Wells Research & Development

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Model OS210B - Tabletop Lens Test Bench

OS210B PixelScope System OS210B
OVERVIEW
  • The OS210B is a tabletop system for testing lenses with focal lengths from 0.5mm to 500mm.
  • The base OS210B is configured for testing at infinity. An option is available for testing at finite conjugates as well.
  • The base OS210B is manual, but motorized stages are available for 1, 2, or 3 axes.


















Tips for Lens Designers:

The OS210B can display wavefront aberrations at the lens pupil and crate "ray fan" plots.
USED BY
  • R&D to evaluate performance of commercial lenses for use in larger systems
  • Lens Designers to validate performance of custom lens prototypes
  • Operations to track performance of incoming batches of lenses
  • Production Engineering to diagnose imaging problems
    • PRINCILPE OF OPERATION

    The lens under test forms an image of the pattern on a test reticle. The image is viewed by a telescope, and captured by a FireWire video camera for analysis.

    This configuration eliminates the need for the microscope lens required in older lens test systems, removing a source of potential error.

    FLEXIBILITY

    The OS210B is completely modular, and is compatible with a wide range of OpticStudio™ components.

    AUTOMATION

    The standard OS210B is a manual system. However automation modules, including auto-focus, are available as add-on options.
    MEASUREMENTS MADE
  • Visual evaluation of image qualit
  • Quantitive tests of image quality: MTF, 3-Bar contrast, enslitted energy
  • Measurement of lens parameters: EFL, BFL, FOV, F-number
  • Evaluation of depth of field, field flatness, distortion, chief ray angle, vignetting, centration
  • On- and off-axis color aberrations, astigmatism, veiling glare
  • Visualizations of wavefront aberrations at lens pupil. Construction of "ray fan" plots
    • RANGE OF LENSES TESTED

    The base system includes a 200 mm telescope. This is compatible with lenses with CA from 2 mm to 20 mm, and EFL from 4 mm to 500 mm.

    Because no microscope lens is involved, very fast lenses may be tested.

    OPTIONAL TELESCOPES

    Telescopes are available with EFL from 18 mm to 900 mm, extending the EFL range to 0.5 mm - 500 mm, andCA rangeto0.5mm-100mm.
    ACCURACY AND REPEATABILITY

    Unfortunately, MTF measurements have come to be viewed with suspicion by many in the industry, perhaps because of bad experiences with older systems. Wells Research is out to change this: The OS210B provides repeatable, traceable measurements you can have confidence in. Questions you should ask include the following:

    • Are the camera images representative of the lens under test or does the system itself add wavefront error?
      After all, the MTF calculation is just math, and will be accurate to many decimal places. However, the calculated MTF is only as valid as the image captured by the camera. Unless the image reflects the flaws of the lens under test, and only those, flaws, the calculated MTF will be of dubious value. The OS210B optics are diffraction limited, and an inspection certificate is included.
    • Has the operator correctly setup the system?
      In PixelScope, system parameters are entered into graphical pages to minimize the chance of operator error.
    • Is it possible to trace the MTF value to a known standard?
      The OS210B includes a certified “golden lens” for setup and verification, and can save measured images for later review. The OS210B can measure both MTF and 3-bar contrast. In the initial stages of an investigation you may wish to measure both and verify correlation. This provides increased confidence, and is another safeguard against operator setup error.
    LIGHT SOURCE

    The OS210B uses an LED light source, which is brighter, more stable, and more uniform than the halogen source used in our OS210A.. The system includes 4 quick-change LEDs, (3 narrow band colors and broadband white). Illumination intensity is adjustable over a 300:1 range with no shift in color temperature.

    COMPUTER AND SOFTWARE

    The OS210B includes one copy of PixelScope-OS software. We provide a Windows XP computer, along with all othernecessary hardware and software is provided, including a FireWire interface card and cable.

    RETICLES

    The OS210B includes the following 3 reticles, plus one ”bonus reticle” which you may select from our catalog:

    • Cross target with 1 um line-width and small 50 um central square.
      The primary target for MTF and EFL measurement. The very narrow line permits MTF measurements up to 500 L/mm
    • Small USAF target, with groups 4-7
      This is the Industry standard target for 3-bar contrast. Also handy for setup and visual evaluation of image quality.
    • Veiling glare target. A 2 mm clear area surrounds a small square target.
      Lenses with veiling glare will show much worse contrast at the central target.