What's it about?

This paper will first detail where slope error originated from, what it represents and the role it plays in optical performance. The three attributes that make up a complete slope error specification will be discussed along with examples of a complete slope error specification. Finally, it will conclude with techniques for measuring slope error.

1. SLOPE ERROR: A REFINEMENT OF FORM ERROR

Specifying an optical component begins with choosing a combination of mechanical dimensions, optical material and surface shape to satisfy an existing system performance requirement¹. Deviation from the nominal effects system performance.

Looking specifically at surface shape, deviation falls into one of two categories: uniform and nonuniform deviation. Uniform deviation is where the as-manufactured surface is uniformly offset relative to nominal, and power in spherical surfaces would be an example. Nonuniform deviation is anything else, and it can have a periodic or random structure. The broad term “irregularity” is applied here, and it represents...