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Optical Testing

Calculation of the Vertex Radius of an Off Axis Parabolic Surface using the Sag Measured with a Three Ball Spherometer (ABSTRACT)

ABSTRACT: A paper by An and Parks describing a method of calculating the vertex radius of an off-axis parabolic segment using a three ball spherometer to measure the sag. The vertex radius is found by solving a set of six simultaneous, non-linear equations for the three coordinates of the ball centers and the corresponding three coordinates of the point of contact of the ball with the parabolic surface.

Dual Light Source Microscope For Inspection of Micro-Optics (ABSTRACT)

ABSTRACT: Desription of using both the single mode fiber (SMF) point source and the full field LED source of the Point Source Microscope (PSM) for the inspection of the surfaces of micro-optics including surface defects and tool marks.

Swing Arm Optical Coordinate-Measuring Machine: High Precision Ground Aspheric Surfaces using a Laser Triangulation Probe (ABSTRACT)

ABSTRACT: A paper by Wang, et. al., describing a swing arm optical coordinate-measuring machine (SOC), a spherical profilometer, with a distance measuring triangulation sensor for in situ measurement of the topography of ground surfaces. Precise measurement of ground surfaces speeds their figure correction and subsequently reduces total grind and polish time.

The Structure Function as an Optical Surface Specification (ABSTRACT)

ABSTRACT: A tutorial paper on how to use the structure function as a specification (SF) to limit the effects of mid-spatial frequency roughness. It also points out that the SF units of measurement are familiar to opticians and optical engineers and that it is easy to calculate the SF without making ambiguous assumptions as opposed to the use of Power Spectral Density (PSD).

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.