• Can I install the OptiLayer package at several computers?

Yes, of course. But you will be able to work only at the computer with hardware key attached.

•  What is the policy for software updates?

One year of updates is included with initial purchase. To receive further updates and support it is necessary to renew the maintenance agreement (please, contact our dealers).

• When I tried to launch OptiLayer at my computer, I've got the error message: "Network key was not found. Please, check Server and Client configurations and Firewall settings!". Could you please advise me how to resolve this issue?

This error message means that the drivers for Guardant key are not installed properly. These drivers are included to installation of OptiLayer and should be configured by the OptiLayer installer. In some cases it doesn't work, most often due to some 3rd party Antivirus software (Microsoft Windows Defender does not make any problem). If the drivers are not installed properly, you will see the key in "Other devices" group and a yellow exclamation mark indicating the problem. We recommend the following steps to fix the problem.

1. Unplug the key.
2. Try to install the drivers manually. OptiLayer installer places required Driver installation pack to the location: "c:\Program Files\Common Files\Guardant\Setup\GrdDrivers-x64.msi" (for 64 bit Windows system). OptiLayer installer also creates a shortcut to this Guardant Installer in Start menu -> Programs -> OptiLayer group, where you can find "Guardant Drivers" menu item. You can use any of these ways to start the driver installation. You can try to start this file manually in order to install the drivers. The installer should finish the installation without any error messages.
3. Plug the key to the computer. It should be recognized as "Guardant Stealth III Sign" key.

If you see an error message during the installation, or it doesn't help, you need to disable Antivirus for the time of installation. Repeat the steps above with disabled Antivirus. Usually "Run-time check" or "Proactive monitoring" option need to be disabled. Unfortunately, different antivirus packages have different options. Some of them have to many "false-positive" diagnostics or affect normal Windows operations quite significantly. For safety you can also disable Internet connection during this operation.

• I wanted to try working with OptiLayer and installed the Demo version. But I see that the Demo can only execute the tutorial exercises. I cannot open a new project, create a target and specify my own materials. What I am doing wrong?

OptiLayer DEMO version is quite limited, since the main function of the DEMO is to demonstrate main abilities, power and computational efficiency of OptiLayer. Demo version gives you an impression about the interface as well. If you would like to try full functionality of OptiLayer, you may contact the dealer from your region. It is possible to use Trial version of OptiLayer with time-limited hardware key (dongle). You need to ask for such trial key if necessary.

First of all, check you spam filter – probably, OptiLayer mail is in the spam bin. Secondly, check exactly e-mail that you typed in the request. If these options do not help, please contact us and we send you the link and the password.

• I traveled and lost my OptiLayer hardware key. What should I do?

Unfortunately, the hardware key acts as a proof of owning the license and cannot be replaced in this case. For the key replacement you need to return the broken or malfunctioning key back. If you lost your key, a new license should be purchased. Of course, it will be considered as the next license with corresponding multi-license discount.

• When I started with OptiLayer, I worked with Tutorial examples and created my own materials and designs directly in example directories (Ex1, Ex2,…). Now my colleague will study OptiLayer. How can I remove all my files, I do not remember what exactly I did, I have many useless data there.

First of all, we do not recommend to store any important data in the Examples or Tutorial Problem Directories. Please, create your own Problem Directories for this purpose. The reason is that when you install a new version of OptiLayer, the content of these directories can be overwritten and your files will be lost.

If you want to perform the clean-up of Tutorials and Example directories, you can simply remove them using Problems Dialog (Delete button) and after this you can reinstall OptiLayer. Make sure that Examples are selected during re-installation procedure.

• Today I switched on the OptiLayer program and see that it is frozen immediately after starting. Yesterday it worked fine.

The most likely, you have a problem with USB bus controller at your computer. It may suspend communications with the hardware key in some quite rare cases. For example, we had issues with USB III controllers at some modern computers. If it is your case, it is quite easy to fix: just try other USB ports! It is better to use not USB III, but classical USB II ports. In cases if your computer has only USB III connections, you can use any cheap USB hub that will automatically downgrade USB III to USB II.

• If we decide to purchase OptiLayer, do we buy the package or just a license for a period of time?

You purchase a license (or licenses) for specified number of working places. These licenses have no time limit. Even more, you can try the software before buying it, since we provide customers with Trial keys (so called “time limited trial versions”). It is simple: if you are happy with Optilayer, you can buy it.

• What is the OptiLayer policy for software updates?

One year of updates is included with initial purchase. To receive further versions (releases), it is necessary to renew for payment.

• I have a problem: my hardware key is not recognized by OptiReOpt and Optilayer. This hardware key works perfectly on a different computer. It worked on this computer two weeks before. Can you tell me how to proceed?

According to your notes it looks like your PC problem. There are 2 kinds of hardware keys, and one kind requires "Guardant Drivers". Please, Open "OptiLayer" group in the Start menu and look for "Guardant Drivers" shortcut. Unplug the key and try to reinstall the drivers. If they are installed - uninstall them and install again. After this plug the key again.

In principle, drivers should be installed by default, it is included to general installation procedure of OptiLayer/OptiReOpt. Potentially some maintenance or security procedures may affect this. In particular some antivirus software may be too aggressive and can block correct driver installation.

Be sure that you see the green LED on the key.

If reinstallation of the drivers does not help, unplug another device at the same computer (for example, mouse) and plug the key to this USB. If it works, it means that you have a problem with your USB. Please note, that the non-working ports issue may be connected just with poor internal contact of wires coming from the port to the motherboard. Often this could be easily fixed. Of course, it is easy to buy a USB extension card or a USB hub if necessary.

### OptiLayer (design, evaluation, error analysis, monitoring, simulations)

• What is the maximum number of design layers in OptiLayer software?

You can design coatings containing any number of layers. You can find design solutions for problems of any complexity. In the current version the number of layers formally limited by 65535, it allows to consider rugate coatings as well.

• Does OptiLayer provide a database of layer materials?

Yes, OptiLayer provides a Catalog containing optical constants of a wide set of layer materials, glasses and substrates. For all materials, the corresponding data sources are presented. The details are here. Starting from 12.12, OptiLayer provides the access to https://refractiveindex.INFO database: the convenient database browser and the ability to transfer any data file from RefractiveIndex.INFO to Substrate or Layer Material databases of your current OptiLayer Problem Directory.

• Do I have a possibility to create my own files of optical constants?

Yes, you can create your own materials and specify their optical constants in tabular or/and in formula forms. If necessary, you can store this information in a specialized directory, like "My_Catalog", for example.

• We work in the far and extreme ultraviolet, our wavelengths may be as short as few nanometers. Does OptiLayer take specific features of these spectral ranges into account?

OptiLayer operates in any spectral ranges. The concept of grazing angle was implemented, refractive indices can be specified in a form suitable for X-ray applications. You can take into account inter-layers and inhomogeneities of layers in the course of coating analysis and refinement.

• We need to fit a set of about 200 targets of reflectance or transmittance type (either s, p or average polarizations) at specified spectral and angular ranges. We also may need to combine reflectance and transmittance at various wavelengths and incidence angles in a single target. We need to design complex filters that combine high or low transmittance bands with high or low reflectance bands. Is it possible in OptiLayer?

Yes, OptiLayer allows you to specify complicated targets for different types of spectral characteristics – reflectance, transmittance, s, p and average polarizations, in any wavelength and angular spectral ranges; you can also specify target values for phase, group delay and group delay dispersion, electrical field, color targets of different types.

• Does OptiLayer provide convenient options to save initial parameters, designed structures and to export the results to graphical and text formats?

Of course, it does. There is a large variety of import/export options, which make OptiLayer compatible with other software programs. You can store designs, targets of different types, materials, etc. in OptiLayer databases as well. You can export your data to Excel or Origin spreadsheets.

• I have to design anti-reflection coating (or coatings) so to achieve a minimum reflectance for a system of parallel glasses. All glasses have different refractive indices and different thicknesses. Should I design anti-reflection coatings for each glass and then average thicknesses? Or another solution exists?

Of course, another solution exists. OptiLayer design such systems automatically, you need to specify substrates thicknesses and refractive indices of thin film materials. This can be done using Stack options. See also, Advanced Example 16 from OptiLayer package.

• I use Random Optimization design option quite often. I have noticed that if I specify a non-zero lower limit of the layer thicknesses, then the number of design layers do not changes. If the lower limit is zero, then the number of design layer vary. What is the reason?

The reason is very simple. When the lower limit is zero, then in some designs layers with zero thicknesses can appear. In this case the consequent layers of the same material are merged and the number of layer decreases.  When there is a lower limit of layer thicknesses, then layer thicknesses cannot be zero because of the constrains.

• I want to design a coating with specified color properties in the VIS and specified target transmittance in the NIR-IR. Is it possible to take into account two types of targets simultaneously?

Yes, of course, in OptiLayer you can combine targets of various types, for example, color and conventional (as in your case) or color and integral, or integral and conventional. For each target you can specify own spectral range. In the latest version you can balance targets using weight coefficient (see more…)

• I am a beginner in OptiLayer. I design a coating using Needle Optimization AUTO, but I see that my design contains several thin layers. When I remove them simultaneously, approximation of my target is getting worse essentially. Maybe I am doing something wrong?

OptiLayer provides two options (Thin Layer Removal and Design cleaner), which allow you automatically remove thin layers. Of course, design performance is getting worse but in these options you are able to control merit function increase. In some cases, it may happen that some of these thin layers are very important for the design.

• I need to design a narrow band pass filter containing only quarter-wave layers. Is it possible with OptiLayer?

Yes, for your purpose you can try WDM design option. See more…

• I have to design a beamsplitter merged between two glasses. How can I specify this structure in OptiLayer?

You need to load one glass as a substrate and another glass as an incident medium.

• I have a problem to design a color coating. Target colors are specified in LAB system, light source is D65. I have my own program that computes some coating characteristics. I calculated color coordinates in my program and compared with OptiLayer results for the same test multilayer (layer thicknesses are 100 nm and 200 nm, refractive indices 2.35 and 1.45, substrate refractive index is 1.52). My LAB coordinates for R(normal incidence) are a*=16.39, b*=18.06, L*=45.06, OptiLayer gives a*=21.11, b*=21.32, L*=45.73. I see the differences. I am sure that my program calculates correctly, all optical constants (refractive indices of materials and substrate) are the same as in OptiLayer. What is the problem?

You did not load D65 light source and it was not included into OptiLayer calculations. Actually, if we do not include the light source, we obtain a*=16.39, b*=18.06, L*=45.06. If we include it, we obtain exactly the same values that you show a*=21.11, b*=21.32, L*=45.73.

• I need to calculate reflectance and transmittance of my design with 7 decimals, I perform calculation on a very dense wavelength grid (step is 0.000001 nm) and in a extremely narrow spectral range (from 532.599 nm to 532.601 nm). I specify 0.000001 step in the Design > Evaluation report but I see R/T only with 5 decimals. Can I fix this problem somehow.

You should open Analysis > Plot Engine option and specify your spectral range in the Y=f(X) tab (from 532.599 to 532.601) and step 0.000001 in the corresponding fields. The number of points will be automatically calculated. After pressing Next button you will see a plot R/T. Click right mouse button and go to Chart Editor. Go to  Export option and choose Data tab there. Choose Excel format and press Save button. After a standard save dialog you will have the Excel file with the results of your calculations. Using Excel tools you can format cells and specify the required number of decimals.

• I obtained several solutions of the same design problem and want to compare them with respect to stability to errors in layer thicknesses and refractive indices. It is my understanding of  Error analysis options that I can compare the design stability with respect either errors in thicknesses or errors in refractive indices. Do I understand correctly?

No, you can analyze sensitivity of your designs  to errors in thicknesses and refractive indices simultaneously. In order to do this you have to specify errors in layer thicknesses in one of the tabs Thickness > Coating, Thickness > Materials, Thickness > Thicknesses and errors in refractive indices in Refractive index tab. In the course of calculations OptiLayer will take errors in layer thicknesses on the tab that was opened just before the calculations or before moving to Refractive index tab. For example, if you specified Abs. RMS=1% on Thickness > Coating tab, 2% RMS for all materials on Thickness > Materials tab and 1.5% RMS for all layers on Thickness > Thicknesses tab,  move to Refractive index tab  and specify 0.01 error for all refractive indices then in the course of calculations OptiLayer will take into account 1.5% errors in layer thicknesses and 0.01 offset for all refractive indices. Learn more here.

• How can I add refractive index file to the Catalog in Optilayer? I have added several materials to the Layers Material database, but they don't show up in the Catalog.

OptiLayer/OptiChar/OptiRE Catalog databases were designed to be read-only. Typically we use already published data and provide corresponding references.

As a solution you can create a Problem Directory that will be used as an additional Catalog (MyCatalog, for example). You can place all your layer materials files there and use "File Transfer" option to take necessary files to your directories. Network shared locations are also supported.

In each new release, we extend data in the Catalog. If you think that your data deserves placing to Catalog and to be accessible by all OptiLayer customers, please, let us know. But in this case we will need to indicate all details related to the data.

• My target transmittance has a complicated shape. I cannot create the target using OptiLayer standard tools. Could you help me?

You can create an Excel file, specify your target there by a formula or manually and then import target values into OptiLayer using clipboard (Copy-Paste buttons).

• I need to cover a glass substrate with two different coatings from front and back sides. What OptiLayer option should I use?

You can specify a stack consisting of one medium (your glass) and specify designs for both sides. Then you can use any of OptiLayer design algorithms. Learn more about stacks…

• Can I use in OptiLayer layer materials, which I created in OptiRe or OptiChar?

OptiLayer, OptiChar, and OptiRE  use the same Problem Directories and share the same data including materials and substrates. Designs also can be accessed through the Design database by both programs. Even material abbreviation assignment can be easily transferred from/to OptiLayer/OptiRE/OptiChar project files.

• I have a question related to Error analysis setup. I would like to understand how relative RMS errors are applied to the layers’ thicknesses. Let’s say: I specify 2% relative RMS errors for all thicknesses of a design. Could you explain what happens during the computations?

During Error analysis, variations of thicknesses are performed according to normally distributed random values. More specifically: Let the thickness of the layer $$j$$ is equal to $$d_j$$. Then the RMS of 2% (for example) for this layer is determined as $$\sigma_j=0.02\cdot d_j$$. The variation of this thickness is determined as $$\Delta(d_j)=N(0;\sigma_j)$$, where $$N(m,s)$$ is a normally distributed random value with average equal to m and RMS equal to $$s$$ (Variance $$s^2=RMS^2$$).  See also http://en.wikipedia.org/wiki/Normal_distribution. For safety we also perform additional truncation of values outside the corridor of $$\pm3RMS$$ (they have quite low probability) in order to avoid too large rare variations. A similar procedure applies for absolute random errors, but in this case the variation is expressed absolute units.

• How can I properly calculate La*b* color values for transmission and reflectance? I evaluate La*b* color coordinates for a simple green glass substrate (Observer 2°, D65 light source) and OptiLayer gives a result that does not coincide with the result obtained by a different software. D65 light source is chosen in the color checkbox (Color tab of General Configuration Window). If I additionally enter normalized D65 spectra as "Light Source", it works properly. I consider this as an inconvenience because I expect the program to calculate color values properly if I only check D65 in the checkbox!

In OptiLayer, it is not the case. Light Source that you select in Color tab (General Configuration Window) affects the position of the so-called Reference White point, that is used for the definition of some color spaces, including La*b*. Therefore, the role of this selection is just the definition of the Color space itself. Actual Light source can be different, and it is required by many applications. You load current Light Source (and optionally Detector) from the corresponding database. Of course, if you need to use D65 only, you need to specify this color source in two places: in Color tab of General Configuration window and load it to memory from the database. Maybe it requires an additional operation and more attention, but this approach provides more flexibility. Even more, using Environments Manager you are able to formulate and to solve problems with a set of different light sources for the same color space.

• I am working with monitoring spreadsheet (OptiMonitor) and observe that the Swing values do not coincide with the ones provided by Essential Macleod program. What is the reason?

Our definition of Swing is different from the one by Essential Macleod. In the case when no extrema is present inside the layer, we use "virtual" extremum concept, i.e., the extremum that may occur if we continue the deposition of this layer without interruption (see the details here). Essential Macleod just uses ratios of initial and final values of the signal that is less informative from our point of view.

Small differences in the obtained values are most likely connected with the definition of the spectral line width or shape. It is obvious, that OptiLayer and Essential Macleod software perform numerical integration using different algorithms with a different number of nodes. In addition to this, "Half-Width parameter" in OptiLayer has a different meaning; it is not directly related to FWHM parameter. In the case of rectangular shape, it is straightforward that FWHM is half-width of this rectangle. In the case of Gaussian shape, it is $$A$$ parameter in the formula defining spectral line profile, $$\Delta\lambda$$, - the deviation of the wavelength from the central value: $$W(\Delta\lambda)=\frac{1.0}{2\sqrt{\pi} A} \exp{\left(\frac{\Delta\lambda}{2A^2}\right)}$$. It is easy to see that "Half width at half maximum" (HWHM) is connected with $$A$$ with the formula: $$HWHM=A\cdot 2\sqrt{\ln 2}\approx 1.66\cdot A$$. These notes will help you to improve the correspondence of the results from OptiLayer and from Essential Macleod software.

Note, that in any case, the accuracy of measurements even in the most advanced in situ monitoring devices is lower that observed discrepancies.

• I need to calculate reflectance/transmittance of a single layer (3.0$$\mu m$$) on a thin B270 substrate (100$$\mu m$$) and to take into account substrate interference. As I understand, in OptiLayer the substrate is considered without interference. How to deal with this issue?

You should specify the “Air” substrate and create a design consisting of two layers (B270 of 100$$\mu m$$ thickness and your thin film material of 3.0$$\mu m$$ thickness).

• I would like to learn example with COM Automation. Where I can find them?

You easily find these examples on your Desktop. They are automatically placed there during the installation of OptiLayer.

• We use each witness chip for deposition of several layers and then reuse it for some other layers. Let’s say, we use Chip1 for monitoring of layers 1, 2 and layers 8, 9. We use Chip2 for monitoring of layers 3, 4 and layers 10, 11. I would like to create a monitoring spreadsheet for our case but I cannot find how to do it.

In OptiMonitor you should use right-click menu and choose Misc. Options. In the corresponding window you should check “Permit reusing of chips”. Detailed description with examples for the case of indirect optical monitoring can be found here.

• I would like to calculate absolute value for phase. I mean unwrapped phase (not modulo 360 degrees)?

In order to calculate absolute phase (or unwrapped phase), you just need to activate "Continuous phase" option:

Synthesis --> Options --> Axis tab (Top) -->  Axis tab (Bottom) -->  Check "Continuous phase plots".

When you activate "Continuous Phase Plots" it will affect not only plotting. OptiLayer will try to use unwrapped phase during synthesis as well. This improves the results significantly. In this case phase targets should not have gaps in spectral dependencies. Also you may want to use "Automatic" scaling in this case, since phase will change in much wider limits. Please read our article about evaluation of spectral characteristics.

• I know reliable dispersion of the refractive indices of our thin film materials in the visible spectral range. If I synthesize a coating for the infra-red range or in the VIS-IR spectral range, what refractive index values are used by OptiLayer in the optimization/evaluation process?

If your indices are specified by a formula (for example, Cauchy formula or Sellmeier formula), then OptiLayer will calculate refractive index values in the IR spectral range with the help of this formula. If you have dispersion tables, then OptiLayer will use in the IR range the constant values of refractive indices equal to the last values in the tables.

### OptiChar (characterization of single layers, import of measurement data, characterization of substrates)

• I am going to determine the refractive index of a thin slightly absorbing layer on a thick glass substrate. So I tried to use OptiChar. I load my measured reflectance data and see that theoretical reflectance of the uncoated substrate is about 4% instead of 8%. Layer characterization gives inconsistent results. What am I doing wrong?

Please check, whether you included substrate back side into the calculations. To include it, open Characterization Options and uncheck the box “Reflectance without back side”. Learn more about calculations with back side…

• Is it possible to determine refractive index and extinction coefficient of a thin film deposited on a thick substrate just by giving input data collected with the spectrometer (e.g. reflectance and/or transmittance) without the necessity of the measure with ellipsometric data?

Yes, it is possible to use only photometric data (R and/or T measured by a spectrophotometer), it is possible to use only ellipsometric data, or it is possible to use combined sets of data (photometeric + ellipsometeric). OptiChar allows you to use any of these approaches. It is demonstrated in our examples.

• I have imported my experimental data to OptiChar. I loaded the data and in fitting window I see that the data are zero. I see the reasonable model transmittance shown by the black curve and measurement transmittance close to zero. What am I doing wrong?

Please check transmittance units. Probably, in OptiChar settings you set up % for R/T. At the same time, experimental transmittance was recorded in your data file in absolute units. If so, go to General Configuration --> Units tab and change T/R units from % to 0-1. Then repeat data import. Specific data import options (Varian, Agilent, PerkinElmer, X/Y files) allow to set units in the course of the data import procedure, without necessity to change global configuration settings.

• I have measurement data from a Woollam ellipsometer. I have Psi, Delta and also R/T.  What is more convenient: to record all these data in the same measurement file or to import the data into different files? I am asking because I want first to process Psi, Delta and R/T separately.

You can do this by any of these two ways. If you import all the data into one file, you can use Modify Measurements option and temporarily remove, for example, R/T data before you start the characterization process. Or, you can save the data into separate files and, in the case if you want to see all fitting simultaneously you can use Append to Loaded option and append R/T data to Psi/Delta fitting.

### OptiRE (post-production characterization of optical coatings, import of measurement data)

• I have a complicated post-production characterization problem. I am going to come to the next OptiLayer workshop and bring this problem with me. Will it be possible to discuss my problem confidentially during the workshop? Unfortunately, I cannot give you my measurement data.

We can look at your problem in the course of the workshop (of course, confidentially). We could have look at your data them at your laptop.

• I am going to correct refractive index of my high-index material in the course of reverse engineering. In the Indices Correction option,  I have a choice between constant drift, linear drift and exponential drift. It is my understanding that constant drift is index offset? Is it correct?

Yes, you are right. Index drift in this context is index offset. These are two different notations of the same thing. If you choose this option, it means that in the course of your reverse engineering procedure, OptiRE will look for a model refractive index with refractive index offset. Learn more…

• I am performing post-production characterization of a produced multilayer sample on the basis of T/R data measured in the range from 320 nm to 1500 nm. In Fitting Window, I observe that fitting in the range from 320 to 400 nm is very bad. At the same time fitting in the range 400-800 nm is good. I have looked at Refractive index window and seen that refractive index is a constant in the range from 320 to 400 nm.

If refractive index is constant in 320-400 nm spectral range, it means that you specified refractive index starting with 400 nm only. Please check this. If refractive index dispersion is not specified in a spectral range, then OptiLayer automatically use a constant for calculations in this range. The constant is equal to the refractive index value at the boundary of the spectral range. In your case, refractive index in the range from 320 to 400 nm was taken equal to n(400nm). In order to observe fitting of your experimental data by model data, you should know refractive index in the whole spectral range of interest. For this purpose, you can produce single layer samples and determine refractive index in the range from 320 to 850 nm using OptiChar.

• We use Agilent Cary 7000 Spectrometer in our laboratory. Is it possible to import Agilent measurement data to OptiRE/OptiChar?

Of course. OptiRe and OptiChar have import option allowing you easily preview and import Agilent Cary data (including data from 7000 model).

• I covered the front side of the substrate, that was already covered from the back side. Finally, I have a substrate covered from both sides. How can I provide post-production characterization of the front side coating?

You can do it using OptiRE module. In OptiRE you need to load your substrate and load back side coating (right-click menu at Designs database). Do not forget to specify properly substrate thickness and be sure that the boxes “Reflectance without back side”/”Transmittance without back side” are unchecked.

### Easy to start

OptiLayer provides user-friendly interface and a variety of examples allowing even a beginner to effectively start to design and characterize optical coatings.        Read more...

### Docs / Support

Comprehensive manual in PDF format and e-mail support help you at each step of your work with OptiLayer.