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2 Getting started.
By way of introduction we will describe the program features that
are required for the simple data reduction process.
If you follow through this chapter, you should be able to
produce wavefront measurement from your own images with little difficulty.
If you are using the software at a new site you will need to define the
optical system you are using, this will probably require some research
on your part.
In our experience problems with ef can usually be traced back to
the use of optical system parameters which are slightly in error, or
images which are insufficiently defocussed.
Laplacian Optics Inc. would be happy to review example extra-focal images from your system,
and determine if the optical parameters match the images.
If you have access to an anonymous FTP site, please place the images on this
site and contact us by mail at laplace@laplacian.com.
If you do not have access to an anonymous FTP site please
visit our web site
for instructions on downloading images to Laplacian Optics Inc. .
We supply ef with a pair of example extra-focal images which can
be found in the documentation directory in the sub-directory example.
In the following section we give step by step instructions for obtaining
wavefronts from this data. The example data are computer generated
extra-focal images assuming 0.5" seeing with the following
wavefront errors.
|
Zernike name | Zernike Number | Amplitude (RMS nm) |
|
Focus | 4 | 1000 |
|
Astigmatism | 5 | 330 |
|
Coma | 8 | -220 |
|
Trefoil | 9 | -220 |
|
Spherical | 11 | 220 |
|
High order coma | 17 | 100 |
|
|
On the original distribution CD, you will find a directory named
examples, which contains many other example images.
In the following tutorial it is assumed that the extra-focal images
being reduced will be in standard FITS format.
It is further assumed that there is a separate file containing each
extra-focal image.
The program can also unformatted image files containing no header
information, provided the file name follows a convention
which allows the program to determine the image type and size. See
reading an image file
for more details.
The program remembers most of its settings, optical and data reduction
configurations and sub-window positions from invocation to invocation.
For more details
.
Laplacian Optics Inc. Email: laplace@laplacian.com