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Publication Number: FHWA-HRT-04-137
Date: December 2005

Enhanced Night Visibility Series, Volume VI: Phase II—Study 4: Visual Performance During Nighttime Driving in Fog

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APPENDIX K—AIMING PROTOCOL



PROTOCOL SUMMARY

Vehicle/Headlamp Combinations Acronym List:

WH HLB 1 WH HLB 2 SUV # 1
    Halogen Low Beam 1 & 2
WH Hybrid UV–A 1 WH Hybrid UV–A 2 SUV #1
    Hybrid UV—A 1 & 2
WH HLB 1 WH HLB 2 SUV #2
    Halogen Low Beam 1 & 2
WH UV–A 1 thru WH UV–A 5 SUV #2
    Five UV–A 1-5
EX HID 1 EX HID 2 SUV #3
    High Intensity Discharge
  • It is very important to make sure that you have enough time to align all of the headlights prior to the team meeting, and especially prior to the road preparations. Minimum alignment time is 1 hour when no headlamps need to be switched between vehicles, but you should plan on 1 ¼ - 1 ½ hours as a general rule. Alignment times will be greater on days when headlamps must be moved.
  • It is important to remember to use the ZERO function on the photometer prior to aligning each light. This is particularly important when recording the photometer values on the Headlamp Alignment form.

Setting up the Non-UV–A headlamps

Applies to the following Vehicle/Headlamp combinations:
SUV #1 HLB (1&2), SUV #2 HLB (1&2)
SUV #3 HID (1 & 2)

  • Use the laser to make sure the target board is centered to the vehicle. Each vehicle has a different line on the target board. The lines are labeled directly on the target board. The lines from left to right are: SUV #1 Laser Line, SUV #2 Laser Line, and SUV #3. Locate the appropriate markings on the target board for each VES.
  • Turn on the appropriate headlamps, making sure no auxiliary lights (parking lights, fog lights, daytime running lights) are on.
  • Cover up or unplug one headlamp so that you are only taking readings for one light at a time.

Finding the Hotspot:

Align the VES so that the “hotspot” is located within the circle located on the aiming board. The headlamps have both gross and fine adjustments. Typically, only fine adjustments will be required if the headlights are not switched; gross will be required if the headlights are switched.

Using the Photometer:

To determine if the hotspot is in the correct location, you will need to use the International Light, Inc., IL1400A Radiometer/Photometer to measure the area of greatest intensity. There are two sensors for the photometer; the sensor for the visible light is marked with a “REG” label, and the sensor for the UV light is marked with a “UV–A” label. Use the sensor marked “REG.”

Zero the Photometer:

Remember to “ZERO” the photometer prior to checking each measurement. To do this, make sure that all headlamps are turned off. Remove the cap from the photometric sensor. Place the sensor at the alignment location for the headlamp to be aligned. Press the “ZERO” button; this will allow the photometer to measure any undesired background light and remove its effects from the actual light source value. The photometer is ready when the “ZEROING” message has changed back to the “SIGNAL” message. Turn the headlamp on and begin alignment.

Isolating the Hotspot:

Once you find the area you believe has the highest intensity, readings need to be taken in all directions around that location to ensure that is the hotspot. If the hotspot is in the correct location, the light is aligned and you can align the other light(s).

Note that for non-UV lights, the HLBs in particular, the hotspots actually span a large horizontal swath, 2-4 inches wide. It is relatively easy to determine the hotspot vertically, but determining the hotspot horizontally requires more effort and patience given that the horizontal hotspot can be 2-4 inches wide.

Special Instructions for HID alignment in the Blue Box:

Remember that the HIDs require alignment with the photometer for rightmost (no. 2) headlamp and visual alignment based of the left (no. 1) headlamp based on the aligned right headlamp. This is noted on the alignment form.

 

Setting up the UV–A headlamps

Applies to the following Vehicle/Headlamp combinations:

SUV #2 Five UV–A (1-5)

SUV #1 Hybrid UV–A (1&2)

  • Use the laser to make sure the target board is centered to the vehicle. Each vehicle has a different line on the target board. The lines are labeled directly on the target board. The lines from left to right are: SUV #1 Laser Line, SUV #2 Laser Line, SUV #1 UV, and SUV #2 UV. If you are aligning the UV headlamps on SUV number 2, you should use the SUV #2 -UV laser line. All other vehicles require the use of the standard alignment point.
  • Turn on the appropriate headlamps, making sure no auxiliary lights (parking lights, fog lights, daytime running lights) are on.
  • Locate the appropriate markings on the target board for that headlamp.
  • Cover up the headlamps so that you are only taking readings for one light at a time.

Finding the Hotspot:

Align the headlamps so that the “hotspot” is located on the crosshairs. The hybrid UV–A headlamps have fine adjustments. The five UV–A headlamps require shimming for the vertical location and wrench adjustments for the horizontal adjustment.

Note that it is sufficient to line up the sensor on the crosshairs such that at least the edge of the sensor touches the center of the crosshairs. This means that there is a circular space around the center of the crosshairs, with a radius the size of the sensor in all directions (about 2 inches in diameter), in which the hotspot may be found. This is a larger margin of alignment error than allowed for the non-UV lights and is due to the nature of the mounting of the lights.

Hotspot location. Click here for more detail.

Using the Photometer:

To determine if the hotspot is in the correct location, you will need to use the International Light, Inc., IL1400A Radiometer/Photometer to measure the area of greatest intensity. There are two sensors for the photometer; the sensor for the visible light is marked with a “REG” label, and the sensor for the UV light is marked with a “UV–A” label. For UV–A light, use the photometer sensor marked “UV–A.”

Zero the Photometer:

Remember to “ZERO” the photometer prior to checking each measurement. To do this, make sure that all headlamps are turned off. Remove the cap from the photometric sensor. Place the sensor at the alignment location for the headlamp to be aligned. Press the “ZERO” button; this will allow the photometer to measure any undesired background light and remove its effects from the actual light source value. The photometer is ready when the “ZEROING” message has changed back to the “SIGNAL” message. Turn the headlamp on and begin alignment.

Isolating the Hotspot:

Once you find the area you believe has the highest intensity, readings need to be taken in all directions around that location to ensure that is the hotspot. If the hotspot is in the correct location, the headlamp is aligned and you can align the other light(s).

Reference values for the Various Headlamps:

Note: You look at this table as you look at the target board for calibration; it’s backwards when looking directly at the vehicles.

HID
1 (Left) 2 (Right)
visual alignment based on other light 41.6 W/cm²


# 1 HLB & #2 HLB
1 (Left) 2 (Right)
44.7 W/cm² 50.1 W/cm²


Hybrid UV–A [#1]
1 (Left) 2 (Right)
100 µW/cm² 92.0 µW/cm²


Five UV–A [#2] Top Row lights
1 (Top Left) 2 (Top Center) 3 (Top Right)
590 µW/cm² 472 µW/cm² 484 µW/cm²


Five UV–A [#2] Bottom Row lights
4 (Bottom Left) 5 (Bottom Right)
486 µW/cm² 565 µW/cm²




Headlamp Alignment Form

Date:______________________________

Inits:____________________________


HID
1 (Left) 2 (Right)
visual alignment based on other light


Actual:
41.6 W/cm²
Black SUV

Actual:


#1 HLB
1 (Left) 2 (Right)
44.7 W/cm²


Actual:
50.1 W/cm²


Actual:


#2 HLB
1 (Left) 2 (Right)
44.7 W/cm²


Actual:
50.1 W/cm²


Actual:


Hybrid UV–A [#1]
1 (Left) 2 (Right)
100 µW/cm²


Actual:
92.0 µW/cm²


Actual:


Five UV–A [#2] Top Row lights
1 (Top Left) 2 (Top Center) 3 (Top Right)
590 µW/cm²


Actual:
472 µW/cm²


Actual:
484 µW/cm²


Actual:


Five UV–A [#2] Bottom Row lights
4 (Bottom Left) 5 (Bottom Right)
486 µW/cm²


Actual:
565 µW/cm²


Actual:

 

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