TABLE OF CONTENTS This chapter will be devoted to the first-order optics of several typical optical systems. The number of systems covered here is, of necessity, limited, and the emphasis is placed on those fundamental principles which are applicable to a broad range of optical systems. The rather straightforward algebraic manipulations and the considerations of image size and position which follow are quite typical of those encountered in the preliminary stages of optical system design. Constructional details of the optical components have been deliberately omitted and are discussed at considerable length in later chapters. Note that the system diagrams in this chapter show the components as simple lenses. These could equally well be mirrors instead of lenses, and typically are fairly complex assemblies of lens elements.
The primary function of a telescope is to enlarge the apparent size of a distant object. This is accomplished by presenting to the eye an image which subtends a larger angle (from the eye) than does the object. The magnification, or power, of a telescope is simply the ratio of the angle subtended by the image to the angle subtended by the object. [1] Nominally, a telescope works with both its object and image located at infinity; it is referred to as an afocal instrument, since it has no focal length. In the following material, a number of basic relationships for telescopes and afocals will be presented, all based on systems with both object and image located at infinity. In practice, small...
