# OSLO FAQ¶

EE/PHY 448/548

Scott Prahl

Oct 2018, Version 1

## Questions¶

This is a first pass at questions and answers. There are certainly errors.

How to get my lens spreadsheet (aka Surface Data Window) back?

Don't panic. Click the tiny lens icon (second from left) in the toolbar of the main window.

There is no drawing of my lens!

Have you clicked the "Draw Off" button in the Surface Data Window to cause the Autodraw window to appear

I did that, but my lens is still not drawn!

If the GLASS for lens is AIR, nothing will be shown in the Autodraw window. Alternatively, the lens may be to small (i.e., the aperture radius is tiny).

It won't let me change the object size?

This is because the object is effectively at infinity. Change the thickness of the OBJ to something finite and the height becomes available. (it is in the General dialog)

How can I set the field angle?

If you have set the object height, there is a bug that prevents you from setting the field angle from the GUI. Instead, type "ang 3" to set the field angle to 3 degrees. You can now change it to whatever angle you would like.

How can I get the object (or image or whatever) to be shown?

In the row for the surface of interest, click on the box on the far right, select Surface Control (F) -> General and enter "DRAWN"

What is this AST thing and why is it always annoying me?

AST stands for aperture stop. In any optical system there is an aperture stop. It is one of the primary controls that an optical designer has to improve performance. On the other hand, for simple classroom projects it is just noise. Feel free to ignore it and just treat that line in the lens table like any other line. (You'll notice that the surface numbering starts at 1 and increases with each row. The number for the line with the AST is not shown (because AST) but the next line down has the next number.)

Where to I enter my name as designer?

That's in the dialog that appears when you click the Gen button in the Surface Data window.

How do I get more than three rays to be drawn?

That's under Lens menu. Select Lens Drawing Conditions.

Hello? my biconvex lens is now biconcave!

Ooh. Confusing right? If you give your lens a thickness, it will look more normal.

Why can't I use the entering beam radius as my object height?

Because geometry. They're different things (but happen to be the same when the object is infinitely far away.)

How do I zoom into a drawing window?

You have to create a new drawing window. Create a new drawing window and, in that window, you can draw a rectangle around the region of interest.

How do I use OSLO on my macOS (or Linux)?

Nearly all the Virtual machine solutions will work. I use WINE because I did not want to deal with yet another OS on my machine. Install WINE and then install OSLO. It works pretty well.

How do I use OSLO for all my simple lens homework?

So you don't want to mess around with formulas and think that the computer will do it all for you. The trick is to make your lenses have zero thickness. The drawings are wonky but what did you expect?

My windows are wonky!

Usually this can be fixed by selecting Tile Windows under Window menu.

I still hate OSLO.

That is not a question.