OSLO uses spreadsheets for entry and display of lens data. These spreadsheets are like other Windows spreadsheets. They contain rows and columns of cells. You can move between cells with the mouse or arrow keys, and you enter numeric data into the cells. OSLO spreadsheets also have the special features of the Click/CommandÔ interface described before. There are several dozen spreadsheets, but they all work similarly, so only the principal ones are described in detail here.

Each spreadsheet has a title bar and a control bar. The title bar displays the spreadsheet title, and includes the standard windows buttons. The control bar contains 4 (OK) and 8 (Cancel) buttons. The ? button displays context-sensitive help for the current spreadsheet. If the spreadsheet has a variable number of rows, six additional icons are added to provide cut-and-paste editing, as described below.

The Surface Data Spreadsheet is where data that specifies lens surfaces is entered and updated. The spreadsheet is opened from the Update menu, by clicking on the lens entry tool on the tool bar, or by entering the command lse.

Once the spreadsheet is open, the highlight can be moved to a desired location using either the mouse or arrow keys and numbers can be entered using the keyboard (or mouse).

View ¾ The two view option buttons, labeled Srf and Grp, select different views of the lens data.

In Srf (Surface) mode, each surface is listed individually with values for all parameters including the radius of curvature. Grp (Group) mode is used with catalog elements, non-sequential groups (OSLO SIX), and user-defined groups.

In Grp mode, Grouped surfaces are shown as a single entity that takes two lines in the spreadsheet. For example, with a Catalog lens, the radius column of the spreadsheet displays the part number of the element. The element can then be treated as a whole, so all its surfaces can be edited (cut, copy, paste, etc.) at the same time. If there are no groups in a system, this setting has no effect. Non-sequential groups display only the entrance and exit port surfaces in group mode. User-defined groups similarly show the entrance and exit surfaces.

Autodraw ¾ In the same row as the view field is the Autodraw field.

When Draw is turned on, OSLO opens a window with a plan view of the lens. This view includes the rays selected by the current operating conditions. The surface or surfaces currently selected on the Surface Data Spreadsheet are shown in a different color. This view is updated whenever the lens data is changed or whenever the highlight is moved to a new surface in the spreadsheet.

If Draw is turned off, the Autodraw window is automatically closed.

Options buttons ¾ To the right of each SmartCell is a button used to select various options to specify data in the adjoining cell, for example, applying a solve or pickup constraint. Click on the button with the mouse, or select the button with the arrow keys and press the space bar. A pop-up menu is displayed to show the possible choices, as shown below.

Row buttons ¾ The spreadsheet contains several rows. Each row is separated from the next by a gray line when there is air between the corresponding surfaces.

At the left end of most rows is a row button. It is used to select the row. In Grp (Group) mode, two or more rows correspond to the same row button.

To select a row, click on the row button. To select a range of rows, first click on the row button at either end (beginning or ending) of the desired range. This anchors the range. Next click on any other row button. The range between the anchor and the new row is selected. You can re-select the new row (by clicking a different row button) but the anchor row remains fixed. To cancel the selection, press mouse button 2 or click Cancel.

The above figure shows a lens spreadsheet with row 2 selected. Once a row or range is selected, the edit menu is enabled, and you can use the cut, copy, and paste tools, or the menu options to edit the selected rows. For example, to duplicate a lens element in an optical system, you would select it, copy it to the clipboard, and then paste it in wherever you want. The surface numbering of other surfaces is automatically adjusted.

The second group of toolbar icons in the spreadsheet is used for reversing ranges of rows, or inserting extra rows, either before or after the selected range.

Note that although spreadsheet row editing is illustrated here with reference to lens surfaces, the method is applicable to wavelengths, variables, operands or other data that are organized by rows.

The performance of a lens depends on the operating conditions under which it is used. The basic paraxial operating conditions that specify aperture and field are shown on the second row of the surface data spreadsheet. At the right-hand end of the row is an options button that invokes the paraxial properties spreadsheet, which allows a more flexible specification of these operating conditions.

Each column of this spreadsheet specifies one paraxial property for the lens. These properties are Aperture, Field, and Conjugates. Each of these properties can be specified in more than one way. You must enter one value in each column (or accept the default) for a complete set of properties.

The Paraxial Properties Spreadsheet functions like other Windows spreadsheets in that an entry in one cell can affect values in many other cells. For example, if you change the image distance, then the object distance, magnification and working f-number all change accordingly. This means you can enter these properties using the parameters that are most natural for your problem and OSLO will calculate the other ones. Parameters not allowed in the current context are dimmed. Before clicking OK, be sure all values are as you entered them.

It is important to understand that this spreadsheet only sets the initial values of the parameters. It does not place any constraints on the lens to maintain these values. For example, if the focal length of the lens changes during a design, this may change the conjugates and aperture parameters.

The primary wavelength used for analyzing the current lens is shown on the third row of the surface data spreadsheet. If more than one wavelength is used, an asterisk appears on the options button in this row. Clicking on this button invokes the Wavelengths spreadsheet, which allows you to specify which wavelengths OSLO will use for analysis. For a monochromatic application, e.g., a laser, a single wavelength is appropriate. For a polychromatic application, OSLO defines three default wavelengths for its analysis. More can be added by the user.

Wavelengths should be spaced across the wavelength range of interest. They should be entered such that the central wavelength is #1. The remaining wavelengths are given in short-long pairs. For example, in the visible spectrum, the order should be green-blue-red. This will make the chromatic aberrations meaningful. Wavelengths in OSLO are always given in micrometers.

The evaluation routines in OSLO are based on the "current" wavelength, normally set to 1. If the current wavelength is set to some other value, aberrations and (single wavelength) ray-trace analyses will be carried out in that wavelength. If the wavelength used for such an analysis is not wavelength 1, the text output indicates which wavelength was used.

Each wavelength can be assigned a weight, which is used in optimization and in spot diagram analysis routines (rms spot size, MTF, PSF, etc.)

Editing the Wavelengths Spreadsheet is like editing the Surface Data Spreadsheet. Rows or groups of rows are selected, cut, copied, pasted, and inserted in the same way. For example, to reduce the number of wavelengths from 3 to 1, click on row button 2, then click on row button 3. Rows 2 and 3 are now selected. Click on the scissors tool on the tool bar. Only row 1 remains. To insert additional wavelengths, select a row button, then click on the Insert After toolbar icon, or press SHIFT+SPACE to create an additional line, then fill in the required data.

To change wavelengths, click on the wavelength SmartCell. When this cell is selected, you may enter the new wavelength manually, or click on the cell again to display the wavelength options box. This box includes standard wavelengths throughout the range most often used by OSLO.

There are many additional spreadsheets that are used to enter data into OSLO. All of them work according to the principles described for the surface data, paraxial properties, and wavelengths spreadsheets. Most are provided for entering operating conditions, special surface data, or optimization data.

OSLO has a preference, Revert_enable, which allows you to cancel changes made to a lens by a spreadsheet. If this preference is set, whenever you exit a spreadsheet by clicking Cancel, a confirmation box will appear asking you to confirm that you want to revert to the state that the lens was in when you entered the spreadsheet.

Note that the normal response to this box is Yes.

The main function of the Gaussian beam spreadsheet is to study the propagation of Gaussian beams through a lens system. You can enter any two independent variables from the set of spot size, waist size, waist location and wavefront radius, and the program will automatically compute all the remaining data and update the display. In addition, you can click on a button in the spreadsheet to draw an anisotropic picture of the beam propagating through the system.

The Gaussian beam spreadsheet can be used for laser cavity analysis and design by making the object surface one of the mirrors and the image surface the other mirror. Then, by setting the object wavefront radius equal to the first mirror radius, the object spot size can be varied until the wavefront radius on the image surface matches the radius of the other mirror. This is the condition required for the Gaussian beam to be a mode of the cavity.

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