Non-Sequential Raytrace (in Premium): Zero Documentation?

[Justine Haupt]

Greetings,

Could someone please point me toward a tutorial or manual entry for making a non-sequential raytrace in Premium?

The only information I can find is:

-A single reference in the appendix of the manual that doesn't lead anywhere
-An unhelpful entry in the help pages for "Non-Sequential Surface (NSS) Group
-A couple of topics on this forum which don't give any clues about actually working with these systems
-Plenty of bullets in the Lambda advertising literature proclaiming OSLO's non-sequential capabilities
-An oddball Sinclair Optics page
-A powerpoint from a university saying OSLO can't do non-sequential optics
-A grayed out entry for "Non-Sequential Group" in the context menu on the surface data spreadsheet

I have some sense that the functionality is accessed by creating a non-sequential group within the normal (sequential) spreadsheet, but that's it.

I've had great success working with non-sequential analyses in ZEMAX (with the help of their wonderful and active Knowledge Base). I don't mean to cause trouble, but this is just silly.


Is this considered sacred knowledge?

~Justine

[Don Perrault]

The only luck I have had was to go through some of the nonsequential examples in a paid version of OSLO. However I never got really far with these.

Don

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From: Justine Haupt <justin...@gmail.com>
To: oslo...@googlegroups.com
Sent: Tuesday, July 9, 2013 2:51 PM
Subject: {OSLO-Talk} Non-Sequential Raytrace (in Premium): Zero Documentation?

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[Joe Howard]

We regularly use them for segmented telescope modeling here at NASA … I can't recall our learning approach, but I'm sure we used the examples, and perhaps got some help with the staff.

Joe

[Daniel Lid Rad]

You have to follow the instructions in the Oslo help, just put in the line non sequential group... the follow a example  i tried to guess where are the command to change: Like action... in the

5x linear regular lens array. you have to use the  oslo premiun... do you have? this is a good examples...

[Michael Gauvin]

Dear Justine:

You can enter the surfaces one after another in the OSLO spreadsheet as usual but you do need the OSLO premium version. Once you are done entering the information in the OSLO spreadsheet select the portion of the spreadsheet that you want to create as an Non-sequential group and right click and select the Non-sequential group from the drop down list. You now have a non-sequential group definition. The rules for non-sequential raytracing are shown below directly from the manual. If you want examples, they are 20 of them in the demo-->premium-->nonseq subdirectory. You can reverse engineer these as examples as needed..

From the OSLO Help under Non-sequential:

A non-sequential surface (NSS) group is treated as a sub-group of surfaces that is associated with a selected surface in the sequential portion of the lens. The first surface of a non-sequential group is called the "entry port". Surfaces in the non-sequential group itself are numbered in the usual way, although rays will not generally strike them in the given order. The last surface in the group is called the "exit port".

When any traced ray reaches the entry port, a special raytracing procedure is invoked that attempts to find a path through the non-sequential group to the exit port surface. Surfaces within the group will be traversed in whatever sequence is necessary to produce a real path to the exit port, i.e., the path length from each surface to the next surface through the group is required to be greater than or equal to zero. Total internal reflection is allowed and the same surface may be visited multiple times.

A number of special rules apply to the tracing of rays through a non-sequential group. In particular, since a surface may be approached from either side, it is necessary to specify how rays are to be reflected, refracted, or obstructed depending upon the direction from which the surface is approached. If a special action is not specified, the action defaults to whatever is specified by the normal lens data.

In the local coordinate system of a surface in a non-sequential group, the surface may be viewed as dividing space into two regions. Since the surface always passes through the local origin, a point on the local z-axis, slightly displaced from the origin in the negative z-direction, will lie in one of these regions, which we call the "negative" region. Conversely, a point on the local z-axis that is slightly displaced from the origin in the positive z-direction will lie in the other region, which we call the "positive" region. A ray is said to be traveling "to positive" if it approaches the surface from a point in the negative region. It is said to be traveling "to negative" if it approaches the surface from a point in the positive region.

Special actions are specified in this spreadsheet. You can specify both a special action and a condition under which the action is to be taken. One action may be specified for ordinary rays and one action may be specified for the reference raytraced from a new object point. If a special action is specified for ordinary rays but not for reference rays, the action specified for ordinary rays will apply to reference rays as well.

The possible special Actions are:

• Pickup from group surface
  The ray is to be refracted into the medium defined by the glass entry on the specified group surface indicated by Surface.
• Reflect means that the ray is always reflected.
• Obstruct means that the ray is always blocked.
• Pass undeviated means that the ray is not refracted, reflected, or blocked by the surface.
• No action means that the normal glass specification for the surface determines the action.
• Trace to exit port only means that the next surface must be the exit port of the ray will fail.

The possible Conditions are:

• To negative means that the specified special Action will be taken for rays traveling "to negative"; other rays will behave according to the normal glass specification.
• To positive means that the specified special Action will be taken for rays traveling "to positive"; other rays will behave according to the normal glass specification.
• Before n-th hit means that the specified special Action will be taken for a ray the first Hit Number – 1 times it hits the surface; subsequent rays will behave according to the normal glass specification. The default Hit Number of 2 means that the first hit uses the special Action and the second and following hits behave normally.
• After n-th hit means that a ray will behave according to the normal glass specification the first Hit Number times it hits the surface; subsequent rays will behave according to the specified special Action. The default Hit Number of 1 means that the first hit behaves normally, and the second and subsequent hits use the special Action.
• Element Id Number is used only for identification purposes for lens drawings: surfaces with the same (nonzero) element ID are drawn as if they are in the same element (i.e. their edges are connected).