Technical Issues - FilmStar News 2018

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January 2    Collector to Targets

DESIGN...Reverse-engineering can be more reliable when P/S measurements at angles > 0 are included. New multi-angle attachments (Cary UMA, PE Lambda with ARTA/TAMS) and the Spectra Collector enable users to save data in a single file. That capability has been enhanced with DESIGN  2.61.4150 able to quickly convert multi-angle spectra to Optimization Targets. (Previously this required opening multiple spectra and tediously converting one at a time or writing a macro utilizing BASIC Function SpecTargets.)

The procedure is as follows:

1. Open the DESIGN Collector (Spectra...Collector <Shift+F8>).

2. Open the Targets dialog (Optimize...Targets <Ctrl+T>). New targets supplement current ones, so you may need to clear the grid (File...Clear Targets <Shift+Del>) before clicking <Collector to Targets>.

Note that blue cells in the Collector grid indicate calculated data. Also note that Collector wavelength units (nm) were converted to current DESIGN units (Ám).

January 8    IndexSolve Updated with Collector

IndexSolve.bas was originally developed some years ago to partially automate (executable video file) a user's manual procedure for deducing n,k for silver through %R/%T measurements at multiple angles. The method is useful for metals of known thickness when it is impossible to utilize dispersive functions. The method depends on selecting a film thickness wherein both %R and %T can be accurately determined.

New IndexSolveCL.bas (CL for Collector) makes it much easier to load spectra. Users without MEASURE can duplicate Collector format in Excel by paying attention to row headers: TR = %T Random-pol, RP = %R P-pol, etc. Data can be placed in a single worksheet or in multiple sheets (tabs) with identical wave ranges. Click Spectra.. Sort to start with high wavelength.

DESIGN 2.61.4160 adds Function CLcell (Collector values) and CLinfo (row and column counts) (similar to Excel functions XLcell and XLinfo). Our example may be downloaded. Ag Setup.faw creates the Collection, while Ag Solve.faw deduces (n, k). If things work as expected (n, k) will match Ag_Sopra.itw values.

Blue cells indicate DESIGN-calculated test spectra

You need to run the calculation twice, for %T and %R. The values shown below were utilized.

Upon running this you obtain TP/TS and RP/RS 6░ columns. These were averaged (giving TR and RR) by highlighting adjacent 6░ columns and clicking Spectra.. Average P and S. If columns are not highlighted all P and S columns are averaged. In practice, data are generated by FilmStar MEASURE or by other programs via Excel transfer to Collector format.

As shown below, the solution (blue lines) overlaps original Sopra Ag.itw values (red lines)

Exercise for advanced users: Add noise to calculated spectra and see how it affects results.

January 29    Spektrum Support for CEC Deposition Systems

Cutting Edge Coatings (CEC) in Hannover, Germany manufactures deposition systems utilizing the Laser Zentrum Hannover (LZH) Spektrum file format (.dsg). Click here to view or download a sample design file created in FilmStar DESIGN; open in Notepad or (recommended) Notepad++. Note that some of the '##' settings refer to Spektrum software and are not utilized by CEC.

FilmStar compatibility required 4 new DESIGN/INDEX dispersion functions: CE-CY6 (6 coefficient Cauchy), CE-CY6K (Cauchy & k-Formula), CE-SM6 (6 coefficient Sellmeier, same as SELLG), CE-SM6K (Sellmeier & k-Formula). k-Formulas require that 9 coefficients be specified in File.. Configuration.. Capacity. Index tables are also supported. CEC users should check CE functions (click button <CEC>) in Index Functions .. Built-in. In addition, two BASIC programs were developed for creating .dsg and .dsp files.

Assuming n is well known but k varies with deposition conditions, User-Defined Function TIO2K combines fixed n vs. wavelength with Spektrum's k-Formula utilizing 3 coefficients. As shown below, click Special.. Insert Spektrum to ensure correct format. Table 1 file TiO2 Frank k=0 includes n vs. wavelength with k column = zero. Use Functions.. Create Table in FilmStar INDEX to verify k values.

User-Defined Function adds absorption to n,k Table

Users unfamiliar with this advanced dialog should contact FTG Software to arrange a Glance session. At this time the Spektrum Oscillator Model is not supported. The Spektrum .dsg file includes a ##RATE entry which is specified by adding 'R=' in the Film Indices dialog Description field as shown below. User-Defined Functions are also useful for mixed material models as in 'My TiO2', a mixture of 'good' and 'bad' TiO2.

BASIC programs C:\Winfilm\Spektrum.bas (DESIGN) and SpektrumNK.bas (INDEX) are run via File.. Export To. (If the command is missing, check Add File.. Export menu in File.. Configuration.. Preferences.) Back up Spektrum.bas and/or SpektrumNK.bas if making any modifications. Reinstall by deleting the file(s) and running Setup32. BASIC codes can also be run from a macro button. Please contact FTG Software with any questions or issues.

IMPORTANT: The CEC system recognizes if the expected Spektrum syntax is incorrect, for example if it cannot read material data. It cannot, however, detect erroneous values. Users must inspect layer values and verify that the final transmission spectrum matches DESIGN's. It is the user's responsibility to ensure that proper information has been uploaded to the system prior to deposition.

February 26    Peaks and Valleys in MEASURE

The ability to show peaks in FSPlot was added in 2011. In response to a user utilizing the holmium spectrum to determine wavelength accuracy in a Lambda 950, we added valleys in FSPlot Setup.. Peaks <Ctrl+K>.  Note that annotations (here vertical lines displaying NIST wavelengths) must be added before plotting the spectrum. Finally, don't forget to check View.. Peaks <Ctrl+P>. As can be seen below, %T peaks are not of much use in this calibration procedure; NIST wavelengths refer to valleys.

Use the Zoom function to examine and verify results. Asymmetric extrema might be problematic.

Annotations are saved with Scan Method; in addition you can click Setup.. Annotations.. Create BASIC Code to encapsulate standard wavelengths in a BASIC program.

  ' FSPlot Annotation code for FilmStar BASIC:
  s$ = vbCrLf
  PlotAnnotate True
  PlotAnnotation = "VERS3" & s$ & _
  "vline 279.3,9,|t279.3 ,16711680;0" & s$ & _
  "vline 360.8,9,|t360.8 ,16711680;1" & s$ & _
  "vline 418.5,9,|t418.5 ,16711680;2" & s$ & _
  "vline 459.9,9,|t459.9 ,16711680;3" & s$ & _
  "vline 536.4,9,|t536.4 ,16711680;4" & s$ & _
  "vline 334.8,9,|t333.8 ,16711680;5"

Finally, click Setup.. Calibrate Wavelength in the event a correction algorithm is required. Note that the NIST values listed here are reckoned to be accurate within ▒0.2 nm. Be sure to utilize values given in your traceable calibration. We note that holmium glass filters are stable, while liquid filters require periodic recalibration.

Average difference ~0.3 nm

New BASIC Sub WaveCorrect applies the Correction Function to an existing uncorrected spectrum. This should only be run ONCE!