## Zemax Diffractive Optical Element Sag Macro

This article explains how to measure the sag of a diffractive optical element using a sag macro in OpticStudio.

Authored By: Serhat Hasan ASLAN

Published On: June 24, 2015

## How is Ln Different to Hn?

Question; Zemax supports both the Hn and Ln filter strings. How are these different, and when should I use one over the other?

Authored By: Mark Nicholson

Published On: September 25, 2009

## How to Use the Tolerancing Cache

This article explains the benefits of the tolerancing cache feature.  This article also warns when it may be inappropriate to use this feature.

Authored By: Andrew Locke

Published On: May 7, 2007

## Why is the Optical Performance Sometimes Different at the Image Surface Versus a Co-Located Surface?

This article explains why you may see different results at two co-located surfaces that are at the same location in space, when one of the surfaces is the image surface.

Authored By: Andrew Locke

Published On: December 25, 2015

## Why Can I Not Place a Thermal Pickup on the Conic Constant?

On certain surface parameters, Zemax does not allow the placement of a thermal pickup solve. This article explains why.

Authored By: Nam-Hyong Kim

Published On: March 19, 2007

## Why Are FFT and Huygens MTF Results Different on Tilted Image Surfaces?

An explanation of why FFT MTF and Huygens MTF yield different results in system with tilted image surfaces.

Published On: December 23, 2015

## How to Modify String Variables in ZPL Macros

• How to use the $LEFTSTRING(A$, n) and $RIGHTSTRING(A$, n) string fuctions
• How these functions can be combined together to effectively scan and modify string variables

Authored By: Andrew Locke

Published On: August 23, 2006

## What is the Difference Between the FFT and Huygens PSF?

This article discusses the Huygens and the FFT PSF computations, gives a quick test of validity of the FFT PSF, and concludes with a list of system parameters which require the use of the Huygens calculation.

Authored By: Betsy Goodwin

Published On: October 30, 2015

## Zemax OpticStudio 30-Day Money-Back Guarantee

What is the Zemax OpticStudio 30-Day Money-Back Guarantee?

## How To Use the ZRDPLAYBACK Keyword To Obtain Filtered Results

This article describes use of the ZPL keyword ZRDPLAYBACK to restore data from a previously saved ZRD file onto detectors in a non-sequential system. Analysis of the data can then be undertaken using the standard non-sequential functions (e.g. NSDD, NSDE, etc.). Using ZRDPLAYBACK, the saved data may be optionally filtered prior to analysis.