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TitleUsing a Co-ordinate measuring machine to align multiple element large optical systems
Publication TypeConference Paper
Year of Publication2007
AuthorsHowick, E.F., Cochrane D., and Meier D.
Conference NameProceedings of SPIE - The International Society for Optical Engineering
Date Published2007
KeywordsComputational geometry, Coordinate measuring machines, Gages, Lens alignment, Lenses, Optical systems, Rotating machinery, Table setups, Tolerance
AbstractA high precision Co-ordinate Measuring Machine (CMM) is an ideal instrument for aligning mid to large (400 to 600 mm) diameter multiple element lens assemblies. The CMM has many advantages over simpler dial gauge and rotary table setups. For example, these traditional methods do not necessarily make it easy to separate the out-of-roundness of a lens or its mounting cell, from a misalignment of the lens and cell. With a CMM, the 'as made' geometry of both the lenses and their mounting cells can be determined before the mounting and alignment process begins. By considering the actual shape of the lenses and cells, adjustments can be made during the alignment process to ensure that the complete assembly meets the designer's tolerances. This paper discusses CMM alignment techniques used and experience gained while assembling large lens corrector assemblies (for example, the three element Prime Focus Unit for FMOS, the Subaru Fibre Multi-Object Spectrograph) destined for installation in astronomical telescopes.

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