FRED Knowledge Base

Cassegrain Telescope Builder

A while ago, I was reading through Joe Geary’s excellent book, “Introduction to Lens Design” 1, and it occurred to me that his first order construction of a Cassegrain telescope could be very easily written up as a BASIC script in FRED. The example file that...

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Stepped Advanced Raytrace with Analyses

It is important to remember that Analysis Surfaces in FRED only post-process (filter) rays at the end of the raytrace when an analysis is requested.  They do not collect ray information during the raytrace, regardless of whether the ray trajectory passes through the analysis grid. ...

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Beam Footprint Analysis

It is important to remember that Analysis Surfaces in FRED only post-process (filter) rays at the end of the raytrace when an analysis is requested.  They do not collect ray information during the raytrace, regardless of whether the ray trajectory passes through the analysis grid. ...

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Application Example: Polarizers

The term minimalism is also used to describe a trend in design and architecture where in the subject is reduced to its necessary elements. Minimalist design has been highly influenced by Japanese traditional design and architecture. In addition, the work of De Stijl artists is...

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Spatial Filter

The term minimalism is also used to describe a trend in design and architecture where in the subject is reduced to its necessary elements. Minimalist design has been highly influenced by Japanese traditional design and architecture. In addition, the work of De Stijl artists is...

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Monitoring network license usage

To monitor the usage of a FRED Network license,  open a web browser on the license server computer and go to http://localhost:6002 This opens up the Sentinel License Monitor (will install Java if not already on there) which will allows the viewer to see the available licenses...

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Calculating MTF

The Modulation Transfer function (MTF) is commonly used to describe the performance of an imaging system – specifically how the contrast varies with spatial frequency. It is defined as the normalized Fourier Transform of the Point Spread Function. This stand-alone FRED script can be run after...

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Looping Through Raypaths

FRED has many tools for helping the optical engineer determine the contribution and causes of stray light in an optical system including the Image Artifact Diagnostic Tool and the Stray Light Report. The Stray Light Report, for example, provides a detailed report of system scatter...

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Combining Spectra

The script utility shown in this knowledge base article is intended to serve as a “user tool”, whereby multiple spectra can be multiplied together over a wavelength range and form a unique resultant spectrum.  This knowledge base article also discusses how to add user-tools to...

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Remote Desktop Access

The Safe-Net Sentinel hardware dongles come in both network and single-user formats.  The single-user dongles, however, can also be used to run FRED via Remote Desktop if the dongle is located on the PC which will be running FRED.  Before the dongle will allow you...

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