Straightness And Flatness Of Air Bearings

1. Introduction

When working with air bearings, we often describe the quality of motion as one of the key factors in selecting an air bearing; specifically, the straightness and flatness of travel of linear bearings and stages. Just how straight and flat? What levels of precision are achievable?

In this technical note, we will discuss several aspects: the error motion over full travel, impacts on error motion, the repeatability of the error, and the short-term errors.

2. Definitions: what is straightness and flatness?

Define our coordinate system. See Figure 1. X = axis of motion for a linear stage.