           TEX - MIRROR NUMBER CRUNCHING MADE EASY
			Version 3.2b

Tex is a program that performs the tedious and error-prone calculations
required to reduce the Foucault knife edge readings to a quantitative
measure of the surface profile and the wavefront accuracy.  Once the raw
data has been entered, the user has two ways to evaluate it:

1) Jean Texereau's algorithm, as described in his classic book, 
   "How to Make a Telescope" (Willmann-Bell, 1984). The book
   includes a program to perform these calculations, but it is
   flawed by its frequent failure to find the correct "reference
   parabola" (a necessary step to getting the wavefront error).
   The reference parabola is surprisingly difficult to determine
   in software; this program does it correctly.

2) Millies-Lacrois tolerance graph. Described in Sky and Telescope
   February, 1976. It does not provide a wavefront error value, but
   is generally considered a useful supplementary method.

Other features of the program include:

1) Can handle inches, millimeters, or centimeters.

2) Can save mirror constants, so they don't have to be entered by hand after
   each test session.

3) Producing a file suitable for use by the Aperture program (available
   from Willman-Bell).

4) Computing the mask opening boundaries for a couder mask.  Can print out
   the resulting mask (see note below).

5) Provides a "monte carlo" readings simulator, which can be used to
   determine the confidence of your data.

NOTE: printing is supported for PostScript only. For systems without a
   PostScript printer/viewer, there is a free one called ghostscript (or
   ghostview for the viewer) for just about any computer/printer you can
   imagine (see http://www.cs.wisc.edu/~ghost/ for information).

Tex has been compiled and run on the following OS's:

	- MS-DOS
	- Linux 2.0 (intel platform, ELF format)
	- HP-UX 9.0
	- Solaris 2.4 and 2.5.1 (sparc platform)
	- Apple Macintosh

Note that on UNIX platforms, the preferred name is texereau, not tex, as
there already is a UNIX program called tex (Knuth's TeX typesetting program).
If you compile the source code for another OS/platform, please send the
authors the binary, and we'll be happy to post it (space permitting).

The program is menu driven, and should be easy for anyone familiar
with the general techniques to use. Once the program has computed
the data sheet values, it can then output a pair of graphs, one of 
the surface profile, and the other the Millies-Lacrois envelope
chart. Also, the data sheet is saved in a file, so that it can be 
printed outside the program.

Some less obvious program features:

- The mirror parameters can be saved in a file. The program can
  then read this file after a later figuring session, in lieu of
  typing them again from the keyboard.

- The units of measure can be changed from the default of inches
  to either millimeters or centimeters. This must be done BEFORE entering
  or reading in any data.  All data must be entered in the same units.

- When multiple sets of readings are taken, the program computes
  the wavefront error from each set of readings, as well as for
  the average of the readings. This gives the user some indication
  of how repeatable and reliable his/her measurements are.
  A more sophisticated way is to use the Monte Carlo simulation
  option of the program. The program computes the mean and standard
  deviation of the readings taken at each zone. It then generates 
  random sets of readings that are normally distributed with the same 
  mean and standard deviation, and gets the wavefront error for each
  set. A histogram is then produced that shows how the wavefront
  values would be spread out. If effect the program says: if you
  made, say 5000, more sets of readings, this is how your wavefront
  results would be spread out. 

- The y-axis units of the surface contour graph is wavelengths;
  Texereau uses microinches. 

- Some users may want a printout of the graphs. Here's one way to
  do this from DOS:
  + Start the program from MS Windows. If the display is in full
    screen mode, change to a window (press Alt-Enter).
  + With the graph displayed, select Edit/Mark from the control
    menu (box in upper-left).
  + Drag the mouse to select the entire graph.
  + Select Edit/Copy from the control menu. This copies the graph to
    the clipboard.
  + Back in Windows, start Paintbrush, and Edit/Paste the image.
  + Use File/Print to send it to the printer.
  Obviously the graphs can also be pasted into other programs, such 
  as MS Word.

  Non-DOS users will already have the graphs as PostScript files, and can
  simply print the files (either on a PostScript printer or using a PostScript
  emulator, like ghostscript - see above).

- Normally, of course, the program computes the surface error relative
  to a parabola. However, if it is invoked as "tex -s", (s for sphere)
  the error is relative to a spherical surface. Some may find this useful
  in the polishing just before parabolizing.

- Tex can compute the dimensions of a standard Couder mask,
  given the mirror diameter and the number of zones. This
  can be done with pencil and paper, but why bother?

Tex is written in ANSI C, and the source is included. However, the 
graphics are displayed from within the program only for MS-DOS users
On other platforms, the graphics are converted to PostScript and saved
in a file, which can be printed or viewed.

The DOS executable uses the floating point hardware if present, and
will work with VGA and EGA graphics hardware, (if you have CGA, all
bets are off).

If this software is (re)distributed, it is requested that the source,
executable, and this readme file be included.

We welcome user's comments.

VERSION HISTORY

version 1.0	first release. Basic Texereau algorithm
version 2.0	first release of graphics version
version 2.1	6-27-95
		added centimeters, millimeters, or inches menu selection
		added y label to surface and ML graphs.
		corrected bugs in Focus method of COC search.
		corrected bug in display of COC constant.
		Thickened the data line in surface and ML graphs.
version 2.2	11/11/95 fixed bug that sometimes occured when readings on
		2 diameters was entered.
version 2.3	1/22/96 Add "-s" option so that errors can be computed
		relative to a sphere instead of a parabola.
version 3.0	12/1/97 fixed several bugs, added cross-platform support
		as well as PostScript graphics support, added ability to print
		a couder mask.
version 3.1	12/9/97 fixed bug in calculation of surface error.
version 3.2	12/29/97 REALLY fixed bug in calculation of surface error.
version 3.2a	1/20/98 Added support for Macintosh platform
version 3.2b	1/22/98 Fixed file input of tester type for DOS platform,

1/98
Michael Lindner	mikel@att.com			http://home.att.net/~mikel
Larry Phillips  lwphillips@lucent.com
Dale Eason      deason@NILE.STPAUL.NCR.COM

