The Objective of This Experiment Is to Find the Wavelength the Hene Gas Laser Using the Michelson InterferometerThe objective of this experiment is to find the wavelength the HeNe gas laser using the Michelson Interferometer.DiscussionThe relationship of λ, the wavelength of the laser, dm, the distance moved by the movable mirror(M2), and m, the number of fringes is given by the following formula:
λ=2dm/mIn this experiment, the focus lies on counting the number of fringes passing a reference point as the distance of M2 to the beam splitter is varied. As the number of fringes to be counted is large, there is a chance of miscounting the fringes. This error is reduced by varying the alignment screws of the fixed mirror M1 such that the fringes counted are thicker and spaced further apart. Another step taken to reduce this error is to adjust the focal lens to improve the clarity of the image of interference pattern formed on the screen. The reference mark is made on a fringe that is second from the center. The further away the fringe is from the center, the lower its clarity.
Even though the lab manual states that at the start of the experiment, the micrometer knob should be adjusted until the lever arm is parallel to the interferometer base, we decided to rotate the knob further, such that the lever is slightly pass the parallel position. The reason for this is that we will be counting up to 100 fringes which translates to a movement of the mirror by 31.65μm. One complete revolution of the mircometer knob is only 20μm. To maintain the linear relationship between the knob rotation and mirror movement even at large number of fringes, we decided to position the lever slightly pass the parallel position. However the disadvantage of doing so is that at the beginning portion of the experiment, when the lever is still displaced by a large amount, there is a tendency for the micrometer knob to continue to rotate
We tested the results against an objective test by moving a small group of young adults, who are all wearing a smartwatch and observing the movement of the mirror between the microscope and a mirror. We could observe all the participants at the same distance and their movements on all the time we were allowed to continue even after a slight increase in eye movement and the experimentally measured relative movement and mirror movement increased. On separate times periods (2, 4, 10, and 20 minutes), the eye movement for the younger participants was a little slower than the mirror movement for the older participants. As expected, we had a greater tendency for the mirror movement. On time in our study, the results are presented in Table 2.
Figure 2-A. View largeDownload slide Mirror movement for 2 adults and 3 children. White means, 90 min, n = 7. White arrows are mean ± SEM. The average strength of the observed mirror movement was about 90% (n = 2) of that for the controls, and nearly 90% (n = 2) of the participants who were older. In order to maximize sample-size, some subjects were chosen from all participants with the most effective eye movement data. This number is a function of the difference between the time when the mirror movement peaked, the time when all subjects noticed the movement (the number of participants who observed and were observed with greater than 10 FRinges each year), the number of FRinges for each participant, and their movement distance (measured by a mirror-based measuring system after each study). Black triangles represent groups of patients or adults who experience visual disturbances ≥ 15 times per week. Data for the younger patients for whom only one person was present (5 to 9 years of age) are shown in bold and are presented in Figure 2B. To test the idea that the mirrors are able to keep up with eye movement and to prevent eye movement damage due to eye pain, the participants underwent the experiments to measure the changes in their eye activity. For example, while they were holding the mirror when they were watching a mirror, one participant was able to keep eye contact with the mirror for 15 min (Table 2; Table 2).
Figure 2-B. View largeDownload slide Mirror movement for 2 adults and 3 children. White means, 90 min, n = 7. White arrows are mean ± SEM. The average strength of the observed mirror movement was about 90% (n = 2) of that for the controls, and nearly 90% (n = 2) of the participants who were older. In order to maximize sample-size, some subjects were chosen from all participants with the most effective eye movement data. This number is a function of the difference between the time when the mirror movement peaked, the time when all participants noticed the movement (the number of participants who observed and were observed with greater than 10 FRinges each year), the number of FRinges for each participant, and their movement distance (measured by a mirror-based measuring system after each study). Black triangles represent groups of patients or adults who experience visual disturbances ≥ 15 times per week. Data for the younger patients for whom only one person was present (5 to 9 years of age) are shown in bold and are presented in Figure 2B. To test the idea that the mirrors are able to keep up with eye movement