How to Put a Lens in a Computer

Abstract

To begin tracing rays with a computer, you must first enter imaging system into design program. There are two primary sets of information needed to set up a new optical design: system data and prescription. The system data describes how will be used (e.g., object size, wavelength, aperture size), whereas prescription consists of shape, location, and material of elements. If image distance is not given as part of prescription, then a solve, an operation that will described in Section 3.3, is often entered into program to find paraxial image location. There are two ways to enter necessary data into V's user interface (see box, CODE V's User Interface for a description of its layout). One is graphic user interface (GUI), which uses a series of windows, menus, and clickable buttons. The other approach is command line interface (CLI), where all user entry is done by typing a series of commands. After a brief introduction to GUI in this chapter, we will primarily use CLI in command window for remainder of text. As you will see from lengthy descriptions needed to show you how to enter values using series of windows that make up GUI, it is much easier to use CLI to type in a string of commands that accomplish same purpose with very little fuss. These commands are a series of two- and three-letter strings followed by modifiers and value of a quantity. For example, to set a thickness of value thick beyond kth surface of a lens, you would enter THI Sk thick. We will indicate CLI commands by shading commands as we have done here. These commands will be introduced as they are needed, but there will be no attempt to cover all of the commands that are used in V. That information is available from the User Guide, Prompting Guide, and Reference Manual that is accessible within program. For brevity within this text, we will also use an abbreviated CLI nomenclature when describing a design. For example, instead of referring to the third surface in system, we will use S3. And radius of curvature of second surface of lens (RDY S2 in CLI) will be abbreviated as R2. Distances between two surfaces (written in CLI as THI Sk, where k is number of surface) will be referred to as Tk. And glass of second medium will be abbreviated as G2. Design references will be distinguished from CLI commands, which are displayed in a sans serif typeface with a shaded background.