This book covers all areas of electro-optical system design and construction. The material was gathered by doing many conceptual designs from square one: thinking up a measurement concept, doing the math to predict its detailed performance analytically, and comparing that to other concepts before actually building anything. The author covers the full range of topics needed for a successful instrument design, and gives references for further reading in greater depth. The range of topics chosen is calibrated to give the gist of each device or technique, and what it's good for or not good for. The style of the book is written to convey a colloquial conversation to aid the reader’s comprehension.