This article describes how to use the two tools in the Adjust drop-down: Quick Focus and Slider.

Authored By Thomas Pickering

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The Quick Focus tool

The attached file contains a singlet design. The following images show the Layout and the Spot Diagram for this lens.

As can be seen from the large spot sizes at the bottom of the Spot Diagram, the performance of this singlet at this point is certainly not optimal. A big factor in this poor performance is the arbitrary location of the image plane at a distance of 100 mm from the back side of the singlet. Even from viewing the Layout, it is obvious that the currently selected image plane is not at the "best focus." We can use the Quick Focus tool within OpticsViewer to better position the image plane. Quick Focus is a feature in OpticsViewer which adjusts the thickness of the surface prior to the image plane to position the image at the "best focus" location.

Open the Quick Focus dialog by selecting Adjust...Quick Focus. The targeted "best focus" will depend on the criterion selected. For the singlet design, we will use radial spot size with respect to the centroid. Select Spot Size Radial and  check Use Centroid.

Click OK to run and close the Quick Focus tool dialog.

Note the automatic change to the thickness of the surface prior to the image plane. The analysis windows will automatically update by default, but if they do not, you can update each of them individually by clicking Update in the upper-left hand corner the window. You should see fairly significant changes in performance simply due to the new selection of the image plane location. Most importantly, the RMS and Geometrical spot sizes at the maximum field decreased by a factor of two or more!

The Slider

Let's say you were interested in how the spot size of the singlet varies as the radius of curvature of the rear surface changes. This is useful to study the behavior of a system over the tolerance range of one or more parameters.

Open the Slider tool by selecting Adjust...Slider, and set it up as follows:

You can enter start and stop values of the radius of surface 2 (OpticsViewer makes a reasonable guess as to what values you want) and then you can either use the slider to manually adjust the value within this range or press the Animate button to have OpticsViewer loop through the values. The Spot Diagram will update automatically as the radius of Surface 2 changes. You can choose to update all open windows or just a nominated window as the parameter is varied.

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