1. Using the Michelson Interferometer
Physical Experiment Center
2007 Laboratory

2. 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

3. Structure of Michelson Interferometer

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

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

6. measuring laser wavelengthd
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

7. Experiment Demonstration

8. Experimental Procedure
Adjustment screw
Convex lens
Laser
Observation screen

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

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

11. 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.

12. 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.

13. Thank You！