Using the Michelson Interferometer Physical Experiment Center 2007 Laboratory

Purpose （1）Learn to use Michelson Interferometer （2）Study the fringe patterns resulting from a point source, and make a precise measurement of the wavelength of the He-Ne laser

Structure of Michelson Interferometer

Experiment Principle M2 Mirror d M1' M1 Mirror S G2 G1 Compensating Beam splitter G2 Compensating plate d M1' M1 Mirror S Observation screen

Pointolite Non-localized Interference SG＝S'G L>>d，ignore , then d L The condition of bright fringe is d

measuring laser wavelength d When k、 are invariable, with the decrease of d,  decreases . Then radius of ring fringe of the same k order decreases, as appears that interference circles contract entad. Similarly with the increase of d, interference circles expand forth. If the fringes in the circle center contract entad or expand forth N times, the variation of optical path difference is 2△d=N, then we have

Experiment Demonstration

Experimental Procedure Adjustment screw Convex lens Laser Observation screen

xx． xx xxx Data Reading 36.71503mm Graduated scale Reading data window Fine adjustment drum wheel xx． xx xxx 36.71503mm

Data recording d0 d50 d100 d150 d200 mm d250 d300 d350 d400 d450 △d250

Experimental Procedure 1．Let laser irradiate directly in the middle of beam splitter, and adjust adjustment screws to make the two biggest and brightest faculae on the observation screen coincide with each other completely. 2．Put the convex lens on the bracket and let the light irradiate on the beam splitter uniformly. Then adjust tension spring screws to move the circle center of the rings to the center of the observation screen. 3．Rotate the fine adjustment drum wheel in the same direction for some cycles until fringes on the observation screen contract entad or expand forth. Then record the position of M1, which is designated as d0 4. Continue to rotate the fine adjustment drum wheel in the same direction. When contracting entad or expanding forth every 50 fringes, record the position of M1. Ten records should be got.

Notice Never touch any optical surface Before measuring data, null-space must be eliminated. When measuring, rotate the fine adjustment drum wheel only in the same direction, never rotate reversely.

Thank You！