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Tagged with: Bessel beams

Aligning reflecting optics with Bessel beams (ABSTRACT)

ABSTRACT: Bessel beams have found use in the alignment of transmissive optics for some time. They are also used for the alignment of reflecting optics when used in the imaging mode, that is, when the wavefront is near spherical. However, there are cases where it would be useful to use the Bessel beam for alignment of far-off axis aspheres to order to get the asphere aligned close enough to its final position that light will go through the system in the imaging mode. In another mode, the Bessel beam is used to determine the normal to a free form surface.

Practical considerations for using grating produced Bessel beams for alignment purposes (ABSTRACT)

ABSTRACT: Bessel beams are useful for alignment because they create a small diameter, bright, straight line image in space perpendicular to the Axicon grating producing a beam that is an exact analog of a single ray in a ray tracing program. Bessel beams are produced by plane Axicon gratings whose pattern is chrome on glass, evenly spaced, concentric circles that are illuminated by a point source of light on the grating axis. The grating produces a more nearly ideal Bessel beam than a cone shaped type Axicon. The plane grating also serves as a plane mirror in an alignment setup to define four degrees of freedom in space rather than the usual two a plane mirror does.

Most discussions of Bessel beams assume illumination with collimated light. We have found it advantageous to use a point source for illumination because it is easy to implement and less expensive using a single mode fiber as a source than a precision collimating lens the diameter of the Axicon. Besides, collimated illumination produces a Bessel beam of finite length in transmission while, in theory, a beam of infinite length is created using a point source.

With these assumptions about how Bessel beams are produced with plane gratings and details about the grating diameter and line spacing it is easy to calculate the useful length of the Bessel beam in reflection from the grating. Other practical matters are also discussed such as 4 degree of freedom lens centering with a test apparatus with no moving parts.

Precision cementing of doublets without using a rotary table (ABSTRACT)

ABSTRACT: 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.

Case Studies & Testimonials

  • "Just wanted to share a recent success aligning an adaptive optics test bed with the PSM. We used to use a traditional alignment telescope in the past, but the PSM made the whole process really easy and fast. The main requirements were to quickly determine the quality of beam collimation and pupil conjugates since there are several beam expanders and compressors with multiple pupil and focal planes."

    Suresh Sivanandam
    Dunlap Institute for Astronomy and Astrophysics
    University of Toronto

     

  • "You are always responsive and give us lots of useful information!!"

    Dr. Shaojie Chen
    Dunlap Institute for Astronomy and Astrophysics
    University of Toronto

     

  • "As always we are very much loving the instrument, I personally love the camera upgrade from what I'm used to!"

    Weslin Pullen
    Hart Scientific Consulting International, LLC
    Tucson, Arizona

     

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清原光学 営業部   Kiyohara Optics / Sales
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Kiyohara Optics Inc.
3-28-10 Funado Itabashi-Ku Tokyo, Japan 174-0041

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Armstrong Optical

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