## How To Model a Gradient Index Version of a Sellmeier1 Glass Using the Gradient 5 Surface

This article explains how to convert Sellmeier 1 dispersion coefficient data into dispersion coefficient values for the Gradient 5 surface. After doing so, the Gradient 5 surface may then be used to model the variation of index with position for a Sellmeier 1 glass.

Authored By: Brian Bauman

Published On: June 22, 2009

## Take Care With "Exact Equivalent" Glasses

A few years ago the manufacturers of optical glasses started the process of reformulating their glasses to remove arsenic and lead. At first glance, most of these glasses appear to be the exact equivalents of the original glasses. However, examining the indices in the near UV and the NIR shows that the indices can differ in the 3rd decimal place.

Further more, many other properties of the glasses differ significantly: the new formula glasses absorb earlier at each end of the spectrum, and there can be massive differences in the thermal properties between the old and new formulations.

This article discusses these topics, and shows some traps it is easy to fall into with 'Exact Equivalent' glasses.

Authored By: Eddie Judd

Published On: February 13, 2007

## How OpticStudio Calculates Refractive Index at Arbitrary Temperatures and Pressures

This article explains how OpticStudio calculates the refractive index of a material for a given wavelength, temperature, and pressure.

Authored By: Sanjay Gangadhara

Published On: December 25, 2015

## How To Return the Index of Refraction at a Specific Wavelength

This article describes the different ways to return index data in Zemax OpticStudio.

Authored By: Dan Hill

Published On: December 23, 2015

## How To Enter Glass Data at Specific Wavelengths

This article explains:
• What the table glass is
• What is the format required for the table glass
• Benefit and simplicity of the table glass

Authored By: Dan Hill

Published On: October 6, 2005

## How to Model a GRADIUM Lens in Non-Sequential Mode

This article illustrates how to model GRADIUM lenses in non-sequential model

Authored By: Sanjay Gangadhara

Published On: July 1, 2010

## How to Choose the Best Glasses for Your Optical Design

This article explains:
• The limitations of traditional glass choice methods like Conrady d-D and the use of model glasses
• How to use the Glass Substitution method for direct glass optimization
• How to further restrict glass choice to include factors like glass availability, cost, climate resistance etc.

Authored By: Nam-Hyong Kim

Published On: October 5, 2006

## How to Use the Model Glass

This article explains:
• What is a "model" glass in Zemax?
• How and when to use the model glass
• How accurate is the model glass?

Authored By: Dan Hill

Published On: September 30, 2005

## What is the "Reference Temperature"?

When a glass is defined in a glass catalog, a "reference temperature" is also entered. The nature of this temperature is sometimes misunderstood. This article explains the correct usage of the reference temperature.

Authored By: Mark Nicholson

Published On: October 28, 2005

## How To Add New Materials and Glasses in OpticStudio

This article describes how to create a Materials Catalog to contain your own material or glass data.

Authored By: Mark Nicholson & Kristen Norton

Published On: October 20, 2015

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