Modern optical metrology uses precise lines and planes in space from which measurements are made. Because this method creates these features using light it has become known as optical tooling. The 35 year old historical development and current technology of laser instrumentation as used in optical tooling is discussed in detail. This includes the how the measurements are made, applications, and the technology of alignment lasers and position sensing targets developed for sensing position within a laser beam or plane. The various geometries used to make alignment measurements are discussed in detail. Applications are discussed and the challenges each poses are discussed. The challenge of long range alignment and the effect of the turbulent atmosphere on the measurement process is discussed along with methods of handling the associated errors them.
WHAT IS OPTICAL TOOLING?
Optical tooling is a means establishing and utilizing a line of sight (LOS) to obtain precise reference lines and reference planes from which accurate measurements are made with position sensitive targets. [1] Formerly the measurements were done by a person interpreting a scale or optical micrometer by looking through an alignment telescope; today the lines and planes are created by a laser; the measurements are digital and require no interpretation.
Optical tooling uses the principle that light travels in straight lines to produce precise measurements that cannot be reached by manual or mechanical methods. Level lines can be established over great distances so accurately that every point is exactly perpendicular to the force of gravity. Plumb lines can be set to a given level. Right angles can be produced quickly and precisely with auxiliary components.
In the assembly, maintenance and calibration of industrial equipment or in the alignment of precision systems, one or as many as four basic questions always must be answered: is it straight, is it flat, is it