Skip to contentUnited States Department of Transportation - Federal Highway Administration FHWA Home
Research Home
Report
This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-HRT-04-148
Date: December 2005

Enhanced Night Visibility Series, Volume XVII: Phases II and III—Characterization of Experimental Vision Enhancement Systems

PDF Version (5.65 MB)

PDF files can be viewed with the Acrobat® Reader®

Alternate Text

Figure 1. Equation. Radiant flux. Phi equals the integral of P of lamda times the differential of lamda. Back to Figure 1.

Figure 2. Equation. Luminous flux. Phi equals variable k times the integral of variable P of lamda times variable V of lamda times the differential of lamda. Back to Figure 2.

Figure 3. Equation. Radiant or luminous intensity. Variable I equals a quotient with numerator of the differential of phi and denominator of the differential of omega. Back to Figure 3.

Figure 4. Equation. Irradiance or illuminance. Variable E equals a quotient with numerator of the differential of phi and denominator of the differential of variable A. Back to Figure 4.

Figure 5. Equation. Radiance and luminance. Variable L equals a quotient with numerator of the differential squared of phi and denominator of the differential of omega times the differential of variable A times the cosine of theta. Back to Figure 5.

Figure 6. Diagram. Comparison of vertical reference point for 25-foot and 35-foot headlamp alignment distances. The elevation view diagram shows the front end of a sedan with its headlamps turned on at the right of the diagram. A blue field represents the maximum extent of the headlamp beam. Bold vertical lines at the left represent the alignment board at 25 feet and 35 feet from the vehicle. A horizontal line represents the headlamp optical center height, measured from the ground. When the vehicle is 25 feet from the alignment board, a point 5 centimeters below the optical center height is marked. When the vehicle is 35 feet from the alignment board, a point 7 centimeters below the optical center height is marked. Back to Figure 6.

Figure 7. Diagram. Visually optically aligned left aiming. This diagram has a vertical axis and a horizontal axis. A horizontal line runs parallel to the horizontal axis, but 0.6 degrees lower. This line is labeled "Vertical aiming plane." The headlamp beam is represented by a shaded blue region. The nonuniform boundary of the headlamp beam is a dark blue line. In the lower left quadrant, the boundary curves up steeply from the left and is level along the vertical aiming plane until it reaches the vertical axis, where it moves up and right at about 50 degrees. Back to Figure 7.

Figure 8. Diagram. Visually optically aligned right aiming. This diagram has a vertical axis and a horizontal axis. The horizontal axis is labeled "Vertical aiming plane." The headlamp beam is represented by a shaded blue region. The nonuniform boundary of the headlamp beam is a dark blue line. In the lower left quadrant, the boundary curves up steeply from the left, levels roughly until reaching the vertical axis, where it curves up and right sharply. The boundary then intersects the vertical aiming plane and remains level with it. Back to Figure 8.

Figure 9. Diagram. Hotspot aiming for mechanically aimed lamps. A large blue circle is located in the bottom right quadrant of a crosshair. The vertical and horizontal axes are tangent to the circle. The circle is outlined in black and fades from light blue to white near the center, which is labeled "Maximum luminous intensity." Back to Figure 9.

Figure 10. Graph. Misaim from the Copenhaver and Jones data. The title of the graph is "Headlamp Misaim." The X-axis, labeled "Horizontal Misaim (inches at 25 feet)," ranges from negative 12 inches to positive 10 inches. The Y-axis, labeled "Vertical Misaim (inches at 25 feet)," ranges from negative 15 inches to positive 15 inches. The legend notes the indicators for the following areas (SD means standard deviation): 1 SD, 2 SD, 3 SD, and SAE Regions. The legend also notes the markers for the ENV misaim and mean misaim. Moving from the origin outward, the graph consists of increasingly larger shaded rectangles. The 1 SD rectangle has corner coordinates of approximately: (negative 4, negative 3.5), (negative 4, positive 4), (positive 1.9, positive 4), (positive 1.9, negative 3.5). It is followed by the SAE Regions rectangle with corner coordinates of approximately: (negative 4, negative 4.1), (negative 4, positive 4.2), (positive 4, positive 4.2), (positive 4, negative 4.1). It is followed by the 2 SD rectangle with corner coordinates of approximately: (negative 7, negative 7), (negative 7, positive 7), (positive 4.8, positive 7), (positive 4.8, negative 7). It is followed by the 3 SD rectangle with corner coordinates of approximately: (negative 9.9, negative 10), (negative 9.9, positive 10.5), (positive 7.8, negative 10), (positive 7.8, positive 10.5). The mean misaim is at approximately (negative 1.5, positive 0.3), falling within one standard deviation and the SAE Region. The ENV misaim is at approximately (negative 9.5, positive 8), falling within the third standard deviation. Back to Figure 10.

Figure 11. Diagram. Hotspot aiming for UV–A lamps. Four small, overlapping blue circles are inscribed in a larger circle. An arrow points to the center of the diagram, where all four smaller circles converge, which is labeled "Center of hotspot aiming region." Back to Figure 11.

Figure 12. Line graph. Visible light spectral power distribution of halogen lamp ranging from 380 nanometers to 730 nanometers. The graph is titled "Spectral Distribution of Halogen Lamp." The X-axis is labeled "Wavelength (nanometers)" and ranges from 380 to about 735. The Y-axis is labeled "Relative Spectral Power." The graph shows an almost straight red line increasing from the lower left up to the right starting at 0.00 relative spectral power at about 387 nanometers to just above 0.08 relative spectral power at about 735 nanometers. At about 650 nanometers, the line switches from a smooth, steady increase to a line that fluctuates slightly. Back to Figure 12.

Figure 13. Line graph. Spectral power distribution of HID lamp ranging from 380 nanometers to 740 nanometers. The title of the graph is "Spectral Distribution of HID Lamp." The X-axis is labeled "Wavelength (nanometers)" and ranges from 380 to 740. The Y-axis is labeled "Relative Spectral Power." The graph shows a series of large peaks at the following approximate values: 0.10 relative spectral power at 470 nanometers, 0.125 relative spectral power at 515 nanometers, 0.105 relative spectral power at 550 nanometers, 0.125 relative spectral power at 570 nanometers, and 0.115 relative spectral power at 590 nanometers. After approximately 600 nanometers, there is a downward trend with some small peaks. Back to Figure 13.

Figure 14. Photo. Example of an original equipment manufacturer mount. This nighttime photo shows the front end of a sedan with its headlamps on. Back to Figure 14.

Figure 15. Photo. Rack mount. This daylight photo shows the front end of a white SUV with headlamps mounted on a metal rack slightly in front of the normal headlamp position. Back to Figure 15.

Figure 16. Photo. Glare rack mount. The photo shows a portable metal rack with a handle on one end and wheels on the opposite end. The rack has two levels. The top level contains two headlamps and their housings inside two removable headlamp containers held on by clamps. The bottom level contains a power supply. Back to Figure 16.

Figure 17. Photo. Halogen low beam front view. The photo shows the front view of a halogen headlamp. Back to Figure 17.

Figure 18. Graph. Halogen low beam isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal." The Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from negative 24 degrees horizontal to the edge of the graph at positive 25 degrees horizontal and from negative 12 degrees vertical to positive 7 degrees vertical. The regions of luminous intensity increase in roughly concentric rings toward the maximum luminous intensity at approximately positive 1 degree horizontal and negative 2 degrees vertical. Back to Figure 18.

Figure 19. Photo. Halogen low beam low profile front view. This photo shows the front view of a halogen headlamp displayed against a grid background. Back to Figure 19.

Figure 20. Graph. Halogen low beam low profile isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from negative 27 degrees horizontal to beyond the right edge of the graph at 30 degrees horizontal and from negative 14 degrees vertical (with an outcropping at negative 15 degrees horizontal that goes beyond the bottom edge of the graph at negative 15 degrees vertical) to positive 7 degrees vertical (with an outcropping at positive 5 degrees horizontal that extends to positive 9 degrees vertical). The regions of luminous intensity increase gradually from the bottom to the maximum luminous intensity at positive 2 degrees horizontal and negative 1 degree vertical; the intensity increases quickly from the top of the footprint to the maximum luminous intensity. Back to Figure 20.

Figure 21. Graph. Halogen high beam isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from beyond the left edge of the graph at negative 30 degrees horizontal to positive 30 degrees horizontal and from beyond the bottom edge of the graph at negative 10 degrees vertical to beyond the top edge of the graph at positive 10 degrees vertical. The regions of luminous intensity increase in roughly concentric rings toward the maximum luminous intensity at approximately positive 1 degree horizontal and negative 1 degree vertical. Back to Figure 21.

Figure 22. Graph. High output halogen low beam isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from beyond the left edge of the graph at negative 25 degrees horizontal to beyond the right edge of the graph at positive 25 degrees horizontal and from beyond the bottom edge of the graph at negative 15 degrees vertical to positive 14 degrees vertical. The regions of luminous intensity increase gradually from the bottom to the maximum luminous intensity at 0 degrees horizontal and negative 1 degree vertical; the intensity increases quickly from the top of the footprint to the maximum luminous intensity. Back to Figure 22.

Figure 23. Photo. High intensity discharge front view. This photo shows the front view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 23.

Figure 24. Photo. High intensity discharge side view. This photo shows the side view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 24.

Figure 25. Photo. High intensity discharge plan view. This photo shows the plan view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 25.

Figure 26. Photo. High intensity discharge rear view. This photo shows the rear view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 26.

Figure 27. Graph. High intensity discharge low beam isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from beyond the left edge of the graph at negative 25 degrees horizontal to beyond the right edge of the graph at positive 25 degrees horizontal and from beyond the bottom edge of the graph at negative 10 degrees vertical to positive 4 degrees vertical (with an outcropping at positive 3 degrees horizontal that extends to positive 12 degrees vertical). The regions of luminous intensity increase gradually from the bottom to the maximum luminous intensity at positive 1 degree horizontal and 0 degrees vertical; the intensity increases quickly from the top of the footprint to the maximum luminous intensity.
Back to Figure 27.

Figure 28. Graph. Companion headlamp to near infrared 2 and far infrared isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from beyond the left edge of the graph at negative 30 degrees horizontal to beyond the right edge of the graph at positive 30 degrees horizontal and from beyond the bottom edge of the graph at negative 15 degrees vertical to positive 4 degrees vertical. The regions of luminous intensity increase gradually from the bottom to the maximum luminous intensity at positive 1 degree horizontal and negative 1 degree vertical; the intensity increases quickly from the top of the footprint to the maximum luminous intensity. Back to Figure 28.

Figure 29. Graph. Companion headlamp to near infrared 1 isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from negative 30 degrees horizontal to beyond the right edge of the graph at positive 30 degrees horizontal and from negative 7 degrees vertical to positive 13 degrees vertical. The regions of luminous intensity increase a little more gradually from the bottom to the maximum luminous intensity at positive 1 degree horizontal and positive 4 degrees vertical than from the top to the maximum luminous intensity. Back to Figure 29.

Figure 30. Photo. High intensity discharge 1 front view. This photo shows the front view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 30.

Figure 31. Photo. High intensity discharge 1 side view. This photo shows the side view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 31.

Figure 32. Photo. High intensity discharge 1 plan view. This photo shows the plan view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 32.

Figure 33. Photo. High intensity discharge 1 rear view. This photo shows the rear view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 33.

Figure 34. Graph. High intensity discharge low beam 1 isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from beyond the left edge of the graph at negative 30 degrees horizontal to beyond the right edge of the graph at positive 30 degrees horizontal and from beyond the bottom edge of the graph at negative 15 degrees vertical to beyond the top edge of the graph at positive 10 degrees vertical. Inside the two outer luminous intensity regions, which are very large, the regions of luminous intensity increase a little more gradually from the bottom to the maximum luminous intensity at negative 2 degrees horizontal and negative 1 degree vertical (about 3 degrees to the right and 1 degree up, there is a second region of high intensity, although it is not as intense as the maximum). The intensity increases quickly from the top of the footprint to the maximum luminous intensity. Back to Figure 34.

Figure 35. Photo. High intensity discharge 2 front view. This photo shows the front view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 35.

Figure 36. Photo. High intensity discharge 2 side view. This photo shows the side view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 36.

Figure 37. Photo. High intensity discharge 2 plan view. This photo shows the plan view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 37.

Figure 38. Photo. High intensity discharge 2 rear view. This photo shows the rear view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 38.

Figure 39. Graph. High intensity discharge low beam 2 isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from beyond the left edge of the graph at negative 30 degrees horizontal to beyond the right edge of the graph at positive 30 degrees horizontal and from beyond the bottom edge of the graph at negative 30 degrees vertical to positive 9 degrees vertical. The regions of luminous intensity increase gradually from the bottom to the maximum luminous intensity at positive 2 degrees horizontal and negative 1 degree vertical; the intensity increases quickly from the top of the footprint to the maximum luminous intensity. Back to Figure 39.

Figure 40. Photo. High intensity discharge 3 front view. This photo shows the front view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 40.

Figure 41. Photo. High intensity discharge 3 side view. This photo shows the side view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 41.

Figure 42. Photo. High intensity discharge 3 plan view. This photo shows the plan view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 42.

Figure 43. Photo. High intensity discharge 3 rear view. This photo shows the rear view of a high intensity discharge headlamp displayed against a grid background. Back to Figure 43.

Figure 44. Graph. High intensity discharge low beam 3 isocandela plot (right headlamp). The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall region of luminous intensity extends from negative 25 degrees horizontal to beyond the right edge of the graph at positive 30 degrees horizontal and from beyond the bottom edge of the graph at negative 15 degrees vertical to positive 9 degrees vertical. The regions of luminous intensity increase gradually from the bottom to the maximum luminous intensity at positive 3 degrees horizontal and negative 1 degree vertical; about positive 2 degrees to the left and positive 1 degree down, there is a second region of high intensity, although not as intense as the maximum. The intensity increases quickly from the top of the footprint to the maximum luminous intensity. Back to Figure 44.

Figure 45. Graph. Spectral power distribution of the UV–A source. The graph is titled "UV–A Spectral Output." The X-axis is labeled "Wavelength (nanometers)" and ranges from 250 to 750. The Y-axis is labeled "Spectral Power (Watts per nanometer)." The graph begins at 300 nanometers and has two major peaks. One peak is approximately 4.1 Watts per nanometer at about 340 nanometers, and the other is 5.3 Watts per nanometer at about 370 nanometers. The graph line dips to about 1.5 Watts per nanometer between these two peaks and returns to 0.0 Watts at approximately 405 nanometers. Back to Figure 45.

Figure 46. Graph. Spectral power distribution of the hybrid UV–A source. The title of the graph is "Hybrid UV–A Spectral Output." The Y-axis is labeled "Spectral Power (Watts per nanometer)." The X-axis is labeled "Wavelength (nanometers)" and ranges from 250 to 750. The graph begins at approximately 290 nanometers and ends at approximately 550 nanometers. The graph consists of many sharp peaks at about 9.2 Watts per nanometer at 360 nanometers with peaks between 0.5 Watts per nanometer and 5.1 Watts per nanometer leading up to it, starting at about 300 nanometers, and with peaks between 5.6 Watts per nanometer and 0.8 Watts per nanometer trailing away from it, ending at about 440 nanometers. Back to Figure 46.

Figure 47. Photo. Hybrid UV–A front view. This photo shows the front view of a hybrid UV–A headlamp. A tape measure displayed in front of the headlamp shows that the headlamp is approximately 20.32 centimeters (8 inches) wide. Back to Figure 47.

Figure 48. Photo. Hybrid UV–A side view. The photo shows the side view of a hybrid UV–A headlamp. A tape measure displayed in front of the headlamp shows that the headlamp is approximately 13.97 centimeters (5.5 inches) in depth. Back to Figure 48.

Figure 49. Photo. Hybrid UV–A plan view. The photo shows a top-down view of a hybrid UV–A headlamp. A tape measure displayed in front of the headlamp shows that the headlamp is approximately 20.32 centimeters (8 inches) wide. Back to Figure 49.

Figure 50. Photo. Hybrid UV–A rear view. The photo shows a rear view of a hybrid UV–A headlamp. A tape measure displayed in front of the headlamp shows that the headlamp is approximately 20.32 centimeters (8 inches) wide. Back to Figure 50.

Figure 51. Graph. Hybrid UV–A radiant intensity. The graph is three-dimensional. The X-axis is labeled "Degrees Horizontal," the Y-axis is labeled "Watts," and the Z-axis is labeled "Degrees Vertical." A legend indicates the colors associated with incrementally increasing intensity from 0 to 210. The radiant intensity appears pyramidal and very evenly graduated from the bottom (0 Watts) to the maximum radiant intensity (110 to 120 Watts) at the tip. The bottom of the pyramid covers an area from negative 10 degrees horizontal to positive 10 degrees horizontal and from positive 5 degrees vertical to negative 5 degrees vertical.
Back to Figure 51.

Figure 52. Graph. Hybrid UV–A isoWatt plot of radiant intensity. The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The oblong overall radiant intensity region extends from beyond the left edge of the graph at negative 20 degrees horizontal to positive 17 degrees horizontal and from negative 5 degrees vertical to positive 7 degrees vertical. The two outer regions of radiant intensity are very large. The remaining inner regions, starting at negative 10 degrees horizontal to positive 10 degrees horizontal and negative 5 degrees vertical to positive 5 degrees vertical, are concentric and diamond-shaped, and they increase in intensity fairly evenly to the maximum radiant intensity at 0 degrees horizontal and 0 degrees vertical. Back to Figure 52.

Figure 53. Photo. UV–A lamps on the rack mount. This photo shows the front end of a white SUV. There are two levels of headlamps mounted on the vehicle, upper and lower. There are two halogen headlamps on either end of the upper level, just in front of the vehicle's own headlamps, with three circular headlamps between them. Circular headlamps are on the lower level, below each of the regular halogen headlamps. Footnotes indicate that the upper row of headlamps was used for the three UV–A configurations, and the upper and lower rows of headlamps were used for the five UV–A configurations. Back to Figure 53.

Figure 54. Photo. UV–A front view. This photo shows the front view of a UV–A headlamp. A tape measure displayed in front of the headlamp shows that the headlamp is approximately 20.32 centimeters (8 inches) wide. Back to Figure 54.

Figure 55. Photo. UV–A side view. This photo shows the side view of a UV–A headlamp. A tape measure displayed in front of the headlamp indicates that the headlamp is approximately 24.13 centimeters (9.5 inches) in depth. Back to Figure 55.

Figure 56. Photo. UV–A top view. This photo shows the top of a UV–A headlamp. A tape measure displayed in front of the headlamp shows that the headlamp is approximately 20.32 centimeters (8 inches) wide. Back to Figure 56.

Figure 57. Graph. UV–A radiant intensity. The graph is three-dimensional. The X-axis is labeled "Degrees Horizontal," the Y-axis is labeled "Watts," and the Z-axis is labeled "Degrees Vertical." A legend indicates the colors associated with incrementally increasing intensity from 0 to 210. The radiant intensity appears conical and very evenly graduated from the bottom (0 Watts) to the maximum radiant intensity (190 to 200 Watts) at the tip. The bottom of the cone covers an area from negative 4.5 degrees horizontal to positive 4.5 degrees horizontal and from negative 4 degrees vertical to positive 4.5 degrees vertical. Back to Figure 57.

Figure 58. Graph. UV–A isoWatt plot of radiant intensity. The X-axis is labeled "Degrees Horizontal," and the Y-axis is labeled "Degrees Vertical." The circular overall radiant intensity region extends from negative 4.5 degrees horizontal to positive 4.5 degrees horizontal and from negative 4 degrees vertical to positive 4.5 degrees vertical. The regions of radiant intensity are roughly concentric, and they increase in intensity rapidly toward the maximum radiant intensity at 0 degrees horizontal and 0 degrees vertical. Back to Figure 58.

Appendix A. Low beam alignment for hotspot. The diagram depicts a set of crosshairs with a circle centered in the lower right-hand corner. The caption above the diagram says "Hotspot Location: The circle represents the target hotspot location with respect to the target crosshairs. The center of the circle is the center of the hotspot." Back to Diagram.

Appendix A. UV–A alignment for hotspot. The diagram depicts a set of crosshairs centered on a large circle. Two smaller circles are centered horizontally inside the large circle. Two smaller circles are also centered vertically inside the larger circle, but portions of them are overlapped by the horizontal circles. The caption above the diagram says "Hotspot Location: The large outer circle represents the overall target area. The center of the large circle is the target hotspot location." Back to Diagram.

 

ResearchFHWA
FHWA
United States Department of Transportation - Federal Highway Administration