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| -rw-r--r-- | interferometry.tex | 7 |
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diff --git a/interferometry.tex b/interferometry.tex index 02c1b3d..186b4fa 100644 --- a/interferometry.tex +++ b/interferometry.tex @@ -201,7 +201,12 @@ Align the interferometer one more time such that the distance between two mirror \begin{enumerate} \item Turn off the laser, remove the viewing screen and the lens, and place the interferometer on the adjustable-height platform, or alternatively place the Na lamp on it's side and plan to adjust it's height with books or magazines. With the diffuser sheet in front of the lamp, check that you see the interference fringes when you look directly to the lamp through the interferometer. If necessary, adjust the knobs on the adjustable mirror to get the best fringe pattern. -\item Because the Na emission consists of two light at two close wavelengths, the interference picture consists of two sets of rings, one corresponding to fringes of $\lambda_1$, the other to those for $\lambda_2$. Move the mirror back and forth (by rotating the micrometer) to identify two sets of ring. Notice that they move at slightly different rate (due to the wavelength difference). +\item Because the Na emission consists of two lights at two close + wavelengths, the interference picture consists of two sets of + rings, one corresponding to fringes of $\lambda_1$, the other to + those for $\lambda_2$. Move the mirror back and forth (by rotating + the micrometer) to identify two sets of ring. Notice that they move + at slightly different rates (due to the wavelength difference). \item Seek the START condition illustrated in Fig.(\ref{fpfig4.fig}), such that all bright fringes are evenly spaced. Note that alternate fringes may be of somewhat different intensities. Practice going through the fringe conditions as shown in Fig.(\ref{fpfig4.fig}) by turning the micrometer and viewing the relative movement of fringes. Do not be surprised if you have to move the micrometer quite a bit to return to the original condition again. |