TFCalc 3.4 Changes
Major New Features
These features and many others are described in more detail below. There are a number of very minor changes that are not described here.
Analysis
-
Cone-angle average computation allows user-defined radiation distributions. In previous versions of TFCalc, the radiation source in the cone-angle computation was limited to Lambertian (i.e., the intensity varied with the cosine of the angle). This new feature enables the user to simulate any type of circularly symmetric radiation source.
- User may analyze the performance from both sides of a coating. This has always been possible, but now it is much simpler. The Environment dialog allows the user to specify the surface that light first encounters: Front or Back. Also, all the plots and printouts are labeled to indicate on which side the light originated.
- Default analysis range is 380 to 780 nm. When the user begins a new coating design, the analysis range is now 380 to 780 nm, which makes the color calculations available immediately. (The user can override this by creating a coating file called DEFAULT, which TFCalc reads every time the user creates a new coating.)
- Phase shift fix. In rare cases, the phase shift was reported to be -90 degrees instead of 270.
Optimization
-
R*T can be optimized. Now the user may optimize R*T, the product of reflectance and transmittance, which is important in the design of some types of beamsplitters. There are three new types of targets that the user can enter in the Targets-Discrete and Targets-Continuous windows.
In the row labeled “Refl/Tran”, where R or T is usually typed, now R*T, Rp*Ts, or Rs*Tp can be typed, where the p and s suffix indicates the polarization. If R*T is entered, then the window’s polarization row can be used to select whether Rs*Ts, Rp*Tp, or Rave*Tave is optimized.
This feature works with all of TFCalc’s optimization methods, including needle optimization. (Added in version 3.3.6.)
-
Needle optimization and tunneling can be used on back layers. Previously, needle optimization and tunneling could be used only on the front layers. Now, if the coating has back layers, needles will be inserted into both front and back layers. This also works if the design has only back layers.
-
Needle optimization can be controlled on a layer-by-layer basis. The front and back layers windows each has a new row labeled “Needles?”. This allows the user to select which layers may have needles inserted into them during needle optimization. The default is to allow needles to be inserted into every layer whose thickness is being optimized.
- “Optimize first” option in needle optimization. If the designer wants to insure that the design is locally optimized before needles are added, this option can be selected in the Needle Optimization dialog. This option is very useful after the user has manually stopped an optimization and then wants to resume optimizing.
-
User may optimize the performance from both sides of a coating simultaneously. In previous versions of TFCalc, the user could optimize the coating performance from just the front side. Now, by using multiple environments, the user can optimize the performance from both sides
of a coating. So, for instance, the reflected color could be controlled for both the front and back surface. The Environments window has a new “First Surface” row, which indicates the surface that the light strikes first: Front or Back.
Refractive Index
- Interpolate missing data. Sometimes the user may have data for n at some wavelengths and data for k at different wavelengths. In this version, it is possible for TFCalc to read this data and automatically interpolate to fill in the missing data.
-
Materials may have gain. For simulating thin film devices such as VCSELs, it is useful to have materials whose extinction coefficient k is negative. Coatings containing gain materials can have R and T greater than 100%. Optimization targets can be greater than 100%. To use this feature,
it must be activated in the Configure dialog.
-
Internal transmittance can be read for substrates. For substrates such as colored glass, manufacturers give tables of internal transmittance. TFCalc can now use this information. This feature is a new option in the Read Substrate Data command.
Miscellaneous
-
User can control the resolution of the monitor chart. The user can specify the thickness increment used in the calculating the monitoring curves. This option can be found in the Set Monitoring Parameters dialog.
- Wavelength units can be selected when data files are read. When the user commands TFCalc to read data files containing wavelengths, the user is asked for the wavelength unit.
- File menu has a Reopen command. TFCalc keeps track of the last 20 coating designs opened by the user. These files are displayed on a menu when the user selects the Reopen command.
- Fixed multiple environments problem. There was an error when a variable material was used as an active material in the Environments window.
- Cone-angle plots and printouts labeled. When the results of a cone-angle average calculation are plotted or printed, the cone’s half-angle is shown.
- Serial number in About dialog. Each copy of TFCalc has a serial number, which is stored in the hardware key. This number is now displayed in the About TFCalc dialog.
- Check for missing directories. TFCalc requires directories for the materials, substrates, illuminants, and detectors. An error message is displayed if any of these are missing.
