Wells Research & Development

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Model OS200B - Lens Bench with 1 m Optical Rail

OS200B PixelScope System OS200B
OVERVIEW
  • The OS200B combines a classical lens test bench with live video and MTF image analysis software.
  • The OS200B is extremely flexible, and can test positive lenses, negative lenses, and even afocal modules. Tests can be done at infinity or at finite conjugates.
  • The base OS200B is configured for on-axis testing, but options are available for off-axis testing as well.













Tips for Lens Designers:

The OS200B can display wavefront aberrations at the lens pupil and create "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.

    Two basic sources are supplied: A collimator, for testing at infinity, and a back-lit reticle for testing at finite conjugates.

    Two basic detectors are supplied. A telescope for viewing virtual images at infinity, and a microscope for viewing real images.

    FLEXIBILITY

    The OS210B is completely modular, and is compatible with a wide range of OpticStudio™ components.
    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, centration, on-axis color and astigmatism, veiling glare
  • Visualization of wavefront aberrations at lens pupil. Construction of “ray fan” plots
    • RANGE OF LENSES TESTED

    The base system includes a 400 mm collimator, which is supports testing of lenses with CA up to 45 mm. Larger collimators are available, up to 100 mm CA.

    The OS200B supports so many different test configurations that a separate sheet is needed to explain the range of lenses that can be tested in each configuration.
    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.
    OFF AXIS MEASUREMENTS

    The base OS200B does not include provision for off-axis measurements. Most (but not all) customers add options to support off-axis testing also. These include a rotary table to pivot the lens under test around the vertical axis, as well plates to allow one or both collimator tubes to pivot around the lens pupil.

    LIGHT SOURCE

    The OS200B uses an LED light source, which is brighter, more stable, and more uniform than the halogen source used in our OS200A. 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 OS200B 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 OS200B 6 standard reticles, plus one ”bonus reticle” which you may select from our catalog.