FAQ on opening multiple Opticstudio instances

This article explains what OpticStudio "instances" are and how they are counted for each license type. 

Authored By Don Dickinson


What are instances?

An "instance" refers to a currently-opened copy of OpticStudio. OpticStudio allows for multiple copies of the software to be open on a single machine, thus allowing you to work on multiple optical systems or run scripts through the ZPL or API.

If you have a network license, "instances" are counted seParately from the number of license "seats" you have purchased. A network license assigns a license seat to a particular client machine, then that machine can open a certain number of instances. There are some caveats, continue reading the sections below. 

You cannot split up some instances to another or multiple machines. 


What is the instance limit for each edition of OpticStudio?

Each license has a limit for how many simultaneous OpticStudio instances may be opened at one time, and the limit is determined by the type of license you own. This section clarifies the limits for each license type and version of the software.

For all OpticStudio 18.9 and lower releases, only 2 instances per machine are allowed. This limit was built into the software. When OpticStudio 19.4 came out, we released a new subscription license type. These license types have some new OpticStudio features, including additional instances for Professional and Premium. 

For those customers who have perpetual legacy licenses and 19.4 or higher, the limit remains at 2 instances for all editions of OpticStudio.

For Ansys licenses, both perpetual and leased (subscription) the limits are similar to the subscription legacy licenses. 

See the chart below for a full breakdown:



If you are interested in converting a perpetual license to a subscription or Ansys license, contact your Zemax account manager or the sales team.


How do I tell how many instances my license supports?

The number of OpticStudio instances you may have running at one time is determined by the maximum number of instances your license is eligible for. You can find additional information on identifying your license type in this article. A screenshot from that article is provided below:

NOTE: This section only applies if you have a legacy Zemax license (license numbers starting with L or T, or a 5 digit number such as 22000). 




If you have OpticStudio 19.4 or higher, you can also check the “View License” page in the Zemax License Manager. Subscription licenses will show the license expiration date in bold text. Note: this information is not provided for releases older than OpticStudio 19.4, as they came out before subscription licenses were offered. 

You can also test by trying to open OpticStudio windows. If you have OpticStudio Professional or Premium, are using version 19.4 or higher, and you can open more than 2 instances, you know you have a subscription license.


I have 2 licenses available. Can I open additional instances with the 2nd license?

Zemax Legacy licenses:

No, licenses cannot be “stacked” on a single machine. Only one license seat can be assigned to a machine at one time, and the limit of instances likely would kick in before using the 2nd license.

Ansys license:

No, even with a multiple seat license, there is a limit of open OpticStudio instances on the machine.  

I have access to a network license with multiple seats. Can I open extra instances by using another seat?

No, all instances are counted against overall number of copies of OpticStudio open on a single machine.

Can I split my instances between more than one machine?

No, all instances are allocated to be used on a single machine.


I have 2 people logged into a machine simultaneously. How does that affect instances?

Zemax legacy licenses:

This was never offically supported on single-user licenses as they were licensed for 1 user at a time. Even with Network licenses, each user would share the instances available to the machine. For example, if they are sharing a Professional Network license subscription, each user could have 2 instances open or one could have 3 and the other could have 1.

This is why we don't recommend sharing a licensed machine like this even with a network license. It also means having to share the CPU cores during optimization or raytracing so performance for all users is compromised.

Ansys licenses:

Each logged in user would use a license seat on the server. If you have only a one seat license, then only one user will be able to launch OpticStudio on any particular machine. If you have a multiple seat license, then the same number of users you have seats for can open OpticStudio on the same machine, If you have 2 seats, then 2 users can use the license at the same time. 

However, be aware that in this case, each user would also share the number of instances available to the machine.

For example, if you have an Ansys OpticStudio Professional license with 2 seats, normally this has a maximum of 4 instances. Each user could have 1-2 instances open, or one user could have 3 instances and the other could have 1. One user could even use all 4 instances and not leave any available for a 2nd user. 

So for the above reasons it's not generally recommended to share this way unless users tend to open no more than one or two instances at once. It's better to have people use their own machine to run OpticStudio rather than share one machine. 


What About OpticsViewer?

OpticsViewer can open 1 instance per machine. 


This has been a general overview of how OpticStudio handles instances. If you have additional questions on this topic, you can post them to our License & Installation forum, or open a support ticket

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