H. General Optics

1. Introduction

Most surveying equipment, historical and contemporary, depend on various optical elements to make target sighting more accurate or reading measurement scales easier. Surveying equipment evolution closely followed advancements in optical quality improvement. Compare, for example, the telescope of an nineteenth century Dumpy level to that of a contemporary automatic level. The modern telescope is shorter, has greater magnification, provides a brighter image, and has fewer distortions.

This chapter is not the be-all, end-all tome on optics. It discusses some primary optical elements contained in many surveying instruments and their characteristics. Since so many of our measurements depend on optics, a background in basic principles and behaviors helps understand their effect on instrumental errors.