FORM 2
THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13) 1. Title of the invention: LENS FOR A LUMINAIRE
2. Applicant(s)
NAME NATIONALITY ADDRESS
BAJAJ ELECTRICALS LTD Indian 45/47, Veer Nariman Road, Mumbai
Maharashtra 400 001, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[0001] The present subject matter relates, in general, to optical design of lens used in a luminaire and, in particular, to asymmetrical luminous intensity distribution lens used in streetlights.
BACKGROUND
[0002] Lighting products or luminaires include a light emitter such as a bulb or a Light Emitting Diode (LED) to illuminate an environment. The light emitter is attached to an optical system designed for light distribution depending upon lighting needs and requirements. In a streetlight application, it is desirable to achieve longer and/or greater distribution of light towards the street. Conventional luminaires use mechanical reflectors to intercept and redirect light rays into a desired direction. However, the light distribution provided by a reflector is not sufficient for many applications as reflectors are created from materials that absorb photons and thus, provide reduced light distribution. Additionally, reflectors are expensive to produce and are prone to heating and damage.
[0003] Other conventional systems use asymmetric lens over the light emitter to distribute light. The asymmetric lens includes one or more exterior refractive surfaces which can redirect light. However, conventional asymmetric lens devices do not achieve optimal efficiency and do not minimize unwanted light emission toward desired dark regions.
BRIEF DESCRIPTION OF FIGURES [0004] The features, aspects, and advantages of the present subject matter will be better understood with regard to the following description, and accompanying figures. The use of the same reference number in different figures indicates similar or identical features and components.
[0005] Fig. 1 illustrates a lens for a luminaire, in accordance with implementations of the present subject matter.
[0006] Fig. 2A illustrates a cross-section view of a first arcuate perimeter of the lens for the luminaire, in accordance with implementations of the present subject matter.

[0007] Fig. 2B illustrates a cross-section view of a second arcuate boundary formed at the base of a second convex section of the lens, in accordance with implementations of the present subject matter.
[0008] Fig. 2C illustrates a cross-section view of an outer dividing arcuate of the lens, in accordance with implementations of the present subject matter. [0009] Fig. 2D illustrates a cross-section view of a third arcuate boundary formed at the base of the third convex section of the lens, in accordance with implementations of the present subject matter.
[0010] Fig. 2E illustrates a cross-section view of a second arcuate perimeter of the lens, in accordance with implementations of the present subject matter. [0011] Fig. 2F illustrates a cross-section view of an inner dividing arcuate of the lens, in accordance with implementations of the present subject matter. [0012] Fig. 3A illustrates the luminaire with a plurality of light sources, in accordance with implementations of the present subject matter. [0013] Fig. 3B illustrates the luminaire with each of the plurality of light sources covered by a lens, in accordance with implementations of the present subject matter. [0014] Fig. 4A illustrates the concentration of luminous flux in a lumen pie chart, in accordance with implementations of the present subject matter. [0015] Fig. 4B illustrates the light intensity distribution of the lens at each C-plane of the luminaire, in accordance with implementations of the present subject matter.
[0016] Fig. 5 illustrates the assembly of the luminaire, in accordance with implementations of the present subject matter.
[0017] FIG. 6A illustrates a streetlight pole spacing of 35mts, in accordance with implementations of the present subject matter.
[0018] Fig. 6B illustrates a streetlight pole spacing of 50mts, in accordance with implementations of the present subject matter.
DETAILED DESCRIPTION [0019] The present subject matter relates to a lens used in a luminaire. The lenses of the present subject matter enable an increased efficacy of light intensity distribution of a luminaire, such as a streetlight. The increased and/or longer distribution of light intensity allows for a wider spacing of the streetlights, as they are able to illuminate a wider area. Hence, the present subject matter allows an

increased pole spacing between streetlights, wherein the pole spacing can be increased up to five times the mounting height of the luminaire when the road width is less than or equal to the mounting height of the luminaire.
[0020] In an implementation of the present subject matter, a lens for a luminaire is provided. The lens comprises of an elongated base having a central opening for a light source, an outer lens surface formed over the elongated base, and an inner lens surface formed over the central opening.
[0021] The outer lens surface comprises a plurality of outer convex sections including a first convex section, a second convex section, and a third convex section. The inner lens surface comprises a plurality of inner convex sections including a fourth convex section, a fifth convex section, and a sixth convex section. [0022] The first convex section extends from a first outer end of the elongated base towards a center of the lens in the length-wise direction of the elongated base. Further, the first convex section is bound by a first arcuate perimeter opposite to the first outer end of the elongated base such that the first arcuate perimeter spans a width of the elongated base.
[0023] The second convex section adjoins a first part of the first arcuate perimeter of the first convex section and extends to a second outer end of the elongated base, wherein the second outer end being opposite to the first outer end. [0024] The third convex section adjoins a second part of the first arcuate perimeter of the first convex section and extends to the second outer end of the elongated base, wherein the second and the third convex section adjoin each other. [0025] The fourth convex section extends from a first inner end of the central opening towards the center of the lens in the length-wise direction of the elongated base. Further, the fourth convex section is below the first convex section and is bound by a second arcuate perimeter opposite to the first inner end of the central opening 104. The second arcuate perimeter spans a width of the central opening. [0026] The fifth convex section adjoins a first part of the second arcuate perimeter of the fourth convex section and extends to a second inner end of the central opening, wherein the second inner end is opposite to the first inner end. Further, the fifth convex section is below the second convex section. [0027] The sixth convex section adjoins a second part of the second arcuate perimeter of the fourth convex section and extends to the second inner end of the

central opening. The fifth and the sixth convex section are opposite to each other,
and the sixth convex section is below the third convex section.
[0028] The above and other features, aspects, and advantages of the subject
matter will be better explained with regard to the following description, appended
claims, and accompanying figures.
[0029] Fig. 1 illustrates a lens 100, in accordance with an implementation of the
present subject matter. The lens 100 is made of optic material comprising Poly
Carbonate (PC), Poly Methyl Metha Crylate (PMMA) or silicone, among others.
Example shape and dimensions of the lens 100 are depicted in FIG.s 2A-2F and will
be discussed later. The lens 100 can be used in a luminaire such as a streetlight,
wherein the lens 100 is attached to a light source, such as a Light Emitting Diode
(LED) 302, as depicted in FIG. 3.
[0030] The lens 100, as depicted in Fig.1, includes an elongated base 102
having a central opening 104 for a light source, an outer lens surface formed over
the elongated base 102 and an inner lens surface formed over the central opening
104.
[0031] The outer lens surface comprises a plurality of outer convex sections
including a first convex section 106, a second convex section 108, and a third
convex section 110. The inner lens surface comprises a plurality of inner convex
sections including a fourth convex section 112, a fifth convex section 114, and a
sixth convex section 116.
[0032] The first convex section 106 extends from a first outer end of the
elongated base 102 towards a center of the lens in the length-wise direction of the
elongated base 102. Further, the first convex section 106 is bound by a first arcuate
perimeter 118 opposite to the first outer end of the elongated base 102 such that the
first arcuate perimeter 118 spans a width of the elongated base 102.
[0033] The second convex section 108 adjoins a first part of the first arcuate
perimeter 118 of the first convex section 106 and extends to a second outer end of
the elongated base 102, wherein the second outer end is opposite to the first outer
end.
[0034] The third convex section 110 adjoins a second part of the first arcuate
perimeter 118 of the first convex section 106 and extends to the second outer end of
the elongated base 102, wherein the second convex section 108 and the third
convex section 110 adjoin each other along an outer dividing arcuate 122.

[0035] Thus, the boundary of the elongated base 102 is formed by three arcuate boundaries, a first arcuate boundary 124-1 formed at the base of the first convex section 106, a second arcuate boundary 124-2 formed at the base of the second convex section 108, and a third arcuate boundary 124-3 formed at the base of the third convex section 110.
[0036] Similar to the outer lens surface, the inner lens surface includes a plurality of inner convex sections, such as, the fourth convex section 112, the fifth convex section 114, and the sixth convex section 116 as discussed above. The fourth convex section 112 extends from a first inner end of the central opening 104 towards the center of the lens in the length-wise direction of the elongated base 102. Further, the fourth convex section 112 is below the first convex section 106 and is bound by a second arcuate perimeter 120 opposite to the first inner end of the central opening 104. The second arcuate perimeter 120 spans a width of the central opening 104.
[0037] The fifth convex section 114 adjoins a first part of the second arcuate perimeter 120 of the fourth convex section 112 and extends to a second inner end of the central opening 104. The second inner end is opposite to the first inner end. Further, the fifth convex section 114 is below the second convex section 108. [0038] The sixth convex section 116 adjoins a second part of the second arcuate perimeter 120 of the fourth convex section 112 and extends to the second inner end of the central opening 104. The fifth convex section 114 and the sixth convex section 116 are opposite to each other, adjoined along an inner dividing arcuate 126. The sixth convex section 116 is below the third convex section 110. [0039] Thus, the boundary of the central opening 104 is formed by three arcuate boundaries, a fourth arcuate boundary formed at the base of the fourth convex section 112, a fifth arcuate boundary formed at the base of the fifth convex section 114, and a sixth arcuate boundary formed at the base of the sixth convex section 116.
[0040] The various dimensions of the lens 100 can be understood with reference to three axes - a central axis 128, a major axis 130, and a minor axis 132. The central axis 128 is perpendicular to the plane of the elongated base 102 and passes through a center of the elongated base 102. The major axis 130 is in the plane of the elongated base 102 and passes through the center of the elongated base 102. The major axis 130 is parallel to a length of the elongated base 102. The

minor axis 132 is in the plane of the elongated base 102 and is perpendicular to the major axis 130. Thus, it will be understood that the minor axis 132 passes through the center of the elongated base 102 and is parallel to a width of the elongated base 102. For reference purposes, the central axis 128 is called the z dimension, the major axis 130 is called the x dimension and the minor axis 132 is called the y dimension.
[0041] The light rays from the LED 302 (depicted in Fig.3A) are transmitted through the inner lens surface and the outer lens surface of the lens. Consequently, the light rays are redistributed from rotationally symmetric distribution to asymmetric intensity distribution with a peak intensity shifted from 0° to 70° from the vertical i.e. between a central region of the lens 100 and through the second convex section 108 and the third convex section 110. Further, the inner lens surface receives and converts rotationally symmetric light rays from the light source into asymmetric light rays
[0042] The resultant light intensity distribution from the streetlight has a maximum utilization of luminous flux in the required area on the street wherein the streetlight is fixed. Additionally, the resultant light intensity distribution displays uniform light distribution along the length of the road i.e. longitudinal uniformity and across the road width i.e. transverse uniformity.
[0043] Figs. 2A-2F illustrate various cross-section views of the lens 100, in accordance with implementations of the present subject matter. For discussion purposes, coordinates of certain point that may be used to define the arcs forming the various arcuate sections/ boundaries/ perimeters are provided. It will be understood that these are provided as examples and not as limitations. Various suitable modifications may be made in the arcs based on the teachings provided herein depending on, for example, the elevation, the shift in peak intensity desired, etc. All such modifications are intended to be covered in the scope of the appended claims.
[0044] Fig. 2A illustrates a cross-section view of the first arcuate perimeter 118 of the lens 100 for the luminaire, in accordance with implementations of the present subject matter. The z and y coordinates at various points of the first arcuate perimeter 118 of the lens 100 shown in Fig. 2A are as given below in Table 1. The z coordinates are as measured from the minor axis 132 along the central axis 128 and

the y coordinates are as measured from the central axis 128 along the minor axis 132:
Table 1: Coordinates of points on first arcuate perimeter

Point z coordinate (in mm) y coordinate (in mm)
A1 - 7.00
A2 2.68 6.32
A3 4.00 5.66
A4 5.32 4.55
A5 6.54 2.14
A6 6.32 0.79
A7 5.70 2.11
A8 3.88 4.03
A9 2.01 5.13
A10 - 5.80
[0045] Fig. 2B illustrates a cross-section view of the second arcuate boundary 124-2 formed at the base of the second convex section 108 of the lens 100, in accordance with implementations of the present subject matter. The x and y coordinates of various points on the second arcuate boundary 124-2 as shown in Fig. 2B are as given below in Table 2. The y coordinate is as measured from the major axis 130 along the minor axis 132. The x coordinate is as measured from the minor axis 132 along the major axis 130:
Table 2: Coordinates of points on second arcuate boundary

Points y coordinate (in mm) x coordinate (in mm)
B1 7.00 -
B2 6.88 3.54
B3 6.32 6.10
B4 5.46 7.82

B5 3.13 9.61
B6 1.71 9.91
[0046] Fig. 2C illustrates a cross-section view of the outer dividing arcuate 122 of the lens 100, in accordance with implementations of the present subject matter. The z and x coordinates of various points on the outer dividing arcuate 122 as shown 5 in Fig 2C are as given below in Table 3. The z coordinate is as measured from the major axis 130 along the central axis 128 and the x coordinate is as measured from the central axis 128 along the major axis 130:
Table 3: Coordinates of points on outer dividing arcuate

Points z coordinate (in mm) x coordinate (in mm)
C1 5.80 -
C2 5.89 1.83
C3 5.95 3.93
C4 5.53 6.36
C5 4.51 8.19
C6 3.53 9.04
C7 2.19 9.69
C8 - 10.00
[0047] Fig. 2D illustrates a cross-section view of the third arcuate boundary 124-3 formed at the base of the third convex section 110 of the lens 100, in accordance with implementations of the present subject matter. The x and y coordinates of various points on the third arcuate boundary 124-3 as shown in Fig. 2D are as given in Table 4 below. The y coordinate is as measured from the major axis 130 along the minor axis 132 and the x coordinate is as measured from the minor axis 132 along the major axis 130:
Table 4: Coordinates of points on third arcuate boundary
Points y coordinate (in mm) x coordinate (in mm)

D1 6.47 -
D2 6.46 2.44
D3 6.06 5.71
D4 5.16 7.63
D5 3.05 9.34
D6 1.74 9.80
[0048] Fig. 2E illustrates a cross-section view of the second arcuate perimeter 120 of the lens 100 for the luminaire, in accordance with implementations of the present subject matter. The z and y coordinates of various points on the second arcuate perimeter 120 as shown in Fig. 2E are as given below in Table 5. The z coordinate is as measured from the minor axis 132 along the central axis 128, and the y coordinate is as measured from the central axis 128 along the minor axis 132: Table 5: Coordinates of points on second arcuate perimeter

Points z coordinate (in mm) y coordinate (in mm)
E1 - 5.30
E2 1.17 4.07
E3 2.76 3.01
E4 3.47 1.91
E5 3.93 0.27
E6 3.61 2.07
E7 2.86 3.02
E8 1.74 3.93
E9 - 4.60
[0049] Fig. 2F illustrates a cross-section view of the inner dividing arcuate 126 of the lens 100, in accordance with implementations of the present subject matter. The z and x coordinates of various points on the inner dividing arcuate 126 as shown

in Fig. 2F are as given below in Table 6. The z coordinate is as measured from the major axis 130 along the central axis 128, and the x coordinate is as measured from the central axis 128 along the major axis 130:
Table 6: Coordinates of points on inner dividing arcuate

Points z coordinate (in mm) x coordinate (in mm)
F1 4.20 -
F2 3.94 1.08
F3 3.09 2.10
F4 2.20 2.62
F5 1.02 3.10
[0050] Fig. 3A illustrates a streetlight 300 with a plurality of LEDs 302, in
accordance with implementations of the present subject matter. The luminaire
comprises a plurality of light sources mounted on a circuit board.
[0051] Fig. 3B illustrates the streetlight 304 with each of LEDs 302 covered by a
lens, in accordance with implementations of the present subject matter. Each of the
LEDs 302 are covered by a lens 100 for increased efficacy. Thus, the lens 100
allows the distribution of the light output of the LED 302 to cover a maximum/longer
area for illumination. The lens 100 re-distributes the light output for an optimum
utilization of raw lumen as optical lumen. Raw lumen will be understood to be the
light output from LED 302, while optical lumen will be understood to be the lumen
output transmitted through the lens 100 for the illumination of a desired area.
[0052] Fig. 4A illustrates the concentration of luminous flux in a lumen pie chart
400, in accordance with implementations of the present subject matter. As per
International Commission on Illumination (CIE) convention of streetlight orientation
on a street, the C 0° and C 180° plane deals with the longitudinal distribution of the
luminaire. Further, the C -90° and C-270° plane deals with the transverse distribution
i.e. C -90° street side (across the road) and C- 270° kerb side.
[0053] The peak intensity at C0° plane is defined at ү -70° to achieve a
maximum pole spacing of 5 times a mounting height of the luminaire. As depicted, the C-180° plane is nearly symmetrical to C- 0° plane. All other C planes are not

symmetrical to each other. The luminaire lumen is divided in total 18 different zones from elevation ү 0° - 180° as given below in table 7:
Table 7: Luminaire Lumen in different zones

Zone Elevation Cone Luminaire Lumen (%) Cumulative
Luminaire Lumen
(%)
1 10° 0°-5° 0.3 0.3
2 20° 5°-15° 2.7 2.9
3 30° 15°-25° 5.4 8.3
4 40° 25°-35° 9.5 17.8
5 50° 45°-55° 14.6 32.4
6 60° 55°-65° 19.9 52.3
7 70° 65°-75° 24.4 76.7
8 80° 75°-85° 18.4 95.1
9 90° 85°-95° 4.4 99.5
10 100° 95°-105° 0.2 99.7
11 110° 105°-115° 0.1 99.8
12 120° 115°-122° 0.1 99.9
13 130° 122°-135° 0.0 100.0
14 140° 135°-145° 0.0 100.0
15 150° 145°-155° 0.0 100.0
16 160° 155°-165° 0.0 100.0
17 170° 165°-175° 0.0 100.0

18 180° 175°-180° 0.0 100.0
[0054] The zonal luminous flux of each zone is expressed in percentage of total luminous flux of the luminaire. FIG. 4A expresses the above-provided zonal spread of the luminaire lumen as a lumen pie chart. The Right-hand Side of the graph indicates the concentration of zonal luminous flux in the street side, with a width spanning across the road. Further, the Left-hand Side of the graph indicates the percentage of zonal luminous flux available towards the house side or kerb side. [0055] The rotationally symmetric light rays emerging from the LED 302 are re¬shaped by the inner and outer convex sections to concentrate luminous flux of the light rays in the zones from 4 to zone 8 i.e. elevation 40° to 80° for C-planes lying in a region of longitudinal direction of the lens 100 attached to the streetlight. [0056] Fig. 4B illustrates the light intensity distribution 402 of the lens at each C-plane of the luminaire, in accordance with implementations of the present subject matter. Each individual LED 302 in a luminaire is covered with the lens which redistributes LED light intensity, as depicted.
[0057] Fig. 5 illustrates the assembly 500 of the luminaire, in accordance with implementations of the present subject matter. The major components of the luminaire are the Light Source element comprising an LED Array mounted on Printed Circuit Board (PCB), Electronics elements including a vertical placement of Driver and Controller, and Optical element comprising a secondary composite lens optics with IP66 degree of protection. The IP66 rating stands for an Ingress Protection rating of 66, signifying that the lens is dust tight and protected against heavy seas or powerful jets of water
[0058] The LED comprises housing and heat sink 502. A micro-controller Printed Circuit Board (MC PCB) 504, referred to as circuit board 504, having the plurality of light sources is attached to the housing and heat sink 502, and Is further attached to a lens module 508 through a gasket 506. The lens module 508 is covered by a protective cover 510. The protective cover 510 provides ingress protection against solid particles and liquid as per IP66 standards.

[0059] A pole mounting bracket 512 is attached to the housing and heat sink 502 to facilitate mounting of the luminaire on a streetlight pole. An electronic control gear 514 is attached to a gasket 524 and a control gear cover 526. The luminaire further comprises a surge protection device 528 to protect the luminaire against voltage and current surges, and a glow-in-dark surface 530. The luminaire further comprises a control gear mounting plate 518 and a driver 520 provides constant current and constant voltage to drive a series and parallel array of LED packages. A smart streetlight controller 522 enables the dual communication (Radio frequency (RF) & Power Line Communication (PLC)) of streetlight luminaires through cloud computing system using the communication antenna 516. The lens 100 is specially designed for a long coverage of longitudinal distribution to reduce number of poles on road while enhancing the lighting quality criteria of illumination level on road. [0060] The composite lens design with IP66 protection does not require additional glass cover to protect the LEDs 302. Therefore, transmission losses are reduced by 10-15% as compared to standard streetlight design as described above. [0061] FIG. 6A illustrates a streetlight pole spacing 600 of 35mts, in accordance with implementations of the present subject matter.
[0062] Fig. 6B illustrates a streetlight pole spacing 602 of 50mts, in accordance with implementations of the present subject matter. The following table, Table 8, depicts various installation parameters of the streetlight with lens 100. Table 8: Installation parameters of a streetlight luminaire

Installation Parameters Values
Luminaire Mounting Height (m) 8m -12m
Road Width (m) < Mounting Height
Spacing Between Poles (m) > 5 times of Mounting Height
Luminaire Tilt (°) 0° -10°
Overhang (m) 0-1.5m
[0063] The following table, Table 9, depicts specific installation parameters for
pole arrangement of the streetlight with lens 100.
Table 9: Installation parameters for pole arrangement of a streetlight luminaire

Installation parameters
Luminaire Pole Arrangement Single Sided
Mounting Height (m) 10
Pole Spacing (m) 35 and 50
Road Width (m) 10
Overhang(m) 1.5
Boom length(m) 3
Boom Angle (Tilt in ° ) 5
Calculation Grid 12 * 7 points
Maintenance Factor 0.8
[0064] The following table, Table 10, compares various quality criteria of a Standard Existing luminaire (referred to as regular streetlight hereinafter) without the lens 100, with the minimum requirement for an A2 type of road.
Table 10: Comparison of existing streetlight luminaire with minimum requirement

Standard Existing luminaire Luminaire Photometric data Minimum
Requirement
as per fig. no.
1 for A2 type
of road
Luminaire Lumen (lm) 12000

Luminaire Wattage (W) 120

Luminaire Efficacy (lm/w) 100

Lighting Design Calculation Pole Spacing 35m Pole Spacing 50m

Average Illuminance (Lux) 17 12 15

Overall Uniformity (Uo) 0.513 0.113 0.4
Longitudinal Uniformity (Ul) 0.434 0.053
Transverse Uniformity (Ut) 0.714 0.66 0.33
[0065] Upon comparison of the parameters provided in the table, the illumination of the regular streetlight without the lens 100 matches the quality criteria of illumination level i.e. Average lux, Overall uniformity, Longitudinal uniformity and transverse uniformity ratio, for streetlight installation with a pole spacing of 3.5 times the mounting height. Hence, the optimum performance of the regular lens is achieved for 1:3.5 Mounting height to spacing ratio. Therefore, for a given road stretch of 1000m, a minimum of 29 regular streetlights are required to be installed to match the illumination level quality criteria for a pole spacing 3.5 times of mounting height. However, as seen from the table, the illumination of the regular streetlight without the lens 100 does not match the quality criteria for roadway installation where pole spacing is 5 times of mounting height.
[0066] The following table, Table 11, compares various quality criteria of a luminaire (referred to as streetlight hereinafter) with the lens 100, with the minimum requirements for an A2 type of road.
Table 11: Comparison of streetlight luminaire of present subject matter with minimum
requirement

1:5 Lens 100 Streetlight Luminaire Luminaire Photometric data Minimum Requirement
as per fig. no. 1 for A2 type of road
Luminaire Lumen (lm) 16880

Luminaire Wattage (W) 120

Luminaire Efficacy (lm/w) 140

Lighting Design Calculation

Average Illuminance (Lux) 16 15

Overall Uniformity (Uo) 0.476 0.4
Longitudinal Uniformity (Ul) 0.372
Transverse Uniformity (Ut) 0.634 0.33
[0067] The streetlight with lens 100 satisfies the minimum illumination level
criteria as per Indian standard. Additionally, the streetlight with lens 100 further
improves the lighting levels on road surface as compared to standard streetlight
luminaire. A roadway installation of streetlights with lens 100 requires a reduced
quantity of luminaire and poles. In particular, for the streetlights with lens 100, only
21 number of luminaire and poles are required for illuminating a given road stretch of
length 1000m with 50m pole spacing. This results in a saving in capital cost of
installation of approximately 27% as compared to the regular streetlight luminaire
described above. Additionally, there is further annual energy saving of approximately
27%. Further, an optimum spacing between two luminaires mounted at a mounting
height, is equal to five times the mounting height of the luminaires.
[0068] Thus, the present subject matter enables an increase in light intensity
distribution in a streetlight, which allows the streetlights to illuminate a wider area. Thus, a wider spacing of the streetlights is possible. Hence, the present subject matter allows an increased pole spacing between streetlights, wherein the pole spacing can be increased up to five times the mounting height of the luminaire when the road width is less than the mounting height of the luminaire. The streetlight with lens 100 also decreases installation and maintenance costs, along with energy savings.
[0069] Although the present subject matter has been described with
reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter.

I/We Claim:
1. A lens comprising
an elongated base (102) having a central opening (104) for a light source; an outer lens surface formed over the elongated base (102), wherein the outer lens surface comprises a plurality of outer convex sections including:
a first convex section (106), wherein the first convex section (106) extends from a first outer end of the elongated base (102) towards a center of the lens in a length-wise direction of the elongated base (102), and wherein the first convex section (106) is bound by a first arcuate perimeter (118) opposite to the first outer end of the elongated base (102), the first arcuate perimeter (118) spanning a width of the elongated base (102);
a second convex section (108) that adjoins a first part of the first arcuate perimeter (118) of the first convex section (106) and extends to a second outer end of the elongated base (102), the second outer end being opposite to the first outer end; and
a third convex section (110) that adjoins a second part of the first arcuate perimeter (118) of the first convex section (106) and extends to the second outer end of the elongated base (102), wherein the second convex section (108) and the third convex section (110) adjoin each other; and
an inner lens surface formed over the central opening (104), wherein the inner lens surface comprises a plurality of inner convex sections including:
a fourth convex section (112) extending from a first inner end of the central opening (104) towards the center of the lens in the length-wise direction of the elongated base (102), wherein the fourth convex section (112) is below the first convex section (106) and is bound by a second arcuate perimeter (120) opposite to the first inner end of the central opening (104), the second arcuate perimeter (120) spanning a width of the central opening (104);
a fifth convex section (114) that adjoins a first part of the second arcuate perimeter (120) of the fourth convex section (112) and extends to a second inner end of the central opening (104), the second inner end

being opposite to the first inner end, wherein the fifth convex section (114) is below the second convex section (108); and
a sixth convex section (116) that adjoins a second part of the second arcuate perimeter (120) of the fourth convex section (112) and extends to the second inner end of the central opening (104), wherein the fifth convex section (114) and the sixth convex section (116) are opposite to each other, and wherein the sixth convex section (116) is below the third convex section (110).
2. The lens as claimed in claim 1, wherein the inner lens surface receives and converts rotationally symmetric light rays from the light source into asymmetric light rays, and wherein the inner lens surface and the outer lens surface distribute light rays passing through the plurality of inner convex sections and the plurality of outer convex sections to achieve a peak light intensity distribution.
3. The lens as claimed in claim 1, wherein the plurality of outer convex sections and the plurality of inner convex sections reshape rotationally symmetric light rays coming out of the light source to concentrate luminous flux of the light rays between an elevation of 40º to an elevation of 80º for c-planes lying in a longitudinal direction of the lens attached to a luminaire.
4. The lens as claimed in claim 1, wherein the plurality of outer convex sections and the plurality of inner convex sections redistributes rotationally symmetric light intensity from the light source into asymmetric light intensity, wherein peak light intensity of the light rays is shifted from 0° to 70° while passing through the second convex section (108) and the third convex section (110).
5. The lens (100) as claimed in claim 1, wherein the first arcuate perimeter (118) includes points having z and y coordinates of: (0,7.00), (2.68, 6.32), (4.00, 5.66), (5.32,4.55), (6.54, 2.14), (6.32,0.79), (5.70,2.11), (3.88, 4.03), (2.01,5.13), and (0,5.80).

6. The lens (100) as claimed in claim 1, wherein the lens comprises a second arcuate boundary (124-2) of the elongated base (102) adjoining the second convex section (108), wherein the second arcuate boundary (124-2) includes points comprising y and x coordinates of: (7.00, 0), (6.88, 3.54), (6.32, 6.10), (5.46, 7.82), (3.13, 9.61), and (1.71, 9.91).
7. The lens (100) as claimed in claim 1, wherein the lens comprises an outer dividing arcuate (122) adjoining the second convex section (108) and the third convex section (110), wherein the outer dividing arcuate (122) includes points comprising z and x coordinates of: (5.80, 0), (5.89, 1.83), (5.95, 3.93), (5.53, 6.36), (4.51, 8.19), (3.53, 9.04), (2.19, 9.69) and (0, 10.00).
8. The lens (100) as claimed in claim 1, wherein the lens comprises a third arcuate boundary (124-3) of the elongated base (102) adjoining the third convex section (110), wherein the third arcuate boundary (124-3) includes points comprising y and x coordinates of: (6.47, 0), (6.46, 2.44), (6.06, 5.71), (5.16, 7.63), (3.05, 9.34), and (1.74, 9.80).
9. The lens (100) as claimed in claim 1, wherein the second arcuate perimeter (120) includes points comprising z and y coordinates of: (0, 5.30), (1.17, 4.07), (2.76, 3.01), (3.47,1.91), (3.93, 0.27), (3.61, 2.07), (2.86, 3.02), (1.74, 3.93) and (0, 4.60).
10. The lens (100) as claimed in claim 1, wherein the lens (100) comprises an inner dividing arcuate (126) adjoining the fifth convex section (114) and the sixth convex section (116), wherein the inner dividing arcuate (126) includes points comprising z and x coordinates of: (4.20, 0.00), (3.94, 1.08), (3.09, 2.10), (2.20,2.62), and (1.02, 3.10).
11. A luminaire, wherein the luminaire comprises:
a plurality of light sources mounted on a circuit board; and
a plurality of lenses, each lens to cover a light source of the plurality of light
sources to concentrate a luminous flux of the light source, each lens
comprising:

an elongated base (102) having a central opening (104) for the light source; an outer lens surface formed over the elongated base (102), wherein the outer lens surface comprises a plurality of outer convex sections including:
a first convex section (106), wherein the first convex section (106) extends from a first outer end of the elongated base (102) towards a center of the lens in a length-wise direction of the elongated base (102), and wherein the first convex section (106) is bound by a first arcuate perimeter (118) opposite to the first outer end of the elongated base (102), the first arcuate perimeter (118) spanning a width of the elongated base (102);
a second convex section (108) that adjoins a first part of the first arcuate perimeter (118) of the first convex section (106) and extends to a second outer end of the elongated base (102), the second outer end being opposite to the first outer end; and
a third convex section (110) that adjoins a second part of the first arcuate perimeter (118) of the first convex section (106) and extends to the second outer end of the elongated base (102), wherein the second convex section (108) and the third convex section (110) adjoin each other; and
an inner lens surface formed over the central opening (104), wherein the inner lens surface comprises a plurality of inner convex sections including:
a fourth convex section (112) extending from a first inner end of the central opening (104) towards the center of the lens in the length-wise direction of the elongated base (102), wherein the fourth convex section (112) is below the first convex section (106) and is bound by a second arcuate perimeter (120) opposite to the first inner end of the central opening (104), the second arcuate perimeter (120) spanning a width of the central opening (104);
a fifth convex section (114) that adjoins a first part of the second arcuate perimeter (120) of the fourth convex section (112) and extends to a second inner end of the central opening (104), the second inner end being opposite to the first inner end, wherein the fifth convex section (114) is below the second convex section (108); and

a sixth convex section (116) that adjoins a second part of the second arcuate perimeter (120) of the fourth convex section (112) and extends to the second inner end of the central opening (104), wherein the fifth convex section (114) and the sixth convex section (116) are opposite to each other, and wherein the sixth convex section (116) is below the third convex section (110).
12. The luminaire as claimed in claim 11, wherein the inner lens surface receives and converts rotationally symmetric light rays from a light source into asymmetric light rays, and wherein the inner lens surface and the outer lens surface distribute the light rays passing through the plurality of inner convex sections and the plurality of outer convex sections to achieve a peak light intensity distribution.
13. The luminaire as claimed in claim 11, wherein the plurality of outer convex sections and the plurality of inner convex sections reshape rotationally symmetric light rays coming out of a light source to concentrate luminous flux of the light rays between an elevation of 40º to an elevation of 80º for c-planes lying in a longitudinal direction of the luminaire.
14. The luminaire as claimed in claim 11, wherein the plurality of outer convex sections and the plurality of inner convex sections redistribute rotationally symmetric light intensity from a light source to asymmetric light intensity, wherein peak light intensity of the light rays is shifted from 0° to 70° while passing through the second convex section (108) and the third convex section (110).
15. The luminaire as claimed in claim 11, wherein an optimum spacing between two luminaires mounted at a mounting height, is equal to five times the mounting height of the luminaires.
16. The luminaire as claimed in claim 11, comprising:
the circuit board (504) having the plurality of light sources;

a lens module (508) having the plurality of lenses and disposed over the circuit board;
a gasket (506) disposed between the circuit board (504) and the lens module (508); and
a protective cover (510) disposed over the lens module (508), wherein the protective cover (510) provides ingress protection against solid particles and liquid as per IP66 standards.