- >>> Registering the Software <<<
- Benefits When Using VCS - Virtual Couder Screen
- System Requirements
- Installation and Updates
- How to Use VCS - Virtual Couder Screen
- Step 1 - Environment
- Step 2 - Basic Settings
- Step 3 - Centering and Calibrating the Screen
- Step 4 - Zones and Apertures
- Step 5 - Carrying Out Readings
- Data Evaluation and Graphics
- Auto Compare
- Anti Seeing Mechanism
- Setting Up Auto Compare
- Screen Test Procedure
- Utilities - Toolbar
- Version History
Only the zone you currently want to measure is 'open' - no confusion by other zones
Fully automatical real time comparison of zones by means of brightness histograms
Accuracy of zone comparison is in almost all cases substantially higher compared to visual evaluation
Immediate calculation and graphical display of lateral aberration, transverse aberration and surface error profile.
=> All subsequently outlined settings have to be defined only once, the tool keeps these data - not necessary to start from scratch every time.
=> As long as your setttings are not consistent you get an according status message (window bottom)
'Optimize TA'. This triggers an automatical optimization of factor C until the extrema of transverse aberrations (TA) are equal and opposite in sign. The procedure is very much comparable to the process of focusing at the finished instrument. The focus is moved to a position that delivers the best picture.
'Optimize StD'. Varies factor C until the surface StD (Standard Deviation) error is minimal. Optimizing the StD error is often helpfull to find a balanced surface profile that indicates where the mirror needs further correction.
Using the up/down buttons
which sets C in a way that the longitudinal aberration is zero for the selected zone
=> To use Auto Compare it is strongly recommended to set the computers color resolution to 'True Color' (32-bit)Do not use any kind of pin stick or other equipment positioned in front of the mirror that is visible in the zonal apertures. This would produce wrong measurements!
Select this if the shadowgram is color-neutral or has a moderate color cast.With this setting the conversion to grayvalues uses a formula that includes all three color channels.
Select this, in case the shadowgram has an intensive green hue.Solely the green color channel is evaluated then whereas red and blue channels are skipped.
Analogous as above
When selected, VCS works similarly as you do when comparing zones visually. It evaluates the overall zonal aperture (marked red) and calculates the histograms basing on all these pixels.This method might be beneficial in case of bad seeing or if the shadowgram is impure or of low quality (e.g. optical or imaging errors)
In this case VCS selectively evaluates a thin line that exactely matches the zone's Effective Radius (again marked red).This method has several advantages:
Up till now it was necessary to work with relatively wide zonal apertures, as the human eye fails when comparing extremely narrow zones (because of diffraction and other effects).Unfortunately these wide zones show brightness-gradients, so that - in consequence - finding a fitting effective radius is essential. Over the time various formulas for calculating effective radii have been developed, though all of them are still approximations (see the formulas defined by Texerau, Couder, Carlin or others).This is no longer a problem with VCS!
- 'Auto Compare' internally works as if there were zones that are only one pixel wide. Such narrow "zones" cannot show brightness-gradients.
- Finding the suitable effective radius is no longer critical as the evaluated (compared) areas and the radius generally are one and the same!
- The user can be sure, that the readings he gets at the measuring instrument strictly correspond to the effective radius - however this radius is defined. This way he can calculate the mirror's current curvature with significantly higher accuracy.
- Histograms normally are slimmer and thus their congruency can be determined more exactely.
- Especially the outest and often the inner zone can be compared more precisely
=> Zone apertures or effective radii (depends on setting 'Measured Area') that change their brightness equally and simultaneously will show histograms whose centeroids move up and down the vertical grayscale-axis exactely congruently.
• redirected URLs to new VCS website
• Made dependency between moving o fixed light source and calculation of transverse aberration better visible• Improved user guidance
• Added calculation and automatic optimization for minimal Surface RMS Error• Fixed bug causing wrong absolute values of surface error profile and wrong display of transverse aberration / diffraction disc radius
• Added recommendation for getting best surface error profiles
• Automatic evaluation of measured data.• Immediate calculation and graphical display of lateral aberration, transverse aberration, and surface error profile.• Automatic optimization for 'best fit' transverse aberration• Added Description of Screen Test Procedure• fixed bug 'value zero not correctly restored from configuration file'• set max count readings to 6
• fixed bug 'statusmessages not displayed'
• Auto Compare Mode (automatical brightness comparison of zonal apertures)• Brightness evaluation across full aperture or exactely along effective radius• 'Anti Seeing' mechanism• Improved positioning and calibration of couder screen• Improved definition of mirror diameters (outside-, chamfer-, optical diameter)• Improved definition of zones and effective radii (according to Texereau, Couder, N. O. Carlin, Pinstick plus free definition of radii)• Excludable screen center area• Improved definition of 'Aperture Height'• Pivotable screen orientation• Software configuration can be saved as file or loaded from file• Fixed bug 'Computer Screen Freezes'• Improved software stability• 'One click' screenshot to jpg-file utility• Online Helpsystem• Change of distribution type from freeware to shareware
• Virtual screens and radii• Effective Radii according to Texereau• Variable zones count• Readings management• 'One-click' zones switching