current generated by DC stage  1340  and provided to LED string  1322  via node  1310  between an average bias current (e.g., averaged over multiple periods of maximum duty cycle discontinuities in the current signal) required to produce the lower threshold intensity and an average bias current (e.g., averaged over multiple periods of minimum duty cycle discontinuities in the current signal) required to produce the minimum intensity. 
     In step  1436 , dimming may be adjusted through a combination of both analog and digital controls. As per one example, analog control of light intensities produced by an LED string (e.g., LED string  1322 ) between a maximum intensity and a lower threshold intensity (e.g., 30% of maximum intensity) may be accomplished via appropriate control of DC stage  1340  via control  1348  to generate continuous DC bias current magnitudes required to produce intensities between the maximum intensity (e.g., 1.25 A bias current magnitude) and the lower threshold intensity (e.g., 0.375 A bias current magnitude) in programmable and continuous current steps (e.g., 1 mA steps) for an intensity control granularity substantially equal to, for example, (0.001/(1.25−0.375))*100≅0.1%. As per the same example, digital control of light intensities produced by an LED string (e.g., LED string  1322 ) between the lower threshold intensity (e.g., 30% of maximum intensity) and a minimum intensity (e.g., 1% of maximum intensity) may be accomplished via appropriate modulation of the lower threshold bias current generated by DC stage  1340  via PWM control  1354  to produce discontinuities in the bias current to program light intensities below the lower threshold intensity. In one embodiment, for example, 256 DMX control values via wired node  1308  may be used to vary the intensity between the lower threshold intensity (e.g., 30% of maximum intensity using maximum duty cycle discontinuities in the bias current) and the minimum intensity (e.g., 1% of maximum intensity using minimum duty cycle discontinuities in the bias current) with a control granularity substantially equal to (30%−1%)/256≅0.1%. 
     Through implementation of PWM control only over the lower portion of the current control range (e.g., the lower 30% of the current control range), fidelity may be improved within that range by, for example, reducing conducted emissions, reducing radiated emissions and reducing audible noise pollution. Furthermore, color mixing control across all LED strings (e.g., LED strings  1322 ,  1380  and  1324 ) may be enhanced through the application of digital dimming control beyond the limitations conventionally imposed by analog dimming, which for example, may deteriorate when analog dimming is attempted below a threshold dimming percentage (e.g., 10% of maximum intensity). Furthermore, by limiting the digital dimming control to lower levels of intensity (e.g., 1% to 30% of maximum intensity), the frequency of discontinuities in the PWM control waveform may be increased to frequencies above about 20 kHz (e.g., between about 20 kHz and 1 MHz) that may be less prone to generate detectable flicker and shimmer thereby further enhancing dimming fidelity. 
     In one embodiment, processor  1304  may determine that DC stage  1340  may not provide a magnitude of current that may be required by each of LED strings  1322 ,  1324  and  1380  operating at 100% intensity or lower. In such an instance, processor  1304  may implement a current sharing algorithm whereby each of the LED strings  1322 ,  1380  and  1324  may be operated at a percentage intensity that may be accommodated by DC stage  1340 . For example, DC stage  1340  may only be capable of providing an upper limit of current magnitude (e.g., 1.2 A) and in such and instance, processor  1304  may apportion a percentage of the upper limit current magnitude to each of LED strings  1322 ,  1380  and  1324  as may be necessary using analog control, digital control or a combination of analog and digital control as discussed above. 
     It should be noted that any one LED string may be apportioned 100% of the available current from DC stage  1340  using the current sharing algorithm. Conversely, any number of LED strings may share any portion of the available current from DC stage  1340 . As per one example, each LED string may equally share in the available current, whereby the magnitude of current apportioned to any one LED string may be calculated as the maximum current available divided by the number of activated LED strings (e.g., three activated LED strings may each receive 0.4 A of the available 1.2 A from DC stage  1340 ) by any of an analog, digital or combination of analog/digital current control algorithm as discussed above. 
     In an alternate embodiment, for example, processor  1304  may determine that DC stage  1340  may provide a magnitude of current that may meet or exceed the requirement of any one or more LED strings  1322 ,  1324  and  1380  operating at 100% intensity or lower. In such an instance, processor  1304  may implement a current provisioning algorithm whereby any one or more of the LED strings  1322 ,  1380  and  1324  may be operated at a commanded percentage intensity using a combination of analog and/or digital current control as discussed above. 
     As per one example, DC stage  1340  may be commanded to a current magnitude of 1.2 A, but each of LED strings  1322 ,  1380  and  1324  may only require 0.4 A on average via appropriate PWM control of their associated power switches (e.g., FETs  1350 ,  1352  and  1386 , respectively) to operate at their respective commanded intensity. In such an instance, 1.2 A may be conducted instantaneously by any one LED string  1322 ,  1380  and  1324  at a time (e.g., only one of LED strings  1322 ,  1380  and  1324  may be conductive at any given time), but through time division multiple access (TDMA) control, each LED string may be operating at 33% duty cycle to receive only the required 0.4 A on average to operate at its commanded intensity. It should be noted that through analog and/or digital current control and proper time division multiple access to such controlled current, any one LED string may operate at any intensity (e.g., 0-100%) at any given time (e.g., any one LED string may be conductive to the mutual exclusion of all of the other LED string conductivity states) to operate on average at the commanded intensity. 
     Examples of such TDMA control are illustrated in  FIGS. 15A, 15B and 15C . In  FIG. 15A , for example, in any given TDMA period  1502 , any LED string (e.g., any of LED strings  1322 ,  1380  and/or  1324  of  FIG. 13 ) may be allocated a time slot (e.g., time slots  1504 ,  1506  and  1508 , respectively) within which any one LED string may receive any magnitude percentage (e.g., 0-100%) of any of an analog and/or a digitally controlled current signal (e.g., current signals  1392 ,  1394  and  1396  of  FIG. 13 , respectively). 
     In time slot  1504 , for example, processor  1304  may command LED string  1322  to conduct a percentage (e.g., 100%) of the maximum available current by causing a maximum magnitude of bias current from a corresponding DC stage (e.g., DC stage  1340 ) to be conducted by LED string  1322 . Capacitor  1368  may, for example, be utilized to extend the on-time of LED string  1322  by allowing the current conducted at the end of time slot  1504  to decay into the beginning of time slot  1506  in accordance with the RC time constant created by capacitor  1368  in combination with the resistance of each LED in LED string  1322 . In such an instance, for example, the light emitted by LED string  1322  at the end of time slot  1504  may be blended with the light emitted by LED string  1380  at the beginning of time slot  1506  so as to implement true mixing of the light emitted by LED string  1322  with the light emitted by LED string  1380  across the end of time slot  1504  and into the beginning of time slot  1506 . 
     In time slots  1506  and  1508 , LED strings  1380  and  1324 , respectively, may similarly be programmed to receive analog and/or digitally controlled current signals so that a percentage (e.g., 100%) of the maximum available current from DC stage  1340  may be received by each of LED strings  1380  and  1324  in their respective time slots. Capacitors  1372  and  1370  may, for example, be similarly utilized to extend the on-time of LED strings  1380  and  1324 , respectively, by allowing the current conducted at the end of time slot  1506  to decay into the beginning of time slot  1508  and by allowing the current conducted at the end of time slot  1508  to decay into the beginning of time slot  1504  in accordance with the RC time constants created by capacitors  1372  and  1370 , respectively, in combination with the resistance of each LED in LED strings  1380  and  1324 , respectively. In such an instance, for example, the light emitted by LED string  1380  at the end of time slot  1506  may be blended with the light emitted by LED string  1324  at the beginning of time slot  1508  and the light emitted by LED string  1324  at the end of time slot  1508  may be blended with the light emitted by LED string  1322  at the beginning of time slot  1504 . 
     It should be noted that since each of LED strings  1322 ,  1380  and  1324  receive a maximum bias current magnitude in each of respective time slots  1504 ,  1506  and  1508  and since each of time slots  1504 ,  1506  and  1508  are of equal time duration, the average amount of current conducted by each of LED strings  1322 ,  1380  and  1324  over multiple time periods  1502  is substantially equal to about ⅓ the maximum current available from DC stage  1340 . 
     It should be further noted that current conducted by LED strings  1322 ,  1380  and  1324  in each of time slots  1504 ,  1506  and  1508 , respectively, may be modulated (e.g., pulse width modulated) to further reduce the average amount of current conducted over time. As discussed above, for example, any one of 256 duty cycle selections may be made by processor  1304  such that the amount of current conducted by each LED string  1322 ,  1380  and  1324  in each time slot  1504 ,  1506  and  1508 , respectively, may be further reduced on average by the duty cycle selection of control signals  1354 ,  1342  and  1356 , respectively. 
     Turning to  FIG. 15B , in any given TDMA period  1510 , any one or more LED strings (e.g., any of LED strings  1322 ,  1380  and/or  1324  of  FIG. 13 ) may be denied a time slot (e.g., time slot  1514  does not provide for an active current conduction state within which LED string  1380  may receive current). As per an example, only two time slots (e.g., time slots  1512  and  1516 ) may be allocated within which any two LED strings (e.g., LED strings  1322  and  1324 , respectively) may receive any of an analog and/or a digitally controlled current signal. 
     In time slot  1512 , for example, processor  1304  may command LED string  1322  to conduct a percentage (e.g., 100%) of the maximum available current by causing a maximum magnitude of bias current from a corresponding DC stage (e.g., DC stage  1340 ) to be conducted by LED string  1322 . In time slot  1516 , LED string  1324  may similarly be programmed to receive an analog and/or digitally controlled current signal so that a percentage (e.g., 100%) of the maximum available current from DC stage  1340  may be received by LED string  1324 . 
     It should be noted that since each of LED strings  1322  and  1324  receive a maximum bias current magnitude in each of respective time slots  1512  and  1516  and since time slot  1512  is twice the duration of time slot  1516 , the average amount of current conducted by LED string  1322  over multiple time periods  1510  is substantially equal to about ⅔ the maximum current available from DC stage  1340  and the average amount of current conducted by LED string  1324  over multiple time periods  1510  is substantially equal to about ⅓ the maximum current available from DC stage  1340 . 
     It should be further noted that current conducted by LED strings  1322  and  1324  in each of time slots  1512  and  1516 , respectively, may be modulated (e.g., pulse width modulated) to further reduce the average amount of current conducted over time. As discussed above, for example, any one of 256 duty cycle selections may be made by processor  1304  such that the amount of current conducted by each LED string  1322  and  1324  in each time slot  1512  and  1516 , respectively, may be further reduced on average by the duty cycle selection of control signals  1354  and  1356 , respectively. 
     Turning to  FIG. 15C , in any given TDMA period  1520 , any one or more LED strings (e.g., any of LED strings  1322 ,  1380  and/or  1324  of  FIG. 13 ) may be denied a time slot (e.g., time slots  1524  and  1526  do not provide for an active current conduction state within which LED string  1380  and  1324  may receive current). As per an example, only one time slot (e.g., time slot  1522 ) may be allocated within which an LED string (e.g., LED string  1322 ) may receive any of an analog and/or a digitally controlled current signal. 
     In time slot  1522 , for example, processor  1304  may command LED string  1322  to conduct a percentage (e.g., 100%) of the maximum available current by causing a maximum magnitude of bias current from a corresponding DC stage (e.g., DC stage  1340 ) to be conducted by LED string  1322 . It should be noted that since LED string  1322  receives a maximum bias current magnitude in time slot  1522  and since time slot  1522  is the same duration as time period  1520 , the average amount of current conducted by LED string  1322  over multiple time periods  1520  is substantially equal to all of the maximum current available from DC stage  1340 . 
     It should be further noted that current conducted by LED string  1322  in time slot  1522  may be modulated (e.g., pulse width modulated) to further reduce the average amount of current conducted over time. As discussed above, for example, any one of 256 duty cycle selections may be made by processor  1304  such that the amount of current conducted by LED string  1322  in time slot  1522  may be further reduced on average by the duty cycle selection of control signal  1354 . 
     Turning to  FIG. 16 , indoor horticultural system  1600  is exemplified, which may include a horticultural lighting system (e.g., horticultural lighting fixtures  1604 - 1612  as exemplified by the lighting fixtures of  FIGS. 1, 9, 10, 11 and/or 13 ) each implementing any number of wired control topologies (e.g., DMX, I2C, Ethernet, USB, DALI, etc.) and/or any number of wireless control topologies (e.g., Wi-Fi, thread-based mesh, Bluetooth, ZigBee, etc.) that may be utilized to control, for example, intensity, color temperature and/or color spectrum as well as any other attribute of light that may be emitted by the horticultural lighting fixtures. 
     Indoor horticultural system  1600  may also contain any number of area sensors (e.g., sensors  1674 - 1677 ), which may be used to detect, for example, occupancy, room temperature, humidity, etc. and may provide an associated status signal (e.g., thread-based mesh network status signal) that may be indicative of the sensors&#39; status (e.g., temperature reading, humidity level, motion detection, etc.). Plant-based sensors may also be paired with each plant of the grow bed (e.g., plant/sensor pairs  1630 / 1631  through  1646 / 1647 ) so that parameters (e.g., temperature, humidity, light intensity, color temperature, spectral content, moisture, pH, canopy height, etc.) may be sensed for each plant, or group of plants, and reported at regular time intervals via an associated status signal (e.g., thread-based mesh network status signal). It should be noted that each sensor of  FIG. 16  may include a computing module (not shown), which may be used to administer communications, conduct sensor measurements and sensor measurement/status reporting and whose operational power may be derived from a solar cell (not shown) and/or internal battery (not shown). 
     Indoor horticultural system  1600  may also include nutrient distribution  1654  that may provide the nutrients and water that may be required by each plant of each grow bed(s). Nutrient distribution may be implemented as a closed-loop system, whereby nutrients and water may be extracted from their respective storage containers (not shown) and mixed to proper proportions. Once properly mixed, the nutrient solution may be pumped (e.g., at a monitored flow rate) into hydroponic flood benches and/or trough benches (not shown) to be delivered for consumption by each plant of each grow bed that may be contained within indoor horticultural system  1600 . Any unused nutrient solution retrieved from nutrient distribution  1654  may be collected, filtered and prepared to be recirculated to the hydroponic flood benches and/or trough benches. Nutrient distribution  1654  may also include sensors (not shown), which may be used to test the collected nutrient flow for any deficiencies and subsequently reported as additional status information which may then be used to adjust (e.g., automatically via master controller  1688 ) the nutrient/water content for optimized growth of the associated plants in the associated grow beds. 
     As shown, indoor horticultural system  1600  may include lighting systems that may be included within any facility that may exhibit structural components such as walls (not shown) and ceilings (e.g., ceiling  1696 ). Each of the lighting fixtures, sensors and associated control elements of indoor horticultural system  1600 , therefore, may be deployed within such structural components of the facility as a fixed or permanent asset. 
     For example, light controller  1692  may be deployed within ceiling  1696  as a fixed asset within indoor horticultural system  1600 . Light controller  1692  may, for example, include a DMX master controller (not shown) that may receive wireless commands (e.g., from master controller  1688 ) and in response, may control the desired intensity of each horticultural light fixture  1604 - 1612  (e.g., each LED array of each horticultural light fixture  1604 - 1612 ) accordingly. In one embodiment, for example, each LED array of each horticultural light fixture  1604 - 1612  may exist within the same DMX universe and may be responsive to an 8-bit intensity control word received within its uniquely designated DMX slot from light controller  1692 . 
     Other fixed assets within indoor horticultural system  1600  may include, for example, horticultural lighting fixtures  1604 - 1612  and their associated height control mechanisms (e.g., winch mechanisms that may control the length of cable assemblies  1602 ). Cable assemblies  1602 , for example, may be controlled by a height controller (e.g., height controller  1652 ) that may be used to raise and lower horticultural lighting fixtures  1604 - 1612  in accordance with the canopy height of the associated plants (e.g., as may be reported by plant/sensor pairs  1630 / 1631  to  1646 / 1647  to master controller  1688 ). For example, as the plants grow taller, it may be necessary to raise the associated horticultural lighting fixtures  1604 - 1612  in relation to the extended height of the associated plant canopies. 
     In one embodiment, each of the horticultural lighting fixtures and associated sensors/controllers of indoor horticultural system  1600  may be interconnected wirelessly (e.g., via a thread-based mesh network). Accordingly, for example, indoor horticultural system  1600  may be implemented as a wireless personal area network (WPAN) utilizing a physical radio layer (e.g., as defined by the IEEE 802.15.4 communication standard). As such, the thread-based mesh network may utilize an encapsulation and header compression mechanism (e.g., 6LoWPAN) so as to allow data packets (e.g., IPv6 data packets) to be sent and received over the physical radio layer. Messaging between each device within indoor horticultural system  1600  may be implemented using a messaging protocol (e.g., user datagram protocol (UDP)), which may be preferred over an alternative protocol such as the transmission control protocol (TCP). 
     In addition, each device may use an application layer protocol for delivery of the UDP data packets to each device. Such application layer protocols may include the Constrained Application Protocol (CoAP), Message Queue Telemetry Transport (MQTT) or the Extensible Messaging and Presence Protocol (XMPP) within the thread-based mesh network as contrasted with the Hypertext Transport Protocol (HTTP) as may be used, for example, within Internet  1684 . CoAP, for example, may be more conducive for use by the thread-based mesh network, rather than HTTP, due to the smaller packet header size required by CoAP, which may then yield smaller overall packet sizes required by the components of indoor horticultural system  1600  interconnected by the thread-based mesh network. 
     In operation, some components (e.g., horticultural lighting fixtures  1604 - 1612 ) interconnected by the thread-based mesh network of  FIG. 16  may be connected to an alternating current (AC) source that may be used throughout the facility for use with other components requiring AC power for operation, such as heating, ventilation and air conditioning (HVAC) systems, air circulators, humidifiers/dehumidifiers and CO 2  dispensing systems  1694 . Furthermore, operational power derived from the AC source may be further controlled (e.g., via relays) so as to be compliant with, for example, the Energy Star® standard for energy efficiency as promulgated jointly by the Environmental Protection Agency (EPA) and the Department of Energy (DOE). 
     In one embodiment, device  1686  may be used to manually operate indoor horticultural system  1600  wirelessly (e.g., through the use of a thread-based mesh network). For example, device  1686  may send a control signal to light controller  1692  via the thread-based mesh network to cause one or more horticultural lighting fixtures  1604 - 1612  to illuminate in accordance with a particular light prescription (e.g., intensity, color temperature and/or color spectrum) as may be contained within database  1690 . Alternately, device  1686  may send a control signal to height controller  1652  via the thread-based mesh network so as to cause the height between one or more horticultural lighting fixtures  1604 - 1612  to change with respect to a height of the one or more plant canopies contained within indoor horticultural system  1600 . In alternate embodiments, master controller  1688  may completely automate the operation of indoor horticultural system  1600  by accessing grow recipes from database  1690 , which may then be used to control the lighting in a specific manner to produce a specific effect (e.g., modify the intensity, color temperature and/or color spectrum of each of horticultural lights  1604 - 1612  to simulate a rising sun, a midday sun and a setting sun in direction  1698  from east to west). 
     Indoor horticultural system  1600  may, for example, be sensitive to control signals as may be provided by controlling entities (e.g., external BACnet network  1682 ) that may exist external to the thread-based mesh network of  FIG. 16 . As per an example, one or more entities within indoor horticultural system  1600  may be BACnet enabled, which may allow communication with a BACnet enabled border router (e.g., master controller  1688 ). In such an instance, control signals bound for indoor horticultural system  1600  may be transmitted by external BACnet network  1682  via Internet  1684  and propagated throughout indoor horticultural system  1600  via master controller  1688 . Conversely, status information related to indoor horticultural system  1600  may be gathered by master controller  1688  and may then be disseminated to external BACnet network  1682  via Internet  1684 . Accordingly, many grow facilities as exemplified by  FIG. 16  may exist and may be geographically dispersed and remotely controlled via external BACnet network  1682 . 
     Each of horticultural light fixtures  1606 - 1612  may, for example, generate relatively wide beam patterns (e.g., beam patterns  1615 - 1621 , respectively) that may be produced by a particular LED/lens combination (e.g., the LED/lens combination as discussed above in relation to  FIG. 6 ), which may produce maximum intensity at the edges of the beam pattern. Accordingly, for example, the resulting light distribution (e.g., the light distribution of  FIG. 7A ) may produce a uniform illuminance onto a plant canopy directly below each of horticultural light fixtures  1606 - 1612  (e.g., uniform illuminance distributions  1622 - 1628 ) while producing relatively equal intensities on adjacent plants. In alternate embodiments, illuminance distributions  1622 - 1628  may increase as the angle of incidence increases with respect to the optical axis of illuminance distributions  1622 - 1628 . 
     As an example, horticultural light  1606  may produce a uniform illuminance, or an increasing illuminance from centerbeam outward (e.g., illuminance  1622 ) onto a plane that may be defined by the canopy of plant  1632  due to the increasing intensity of light at increasing angles with respect to the optical axis of horticultural light  1606 . Since the intensity of light generated by horticultural light  1606  is greatest at the edges of light distribution  1615 , plants  1630  and  1634  may receive a substantially equal intensity of light as received by plant  1632  from horticultural light  1606  owing to the effects of the inverse square law as discussed above. In such an instance, each plant may not only receive a uniform illuminance, or an increasing illuminance from centerbeam outward, onto its canopy by an associated horticultural light fixture, but may also receive substantially equal intensities of light on the sides of the plant by adjacent horticultural light fixtures, thereby more correctly simulating sunlight, since light is being received by each plant from multiple angles. It should be noted that horticultural light fixtures  1604 - 1612  may be arranged not only as a linear-array, but as a two-dimensional array (e.g., arranged along rows and columns) such that each plant may receive light from its associated horticultural light fixture and adjacent horticultural light fixtures at all angles formed from a 360-degree light distribution (e.g., each plant may receive a substantially uniform cone of light from its associated and adjacent horticultural light fixtures). 
     Plants on the edge of each grow bed (e.g., plants  1630  and  1646 ) may receive light from their associated horticultural lighting fixtures configured at angles that are different than the angles of horticultural lighting fixtures  1606 - 1612 . For example, horticultural lighting fixtures  1604  and  1605  may be angled (e.g., via height controller  1652  and associated cable assemblies  1602 ) as shown to direct light onto their associated plants (e.g., plants  1630  and  1646 , respectively) as well as the adjacent plants (e.g., plants  1632  and  1644 , respectively). In addition, each of horticultural light fixtures  1604 - 1605  may, for example, generate relatively narrow beam patterns (e.g., beam patterns  1613 - 1614 , respectively) that may be produced by a particular LED/lens combination (e.g., the LED/lens combination as discussed above in relation to  FIG. 3 ), which may similarly produce maximum intensity at the edges of the beam pattern as discussed above in relation to  FIGS. 4A and 4B  so as to illuminate adjacent plants (e.g.,  1632  and  1644 , respectively) with substantially the same intensity as associated plants  1630  and  1632 , respectively. 
     In alternate embodiments, each of horticultural light fixtures  1604 - 1612  may, for example, generate relatively wide beam patterns (e.g., beam patterns  1613 - 1621 , respectively) that may be produced by bare LEDs (e.g., standard LED packages producing a Lambertian beam pattern without an associated lens) where each bare LED may be mounted at varying angles with respect to one another. In such an instance, for example, a first bare LED may be mounted within a light fixture (e.g., light fixture  1606 ) such that the optical axis of the first LED may align with a light distribution (e.g., light distribution  1622 ) that may be directed toward a target (e.g., plant  1632 ). Second and third bare LEDs may alternately be mounted within a light fixture (e.g., light fixture  1606 ) at opposing angles such that the optical axes of the first and second bare LEDs may align with the edges of a light distribution (e.g., light distribution  1615 ). For example, a second bare LED may be mounted within light fixture  1606  such that its optical axis may be directed at its respective target (e.g., plant  1630 ) and a third bare LED may be mounted within light fixture  1606  such that its optical axis may be directed at its respective target (e.g., plant  1634 ). Accordingly, light fixture  1606  may, for example, not only provide direct lighting to plant  1632 , but may also provide cross-lighting for adjacent plants  1630  and  1634  without the use of lenses that may optically vary the light distributed by light fixture  1606 . 
     Turning to  FIG. 17 , a schematic diagram of a lighting system is exemplified, whereby the forward voltage of one or more LEDs of an LED string (e.g., LED string  1732 ) of a light fixture (e.g., master light fixture  1722 ) may be utilized as a relatively low-current power supply for auxiliary purposes (e.g., to provide a 0-10V dimming controller without the need for a dedicated 0-10V controller power supply). For example, the forward voltage of several LEDs (e.g., two LEDs  1702 ) may combine in series to form a cumulative forward voltage equal to the sum of the individual forward voltage of each LED (e.g., 2*6=12 volts at node  1734 ) and may be used as an auxiliary supply voltage. The impedance of a rheostat (e.g., potentiometer  1704 ) may be selected such that very little current may be derived from the LED string at node  1734  while allowing a variable voltage to be selected manually (e.g., by an operator in control of potentiometer  1704 ) and applied to the non-inverting input of operational amplifier  1710 . In one embodiment, switch  1708  may be implemented as a removable, hard-wired selector (e.g., PCB jumper) that may allow the wiper voltage of potentiometer  1704  to be applied to operational amplifier  1710 . 
     In operation, operational amplifier  1710  may seek to maintain the voltage at its inverting input substantially equal to the voltage at its non-inverting input through operation of negative feedback applied to its inverting input as shown. As such, the conductive state of transistor  1728  may be selected by operational amplifier  1710  (e.g., through selection of the voltage, V b , applied to the base terminal of transistor  1728 ) such that the voltage at node  1726  (e.g., a 0-10V control voltage, V CTRL ) may be maintained to be proportional to the voltage selected by potentiometer  1704  (V POT ) according to voltage follower equation (1): 
                       V   CTRL     =       V   POT     ⁡     (     1   +       R   1720       R   1712         )         ,           (   1   )               
where R 1720  is the resistance magnitude of resistor  1720  and R 1712  is the resistance magnitude of resistor  1712 . Writing V CTRL  in terms of the current (I 1728 ) conducted by transistor  1728 :
 
 V   CTRL   =V   b   +I   1728   R   1714   +V   EB ,  (2)
 
where R 1714  is the resistance magnitude of resistor  1714  and V EB  is the emitter-base voltage of transistor  1728  and combining equation (1) with equation (2):
 
                       I   1728     =           V   POT     ⁡     (     1   +       R   1720       R   1712         )       -     V   b     -     V   EB         R   1714         ,           (   3   )               
it can be seen from equation (3) that the magnitude of current conducted by transistor  1728 , I 1728 , may be directly dependent upon the base voltage, V b , of transistor  1728  as applied by operational amplifier  1710 . Turning back to equation (1), the voltage at node  1726  (V CTRL ) follows the voltage selected by potentiometer  1704  (V POT ) as modified by the gain constant (1+R 1720 /R 1712 ) and the current conducted by current sink  1718  may be adjusted (e.g., increased) by adjusting (e.g., decreasing) the base voltage, V b , of transistor  1728  via operational amplifier  1710 . As the voltage at node  1726 , V CTRL , decreases below a threshold voltage magnitude, shunt transistor  1736  may be utilized to shunt the voltage at node  1726 , V CTRL , to a reference voltage (e.g., the collector-emitter voltage of transistor  1736  referenced to ground potential) so as to extend the voltage control range at node  1726  below that which may be accommodated by transistor  1728 .
 
     Master light fixture  1722  (e.g., via 0-10V driver  1730 ) and slave light fixtures  1724  may be configured with 0-10V drivers that may source current into node  1726  and may derive their intensity control signal, V CTRL , from node  1726  as well. As the number of slave light fixtures  1724  increases, so may the current magnitude conducted by current sink  1718 . Through operation of equation (3) as discussed above, it can be seen that an increase in current conducted by current sink  1718  (e.g., as may be required through the addition of slave light fixtures  1724  and master light fixture  1722 ) may be accommodated by a corresponding decrease in base voltage, V b . Accordingly, the number of slave light fixtures and master light fixture that may be accommodated by current sink  1718  may be directly proportional to the current conduction capability of current sink  1718 . In one embodiment, for example, the current conduction capability of current sink  1718  may be selected to be approximately 50 mA, which may then accommodate up to 99 slave light fixtures (and one master light fixture  1722 ), such that up to 100, 0-10V drivers may each source 500 uA of current into node  1726 . 
     In an alternate embodiment, switch  1708  (e.g., a PCB jumper) may be selected such that a wireless control module (e.g., wireless control  1706 ) may instead control the voltage at the non-inverting input of operational amplifier  1710 , which may then control the voltage at node  1726 , V CTRL , as discussed above. It can be seen, therefore, that the intensity of multiple lights within an indoor horticultural system (e.g., horticultural lights  1604 - 1612  of indoor horticultural system  1600  of  FIG. 16 ) may be controlled by a light controller (e.g., light controller  1692  of  FIG. 16 ) operated either through manual control (e.g., potentiometer  1704 ) or through wireless control (e.g., wireless control  1706 ) such that all horticultural lights  1604 - 1612  may be operated at substantially equal intensities via a single control input. 
     Turning to  FIG. 18 , an alternate embodiment of agricultural light fixture  1800  is exemplified whereby arrays of LEDs may not be arranged in columns or rows, but may instead be arranged in clusters of between about 2-10 LEDs per cluster (e.g., groups of 3-4 LEDs in each cluster  1802  and  1812 ). Each cluster of agricultural light fixture  1800  may, for example, include any combination of color spectrum LEDs and/or color temperature LEDs. Further, each individual LED in each cluster of agricultural light fixture  1800  may exist within its own LED string, or conversely, may share an LED string with one or more other LEDs in the same cluster. 
     As per one example, a cluster (e.g., cluster  1812 ) may be comprised of four LEDs (e.g., LEDs  1804 ,  1806 ,  1808  and  1810 ), whereby LED  1804  may exist within a first LED string (e.g., LED string  1322  of  FIG. 13 ), LED  1806  may exist in a second LED string (e.g., LED string  1380  of  FIG. 13 ) and LEDs  1808 - 1810  may exist in a third LED string (e.g., LED string  1324  of  FIG. 13 ). The remaining clusters of agricultural light fixture  1800  may be similarly configured, whereby for example, one such cluster  1802  may include LED  1814  that may exist within the same LED string as LED  1804 , LED  1816  that may exist within the same LED string as LED  1806  and LEDs  1818 - 1820  that may exist within the same LED string as LEDs  1808 - 1810 . 
     LED  1804  may, for example, be implemented with an LED having a specific color spectrum (e.g., blue) or a specific color temperature (e.g., 6500K), LED  1806  may, for example, be implemented with an LED having a specific color temperature (e.g., 3000K white LED) and LEDs  1808 - 1810  may, for example, be implemented with LEDs having a specific color spectrum (e.g. red). As discussed above, the remaining clusters within agricultural light fixture  1800  may be similarly configured, whereby for example, LED  1814  may, for example, be implemented with an LED having the same specific color spectrum or the same specific color temperature as LED  1804 , LED  1816  may, for example, be implemented with an LED having the same specific color temperature as LED  1806  and LEDs  1818 - 1820  may, for example, be implemented with LEDs having the same specific color spectrum as LEDs  1808 - 1810 . 
     In one embodiment, the number of LEDs that may exist within any given LED string may be chosen such that the combined forward voltage of any one LED string is substantially equal to the combined forward voltage of the remaining LED strings. As per one example, LEDs  1804 ,  1814  and the remaining LEDs in similar positions within the remaining clusters of agricultural light fixture  1800  (e.g., the upper left-hand corner of each cluster) may exist within the same LED string (e.g., LED string  1322  of  FIG. 13 ) where the LED string may exhibit a combined forward voltage equal to the product of the number of LEDs in the LED string (e.g., 45 clusters with one LED per cluster equals 45 LEDs) and the forward voltage of each LED (e.g., 3 volts) for a combined forward voltage approximately equal to 45*3=135 volts. 
     As per another example, LEDs  1808 - 1810  and the remaining LEDs in similar positions within the remaining clusters of agricultural light fixture  1800  (e.g., the lower row of each cluster) may exist within the same LED string (e.g., LED string  1324  of  FIG. 13 ) where the LED string may exhibit a combined forward voltage equal to the product of the number of LEDs in the LED string. However, since the forward voltage of each LED in LED string  1324  may be different (e.g., 2 volts) than the forward voltage of LEDs in the other LED strings, an increased number (e.g., 67-68 LEDs) for a combined forward voltage approximately equal to 67*2=134 volts or 68*2=136 volts may be utilized. In addition, since a higher number of clusters (e.g., 45) exist than are needed to accommodate two LEDs per cluster, some of the clusters may include only a single, 2-volt LED. In such an instance, those clusters exhibiting only a single, 2-volt LED may be symmetrically arranged within the array of clusters of agricultural light fixture  1800  (e.g., every other cluster may exhibit a single, 2-volt LED). 
     As discussed in more detail below, each cluster of agricultural light fixture  1800  may include an optical puck (e.g., optical puck  1950  as exemplified in the top orthographic view of  FIG. 19B  and the bottom orthographic view of  FIG. 19C ) that may provide an optical lens for each LED in each cluster having between about 2-10 LEDs per cluster (e.g., 4 optical lenses  1952  per cluster as exemplified in  FIG. 19B ). Each optical lens  1952  of optical puck  1950  may, for example, provide optical characteristics (e.g., optical characteristics as discussed above in relation to  FIGS. 3-4 and/or 6-7 ), but may be arranged differently (e.g., as compared to the lens arrays as discussed above in relation to  FIGS. 2A and 2B ). Instead, the LED/lens pairs of agricultural light fixture  1800  may be arranged in groups of about 2-10 LED/lens pairs (e.g., 4 LED/lens pairs), each LED of which may be in electrical communication with one or more LEDs of the remaining LED/lens pairs as discussed above. 
     As discussed in more detail below, cover  1822  may be disposed in relation to agricultural light fixture  1800  such that each optical puck may protrude through apertures disposed within cover  1822  (e.g., aperture  1824 ), such that no further optical treatment (e.g., sheet lens) may be applied to the light generated from each cluster beyond the optical treatment provided by each lens of each optical puck. Accordingly, increased efficiency (e.g., between about 6-12% increased efficiency) may be achieved by eliminating the use of a sheet lens. 
     Turning to  FIG. 19A , orthographic view  1900  of a portion of agricultural light fixture  1800  of  FIG. 18  is illustrated, with the cover (e.g., cover  1822  of  FIG. 18 ) removed to expose the inner rib architecture. In particular, multiple ribs (e.g., ribs  1904  and  1916 - 1922 ) may extend approximately the length of agricultural light fixture  1800  and may support multiple PCBs (e.g., PCBs  1902  and  1908 - 1914 ) that may be disposed upon ribs  1904  and  1916 - 1922 , respectively, and may also extend approximately the length of agricultural light fixture  1800 . As illustrated, each rib (e.g., rib  1904 ) may, for example, support a PCB (e.g., PCB  1902 ) that may include multiple optical pucks (e.g., optical pucks  1906 ), each optical puck including multiple (e.g., 3-4) lenses. Clusters of LEDs (not shown) may be disposed below each optical puck (e.g., LEDs may be disposed within indented portions  1954  of optical puck  1950  as exemplified in  FIG. 19C ), such that each lens of each optical puck may be disposed in relation to each corresponding LED of each cluster. As per one example, each LED and corresponding lens of each LED/lens pair may be disposed in relation to one another as discussed above (e.g., as exemplified in relation to LED  306 /lens  314  of  FIG. 3  and LED  606 /lens  614  of  FIG. 6 ). 
     PCB  1902  may include electrically conductive traces (not shown), such that each LED of each cluster may be electrically connected to each corresponding LED of each remaining cluster on PCB  1902 . Furthermore, corresponding LEDs of the remaining clusters of the remaining PCBs (e.g., PCBs  1908 - 1914 ) may be electrically interconnected to form multiple LED strings (e.g., LED strings  1322 ,  1380  and  1324  as discussed above in relation to  FIG. 13 ), whereby each LED string may exhibit a combined forward voltage that may be substantially equal as discussed above. Each LED string may then be illuminated on command as discussed above (e.g., as in relation to  FIGS. 13 and 15 ). 
     Heat generated by illumination of the LEDs of the clusters of agricultural light fixture  1800  mounted to each of PCBs  1902  and  1908 - 1914  may be conducted away from PCBs  1902  and  1908 - 1914  by the corresponding ribs  1904  and  1916 - 1922 , respectively. Accordingly, panel  1924  may receive the heat conducted by each of ribs  1904  and  1916 - 1922  by virtue of the conductive path implemented by each rib to panel  1924 . Additionally, an electrically insulative, thermally conductive layer (e.g., a polyester film not shown) may exist to conduct heat to panel  1822 ). The conducted heat may then be removed from agricultural light fixture  1800  by convection through circulation of air past panel  1924  and cover  1822 . In addition, ribs  1904  and  1916 - 1922  may provide considerable structural support within agricultural light fixture  1800 , such that in operation (e.g., agricultural light fixture  1800  is inverted as compared to the position shown), panel  1924  may provide a storage surface, or shelf, upon which utility articles may be stored while agricultural light fixture  1800  operates within its associated agricultural facility. 
     Each optical puck may include a trough (e.g., trough  1926  of  FIG. 19B ), within which a compressible device (e.g., an O-ring not shown) may be installed, such that once the panel (e.g., panel  1822  of  FIG. 18 ) encloses agricultural light fixture  1800 , panel  1822  may engage each O-ring of each optical puck to seal the interior of agricultural light fixture  1800  from contaminants (e.g., water, rain, dust, oil, etc.). In addition, gasket  1928  may be utilized to compress against panel  1822  to further protect agricultural light fixture  1900  from external contaminants (e.g., in accordance with the International Electrotechnical Commission Ingress Protection 66 (IP66) standard of protection). 
     Turning to  FIG. 20 , alternate embodiments of lighting fixtures are exemplified, in which bare LEDs (e.g., LEDs without optically varying lenses) may be positioned to project a substantially even target illuminance across a flat surface, or conversely, to project an illuminance onto a flat surface that increases as the angle increases between the lighting fixture and the flat surface. In particular, LEDs exhibiting varying beam angles, but without optical lenses, may be utilized within agricultural lighting fixtures  2002  and  2022 , whereby LED arrays (e.g., LED arrays  2006 ,  2010 ,  2014 ) may exist within agricultural lighting fixture  2002  (e.g., on panels  2004 ,  2008  and  2012 , respectively) and LED arrays (e.g., LED arrays  2026 ,  2030  and  2034 ) may exist within agricultural lighting fixture  2022  (e.g., on panels  2024 ,  2028  and  2032 , respectively) to project illumination beam widths  2016 ,  2018 ,  2020  from agricultural lighting fixture  2002  and to project illumination beam widths  2036 ,  2038  and  2040  from agricultural lighting fixture  2022 . 
     As exemplified in  FIG. 20 , the illumination projected by LED arrays  2010  and  2030  may exhibit wider beam patterns (e.g., greater than 120 degree FWHM) as compared to the narrower beam patterns (e.g., less than 90 degree FWHM) projected by LED arrays  2006 ,  2014 ,  2026  and  2034 . Accordingly, the beam patterns projected by LED arrays  2006  and  2014  may overlap with the beam pattern projected by LED array  2010  at overlap portions  2052  and  2054 , respectively. Similarly, the beam patterns projected by LED arrays  2026  and  2034  may overlap with the beam pattern projected by LED array  2030  at overlap portions  2056  and  2058 , respectively. 
     In addition, the area of overlap portions  2052  and  2054  on surface  2050  may be increased or decreased depending upon the angle at which LED arrays  2006  and  2014  are projecting light with respect to LED array  2010 . Similarly, the area of overlap portions  2056  and  2058  on surface  2050  may be increased or decreased depending upon the angle at which LED arrays  2026  and  2034  are projecting light with respect to LED array  2030 . 
     It can be seen, for example, that by decreasing angles  2042  and  2044 , the area of overlap portions  2052  and  2054  increases. Similarly, for example, by decreasing angles  2046  and  2048 , the area of overlap portions  2056  and  2058  increases. Accordingly, the amount of cross-lighting produced by the agricultural lighting fixtures of  FIG. 20  may be increased or decreased, which may in turn increase or decrease the illuminance projected onto surface  2050 . As such, illuminance variations may be effected without the use of optically varying lenses. 
     Turning to  FIG. 21 , cooling aspects of agricultural light fixture  2100  (e.g., light fixture  100  of  FIG. 1 ) are exemplified. Fan  2108  may, for example, draw external air  2102  into an interior of agricultural light fixture  2100  and may further cause the drawn air to travel in direction  2104  within agricultural light fixture  2100 . As the drawn air travels within agricultural light fixture  2100 , heat may be extracted from within agricultural light fixture  2100  by convection and expelled via exhaust port  2110  as expelled air flow  2106 . Accordingly, expelled air flow  2106  may be expelled from within agricultural light fixture  2100  in a direction opposite to the optical axis of agricultural light fixture  2100  (e.g., optical axis  2112 ). 
     It can be seen, therefore, that if agricultural light fixture  2100  were applied to an indoor horticultural system (e.g., as lights  1604 - 1612  of indoor horticultural system  1600  of  FIG. 16 ), expelled air may be directed toward ceiling  1696  away from plants  1630 - 1646 . By directing the expelled air away from plants  1630 - 1646 , any excess heat that may affect leaf temperature and potentially the reduction of transpiration of the leaves closest to agricultural light fixture  2100  may be mitigated. 
     Turning to  FIG. 22 , cooling aspects of agricultural light fixture  2200  (e.g., light fixture  900  of  FIG. 9 ) are exemplified. Fan  2212  may, for example, draw external air  2202  into an interior of agricultural light fixture  2200  and may further cause the drawn air to travel in directions  2204  and  2206  within agricultural light fixture  2200 . As the drawn air travels within agricultural light fixture  2200 , heat may be extracted from within agricultural light fixture  2200  by convection and expelled via exhaust ports  2214  and  2216  as expelled air flows  2210  and  2208 , respectively. Accordingly, expelled air flows  2210  and  2208  may be expelled from within agricultural light fixture  2200  in a direction opposite to the optical axis of agricultural light fixture  2200  (e.g., optical axis  2218 ). 
     It can be seen, therefore, that if agricultural light fixture  2200  were applied to an indoor horticultural system (e.g., as lights  1604 - 1612  of indoor horticultural system  1600  of  FIG. 16 ), expelled air may be directed toward ceiling  1696  away from plants  1630 - 1646 . By directing the expelled air away from plants  1630 - 1646 , any excess heat that may affect leaf temperature and potentially the reduction of transpiration of the leaves closest to agricultural light fixture  2200  may be mitigated. 
     Other aspects and embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended, therefore, that the specification and illustrated embodiments be considered as examples only, with a true scope and spirit of the invention being indicated by the following claims.