• Dome Centerline Coordinates (DCL)
• Ray trace coordinates (RTC)
  
• primary reflector coordinate system
• dome enclosure drawing.
  

Target location on reflectors

• secondary reflector. .dsn files
• (note that i've renamed them to secref.dat  so the web browser will open them.)

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Survey coordinate systems

    Various coordinate systems are used during surveys.

• Surveying the primary
• surveying the dome position from AO9
  
• Surveying the secondary, tertiary, horn positions from inside the dome, Dome centerline coordinates
  
• Definition of tertiary, secondary reflector shapes (Ray trace coordinates)
  

Dome center line coordinates:(DCL)

• Used when surveying the secondary, tertiary, horns.
• The target locations on the secondary, tertiary, and horns will all be in DCL.
  
• Origin:
• from upgrade drawings, and CRDDFN.M (in /share/megs/survey/AO_align_old_laptop/math/CRDDFN.M).. lynn's ray trace to (DCL) routines
• Where the vertical dome center ine  intersects the top working line of the collar truss
  
  
• directions:
• z - perpendicular to top cord of collar truss
• z=0 is at top cord of collar truss
  
• x - is along the azimuth arm.
•  Positive is uphill
• origin is at center line of the dome. This should intersects the top cord of collar truss
  
• y perpendicular to x-z plane, right handed system
• positive direction is from symmetry axis of secondary (or say the feed focus) toward the stairwell.
  
• 0rigin is at the vertical axis of symmetry of the secondary.
  
• I guess this must also bisect the collar truss in the y direction?
• The .dsn files for surveying the secondary, tertiary, horns use DCL coordinates.
• When surveying in the dome, the theodolite coordinate system is transformed to DCL by measuring about 50 targets on the secondary with known DCL coordinates, and then letting the theodolite software transform the theodolite coord to DCL.
• Pictures of the targest on the secondary in dome centerline coordinates:
• the red dots are targets that were not working on nov2003.
  
• .pdf1
• .pdf2
• .pdf3
• .pdf4

Dome Enclosure drawing (.pdf)

• The schematic is S-33 of the upgrade drawing package.
• the penciled in comments are by mike davis.
• The "apex of caustic" is the origin of the ray trace coordinate system.
• The arrow from the "Dome C/L coordinates" penciled in comments,  points to the origin of the dome centerline coordinate system.
• At the bottom of the dome, i think the penciled in .63 deg angle is on the wrong side of the vertical.
• The tilt about yaxis is +.63 deg (CW) and the Yaxis points into the page..
  

Ray trace  coordinate system (RTC)

• The reflector shapes are defined in a ray trace coordinate system.
• Origin:
  
• at the apex of the caustic.. where the rays from different sides of the primary cross
  
• gregorian optics have the caustic in front of the reflector,
• cassegrain optics have the reflector in front of the caustic
• The caustic should sit on the paraxial surface (435 feet below the center of curvature of the primary ...assuming a 870 foot radius of curvature).
• directions
• z - a ray that goes from the caustic through the center of curvature
• positive is up (away from the primary).
  
• y - perpendicular to the symmetry axis of the secondary
  
• x - perpendicular to y,z (Right handed system).
• x  direction is along the azimuth arm.
  
• positive moves uphill
  

Primary coordinate system:

• 0rigen: center of reflector
• The radius of curvature is about 870 feet
• The reflector is often surveyed from the AO9 monument (at center of the  dish)
• The reflector is offset from AO9 by 1.34 inches east of ao9, .69 in south of AO9.. from primary survey (more info)
• The reflector needs to be centered relative to the rotation axis of the azimuth (main bearing).
• platform/reflector offset
• east-west: platform in -1.11 inches offset (1.11 inches towards the west)
• north-south: platform is 2.88 inches towards the north (more info)
• This agrees with the raw pointing errors.
  
• x: east(positive) west(negative)
• y: north (positive) - south (negative)
• z: vertical (positive is up).
• This is a right handed system.

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Target locations on reflectors

     Lynns description in PNLFDCL directory:

    This subdirectory contains all the data pertaining to the target fiducials on the secondary and tertiary panels.  There is a file for each of the two reflectors named target.dat in both cases.  This file contains the measured locations of the panel fiducial holes in the dome C/L coordinate system and units of inches.  These fiducials were measured on a coordinate measuring machine at RSI when the panels were fabricated.

    When calculating reflector errors it is necessary to have the unit normals to the panel at the fiducial point.  The normals at the fiducial points are obtained from fortran software included in this subdirectory.  The software is a parametric spline interpolation system.  The reflectors are defined by a dense set of points and this interpolation system.  The dense set of points is in the file scndry.dat for the secondary and trtry.dat for the tertiary (these are the ray trace files pjp..)  The data in these files is from the PSK shaping software and is in the ray trace coordinate system and units of feet.

    The basic function of the fortran interpolation system is to accept a r,phi parametric variable pair and calculate the corresponding x,y,z coordinates on the reflector surface.  The software also produces the surface derivatives which can then be used to obtain the surface normals and jacobian of the mapping from parametric space to physical space.  The interpolation system is contained in the two fortran files interp2d.f and surfac.f which are common to both reflectors and contained in the upper directory.

    The calculation performed here is the inverse of basic interpolation.  Given a physical point, calculate the corresponding r,phi parametric variables and then the surface normal and jacobian at that point.  The fortran files scndry_fdcl.f and trtry_fdcl.f perform these tasks.  It starts by reading the file of reflector data points and initializing the interpolation system.  It reads the file of fiducial points and finds the corresponding parametric variables with a root find routine.  It then calculates the unit surface normal and jacobian at that point.  All of the results are output to a file called fiducial.tbl for each reflector.

Secondary targets

• L1 : /share/megs/survey
• L2- L1/AO_align_old_laptop
• L3- L1/AO_data_old_desktop/
  
• LR : L1/reflector_def
• MIW: match ignores white space
  

    There are two sets of  files holding the complete target set.

set #	targets	bytes	fileTimeStamp	file locations
1 All reflector targets except the masked over targets on the first row. Includes the 4 vertex points at the beginning.	1630	53433	22feb99	L3/align/PNLFCL/scndry/target.dat
				L3/align/year99/PNLFDCL/scndry/target.dat
				L3/greg/scndry/pnlset/target.dat
2 all reflector targets and 4 vertex points at the beginning	1661	67678	31oct03	L3/align/PNLFCL/scndry/archive/target.dat
				L3/align/year99/PNLFDCL/scndry/archive/target.dat

Measuring, adjusting the reflectors, then using a subset define the dome centerline coord sys for tert, horn measurements.
    Videogrammetry was used to measure the locations of the targets on the reflector:

• the measurement was made
• the errors in the reflector positions (relative to the theoretical surface) were computed.
• the reflector panels were adjusted to correct for the errors.
• The reflector is remeasured to get the final positions of the targets.
  
• The final positions of the targets will never  be exactly at the theoretical position (since there are always some errors).

    The optics in the dome is referenced to the secondary. When aligning a horn (or  the tertiary), a theodolite is used. The steps are:

• A subset of the 1630 secondary targets  (initially 54 targets) are stored in a .dsn file and used by the theodolite.
• The theodolite shoots the positions of the targets. This allows it to compute the theodolite position in dome centerline coord.
• It  can then shoot the position of the desired horn in dome centerline coordinates.

    The 54 target positions will get updated every time a  videogrammetry survey of the secondary is done. The .dsn files will get updated with the new positions.
We want to use the actual positions of the targets in dome centerline rather than the theoretical ones.. since the theodolite distance is to the actual dome CL position
rather than the theoretical one.

    The table below shows .dsn files that have been used over time. I've included the secondary surveys (which should have generated updated files after being processed.).
The latest .dsn file looks to be the one used on 28jun04.
-->19jun20<--  all of the 031111VidGram  labeled files are probably from 23jun99. Looks like the 031111 survey was never used . (no secref.dsn with those coord).

date of measurement	#targets	set 1st used	file location	assumed source  of dataset
121102	39	990619	L2/121102/secref2.dsn	pre 1999
121031	50	990619	L2/AO_align_old_laptop/year12/oct3112/secref1.dsn
121030	54	990619	L2/AO_align_old_laptop/year12/oct3012/secref.dsn
videogrametry sec  24-28jun04
040628	54	040628	L2/AO_align_old_laptop/year04/jun2804/scndry1/secref.dsn This is from last day of sec videogrammetry.	040628VidGram?
040628_o	54	040409	L2/AO_align_old_laptop/year04/jun2804/scndry1/secref_old.dsn	031111VidGram
040508	54	040409	L1/040508/pc/secref.dsn	031111VidGram
040502	54	040409	L2/AO_align_old_laptop/year04/may0204/secref.dsn	031111VidGram
040501	54	040409	L2/AO_align_old_laptop/year04/may0104/secref.dsn	031111VidGram
040428	54	990619	L2/AO_align_old_laptop/year04/april2804/secref.dsn	pre 1999
040409AM 040409PM	54	040409	L3/AO_data_old_desktop/align/year04/april0904/AM/secref.dsn L3/AO_data_old_desktop/align/year04/april0904/PM/secref.dsn	031111VidGram
040225	54	990619	L3/AO_data_old_desktop/align/year04/feb2504/secref.dsn	pre 1999
040214	54	990619	L3/AO_data_old_desktop/align/year04/feb1404/secref.dsn	pre 1999
031111 videogrammetry of secondary
020331	54	991021	L2/AO_align_old_laptop/year02/mar3102/secref.dsn	jan99-jun99Surv
010801	54	991021	L2/AO_align_old_laptop/year01/aug0101/secref.dsn	jan99-jun99Surv
010730	54	991021	L2/AO_align_old_laptop/year01/july3001/secref.dsn	jan99-jun99Surv
000201	54	991021	L2/AO_align_old_laptop/year00/feb0100/secref.dsn	jan99-jun99Surv
991021	54	991021	L2/AO_align_old_laptop/year99/oct2199/secref.dsn	jan99-jun99Surv
990619	54	990619	L2/AO_align_old_laptop/year99/jun2499/secref.dsn	pre 1999
06jan99 to 23jun99 survey of secondary with theodolite.

• Sometimes the surveys used out of date dsn files.
  

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Reflector definitions.

    The reflector definition files were provided by lynn baker (via don campbell) in 2013.
The files initially sent to mike shields at mit so he could put our reflector system into grasp.
They are the positions where rays cast from the focal point cross the various reflectors. They are not
the locations of the targets on the reflectors.

Lynn's notes:

 Attached are three ascii files corresponding to the tertiary, secondary
and primary reflectors.  Of course the primary is a sphere but I include
the file to help with orientation.  The file organization is in a "ray
trace" parametric format.  Imagine a bundle of rays emanating from the
focus and propagating through the optics.  Each ray reflects from each
reflector forming a set of three points associated with that ray.  These points
are tabulated for each ray in the following format.  There are 64+2
elevation angles giving 66 blocks at constant elevation angles.  Within each
block there are 128 azimuth angles.  The first point in each block is
repeated at the end of each block, giving a closed loop.  The first 64 blocks
 of data correspond to the physical reflectors.  The last two blocks are
extension data points beyond the physical edge of the reflectors. These
are included to help keep interpolants well behaved at the edges.  The
first data blocks in each file are degenerate in the sense that the loop in
azimuth is a single point.  Of course there is spherical reflector beyond
 the edge of the physical ray trace and the simulation should include that
The units are in feet.

The coordinate system origin is at the paraxial point, the half radius
point of the sphere, radius=870.0'.  The ray that goes the center of the
sphere is the paraxial ray and forms the z axis.  The y axis is perpendicular
to the symmetry plane and the x axis forms an RH system.

The focal point is located at         ( -29.5, 0, -19.,5 ). 
The boresight point on the tertiary is (-29.5,0,  -32.
The angle from the focus to the boresight point is 1.736 degrees.
 The nominal edge taper on the tertiary
designed into the optics is -16 db. which maps to a nearly uniform
aperture illumination.  This leads to a roughly -16 db. first sidelobe in the
far field pattern.  Ideally it would be good to taper the aperture
illumination for a lower first sidelobe but that concentrates more power under
the platform blockage and that causes problems.

• primary file
• secondary file
• tertiary file

Table of different design files on disk
Some abbreviations:

• L1 : /share/megs/survey
• L2- L1/AO_align_old_laptop
• L3- L1/AO_data_old_desktop/
• LR : L1/reflector_def
• MIW: match ignores white space
  

location	suf	Match ref	bytes pri,sec,ter	hdrline	notes
L1	.data	Y	566047,566047,566047	64   128  2	current reference
L3/align/PNLFCL/scndry	.data	Y (-w)	x,574496,x	64   128  2	only secondary. MIW
L3/align/PNLFCL/trtry	.data	Y	x,x,566047	64   128  2	only tert.
L3/align/PNLFCL/year99/scntry	.dat	Y (-w)	x,574496,x	64   128  2	only sec. MIW
L3/align/PNLFCL/year99/trtry	.dat	Y	x,x,566047	64   128  2	only tert.
L3/fnlchk/	.dat	Y	x,566047,566047	64   128  2
L3/greg/scndry/pnlset	.dat	Y	x,566047,x	64   128  2
L3/greg/trtry/pnlset	.dat	Y	x,x,566047	64   128  2
L3/greg/set11	.data	Y	566048,566048,566048	64   128  2
	.old	N	668354,668424,668354	64   128  2	2nd line: 1
	.orig	N	668358,668428,668555	64   128  2	2nd line: 1
L3/greg/set10	.data	N	445983,445983,445983	25   128  1	looks like fewer blocks.
	.orig	N	1269234,1268888,1268206	25   128  1	2nd line: 1 some lines 3 #, some 4 #
L3/greg/set8	.data	N	x,184489,184489	25   1   129	looks like this is old hdrline format

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Reference positions:

    I tried to gather together the current reference values used for surveying. Each entry includes a description and a reference to where is came from.

object	value	description
Horn focus in DomeCenterline	x inches y inches z inches TiltX deg TiltY deg -248.145 0. -389.822 .625 0.	found in 16dec12 Lynn baker email,  survey results of other horns. (survey done 02nov12). Be careful with tiltx,tilty tiltx is the angle from the xaxis to the tilt plane with positive moving in +z. This is actually a +rotation (CW)  about the y axis. survey results of other horns (.pdf)
center of Curvature for  primary	x feet y feet z feet .01 -.02 883.125	center curvature for primary coordSys: AO9 origin, x axis east, yaxis north, z up From 2001 primary survey lynn baker email 17jun2002
Radius of Curvature	869.883 feet	from 2001 primary survey lynn baker email 17jun2002
Reflector to AO9 (dimple)	13.242 feet	subtracting above z value and radius above.
Paddles around dome pupil		see lynn baker email 26nov2001
AO9 offsets from platform bearing	x inches east + y inches north positive .2 2.2	using 09aug01 ao9 survey of dome (more info)
ray trace origin in DCL	x y z 8' 5 1/4' 0 -12' 5"	from upgrade drawings. Also used in CRDDVN.M routine (xxold_laptop/math/ Before translating, the RTC coord should be rotated  by (asin(8.4375)/435.) -> 1.11141 deg about the y axis (cw pos).

More info: survey/lynnInfo