2 Introduction
therefore, concentrates on the menu commands, what they are and what they do. It is
purely a description of the operation of the software package. It does not go into details
of the calculation techniques nor does it discuss design technique
The Essential Macleod uses a Multiple Document Interface (MDI). A document can
be a plot, a table, a design, a list of materials and so on. Multiple Document Interface
means that many documents may be displayed at once, the total number being limited by
the capabilities of the computer and of the Windows installation. One document at a time
is active. The menu bar changes as the active document changes so that the menu
commands always apply to whichever of the open documents is the active one. For
example, if a plot is active then the Edit menu will apply to the plot and will permit such
things as changing the parameters of the axes. The user will find that it is often useful to
be able to keep several designs open simultaneously. Should the capacity of Windows or
of the computer be exceeded then the user will simply be requested to reduce the number
of open documents. There is no need constantly to keep track of what is open. We do
recommend, however, that unnecessary documents should be closed to avoid clutter.
Throughout the operation of the package, designs and specifications are saved to
various files. The principal files are known as design files and they contain not just the
sequence of layers but also the calculation parameters that should be used to evaluate the
design. If a design is passed to refinement, the refinement specification also becomes part
of the design file. The operation of saving the design and parameters can be manually
performed at any time by choosing the appropriate menu item but it is also automatically
initiated at those stages where there is a danger that something might otherwise be lost. In
spite of this automatic feature, we do recommend that the user acquire the habit of saving
the work at intervals. In particular when moving from one design to another it often
seems convenient just to write the new design over the old. However, if the existing
design is important the editing process will change it perhaps beyond recovery. No
automatic save is initiated whenever a design is edited - editing is a very simple and
straightforward process. Before beginning major editing, where a design is going to be
substantially altered, it is good practice to save the design twice, once in the existing
design file, thereby preserving the current design for later recall, and once in a new
design file, which can then be edited without fear of changing the original. You may find
this approach useful in other applications such as word processors also.
In the Essential Macleod the optical constant information for the thin film materials is
kept in separate files in one or more materials databases. In the designs, the materials of
the films and substrate are referred to explicitly by name (normally the chemical
formula). A material database consists of a set of materials files together with control
files that are kept in a separate folder, the path being the identifier for the database. Many
different material databases may exist together. This is a particularly useful feature of the
Essential Macleod and we encourage the user to make full use of it. Separate databases
could be used, for example, for infrared materials as distinct from visible materials with
wavelength stated in microns rather than nanometres. Alternatively, different databases
could be used for different customers or for different plants or processes. In order to keep
track of the particular database that was used to generate a design, information on both
the database and the number/name conversion for the materials used, is stored in each
design file. This information is compared with the existing database when a design file is
read and only if an exact match is found can the calculations proceed without
intervention. The material database can easily be changed but only when there are no