Abstract

A systematic method is proposed for designing an optical system for road lighting using an LED and a freeform lens that is optimized to produce a certain luminance distribution on the road surface. The proposed design method takes account of the luminance characteristics of the road surface, the energy efficiency of the system, the glare problem of the luminaire and the effects of four adjacent luminaries illuminating a single road surface. Firstly, the road surface illuminance with a polynomial of cosine functions along the road is optimized to maximize Q (the ratio of the average luminance to the average illuminance) as well as satisfying the lighting requirements provided by CIE. Then, a smooth freeform lens with this optimized illuminance is designed based on the variable separation method and the feedback modification method. Results show that, from two typical observer positions on the 2-lane C2 class road, luminaires with these freeform lenses can provide Q values of 7.90 × 10−2 and 8.69 × 10−2, the overall road surface luminance uniformity of 0.55 and 0.56, the longitudinal road surface luminance uniformity of 0.72 and 0.79, and the glare factors of 10.06% and 6.73% .

© 2010 OSA

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References

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  1. Kim lighting luminaire product catalogs. “WARP 9 LED”, (Kim Lighting, 2009), http://www.kimlighting.com/
  2. Y. Luo, Z. Feng, Y. Han, and H. Li, “Design of compact and smooth free-form optical system with uniform illuminance for LED source,” Opt. Express 18(9), 9055–9063 (2010), http://www.opticsinfobase.org/abstract.cfm?URI=oe-18-9-9055 .
    [CrossRef] [PubMed]
  3. CIE, (commission Internationale del'Eclairage). Calculation and Measurement of luminance and illuminance in Road Lighting (CIE publication 30.2, Vienna, 1982).
  4. CIE, (commission Internationale del'Eclairage). Road surfaces and lighting (CIE publication 66, Paris, 1984).
  5. A. Pachamanov and D. Pachamanova, “Optimization of the light distribution of luminaires for tunnel and street lighting,” Eng. Optim. 40(1), 47–65 (2008).
    [CrossRef]
  6. L. Wang, K. Y. Qian, and Y. Luo, “Discontinuous free-form lens design for prescribed irradiance,” Appl. Opt. 46(18), 3716–3723 (2007).
    [CrossRef] [PubMed]
  7. CIE, (commission Internationale del'Eclairage). Glare and uniformity in road lighting installations. (CIE publication 31, Paris, 1976).
  8. Y. Han, X. Zhang, Z. Feng, K. Qian, H. Li, Y. Luo, X. Li, G. Huang, and B. Zhu, “Variable-separation three dimensional freeform nonimaging optical system design based on target-to-source mapping and micro belt surface construction, ” Sciencepaper Online 1–9(2010). http://www.paper.edu.cn/en/paper.php?serial_number=201002-443
  9. CIE, (commission Internationale del'Eclairage). Recommendations for the lighting of roads for motor and pedestrian traffic, (CIE publication 115, Vienna, 1995).
  10. Cree LED products. “XLamp Xp_G LEDs datasheet”, (CREE, 2010), http://www.cree.com/products/xlamp_xpg.asp

2010

2008

A. Pachamanov and D. Pachamanova, “Optimization of the light distribution of luminaires for tunnel and street lighting,” Eng. Optim. 40(1), 47–65 (2008).
[CrossRef]

2007

Feng, Z.

Han, Y.

Li, H.

Luo, Y.

Pachamanov, A.

A. Pachamanov and D. Pachamanova, “Optimization of the light distribution of luminaires for tunnel and street lighting,” Eng. Optim. 40(1), 47–65 (2008).
[CrossRef]

Pachamanova, D.

A. Pachamanov and D. Pachamanova, “Optimization of the light distribution of luminaires for tunnel and street lighting,” Eng. Optim. 40(1), 47–65 (2008).
[CrossRef]

Qian, K. Y.

Wang, L.

Appl. Opt.

Eng. Optim.

A. Pachamanov and D. Pachamanova, “Optimization of the light distribution of luminaires for tunnel and street lighting,” Eng. Optim. 40(1), 47–65 (2008).
[CrossRef]

Opt. Express

Other

CIE, (commission Internationale del'Eclairage). Calculation and Measurement of luminance and illuminance in Road Lighting (CIE publication 30.2, Vienna, 1982).

CIE, (commission Internationale del'Eclairage). Road surfaces and lighting (CIE publication 66, Paris, 1984).

CIE, (commission Internationale del'Eclairage). Glare and uniformity in road lighting installations. (CIE publication 31, Paris, 1976).

Y. Han, X. Zhang, Z. Feng, K. Qian, H. Li, Y. Luo, X. Li, G. Huang, and B. Zhu, “Variable-separation three dimensional freeform nonimaging optical system design based on target-to-source mapping and micro belt surface construction, ” Sciencepaper Online 1–9(2010). http://www.paper.edu.cn/en/paper.php?serial_number=201002-443

CIE, (commission Internationale del'Eclairage). Recommendations for the lighting of roads for motor and pedestrian traffic, (CIE publication 115, Vienna, 1995).

Cree LED products. “XLamp Xp_G LEDs datasheet”, (CREE, 2010), http://www.cree.com/products/xlamp_xpg.asp

Kim lighting luminaire product catalogs. “WARP 9 LED”, (Kim Lighting, 2009), http://www.kimlighting.com/

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Figures (12)

Fig. 1
Fig. 1

Illustration of the variables of luminance calculation.

Fig. 2
Fig. 2

Luminance distributions produced by luminaires with uniform illuminance. The mounting space S = 35m, mounting height H = 10m, road width W = 7.5m, and the observer position is (−60m, 1.875m, 1.5m). The maximum lighting range along the road of each luminaire is (a) 17.5m or (b) 35m, and the luminance distributions produced by luminaires with these two uniform illuminance distributions are shown in (c) and (d), respectively.

Fig. 3
Fig. 3

Flow diagram of designing LED freeform optical system for road lighting

Fig. 4
Fig. 4

Illustration of the calculation region.

Fig. 5
Fig. 5

Light distribution curves derived from the optimized illuminance distribution. The flux is unified into 1000lm

Fig. 6
Fig. 6

Comparison of lighting parameters produced by luminaires1 (LP1), lumiaires2 (LP2), and luminaires3 (LP3) with the observer’s position at (a) (−60m, 1.875m, 1.5m) and (b) (−60m, 5.625m, 1.5m). Q0 (0.07) is the average luminance coefficient for C2 road

Fig. 7
Fig. 7

(a). The original lens model with an LED source. (b).Light distribution curves derived from the simulation results of the original lens and the optimized illuminance distribution. The flux is unified into 1000lm

Fig. 8
Fig. 8

Q values change with feedback times, which are calculated with the observer’s position at (a) (−60m, 1.875m, 1.5m) and (b) (−60m, 5.625m, 1.5m).

Fig. 9
Fig. 9

(a). The final lens model after six times feedback with an LED source. (b). Light distribution curves derived from the simulation results of the final lens and the optimized illuminance distribution. The flux is unified into 1000lm

Fig. 10
Fig. 10

Luminance distributions on C2 road perceived by observer at (a) (−60m, 1.875m, 1.5m) and (b) (−60m, 5.625m, 1.5m).

Fig. 11
Fig. 11

Effects of the mounting space on the lighting parameters (a) U0 , (b) UL , (c) TI and (d) Q.

Fig. 12
Fig. 12

Effects of the mounting angle on the lighting parameters (a) U0 , (b) UL , (c) TI and (d) Q.

Tables (3)

Tables Icon

Table 1 Lighting parameters calculated from the optimized illuminance

Tables Icon

Table 2 Lighting parameters calculated from the simulation results of the original lens model

Tables Icon

Table 3 Lighting parameters calculated from the simulation results of the final lens model

Equations (22)

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L ( β , γ ) = k = 1 K r ( β , γ ) 10 4 cos 3 γ E k ( c , γ )
L ( x i , y j ) = k = 1 K r k ( x i , y j ) 10 4 cos 3 γ k ( x i , y j ) E k ( x i , y j )
E a v = i = 1 N j = 1 M E ( x i , y j ) N M , E ( x i , y j ) = k = 1 K E k ( x i , y j )
L a v = i = 1 N j = 1 M L ( x i , y j ) N M
E 0 = min ( E ( x i , y j ) ) E a v , i = 1 , 2 , ... N , j = 1 , 2 , 3 , ... M
U 0 = min ( L ( x i , y j ) ) L a v , i = 1 , 2 , ... N , j = 1 , 2 , 3 , ... M
U L = min ( L ( x i , y c e n t e r ) ) max ( L ( x i , y c e n t e r ) ) , i = 1 , 2 , 3 , ... N
L v = 10 k = 1 K E e k θ e k 2
T I = 65 L v L a v 0.8
E 0 ( x , y ) = E x ( x ) E y ( y ) = ( i = 1 J a i cos n i ( π x 2 x max ) ) 1 = i = 1 J a i cos n i ( π x 2 x max )
max ( Q ( a 1 , a 2 , ... , a J , n 1 , n 2 , ... n J ) ) = max ( L a v ( a 1 , a 2 , ... , a J , n 1 , n 2 , ... n J ) E a v ( a 1 , a 2 , ... , a J , n 1 , n 2 , ... n J ) )
L a v ( a 1 , a 2 , ... , a J , n 1 , n 2 , ... n J ) L a v T
U 0 ( a 1 , a 2 , ... , a J , n 1 , n 2 , ... n J ) U 0 T
U L ( a 1 , a 2 , ... , a J , n 1 , n 2 , ... n J ) U L T
T I ( a 1 , a 2 , ... , a J , n 1 , n 2 , ... n J ) T I T
Ω I 0 cos 2 u cos v d u d v = D E 0 ( x , y ) d x d y
u j + 1 = f ( i = 1 n j = 1 j E 0 ( x i , y j ) )
v i + 1 = g ( j = 1 m i = 1 i E 0 ( x i , y j ) )
η l ( x i , y j ) = β l ( x i , y j ) β l 1 ( x i , y j ) β 1 ( x i , y j )
β l ( x i , y j ) = E 0 ( x i , y j ) ( 1 λ ) E 0 ( x i , y j ) + λ E ' l ( x i , y j )
E l + 1 ( x i , y j ) = η l ( x i , y j ) E 0 ( x i , y j )
F l u x w a s t e = ( E a v o p t i E a v s i m u ) × W × S | L a v = 1.5 c d / m 2

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