Adjustable Mirror Fitted Case Lens 18 mm Viewing Screen Beam Splitter Diffuser (2) Component Holder Movable Mirror Plate OS-9255A Precision Interferometer Lens 18 mm Component Holder Base Lens 48 mm OS-9256A Interferometer Accessories (2) Polarizer Glass Plate
Laser beam Component holder base VIEWING SCREEN MICHELSON, TWYMAN-GREEN OS-9255A (optional) Slide the rear of the laser laterally on the alignment bench until the beam is reflected straight back into the laser aperture. ADJUSTABLE MIRROR MICHELSON, TWYMAN-GREEN Movable mirror Lens Beam splitter Figure 5. Aligning the Laser 18mm FL 1 div = NOTE: For ease of installation the placement of the individual components in the various modes is indicated on the label. Thumbscrews Michelson Mode 1. Align the laser and interferometer base as previously described. The laser beam should be approximately parallel with the top of the base, should strike the center of the movable mirror, and should be reflected directly back into the laser aperture. 2. Mount the adjustable mirror on the interferometer base. Position one component holder in front of the laser. Place the other component holder opposite the adjust- able mirror and attach the viewing screen to its mag- netic backing. See Figure 6. 3. Position the beam-splitter at a 45 degree angle to the laser beam, within the crop marks, so that the beam is reflected to the fixed mirror. Adjust the angle of the beam-splitter as needed so that the reflected beam hits the fixed mirror near its center. 4. There should now be two sets of bright dots on the viewing screen; one set comes from the fixed mirror and the other comes from the movable mirror. Each set of dots should include a bright dot with two or more dots of lesser brightness (due to multiple reflections). Adjust the angle of the beam-splitter again until the two sets of dots are as close together as possible, then tighten the thumbscrew to secure the beam-splitter. or P n i n
Experiment 3: The Index of Refraction of Glass EQUIPMENT NEEDED: – Basic Interferometer (OS-9255A) – Laser (OS-9171) – Laser Alignment Bench (OS-9172) – Interferometer Accessories Rotating Table, Glass Plate Introduction In Experiment 2, the index of refraction of air was measured by slowly varying the density of air along a fixed length of one beam path in the Michelson Interferometer. That method obviously won't work with a solid substance, such as glass. Therefore, in order to measure the index of refraction of glass, it's necessary to slowly vary the length of glass through which the interferometer beam passes. This experi- ment introduces a technique for making such a measurement. Procedure 1. Align the laser and interferometer in the Michelson OS-9255A PREC/S/ON plate 1 = 1 Read Angle of Inclination on Degree Scale mode. See Setup and Operation. 2. Place the rotating table between the beam-splitter and movable mirror, perpendicular to the optical path. Figure 3.1. Equipment Setup ➤ NOTE: if the movable mirror is too far forward, the rotating table won't fit. You may need to loosen the thumbscrew and slide the mirror farther back. 3. Mount the glass plate on the magnetic backing of the rotational pointer. 4. Position the pointer so that its “0” edge on the Vernier scale is lined up with the zero on the degree scale on the interferometer base. 5. Remove the lens from in front of the laser. Hold the viewing screen between the glass plate and the movable mirror. If there is one bright dot and some secondary dots on the d