Institute of High Energy Physics

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Comparison and Study in Measurement
Accuracy of Height Difference between
Laser Tracker and Level
Men LingLing Dong Lan Li bo Wang
Xiaolong

• Institute of High Energy Physics
• 13/09/2010

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Introduction

• As we know, in accelerator alignment field ,we
  can get a high accuracy vertical network by
  level. In this meeting, I want to report a
  conclusion that we can also get a high accuracy
  vertical network by
• Laser tracker.
• How is the accuracy of vertical coordinates by
  laser
• tracker measuring in single station?
• From 2001 to 2006,we had ever completed the 4
  comparing measurements in height difference
  between laser tracker and level at BEPCII tunnel.
  Through analyzing data, we obtain the above
  result.

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The measuring method of height difference using
Laser Tracker

• The instrument FARO Laser Tracker
• Measuring process
• Adjusting the tracker to level roughly .
• Let the tracker to measure the levelness of
  the instrument
• finally.
• Measuring the 3 dimensional coordinates of
  control points
• using the laser tracker in single
  station.
• We construct the level coordinate system by
  the levelness
• measured from the tracker in the Insight
  software.
• Extracting the vertical coordinates of
  control points to
• calculate the height difference between
  two points.

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Contents

• Introduction the comparing measurement and
  Analysis Result In 2001
• Introduction the comparing measurement and
  Analysis Result In 2002
• Introduction the comparing measurement and
  Analysis Result In 2004
• Introduction the comparing measurement and
  Analysis Result In 2006
• Conclusion

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1. The comparing measurement and Analysis Result
In 2001
BEPC layout

• The measurement Instruments
• SMX4500 Laser Tracker and N3 Optical Level
• Measuring site
• The tunnel of BEPC storage ring and LINAC

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• Measuring process
• One group measured the height difference
  between two adjacent points from R1 to R29 in
  storage ring tunnel and from G02W2 to G43W2 in
  LINAC tunnel
• with laser tracker.
• Another group measured the height difference
  between two adjacent points from R1 to R2 in
  storage ring tunnel and from G02W2 to G43W2 in
  LINAC
• tunnel with level.

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Data in 2001
Amount of height difference compared is 38
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Calculating method

• We calculated two height differences of
  the same two
• points according to the two sets of data
  from Laser
• Tracker and N3 Level separately .

means the height
difference of Point R1 and R2 in laser tracker.
means the height
difference of Point R1 and R2 in level.
means the comparing error
of the height difference between two instruments .
We calculated the comparing error of height
difference according to the two sets of height
differences. .
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The statistic comparing error of height
difference

• Results of the statistic comparing error
  M00.089mm

M00.089
Fig. result of 2001 year
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2. The comparing measurement and Analysis Result
In 2002

• The measurement Instruments
• FARO Laser Tracker and NA2 Optical Level
• Measuring site Leveling network of BEPC
  storage ring

• Measuring process
• One group measured the height difference
  between two
• adjacent points from R1 to R29 and from
  R1W2 to
• R29W2 in storage ring tunnel with laser
  tracker .
• Another group measured the height
  difference between two
• adjacent points from R1 to R29 and from
  R1W2 to
• R29W2 in storage ring tunnel with level.

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Segment Data in 2002
Amount of comparing height difference compared is
57
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The statistic error of height difference

• Results of the statistic comparing error

M00.097mm
Fig. result of 2002 year
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3. The comparing measurement and analysis result
In 2004

• The measurement instruments
• FARO Laser Tracker and NA2 Optical Level
• Measuring site Leveling network of BEPCII LINAC

Laser tracker
BEPCII LINAC

• The comparing measurement experiment was
  completed during the period of BEPC LINAC
  upgraded to BEPCII LINAC

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• control monuments distributing of BEPCII LINAC

26 monuments fixed on the wall from LH2 to LH58
at a height of 1.8 meters above the floor spaced
at intervals of 8 meters
26 monuments fixed on floor along the foot of
the wall from L2 to L58 at intervals of 8 meters.
24 monuments on floor along the LINAC girder
between L101 and L102 spaced at intervals of 8
meters over 230 meters.
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• The Laser tracker measured three sections forward
  and three backward in each station, and 20
  monuments can be measured.

NA2 level
The tracker was measuring the floor monument
Three sections backward
Three sections forward
Tracker
Floor monument
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Segment data in 2004
Amount of comparing height difference compared is
260
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The statistic comparing error of height
difference M0

• Results M00.096mm

M00.096
Fig. result in 2004
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4. The comparing measurement and analysis result
in 2006

• The measurement Instruments
• FARO Laser Tracker and NA2 Optical Level
• Measuring site Leveling network of BEPCII
  storage ring

Brief introduction of BEPCII storage ring

• It consists of both the positron and the electron
  rings.
• The distance between the beam centerlines of the
  two rings is 1.179 m.
• Their circumference is 237 m.

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control monuments distributing of BEPCII
Storage Ring

• The 3 dimensional tunnel network consist of 201
  control points.
• The 3 dimensional monuments were fixed on the
  floor and wall of the storage ring tunnel.

67 monuments on the wall about 1.8m high
67 monuments along the foot of the wall
67 monuments on floor along the girder spaced
at intervals of 6 meters over 237 meters.
BEPCII layout
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Leveling staff
Wall monument
1.5inches tooling ball
NA2 level
Optical tooling scale fixed on the tooling ball
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Segment data in 2006
Amount of height difference compared is 176
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The statistic comparing error of height
difference
M00.067

• Results M00.067mm

Fig. result of 2006 year
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Tab. Statistic comparing error M0 of height
difference between laser tracker and level in 4
years
year M0
2001 0.089mm
2002 0.097mm
2004 0.096mm
2006 0.067mm
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Results of 4 years
We calculate the statistic error of height
difference to all data of 4 years together.
Amount of height difference compared is 531
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The statistic difference of height difference
M00.087

• Results M00.087mm

Fig. result for 4 years
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Conclusion

• Compare error of height difference between laser
  tracker in single station and level is 0.087mm.
  In the accelerator vertical measurement ,laser
  tracker can
• instead of level certainly.
• From 2007 to 2010,we use laser tracker to measure
  the tunnel vertical network of BEPCII instead of
  level throughly. The result of measurement can
  meet the requirement of accelerator run. The
  BEPCII alignment is brought about the 3
  dimensional measurement in
• single laser tracker only.

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Thank you for attention!
Men Lingling menll_at_ihep.ac.cn
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abstract

• On the basis of data which we measured in the
  last few years in BEPCII tunnel, we compare and
  study in measurement accuracy of height
  difference between laser tracker and level.
  Compare error of laser tracker in single station
  and level is 0.087mm. The results show that the
  accuracy of laser tracker measuring vertical
  network in single station meets the requirement
  of accelerator physics. the accelerator vertical
  measurement ,laser tracker can instead of level
  certainly.

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Closed error in 2002
Closed error MH
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• It was not the closed measurement using laser
  tracker in 2001 and in 2004.

• Closed error of round trip measurement using
  level was
• controlled on a range of 0.3mm in every year.

Closed error MH in 2006
Laser tracker MH0.4mm
Level MH0.25mm