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Exporting an OSLO design to a CAD program

Written by Admin | Aug 30, 2021 4:00:00 AM

Question

I tried exporting an OSLO design to a CAD file format, but I am having trouble seeing the file in my CAD program. I am using AutoCAD 2000. Do you have any suggestions?

Synopsis

Exporting an OSLO design to a CAD program

Symptoms

The biggest problem that OSLO users encounter is to remember that OSLO draws the optical axis along the Z-axis. This means that the normal "side" view of the optical system is in the YZ viewing plane. In CAD programs, the common "plan" view is the XY viewing plane. This means that when you import the lens graphic into the CAD program you generally see an "end on" view of the optical system. If you chose to export the OSLO graphic using the "meridional cut" option, this is essentially a "slice" of the optical system in the YZ plane. If the rays of the graphic are also drawn in the YZ plane and you are viewing the graphic in your CAD program in the XY plane, then all you will see is a vertical line.

Workaround

To correct the above situation, make sure you view the graphic in the YZ plane using your CAD software. In AutoCAD, the commands are: ucs y 90 plan current This will cause the current "plan" view to rotate 90 degrees on the Y-axis. If you are using a different CAD program, the same approach should work (but with different commands appropriate for your software)."

Solution

If you are having trouble getting good results after reading and following the above explanation, follow the series of steps below as a mini-tutorial and you should get a result that looks reasonable. Then you can change some of the steps to get an export file that is more to your liking.
  1. Choose "File>>Export Lens to CAD" from the OSLO menu
  2. If your CAD program accepts DXF as input, we recommend using the DXF file output option (AutoCAD users should definitely choose DXF). If not, choose IGES.
  3. If you choose DXF, then try the "solid model" option. If you choose IGES, then try either "meridional section" or "wireframe" for lens drawing style and "all surfaces" for drawing options.
  4. Keep ""First surface"" = 0 and ""Last surface"" = 0. This will cause OSLO to default to saving all surfaces.
  5. Change the file name if you want, but remember what you change it to.
  6. Now open up your CAD program and import the file you created. Note that the file will be located in the "...private" directory of your OSLO installation. If you are using AutoCAD and created a DXF file, note that the "File>>Open" option allows you to open a "DXF" file type. If you are using AutoCAD and created an IGES file type, note that you can open an IGES file by opening up a new file (blank) and then issuing the "IGESIN" command.
  7. Once the file has been imported into the CAD program, remember to view the file with the YZ plane as the "plan" view, or view the file and a 3D orientation. In AutoCAD, you can view the lens system in the YZ plan view by issuing the commands:ucs y 90 plan currentYou can choose to view the lens system in a 3D view by choosing: vpoint 1,-1,1
OSLO's CAD export function models optical surfaces as spherical curves if the surfaces are spherical. If the surfaces have an aspheric component, the surfaces are represented as groups of lines or polylines. Note that when translated to a CAD program, the resulting optical system surfaces are not modeled as faces, objects, 3D faces, or 3D objects - the end result is that the surfaces appear as a series of straight-line segments. The resulting CAD surfaces may look like facets, but they are really just a series of line segments (or a polyline made up of line segments). Now that you have created some output that you recognize, you can go back and fine-tune the file you created as output:
  • If your solid model export had a quarter of each aperture "cut away", you might want to go to "Lens>>Lens Drawing Conditions" in the OSLO menu and choose "Aperture" = "Full" before exporting the file.
  • You can try other export options if you like (for example "Sagittal Section", ...etc.)
  • You can adjust the resolution so that the "faceting" gets finer, but there is no way to define a completely "smooth" surface. Try using "Lens>>Lens Drawing Conditions". Make "Rings" and "Spokes" larger before doing the export.
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