Patent Publication Number: US-7591567-B2

Title: Luminaire with a compound parabolic reflector

Description:
FIELD  
   The field is related generally to luminaries and, more particularly, to luminaires provided to brightly illuminate a strip-like area in front of and to the sides of the luminaire. 
   BACKGROUND  
   Lighting devices with incandescent and arc discharge lamps are routinely used to illuminate the exterior areas of commercial businesses for purposes of enhancing the appearance of the business at night and for promoting interest in the goods and services of the business by actual and potential customers. Restaurants, shopping malls, and automobile dealerships represent just a few of the business types for which exterior luminaires play an important role in marketing and facilitating product sales. 
   In the example of automobile dealerships, exterior area lighting is frequently used to illuminate the exterior surface parking lots which surround the typical automobile dealership. The lighting fixtures are typically pole-mounted so as to distribute light across the exterior surface parking lot. The purpose of the exterior area lighting is to illuminate the rows of automobiles parked side-by-side outside the dealership so that they can be viewed at night by potential customers driving past the dealership and by customers who may walk onto the dealership property. Since automobiles available for sale on a dealership exterior surface parking lot tend to be organized in rows, it is advantageous to provide exterior area luminaires which project uniform bright light in a generally rectangular pattern to the front and sides of the luminaires, concentrated on the row of automobiles. 
   It is particularly advantageous for automobile dealerships to brightly and uniformly illuminate the outermost row of automobiles which is the row which can be most easily seen by passing customers. This outermost row of automobiles is often referred to as the “front line” of automobiles. Bright illumination of these front line automobiles is useful to attract customers by enhancing the gloss, shine and generally attractive appearance of the automobiles available for sale. 
   While many exterior area lighting products are available, such products are not optimally effective in brightly illuminating a generally rectangular area in front of and to the sides of the luminaire. For example, luminaires which include a vertically oriented lamp tend to be effective in producing a more circular lighting effect because of the upright orientation of the lamp arc or filament but tend to be less than satisfactory in generating a rectangular lighting effect for the same reason. A solution to this problem is to provide a luminaire with a horizontally mounted lamp. The horizontal orientation of the lamp arc or filament is more conducive to production of a rectangular lighting effect. However, horizontally mounted lamps tend to be relatively energy inefficient compared with vertically mounted lamps because more energy is required to operate the lamp to overcome the effect of gravity on the lamp arc. 
   While it is important for businesses such as automobile dealerships to use exterior area lighting for purposes of aesthetics and marketing, it is also important to employ exterior area lighting which is energy efficient and which provides the needed illumination at the least possible cost to the business. One way to achieve these efficiencies is to provide exterior lighting which is optimized for efficient area light distribution, thereby providing an opportunity to space the luminaires far apart so as to minimize the number of luminaires required to illuminate a given area. Another way to achieve these efficiencies is to provide exterior area lighting which optimally illuminates the products and things to be illuminated and nothing else, thereby converting consumed energy to useful light. Yet another strategy is to utilize luminaires with generally vertically oriented lamps so as to minimize energy consumption compared to a horizontally mounted lamp. 
   Many governmental entities are enacting rules and regulations requiring use of more energy efficient luminaires. For example, some governmental entities have enacted rules limiting or banning the use of the relatively less efficient luminaires with horizontally oriented lamps. And, governmental entities are adopting building codes and other rules imposing limits on the amount of electrical energy that can be consumed by a commercial business which utilizes exterior area illumination. Use of more efficient luminaires, therefore, is being driven by a growing body of governmental regulations. 
   An issue related to efficient exterior area illumination is the need to avoid what is called “light trespass.” Light trespass refers to spillage of light from one exterior location to an adjacent exterior location. In effect, light trespass represents wasted light. Not only is this inefficient, but such light trespass can be a violation of governmental regulations. 
   As can be appreciated, automobile dealerships with exterior surface parking lots and numerous exterior luminaires must be mindful of avoiding unwanted spillage of light onto the property of adjacent businesses, residences, and roadways. Illumination of front line automobiles at the dealership should be targeted and effective to promote the sale of product while minimizing any unwanted impact on the enjoyment of adjacent property by others or of operation of motor vehicles passing by the automobile dealership on an adjacent roadway. 
   There exists a need exists for an improved luminaire, particularly a luminaire which provides desired lighting distribution and efficiency. 
   SUMMARY 
   A luminaire for illuminating a target zone area to the front of and to the sides of the luminaire. The luminaire includes a housing, a lamp holder in the housing positioned to support an electric lamp in a generally vertical orientation, and a compound parabolic reflector in the housing. The housing includes walls defining a bottom opening through which light exits the housing. 
   The compound parabolic reflector partially surrounds a lamp with a vertical light source with plural source-sectors which correspond to the three-dimensional space occupied by the light emitting segment of a lamp when mounted in the lamp holder. Preferred embodiments of the compound parabolic reflector include a segmented center portion and segmented side portions. The preferred segmented center portion has first and second side edges and a first plurality of center segments. In the preferred embodiment, each of the first plurality of center segments is parabolic in cross-section, such parabolic cross-sections have focal points in different plural source-sectors, such that each segment directs a preponderance of its reflected light toward a particular target zone subregion in front of the luminaire. 
   The preferred segmented side portions are each joined to the center portion along a respective one of the side edges. The preferred side portions each have a second plurality of side segments each of which is parabolic in cross-section, such parabolic cross-sections have focal points along the source-sectors such that each segment directs a preponderance of its reflected light toward a particular target zone subregion to a respective side of the luminaire. Generally uniform illumination of the target zone is provided by the first and second plurality of parabolic segments. Various other aspects and preferred features of the luminaires are described herein. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS  
     Exemplary luminaires may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements throughout the different views. For convenience and brevity, like reference numbers are used for like part amongst the alternative embodiments. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the accompanying drawings: 
       FIG. 1  is a perspective view of an exemplary luminaire including a compound parabolic reflector shown mounted on a pole; 
       FIG. 2  is a further perspective view of the luminaire of  FIG. 1 ; 
       FIG. 3  is a bottom-side view of the luminaire of  FIG. 1  but with the lamp removed, thereby showing a lamp holder; 
       FIG. 4  is a schematic illustration of exemplary target zones illuminated by the luminaire of  FIG. 1 ; 
       FIG. 5  is a computer-generated isolux map showing a simulation of light produced by the luminaire of  FIG. 1  and an inset of such luminaire; 
       FIG. 6  is a further perspective view of the luminaire of  FIG. 1  but including an exemplary light shield; 
       FIG. 7  is a perspective view of the luminaire of  FIG. 6 ; 
       FIG. 8  is a computer-generated isolux map showing a simulation of light produced by the luminaire of  FIG. 6  and an inset of such luminaire; 
       FIG. 9  is a perspective view of an exemplary compound parabolic reflector for use in the luminaire of  FIGS. 1 and 6 ; 
       FIG. 10  is a front side elevation view of the reflector of  FIG. 9 ; 
       FIG. 11  is a rear side elevation view of the reflector of  FIG. 9 ; 
       FIG. 12  is a plan view of the outer surface of a segmented center portion of the reflector of  FIG. 9 ; 
       FIG. 13  is an elevation view of the outer surface of a segmented first side portion of the reflector of  FIG. 9 ; 
       FIG. 14  is an elevation view of the outer surface of a segmented second side portion of the reflector of  FIG. 9 ; 
       FIG. 15  is a two-dimensional ray trace from the segmented center reflector portion taken along section  15 - 15  of  FIG. 10 . Such sectional view includes a cross-section representation of the center reflector portion indicating its plural different parabolic portions; 
       FIG. 16  is a cross-sectional view of an exemplary segmented center reflector portion taken along section  15 - 15  of  FIG. 10  including a superimposed light-emitting segment location and parabola major axes and foci; 
       FIG. 17  is an enlarged view of the light-emitting segment location of  FIG. 16  showing plural regions; 
       FIG. 18  is a schematic cross-sectional view of an exemplary segmented center reflector portion taken along section  15 - 15  of  FIG. 10  showing representative circular fits for each segment; 
       FIG. 19  is a top plan view of the outer surface of the segmented first side portion of the reflector of  FIG. 13  including parabola major axes and foci in a horizontal plane; 
       FIG. 20  is a cross-sectional view of a first side segment reflector section taken along section  20 - 20  of  FIG. 19  including parabola major axes and foci in a vertical plane; 
       FIG. 21  is a cross-sectional view of a second side segment reflector section taken along section  21 - 21  of  FIG. 19  including parabola major axes and foci in a vertical plane; 
       FIG. 22  is a cross-sectional view of a third segmented side reflector section taken along section  22 - 22  of  FIG. 19  including parabola major axes and foci in a vertical plane; 
       FIG. 23  is a cross-sectional view of a fourth segmented side reflector section taken along section  23 - 23  of  FIG. 19  including parabola major axes and foci in a vertical plane; and 
       FIG. 24  is a schematic view of an exemplary segmented side reflector portion showing a representative circular fit in a generally vertical plane. 
   

   While the apparatus is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments and methods is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
   DETAILED DESCRIPTION 
     FIGS. 1-3  and  6 - 7  show embodiments of a luminaire  10  with a compound parabolic reflector  11 . A “luminaire” as used herein means or refers to a lighting device consisting of one or more electric lamps and with all of the necessary parts and wiring. Reflector  11  is referred to herein as “compound” and “parabolic” because reflector  11  is segmented, with each of the plural segments representing part of a parabola. Reflector  11  takes advantage of the plural segments and the light-directing properties of the partial parabolic portions to produce a lighting effect which brightly, uniformly, and efficiently illuminates a target zone  13  ( FIGS. 4 ,  5 ,  8 ) of a generally rectangular area to the sides and front of the luminaire  10 . For convenience and brevity, the visible spectra electromagnetic radiation discharged from luminaire  10  will be referred to herein as “light” or “light energy.” 
   Luminaire  10  has utility in many different commercial exterior area lighting applications where intense, uniform illumination of a strip of surface area (i.e., target zone  13 ) is desired. Such applications would include, for example, illumination of the “front line” of automobiles parked outside an automobile dealership or illumination of the drive-up lane or lanes of a fast-food restaurant. 
   Luminaire  10  is highly efficient because of the targeted lighting effect provided by the partial parabolic segments of reflector  11 . Luminaire  10  is capable of brightly illuminating large surface areas, thereby providing lighting planners with the opportunity to space the luminaires  10  further apart while providing a consistent high level of lighting. This, in turn, permits usage of relatively fewer luminaires  10  for a given area, thereby reducing energy consumption and the long-term costs associated with operating luminaire  10 . The targeted lighting provided by the partial parabolic segments further increases efficiency because light is directed where needed with little light trespass behind and away from luminaire  10 . Light trespass behind luminaire  10  can be further minimized by use of a light shield  15  as described herein. And, these results are obtained without the need for a relatively less efficient horizontally mounted lamp. These features provide the lighting planner and end user with the opportunity for excellent exterior lighting while controlling costs and providing compliance with government energy and land usage regulations. 
   Referring now to  FIGS. 1-3  and  5 - 6 , exemplary luminaire  10  includes a housing  17 , a generally vertically oriented lamp  19 , and a compound parabolic reflector  11 . Housing  17  may include an optic housing portion  21  and a side arm housing portion  23 . If provided as a separate housing portion, optic housing portion  21  may include center  25 , and a side wall  27 ,  29  portions which enclose reflector  11  and a lamp holder  31  in which lamp  19  is mounted. Housing portion  21  includes front  30  and rear  32  sides. While three wall portions  25 - 29  are shown, any number of walls may be selected in the design of housing  17 . Housing walls  25 - 29  define a generally horizontal bottom opening  33  which lies in a generally horizontal plane  34 . 
   Lamp holder  31  is positioned in optic housing portion  21  to support lamp  19  mounted therein in a generally vertical orientation. A generally vertical orientation means or refers to an orientation which is ± about 15° to vertical. Luminaire  10  may be sold with or without a lamp  19  mounted in lamp holder  31  since the user can install a lamp  19  at the site at which luminaire  10  is located for use. 
   A lens frame  35  supporting a lens  37  is provided to cover opening  33 . In the embodiment, lamp holder  31  supports lamp  19  so that lamp is above plane  34  and lens  37  when frame  35  is closed. Because lamp  19  is above plane  34 , housing walls  25 - 29  provide full cut off of stray light so that useful light is directed at the target zone  13 . Lens frame  35  is relatively movable between luminaire-closed and luminaire-open positions for lamp-changing purposes. Closure of lens frame  35  creates a sealed, weather-tight enclosure about lamp  19 . Lens  37  is preferably of high-impact tempered glass but can be made of other light-transmissive materials. Light energy is discharged through lens  37  toward target zone  13  as described in more detail below. The preferred lens  37  shown in planar. 
   Optional light shield  15  may be mounted to lens frame  35  adjacent housing rear side  32  to extend below plane  34  as shown in  FIGS. 6-7  to block emission of light from lamp  19  rearward from luminaire  10 . In the embodiment, light shield  15  includes continuous rear  39  and side  41 ,  43  panels which extend downwardly from a rear portion of lens frame  35 . The sizing, length and width of panels  39 - 43  is a design choice based on the amount of light which is desired to be blocked. 
   Housing side arm portion  23  encloses the electrical/mechanical components (not shown) necessary to provide proper voltage and current for starting and operation of lamp  19 . These components typically include a power supply, ballast, ignitor, and capacitor. Other components may be utilized depending on the application. Housing side arm portion  23  is preferably designed for attachment to a pole  45  or a surface-mounted support (not shown) by bolts or other mechanical fasteners. 
   Lamp  19  may be of any suitable lamp type. Examples are incandescent and arc-discharge lamp types. An example of a lamp type suitable for use with luminaire  10  is a high intensity discharge (HID) lamp. Lamp  19  is preferably in the range of 400 to 1500 Watts. Such HID lamps include metal halide, high pressure sodium, and mercury vapor lamps. Lamp  19  includes a generally axial light-emitting segment  47  along axis  48  which emits the light energy (see  FIG. 16 ). For metal-halide-type lamps, the light-emitting segment  47  is an envelope  49  ( FIG. 16 ) within lamp  19  which encloses electrodes (not shown) and the metal halide salts. Light energy is emitted from envelope  49  by ignition of a plasma arc between the electrodes which are at opposite ends of envelope  49 . The electrodes define axis  48  within envelope  49  coaxial with light-emitting segment  47 . 
   Light-emitting segment  47  is considered to have upper and lower regions  51 ,  55  and a central region  53  therebetween for the purpose described below. The “light-emitting segment location” also referred to as a “vertical light source with plural source-sectors,” means or refers to the three-dimensional space occupied by the light-emitting segment  47  (see  FIGS. 16 and 17 ). Compound parabolic reflector  11  partially surrounds this light-emitting segment location/plural source-sector to optimize the lighting effect provided by luminaire  19  as described herein. 
   Referring to  FIGS. 3 , and  9 - 14 , compound parabolic reflector  11  includes a segmented center portion  59 , a first segmented side portion  61 , and a second segmented side portion  63 . Segmented portions  59 ,  61 ,  63  partially surround lamp  19  and light-emitting segment  47 . In the example, segmented side portions  61 ,  63  are substantially mirror images of one another. Collectively, portions  59 ,  61 , and  63  partially surround the light-emitting segment  47  of a lamp  19  mounted in lamp holder  31  (extending through opening  64 ) to reflect or redirect light from light-emitting segment  47  of an energized lamp  19  through lens  37  and out of luminaire  10 . 
   Segmented center portion  59  is defined by first and second side edges  65 ,  67  and front  69  and rear  71  ends. Center portion  59  is connected to first side portion  61  along side edge  65  and to second side portion  63  along side edge  67 . In the embodiment, center  59  and side portions  61 ,  63  may be joined together along respective edges  65 ,  67  by means of tabs (examples of which are indicated by ref. no.  72 ) along an upper edge of each side panel  61 ,  63  inserted into a corresponding slotted opening (examples of which are indicated by ref. no.  74 ) along each side of center portion  59  as illustrated in  FIGS. 9-14 . 
   In the preferred example shown, center portion  59  includes a first plurality of two-dimensional parabolic segments  73 ,  75 ,  77 . Each of the preferred three segments  73 ,  75 ,  77  front-to-rear is a separate two-dimensional parabola. Each of the three segments  73 ,  75 ,  77  is a segment which is a set of points formed by parallel movement of a line along a parabolic path. Such segments are also referred to herein as partial parabolas or parts of a parabola. As will be described in more detail below, the two-dimensional parabolic section of each segment  73 - 77  has a focal point  79 ,  81 ,  83  in a different one of the plural light-emitting segments  51 , or  53 , or  55 . This arrangement permits each parabolic segment  73 - 77  to direct a preponderance of light toward a different target zone subregion  133 ,  135 ,  137  in front of and to the sides of luminaire  10 . (See  FIGS. 4 ,  16  and  17 .) 
   Each segmented side portion  61 ,  63  of the preferred example has four sections front-to-rear including a first, or front, section  85 ,  93 , a second section  87 ,  95 , a third section  89 ,  97  and a fourth, or rear, section  91 ,  99 . In the example, side portion  61 , includes sections  85 - 91  each of which is comprised of two segments  101 ,  103 ,  105 ,  107 ,  109 ,  111 ,  113 ,  115 . Segments  101 - 113  represent a second plurality of two-dimensional parabolic segments. Because side portion  63  is preferably a mirror image of side portion  61 , side portion  63 , also includes sections  93 - 99 , each of which is comprised of two segments  117 ,  119 ,  121 ,  123 ,  125 ,  127 ,  131 ,  133 . Segments  117 - 133  also represent a second plurality of two-dimensional parabolic segments. Each of such segments  101 - 133  is a part of its own two-dimensional parabola, and each segment  101 - 133  is shaped and oriented such that it forms part of its two-dimensional parabola in a generally vertical plane and another two-dimensional parabola in a generally horizontal plane, thereby enabling these portions of reflector  11  to direct light both downward and to the side to target area subregions  139 - 169 . 
   In the example, each segment  101 - 133  of each section  85 - 99  is arranged above or below the other providing a total of sixteen segments  101 - 133  along the side panels. Therefore, the exemplary compound parabolic reflector  11  includes a total of nineteen partial parabolic segments  73 - 77  and  101 - 131 . The two-dimensional parabolic section of each segment  101 - 131  has a focal point  138  in the light-emitting segment location corresponding to the space occupied by light-emitting segment  47  and directs a preponderance of light toward subregions  139 - 169  of the target zone  13  to a respective side of luminaire  10 . 
     FIGS. 4-5  and  8  are illustrative of the targeted lighting effect provided by luminaire  10 .  FIG. 4 , which is not to scale, is provided for the purpose of illustrating an exemplary target zone  13  and the reflector  11  segments  73 - 77 ,  101 - 133  which correspond generally to each subregion  133 - 169 . Target zone  13  of the example consists of nineteen subregions along a surface area beneath luminaire  10  targeted for illumination by compound parabolic reflector  11 . Center segmented portions  73 ,  75 ,  77  are targeted to direct a preponderance of light respectively onto center subregions  137 ,  135 , and  133 . Center segmented portions  73 - 77  provide the majority of illumination of target zone  13  produced by luminaire  10 . Segmented side portion  61  segments  101 - 115  are targeted to direct a preponderance of light respectively onto target zone subregions  155 - 169  as indicated in  FIG. 4 . Segmented side portion  63  segments  117 - 131  are targeted to direct a preponderance of light respectively onto target zone subregions  141 - 153  as indicated in  FIG. 4 . Each subregion  133 - 169  indicates in the parenthetical the segment  73 - 77 ,  101 - 131  targeted at that subregion. While each segment  73 - 77 ,  101 - 131  directs a preponderance of light toward a different subregion  133 - 169 , there is overlap of illumination by segments  73 - 77 ,  101 - 131  into more than one subregion, thereby producing a uniform lighting effect. 
   The isolux map computer-generated simulations of  FIGS. 5 and 8  respectively represent the expected light output directed toward target zone  13  from luminaire  10  not including light shield  15  ( FIGS. 1-3 ) and luminaire  10  including light shield  15  ( FIGS. 6-7 ). The models used to produced the simulated isolux maps  171 ,  173  are based on use of a pole-mounted luminaire  10  mounted 22 feet above a flat surface  175  as shown in the inset to the right of each isolux map  171 ,  173 . Each luminaire  10  in the simulation included a compound parabolic reflector  11  as illustrated in  FIGS. 9-14  and a metal halide arc lamp having a luminous flux of 110,000 lumens. The minimum illumination of each zone is indicated on  FIGS. 5 and 8  by the values associated with each zone in units of foot candles. 
   Referring to  FIG. 5 , isolux map  171  shows that luminaire  10 , not including a light shield  15 , casts concentrated bright light of 50 foot candles or greater in an approximate 240 square foot rectangle  177  to the front and sides of luminaire  10  and about 20 foot candles or greater in an approximate 560 square foot rectangle  179  to the front and sides of the luminaire  10 . A typical IES recommendation for illumination of a surface area is 0.5 foot candles. The data indicate that the luminaire  10  provides a bright lighting effect. The lighting effect is uniformly high in the rectangular area of the target zone  13  to the front and sides of the luminaire  10 . 
   Referring to  FIG. 8 , isolux map  173  illustrates that luminaire  10  including light shield  15  provides the bright and uniformly illuminated rectangular areas  181 ,  183  which are generally similar to areas  177 ,  179  of  FIG. 5 , but with relatively less light trespass in the area  185  behind each luminaire  10 . The data indicate that light shield  15  is effective in blocking light emission behind luminaire  10 . And, the data indicate that the shield  15  does not negatively effect the uniformly high illumination of the rectangular area in the target zone  13  to the front and sides of the luminaire  10 . 
     FIGS. 15-17  illustrate the aiming of segmented center portion  59  segments  73 - 77  and  FIGS. 19-23  illustrate the aiming of segmented side portion  61 ,  63  segments  101 - 131  to achieve the results shown in  FIGS. 4 ,  5  and  8 . The improvement in luminaire  10  structure and operation arises in part from the recognition that the light energy emitted from light-emitting segment  47  of lamp  19  has a toroidal-shaped distribution extending outwardly from axis  48  of light-emitting segment  47  with relatively greater amounts of light emitted from the central region  53  of light-emitting segment  47  than from the upper and lower regions  51 ,  55 . Based on this recognition, the partial parabolic segments, particularly the center segment portions  73 ,  75 ,  77 , are positioned and arranged so that the foci  79 ,  81 ,  83  along the major axes of each partial parabola including the respective segment portions  73 - 77  are in a region of light-emitting segment  47  closest thereto, thereby optimizing reflection from each segment  73 ,  75 ,  77  to direct light to the target zone  13 . 
     FIG. 15  is a two-dimensional ray trace for center portion  59  showing three representative light rays traced for each of the parabolas of segmented center portion  59  segments  73 ,  75 ,  77 . Such rays are numbered  73   r ,  75   r , and  77   r , respectively, and illustrate the optical characteristics of a parabolic reflector  11 , that is, the parabolic reflector reflects light rays from the focus of the parabola along directions parallel to the major axis of the parabola.  FIG. 15  also illustrates the efficient design of reflector  11  because light rays are directed out of housing  17  with only a single contact with reflector  11 , thereby minimizing light scattering effects. 
   Referring to  FIGS. 16 and 17 , the parabolas of segmented center portion  59  segments  73 ,  75 ,  77  have major axes  73   a ,  75   a , and  77   a , respectively, directing light generally along directions parallel to such major axes primarily from regions  53 ,  51 ,  55 , respectively, of light-emitting segment  47 . Referring to  FIG. 4 , light from segments  73 ,  75 ,  77  is generally directed toward target areas  137 ,  135 ,  133 , respectively. It should be understood that since the light emitted from light-emitting segment  47  is emitted from entire regions rather than three precise individual focal points, the light reaching the various target areas is spread across the areas and to some degree into neighboring areas, producing the desirable effect of smoothing the distribution of lights across the various areas of target zone  13 . Thus, referring to  FIG. 17 , regions  51 ,  53 ,  55  of light-emitting segment  47  contain the foci  79 ,  81 ,  83 , respectively. It should be noted that simulated isolux maps  171  and  173  of  FIGS. 5 and 8 , respectively, take into account the fact that light is emitted from throughout the volume of light-emitting segment  47  rather than just from the various focal points of the partial parabolas of segmented reflector  11 . 
   In exemplary luminaire  10 , major axes  73   a ,  75   a , and  77   a  are oriented at angles of 10°, 12°, and 34°, respectively, forward of nadir  70 . Nadir  70  is a vertical axis which passes through the center of light-emitting segment  47 . Axis  48  of light-emitting segment  47  is oriented at an angle of about −15° from nadir  70  as can be seen in  FIGS. 16 and 17 . Each axis  73   a ,  75   a ,  77   a  is forward of nadir  70  in that the direction of each axis  73   a ,  75   a ,  77   a  is toward the housing front side  30  and away from the housing rear side  32 . Each major axis  75   a ,  77   a  is in front of another major axis to the extent that it is directed more toward the housing front side  30  than the other major axis. In the example, middle parabolic segment  75  major axis  75   a  is oriented forward of the front parabolic segment  73  major axis  73   a  and the rear parabolic segment  77  major axis  77   a  is oriented forward of the middle parabolic segment  75  major axis  75   a.    
     FIG. 19  is a top plan view of the outer surface of segmented side portion  63  of reflector  11 . In the embodiment, segmented side portions  63  and  61  are mirror images of the other. Therefore, the description of segmented side portion  63  is applicable to describe segmented side portion  61 . As illustrated in  FIG. 4 , each parabolic segment  117 - 131  is shaped and oriented to direct light to a specific target area subregion  139 - 153  of target zone  13 . To achieve such targeting, each segment  117 - 131  is a partial two-dimensional parabola to direct light laterally from reflector  11  at an angle from nadir  70  (a vertical axis) and is also oriented to direct such light laterally from a horizontal axis  170  so that the light is spread both generally forward and to the side across target area subregions  139 - 153  of target zone  13  as desired. Horizontal axis  170  is an axis parallel to horizontal housing opening  33  which passes through the center of light-emitting segment  47  and which symmetrically bisects reflector panel  11  as shown in  FIG. 19 . 
   Side portion  63  includes four sections  93 - 99 , each of which includes a pair of segments, an upper parabolic segment and a lower parabolic segment. Side portion  63  includes: (1) front section  93  with upper segment  119  and lower segment  117 ; intermediate section  95  with upper segment  123  and lower segment  121 ; intermediate section  97  with upper segment  127  and lower segment  125 ; and rear section  99  with upper segment  131  and lower segment  129 . Each of these eight segments has a major axis which passes through its common focal point  138 . 
     FIG. 19  illustrates the orientation of the major axes of these eight segments  117 - 129  with respect to horizontal axis  170 . In exemplary luminaire  10 , the major axes of partial parabolas  117  and  119  of front section  93  are oriented at an angle of about 81°; the major axes of partial parabolas  121  and  123  of intermediate section  95  are oriented at an angle of about 69°; the major axes of partial parabolas  127  and  125  of intermediate section  97  are oriented at an angle of about 71°; and the major axes of partial parabolas  129  and  131  of rear section  99  are oriented at an angle of about 64°. 
     FIGS. 20-23  show four cross-sectional views of segmented side reflector portion  63  taken along the respective sections indicated in  FIG. 19  in order to show the vertical orientation of the parabola major axes of the sections  93 - 99  of side portion  63 . (As above, side portion  61  is configured to be the mirror image of side portion  63  and thus the description of side portion  63  applies to side portion  61 .) The major axes of each upper segment  119 ,  123 ,  127 ,  131  is oriented with respect to nadir at an angle of 40° and each lower segment  117 ,  121 ,  125 ,  129  is oriented with respect to nadir  70  at an angle of 55°. The foci of each segment  117 - 131  are all located at common focal point  138  which is at the intersection of nadir  70  and horizontal axis  170 . 
     FIGS. 18 and 24  illustrate one approach to the fabrication of reflector  11 . When the center  59  and side portions  61 ,  63  of reflector  11  are fabricated from pieces of sheet metal, it is convenient and cost-effective to approximate the partial parabolas as circular sections having radii of curvature.  FIG. 18  shows one such embodiment for fabrication of reflector center portion  59 . In the example, rear segment  77  partial parabola is approximated by a circular section having a radius of curvature of about 13 inches, center segment  75  partial parabola is approximated by a circular section having a radius of curvature of about 7 inches, and front segment  77  partial parabola is approximated by two circular sections respectively having radii of curvature of about 13.5 inches and about 43 inches. 
     FIG. 24  illustrates the same simplified fabrication approach, but with respect to side segment  63 , and side segment  61  which is a mirror image of segment  63 . Each of the four upper segments  119 ,  123 ,  127 ,  131  of side portion  63  (and of upper segments  103 ,  107 ,  111 ,  115  of side portion  61 ) approximates its partial parabolas with circular sections having radii of curvature of about 11 inches. Each of the four lower segments  117 ,  121 ,  125 ,  129  of side portion  63  (and of lower segments  101 ,  105 ,  109 ,  113  of side portion  61 ) approximates its partial parabolas with circular sections having radii of curvature of about 14 inches. In the example, each of the side section  85 - 99  sixteen segments  101 - 131  is fabricated with no curvature in the generally horizontal direction.  FIG. 24  is a single drawing to illustrate the curvatures of each of these sixteen segments  101 - 131  of side portions  61 ,  63 . 
   In the preferred embodiments shown, each of center  59  and side portions  61 ,  63  may be made of a separate piece of aluminum coil sheet stock with a metalized aluminum coating vapor-deposited along the inside of reflector  11  facing lamp  19 . A representative premium reflective material suitable for use in manufacture of center  59  and side portions  61 ,  63  is sold under the trade name Miro 4 and is available from Alanod Aluminum—Veredlung GmbH &amp; Co. The sheet stock material comprising each of center and side portions  59 - 63  may be stamped and rolled to form the circular approximations as described above. Center portion  59  ends  69 ,  71  may be riveted or tack welded to flange  187 . Interconnection of tabs (e.g., tab  72 ) of side portions  61  with slots (e.g., slot  74 ), joins center and side portions  59 ,  61 ,  63  along edges  65 ,  67 . After rolling, each side section  85 - 99  may be riveted or tack welded at its opposite end to flange  187  to provide a compound parabolic reflector  11  for mounting in housing  17  of luminaire  10 . 
   It is envisioned that compound parabolic reflector  11  may have configurations consistent with the improvement, other than those of the preferred embodiment described herein. For example, while nineteen two-dimensional segments  73 - 77 ,  101 - 131  are shown, a greater or lesser number of segments may be used. Four side sections  95 - 99  on each side portion  61 ,  63  are preferred, but a greater or lesser number of side sections could be implemented. In still other embodiments, compound parabolic reflector  11  may be made of aluminum metalized molded plastic or hydro formed metal consistent with the improvement. 
   While the principles of this invention have been described in connection with specific embodiments, it should be understood clearly that these descriptions are made only by way of example and are not intended to limit the scope of the invention.