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From: "Bill Sisk" <bsisk@naic.edu>
To: "Phil Perillat" <phil@naic.edu>
Subject: DI1001 Beamwidth
Date: Mon, 1 Mar 2004 12:54:06 -0400
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Phil,
   I was looking through some old memos on the laser ranging system, and I
found one that had addressed the beamwidth of the DI1001. We have 7 DI1001's
and one DI1000. The target can move +/- 14 inches with the DI1001.

Bill


To : File

>From : Bill Sisk

Subject : DI1001 Distomat Beamwidth

Date : May 5, 1991



The DI1001, mounted on the T2000 theodolite, was set up on a monument.  A
Wild prism, at a range of 157.879 m, was fixed on rod which could be moved
vertically.  The maximum signal strength, when the theodolite is properly
aligned on the target is 4 1/2 bars.  (Note : Bill Hollinshead says that a
maximum of 4 1/2 bars instead of 7 or more is normal.  The distomat has
optical step attenuators that are put in for different ranges.  For the
lowest range, the signal strength was noted for different distances.  The
results were 8 bars @ 15m, 7 1/2 bars @ 75m, and 5 bars @ 117m.)   The
target was moved up and down vertically from the initial aligned position
without changing the alignment of the theodolite, and the signal strength
was read.  The results are tabulated below.



     Delta(in) Strength       Delta(in.)   Strength

     0         4.5            0            4.5

     +4        4.5           -4            4.5

     +8        4.5           -8            4.5

     +10       4-4.5         -10           4-4.5

     +12       3.5           -11           4

     +12.5     3             -11.5         3.5

     +13       2             -12           3

     +13.5     2             -12.5         2.5

     +14       1.5           -13           2

     +14.5     1             -13.5         1.5

                             -14           1-1.5

                             -14.5         0



With a signal strength of 1 bar, a distance measurement takes approximately
8 seconds.



The range of the fine adjustments screws on the DI1001 were also measured
using the theodolite.  The range is 1 - 1.5 degrees for both the vertical
and horizontal adjustments.