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Tagged with: Centering

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.

Centering Steep Aspheric Surfaces (ABSTRACT)

ABSTRACT: We describe a method of finding the optical axis of an aspheric surface by looking at an annulus of the surface as the surface is rotated in azimuth. The method uses either an autostigmatic microscope or an interferometer to view the annulus. Distinctive features of the reflected spot movement, or the changes in Zernike coefficients found with interferometry while the surface is rotated in azimuth permits the separation of decenter from tilt. The method appears to be suitable for use with any aspheric surface.

Conjugate Selection for Precision Lens Centering (ABSTRACT)

ABSTRACT: The concept of centering a precision, symmetric lens system using a high-quality rotary table and an auto-focusing test instrument are well known. Less well known are methods of finding convenient, or easily accessible, lens conjugates on which to focus while performing the centering operation. We introduce methods of finding suitable conjugates and centering configurations that lend themselves to practical centering solutions.

Practical Alignment Using an Autostigmatic Microscope (ABSTRACT)

ABSTRACT: This paper defines optical alignment as placing optical conjugates and centers of curvature at the precise locations specified in the optical design. Auto-stigmatic microscopes (ASM) are the tools used to measure the offset between the optical conjugates and physical datums such as centers of balls and axes of cylinders in alignment fixtures and making precise alignment practical.

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.

Reverse Engineering Lens Elements (ABSTRACT)

ABSTRACT:  Describes using an autostigmatic microscope (PSM) to find the two radii, thickness and index of a singlet lens by making 4 distance measurements similar to those used to measure the radius of curvature of a concave mirror, and then using the 4 distances to iteratively calculate the 4 paraxial lens parameters using an Excel spreadsheet and its Solver application.

Case Studies & Testimonials

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

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


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    Weslin Pullen
    Hart Scientific Consulting International, LLC
    Tucson, Arizona


  • The PSM is an ideal tool for finding the center of curvature of a ball or the axis of a cylinder. The question is for how small a ball or cylinder can the PSM do this?

    The smallest article that was readily available was a piece of monofilament 8 pound test fishing line that was 290 μm in diameter. There was no problem finding the axis of the fishline, and separating the Cat’s eye reflection from the surface from the confocal reflection of the axis. The experiment was done with a 5x objective, and the result would have been even more definitive using a 10x objective.

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清 原 耕 輔   Kosuke Kiyohara
清原光学 営業部   Kiyohara Optics / Sales
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