Tagged with: PSM

Alignment of 4-Mirror Wide Field Corrector for the Hobby-Eberly Telescope (ABSTRACT)

ABSTRACT: Paper by Oh describing the use of an autostigmatic microscope (PSM) to precisely position computer generated hologram (CGH) alignment targets on optical surfaces.

Alignment of Optical Systems (ABSTRACT)

ABSTRACT: Describes the advantages of aligning optical systems using a Point Source Microscope (PSM) where the optical axis of the system is folded in 2 or 3 dimensions  and shows how pseudo aberrations can be generated that show quantitatively the degree of precision of the alignment from the Star image seen in the PSM.

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.

Non-Contact Probe for On-Machine Metrology (ABSTRACT)

ABSTRACT: On-machine metrology is particularly important for diamond turning and grinding as it is difficult to remount and align a part if it does not meet off-line inspection criteria. There is also the issue of tool wear; a process that started well may fail part way through the cut, and if tool replacement is needed, it is vital to know that before removing the part. A means of rapid, noncontact, in situ profiling and roughness measurement could improve the productivity of diamond tool machining.

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.

Prism alignment using a Point Source Microscope (ABSTRACT)

ABSTRACT: The Point Source Microscope (PSM) is used to locate the apex of retroreflecting prisms in 3 degrees of translational freedom with a precision of less than 1 micron. The process is easily explained for right angle prisms, as will be done in this paper, but the explanation is valid for cube corner retroreflectors such as those mounted in spherical balls, spherically mounted retroreflectors, or SMRs, for use with laser trackers. With suitable, simple fixturing, the measurements for all 3 directions are made to a precision of < 1 μm in less than 1 minute.

The Autostigmatic Microscope (ABSTRACT)

ABSTRACT: This relatively recent (1983) paper by W. H. Steel of CSIRO is the only paper found in the archival literature to describe an autostigmatic microscope (ASM) and its most common use, the measurement of radii of curvature, in this case, the radii of contact lenses. The Point Source Microscope (PSM) is a modern version of this classical instrument.

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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