Advanced alignment turning of mounted aspheric and infrared optics

Abstract

The performance of modern optical systems is dominantly determined by the precision of the alignment of single lens elements in the optical path of the system. The highest alignment precision as well as leading productivity in fabrication can be achieved by alignment turning. A lens to be assembled is glued into a metal mount not considering precision orientation yet. The lens and mount are introduced to an alignment turning machine to measure the optical axis and to correct the metal mount by slow tool turning in a way that the optical and mechanical axis have the same orientation after machining. Remaining shifts of down to 1 micron and tilts < 10 arcsec can be achieved within minutes. As the glue has been solidified prior to machining, there are no more subsequent displacements. The new machine system to be presented is the world leading platform for flexible alignment turning of various types of optics. With its recent developments, it is capable of measuring IR optics with a 4.05 μm laser system. In addition, the optical axis of aspherical lenses can be measured by a full aperture confocal scan without any spherical approximation. Full automation applies to the measuring steps, the slow tool machine program calculation as well as subsequent quality assurance steps. Current tests on objectives with aspheric lenses have led to an overall optical system improvement of < 30% at significantly reduced assembly times. The presentation covers an introduction to the technology and the machines as well as sample machining results.