Attachment_0025_Optical_Sight_Adjustment_Point_Procedure_(OSAP).pdf

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OPERATOR

AVIATOR’S NIGHT VISION IMAGING SYSTEM (ANVIS)

OPTIMAL SIGHT ADJUSTMENT POINT (OSAP)

PROCEDURE

The optimal sight picture occurs when the optical axes of the ANVIS is aligned with your visual line-of-sight and the ANVIS’ eyepieces are at the maximum distance from your eyes that still allows you to see the intensified image full field-of-view. To achieve the OSAP, use the following procedure and refer to Figures 1 and 2.

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Figure 1. Optimal Sight Adjustment Point.

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Figure 2. Examples of Sight Picture Variations.

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PROCEDURES

1. Use a lighting condition, either actual or simulated, that is above starlight – (preferably ¼ to ½ moon). The background should be relatively uniform to produce a viewed image of reasonably uniform brightness without very dark or light areas.

NOTE

If the available background is not reasonably uniform (i.e. a blank wall), turn the objective focus ring clockwise to blur the image to obtain a relatively uniform brightness.

2. Initially, preset all the mechanical adjustments (except focus settings) to approximately a middle position. After you have experience obtaining the OSAP, you will be able to use individual preset positions as a starting point for the procedure. Usually you will require more time to fine-tune the fore-and-aft and eye-span settings than the other adjustments.

3. If the ANVIS is in the stowed position, use the lock-release button and rotate the ANVIS to the down position. Turn the power pack’s switch to the ON/primary position. You should see a green glow in each eyepiece. Do not worry about focusing at this time. It is actually better to have the objective lens way out of focus for this procedure.

Figure 3. Vertical Adjustment Knob

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4. Using the vertical adjustment knob, move the ANVIS so the images appear circular and roughly centered. If the ANVIS is too high, the top edges (from 10 o’clock to 2 o’clock) of the viewed image will be clearer than the bottom edges (from 4 o’clock to 8 o’clock). If the ANVIS is too low, the bottom edges will be clearer than the top edges. Move the ANVIS in the direction of the blurred edges until both the top and bottom edges are clear.

If the vertical adjustment is at the end of its range and you still cannot achieve the proper vertical alignment without moving the tilt lever from its middle position, take your helmet to ALSE personnel for adjustment.

5. Look at the edges in one of the monoculars and lightly close the other eye (if you find yourself forcing the other eye closed, place the eyepiece lens cap on that eyepiece). If the edges are blurred all the way around, use the fore-and-aft adjustment knob to move the ANVIS closer to your eyes until at least part of the edge is clear. Continue to move the ANVIS just a little closer to your eyes. Now, turn the eye-span adjustment knob to move the monocular in the direction of the blurred edge If the eye-span is too wide, the inside edge will be blurred; likewise, if the eye-span is too narrow, the outside edge will be blurred. By making the fine eye-span and fore-and-aft adjustment, move the monocular toward the blurred edges until you get a clear circular image.

6. When both the outside and inside edges are clear, use the fore-and-aft adjustment knob to move the ANVIS slowly toward you until you can positively identify the walls of the monocular tube (all edges will be crisp). Move the ANVIS away from your eyes until all the edges just begin to blur.

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• When the ANVIS is at the maximum distance from your eyes that still permits a full field-of-view, you will notice that the edges will blur slightly when you look directly at them and they will clear when you look at the center of the image. This is due to the pupil of your eye moving away from the optical axis of the ANVIS. This effect will help you obtain a very accurate OSAP.

• If the ANVIS is at the maximum aft position and you still see blurred edges, try focusing the eyepiece lens. If the edges are still blurred, change the eye-span distance. If the inside or outside edges clear when the monocular is moved left or right, the distance from the eyepieces to your eye is too great. Contact ALSE personnel to adjust your helmet.

7. Repeat the procedure for the other monocular tube. Adjust your helmet as necessary to allow both tubes to completely align with your eyes.

8. When you are satisfied with the alignment for both eyes, use the fore-and-aft knob to move the ANVIS slightly closer to the eye (about ½ turn). The edges of the ANVIS images should no longer be blurred. This is to return the ANVIS to a full field of view.

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9. Tilt should be adjusted in the aircraft. While sitting in the aircraft when it is on the ground, notice if you have to tilt your head backwards or forwards to see straight ahead and over the glare shield. If so, first check the vertical seat adjustment if it is available on your aircraft then adjust the ANVIS tilt as necessary.

Remember that a change in tilt angle may require a change in vertical adjustment. You should note during the flight if the desired tilt angle changes due to differences in the aircraft’s attitude. The desired tilt angle that is determined when the aircraft is on the ground may not be the optimal tilt angle during flight. You may notice that during flight it is easier to make slight changes in the tilt angle to compensate for slight vertical displacements that it it is to use the vertical adjustment knob. If the desired tilt angle is at the maximum of the adjustment range, and you are able to obtain optical and visual alignment you can still conduct an ANVIS flight. If not, serious consideration should be given to revising the mission.

END OF WORK PACKAGE