PERFORMANCE CALCULATIONS

The Concise Macleod provides a comprehensive set of performance calculations. In addition to the usual Reflectance and Transmittance calculations, the package also includes Density, Absorptance, Ellipsometric parameters, Ultrafast parameters (Group Delay, Group Delay Dispersion, Third Order Dispersion). Color calculations are also available. Tolerancing calculations are provided to enable you to judge the sensitivity of a design to minor thickness changes.

Color calculations are provided for the most popular color spaces:

• Tristimulus
• Chromaticity
• CIE L*a*b*
• CIE L*u*v*
• Hunter Lab

A selection of sources are pre-defined, and you may define others as necessary. The CIE 1931 and 1964 color matching functions are included. Again you may define any other you may require. As well as calculations of the transmitted and reflected color, color may also be specified as a target for refinement and synthesis.

The Concise Macleod is supplied with the fast and stable Nonlinear Simplex refinement technique. This well-proven rapidly reaches very satisfactory performance for thin-film coatings.

Refinement targets may be defined in terms of any of the calculated performance parameters including color. Target linking allows more complex merit functions. Linking causes linked layer thickness' to be changed to occur in step. Special features that help in reverse engineering include refinement in terms of packing density.

Layers in the design may be locked so that they are not changed during refinement.

The Concise Macleod provides support for the identification of errors committed during the manufacturing process. This support is provided by enhancements to the Simplex refinement method.

Simplex provides both index and thickness refinement. It may be readily constrained in different ways so that specific features of manufacturing inaccuracies and other problems may be matched. These constraints may be altered and gradually relaxed until a solution is found, pointing to the nature and magnitude of the possible errors.

Variations in index are reported in terms of changes in packing density. If desired a new material can be created from an existing material modified by the packing density.

The Concise Macleod includes facilities for editing and exporting coating designs to the ZEMAX lens design package (Focus Software Inc, PO Box 18228, Tucson, AZ 85731, USA, Fax: +1 520 733 0135).

Units can often be a problem for users, but not in the Concise Macleod where virtually any consistent set of units for the independent variables may be used. Electron-volts or Gigahertz or wavenumbers for frequency and Angstroms or nanometres or microns or even micro-inches for wavelength are possible. Changing from one unit system to another is simple.

The Concise Macleod features adaptive plotting for performance calculations. This automatically adjusts the plotting interval so that fringes are faithfully followed. The magnitude of the fringes would be lost without the adaptive plotting process.

The Concise Macleod's tolerancing capability allows you to investigate the sensitivity of a design to manufacturing errors. Alternative designs may be compared and the best design selected. Although designs may be similar, their sensitivity to errors may not and this will be shown up by the tolerancing feature.

Real materials exhibit dispersion of their optical constants, that is the optical constants vary with wavelength. Realistic calculations of properties must include such variations. Each material is stored as a table of refractive index and extinction coefficient values as a function of wavelength. This permits any dispersion to be modeled. Powerful editing tools including spline interpolation are provided together with import/export facilities that are easy to use.

Material behavior is not always ideal and optical constants often depend on the particular coating machine and on the deposition parameters. Operating conditions also affect material properties. For example, the operating performance of a cooled infra-red filter may be substantially different from its performance at room temperature. Multiple materials databases are therefore provided. Designs may easily be moved from one materials database to another facilitating the investigation of temperature and coating plant effects. Multiple materials databases have other advantages. For example, they permit materials data belonging to a client to be completely isolated and protected.

Admittance diagrams help you to understand how a design works. They can be looked on as a complete visual record of the way in which the various layers build the performance of a coating by transforming the admittance, or the complex amplitude coefficient, from the rear through to the front of the system.

The support offered by Thin Film Center Inc. is quite simply the best in the business. Technical support backed by over 35+ years experience is provided without further charge. Thin Film Center Inc also provides regular courses both on general design and manufacture of thin film coatings as well as making the most of the Concise Macleod.