ABSTRACT
In this chapter, we consider examples of various ways in which two or more lenses or image-forming mirrors may be mounted together to form opto-mechanical subassemblies or assemblies. The treatment is by no means all-inclusive. The examples were chosen to illustrate multiple uses of the design features described in Chapter 4 as techniques for mounting individual elements and components. Included are discussions of means for establishing the proper spacing between elements, of lens assemblies with and without moving parts, of the lathe assembly technique, of typical refracting and reflecting microscope objectives, of assemblies involving plastic optical and mechanical parts, of techniques for coupling elements with liquids instead of cement, of a variety of catadioptric optical instrument configurations, and of some proven techniques for aligning lenses in assemblies.
In multielement lens assembly designs, elements frequently rest against shoulders or spacers whose axial lengths are carefully machined to obtain the required axial air spaces between surface vertices. A typical example is illustrated in Figure 5.1. The parameters indicated are those needed to find the length Lj,k of the shoulder between the contact points Pj and Pk at heights yj and yk on the spherical surfaces with absolute radii |Rj| and |Rk| to produce the separation tj,k between the adjacent vertices. The sagittal depths of the surfaces measured from planes through Pj and Pk are Sj and Sk, respectively. They are assigned positive signs if contact occurs to the right of the vertex and negative signs if contact occurs to the left of the vertex. In the figure, Sj is negative while Sk, tj,k , and Lj,k are positive. The surface depths and the shoulder length are calculated by the following equations:
