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APPARATUS

In order to measure the speed of light, you will need all the items listed below:

The OS-9261 Complete Speed of Light Apparatus includes:

        -     OS-9263A high Speed Rotating Mirror Assembly

        -    Fixed Mirror

        -     Measuring Microscope

1.  High Speed Rotating Mirror Assembly

The High Speed Rotating Mirror comes with its own power supply and digital display.  The mirror is flat to within 1/4 wavelength.  It's supported by high speed ball bearings, mounted in a protective housing and driven by a DC motor with a drive belt.  A Plastic lock-screw lets you hold the mirror in place during the alignment procedure.  An optical detector and the digital display provide measurements of mirror rotation to within 0.1 % or 1 rev/sec.  The display and the controls for mirror rotation are on the front panel of the power supply.  Rotation is reversible and the rate is continuously variable from 100 to 1,000 rev/sec.  In addition, holding down the MAX REV/SEC button will bring the rotation speed quickly to its maximum value at approximately 1,500 rev/sec.

2.  Measuring Microscope

The 90X microscope is mounted on a micrometer stage of precise measurements of h displacement of the image point.  Measurements are most easily made by visually centering the image point in the microscope cross-hairs before and after the displacement.  By noting the change in the micrometer setting, the displacement can be resolved to within 0.005 mm.

To focus the  cross-hairs, slide the eyepiece up or down in the microscope.  To focus the microscope, loosen the lock-screw on the side of the mounting tube and slide the microscope up or down within the tube.

With the lock screw loosened, the microscope can also be removed from the mounting rube,  This can be helpful when you are trying to locate the image point.  A piece of tissue paper placed over the tube provides a screen that allows you to view the point without focusing the microscope. 

In addition to the microscope and micrometer, the micrometer stage also contains the beam-splitter.  The lever on the side of the stage is used to adjust the angle of the beam splitter.  When the lever points directly down, the beam-splitter is at a fouty-five degree angle.

3.  Fixed Mirror

   The Fixed Mirror is spherical mirror with a radius of curvature of 13.5 meters.  It is mounted to a stand and has separate X and Y alignment screws.

4.  OS-9103 Optics Bench

    The 1.0 meter long Optics Bench provides a flat level surface for aligning the optical components.  The bench is equipped with a one meter scale, four leveling screws, and a magnetic  top surface.  The "fence", a raised edge on the back of the bench, provides a guide for aligning components along the optical axis.

5.  OS-9171 Laser with the OS-9172 Alignment Bench

The O.5 mW. TEM mode, random polarization laser has an output wavelength of 632.8 nm.  The Alignment Bench attaches to the Optics Bench for precise, stable positioning of the laser.

6.  Alignment Jigs (2)

These jigs mount magnetically to the Optics Bench.  Each has a 2 mm diameter hole that is used to alignn the laser beam.

7.    Optical Components

   The various  ways of using the  lenses