Papers Published by Optical Perspectives Group

Robert E. ParksOptical Perspectives Group, LLC Tucson, AZ 85750 Daewook KimJ. C. Wyant College of Optical Sciences The University of Arizona Tucson, AZ 75721 INTRODUCTION Following the discovery of so called non- diffracting Bessel beams [1], they have been used for a number of exotic purposes such as trapping single atoms and aiding in the […]

Robert E. Parks and William P. KuhnOptical Perspectives Group, LLC, 9181 E. Ocotillo Drive, Tucson, AZ 85749 ABSTRACT We give an example of a Point Source Microscope (PSM) and describe its uses as an aid in the alignment of optical systems including the referencing of optical to mechanical datums. The PSM is a small package […]

Authors: Robert E. Parks (Optical Perspectives Group, LLC) and Daewook Kim (J. C. Wyant College of Optical Sciences, University of Arizona). INTRODUCTION Following the discovery of so called non-diffracting Bessel beams[1], they have been used for a number of exotic purposes such as trapping single atoms and aiding in the discovery of exoplanets. We discuss more […]

Traditionally a rotary table is used for optical centering because the table creates an axis as a reference. Previously, we showed that a Bessel beam also creates an axis useful for centering. The Bessel beam axis and the center of curvature of the surface makes it possible to center an optic simultaneously in tilt and decenter. We also showed that simultaneously sampling two arbitrary points along the Bessel beam also permits full adjustment of tilt and decenter of a powered optic. This makes centering possible without either a rotary table or a precision linear stage. In most common instances, however, sampling the beam at two points is unnecessary because of the inability to correct for both tilt and decenter. We discuss an alternative, simpler method using a Bessel beam.

Bessel beams are useful for alignment because they create a small diameter, bright, straight line image in space perpendicular to the Axicon, or Axicon grating, producing the beam that is an exact analog of a single ray in a ray tracing program. Here we limit our discussion to Bessel beams produced by plane gratings whose pattern is evenly spaced concentric circles that are illuminated by a point source of light on the grating axis. The gratings produce a more nearly ideal Bessel beam than a lens type Axicon, and the plane grating serves as a plane mirror as well in an alignment setup, so the combination defines four degrees of freedom in space rather than the usual two.

Methods of centering without using a precision rotary table to establish a reference axis in space are several times faster than with a rotary table. However, finding an optimum method of establishing an alternative reference axis is challenging. We look at the small class of centering situations involving the precision cementing of doublets to illustrate the advantages of using a Bessel beam as the reference axis. Two approaches to centering illustrate the method: one involving first aligning the meniscus element and then adding the positive element, and the other, cementing the two elements and aligning the pair.