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Tagged with: Centering

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.

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

  • How small can the PSM be used for centering on a cylindrical axis?

    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.

  • Why is proper alignment so important?

    Here is a case of a very happy customer due to better optics.

    A few days ago an astronomer friend of mine commented that he had gotten the optics of his telescope improved and the improvement reduced the time it took to get data by a factor of 3. For an astronomer this is a dramatic improvement since observing time on large telescopes can cost thousands of dollars an hour.

    My friend did not say how the optics had been improved, but the important point is that better optics, whether due to figure errors, mounting or alignment mean more productive optics. I generally think of better optics as a better product leaving the manufacturing facility without thinking about how much the better optics mean to the productivity of the customer.