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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

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APPENDIX A—PHASES II AND III HEADLAMP ALIGNMENT PROTOCOL

Protocol Summary

The protocol presented below represents the consensus of experts in the field on the appropriate procedure that should be followed for headlamp alignment:

  • An alignment plate should be mounted onto the ground 35 ft from and parallel to the alignment wall.
  • The alignment wall should be as flat as possible.
  • The wheels should be straight against the plate and perpendicular to the alignment wall.
  • The perpendicular position can be reached by creating a 90-degree angle configuration on the floor that will guide the vehicle to the right position. A simple "L" shape mark on the floor should suffice.
  • A laser that marks the center of the vehicle should be used to make sure the screen is centered to the vehicle. Each vehicle should have its own line on the screen. The lines are labeled directly on the screen to avoid confusion.
  • Markings of the photometric center of the headlamp beam should be performed for each headlamp with respect to the floor.
  • The appropriate headlamps should be turned on, while making sure no auxiliary lights (parking lights, fog lights, daytime running lights) are on.
  • One headlamp should be covered up or unplugged so that readings are taken for only one light at a time.
  • For the HID, HLB, and HOH configurations, align the headlamps so that the "hotspot" is located in the lower right quadrant. This can be performed by positioning the photometer sensor tangent to both the horizontal and vertical lines. When measuring the hotspot in that quadrant, the outside top and left borders of the sensor's circumference (the sensor is 1 inch in diameter) need to touch both axes of the crosshairs. This will position the hotspot half an inch down and to the right from the center of the crosshair.
  • The photometer should be "ZEROed" prior to checking each measurement. To do this, make sure that all headlamps are turned off. Remove the cap from the 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 the background and remove its effects from the actual source value. After zeroing, turn the headlamp on and begin alignment.
  • Adjustment of the headlight aim should be performed as needed.

The only difference between the alignment of the UV–A or HHB headlamps and this previous headlamp alignment procedure (HID, HLB, and HOH) is that the "hotspot" must be at the center of the crosshairs.

Detailed Protocol

Vehicle/Headlamp Combinations Acronym List:

BLK HID 1 BLK HID 2 Black [SUV]

  High Intensity Discharge 1 & 2
BLK HLB 1 BLK HLB 2 Black [SUV]

  Halogen Low Beam 1 & 2
BLK LO UV–A 1 BLK LO UV–A 2 Black [SUV]

  Low output UV–A 1 & 2
WH HID 1 WH HID 2 White [SUV]

  High Intensity Discharge 1 & 2
WH HLB 1 WH HLB 2 White [SUV]

  Halogen Low Beam 1 & 2
WH MID/HI UV–A 1 thru

  WH MID/HI UV–A 5
White [SUV]

  Mid/High output UV–A 1 thru 5
P/U HOH(HHB) 1 P/U HOH(HHB) 2 Pickup Truck, High Output Halogen
(Halogen High Beam)


Special Notes for Sim Bay Room Prep:

It is very important to make sure that you have enough time to align all of the headlights prior to the team meeting, 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.

Since we are leaving half of the lights on, 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.

  1. Setting up the Non-UV–A headlamps

    Applies to the following Vehicle/Headlamp combinations:

    WH HID (1&2), BLK HID (1&2)

    WH HLB (1&2), BLK HLB (1&2)

    P/U HOH(HHB) (1&2)

    Pull the vehicle up to the alignment plate mounted onto the ground. This should be located 35 feet from the alignment wall. Make sure the wheels are straight against the plate.

    Use the laser to make sure the screen is centered to the vehicle. Each vehicle has a different line on the screen. The lines are labeled directly on the screen.

    Locate the appropriate markings on the wall 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.

    Align the VES so that the "hotspot" is located in the first (or lower right) quadrant, tangent to both the horizontal and vertical lines. The sensor, when measuring the hotspot in that quadrant, will touch both axes of the crosshairs. 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.

    Note: Why do we align these lights off-center point?

    When these types of lights are aligned straight ahead, the lights are placed in a "High Beam" configuration. We do not want to use the "High Beam" for these configurations. Our alignment procedure allows each light to be directed slightly to the right and below the exact center line for that light.

    Hotspot location 1. Click here for more detail.

    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."

    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.

    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).

    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.

  2. Setting up the UV–A headlamps

    Applies to the following Vehicle/Headlamp combinations:
    • WH MID/HI UV–A (1-5)
    • BLK LO UV–A (1&2)

    Pull the vehicle up to the alignment plate on the ground. This should be located 35 feet from the alignment wall. Make sure the wheels are straight against the plate. In addition, the vehicle needs to be centered along the white line painted from the wall.

    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 wall for that headlamp.

    Cover up one headlamp so that you are only taking readings for one light at a time.

    Align the headlamps so that the "hotspot" is located on the crosshairs. The UV–A low headlamps have fine adjustments. The UV–A high 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 2. Click here for more detail.

    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."

    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.

    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 wall for calibration; it's backwards when looking directly at vehicles.

P/U HOH(HHB) [Pickup truck]
1 (Left) 2 (Right)
42.2 W/cm² 45.2 W/cm²


WH HID; BLK HID [either SUV]
1 (Left) 2 (Right)
visual alignment based on other light 41.6 W/cm²


WH HLB; BLK HLB [either SUV]
1 (Left) 2 (Right)
44.7 W/cm² 50.1 W/cm²


BLK LO UV–A [Black SUV]
1 (Left) 2 (Right)
100 µW/cm² 92.0 µW/cm²


WH MID/HI UV–A [White SUV] Top Row lights
1 (Top Left) 2 (Top Center) 3 (Top Right)
590 µW/cm² 472 µW/cm² 484 µW/cm²


WH MID/HI UV–A [White SUV] Bottom Row lights
4 (Bottom Left) 5 (Bottom Right)
486 µW/cm² 565 µW/cm²


Headlamp Alignment Date:  ___________________
  Initials:  ____________________



Reference values for the various headlamps are included on the top line. Actual/current values are written inside each box as appropriate. Alignment data should be recorded once a week to provide a continuous record of the health of the headlamps. Note: You look at this table as you look at the wall for calibration; it's backwards when looking directly at the vehicles.



P/U HOH(HHB) [Pickup truck]
1 (Left) 2 (Right)
42.2 W/cm²


Actual:
45.2 W/cm²


Actual:


WH HID; BLK HID [either SUV]
1 (Left) 2 (Right)
visual alignment based on other light


Actual:
41.6 W/cm²


Actual:


WH HLB; BLK HLB [either SUV]
1 (Left) 2 (Right)
44.7 W/cm²


Actual:
50.1 W/cm²


Actual:


BLK LO UV–A [Black SUV]
1 (Left) 2 (Right)
100 µW/cm²


Actual:
92.0 µW/cm²


Actual:


WH MID/HI UV–A [White SUV] Top Row lights
1 (Top Left) 2 (Top Center) 3 (Top Right)
590 µW/cm²


Actual:
472 µW/cm²


Actual:
484 µW/cm²


Actual:


WH MID/HI UV–A [White SUV] Bottom Row lights
4 (Bottom Left) 5 (Bottom Right)
486 µW/cm²


Actual:
565 µW/cm²


Actual:

 

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