Paper 4: Lasers in the Determination of Form Errors in Large Mechanical Structures

This paper discusses alternative approaches to the use of the laser as a metrological tool, and considers the particular qualities required of it when the laser beam is to be used as the reference. Ways in which its usefulness can be extended by associating it with other optical equipment in order to measure parameters other than straightness are referred to. In conclusion some consideration is given to the limitations imposed by the atmosphere upon instrument performance and the ways in which, in part, they can be countered.