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Line 83: − + − + − Originally, it was our intention to perform interferometry to analyze the diamond vibration. After several attempts to use the interferometer, it was determined that the vibration amplitude was simply too high to perform interferometry. Instead, a direct imaging technique was used to analyze the diamond vibration. An interesting phenomenon occurred when the direct imaging device was used. The reflected spot entering the camera lens created an artifact known as a lens flare. Typically lens flares are undesirable, but in our case, the lens flare movement directly correlated to the movement of the reflected beam spot on the lens surface. By careful calibration, the pixel movement on the image versus the angular displacement of the diamond surface was determined. Then, a video of the movement of the flare spot was taken, and then analyzed using a fitting program. − Because of the large number of images, a batching process was developed to aid in the video analysis. First, a built in Linux program, ffmpeg, separates the video into individual frames. Next, a program was developed to determine the center of th flare spot for each image. To find the location of the center of the flare, several lines of code were implemented:+
Construction of a Tabletop Michelson Interferometer (view source)
Revision as of 20:07, 29 April 2010
, 20:07, 29 April 2010no edit summary
Analysis of videos taken of the vibration of the diamond wafer can lead to information about both the frequency and the amplitude of vibration. To perform simultaneous measurements of both parameters, a precise camera calibration was necessary.
Analysis of videos taken of the vibration of the diamond wafer can lead to information about both the frequency and the amplitude of vibration. To perform simultaneous measurements of both parameters, a precise camera calibration was necessary.
== Video Analysis ==
Originally, it was our intention to perform interferometry to analyze the diamond vibration. After several attempts to use the interferometer, it was determined that the vibration amplitude was simply too high to perform interferometry. Instead, a direct imaging technique was used to analyze the diamond vibration. An interesting phenomenon occurred when the direct imaging device was used. The reflected spot entering the camera lens created an artifact known as a lens flare. Typically lens flares are undesirable, but in our case, the lens flare movement directly correlated to the movement of the reflected beam spot on the lens surface. By careful calibration, the pixel movement on the image versus the angular displacement of the diamond surface was determined.
=== Calibration Set-Up ===
=== Calibration Set-Up ===
The following is an image of the device used for the camera calibration:
The following is an image of the device used for the camera calibration:
IMAGE OF CALIBRATION DEVICE
IMAGE OF CALIBRATION DEVICE
This calibration device was used to determine the change in pixel location of the center of the lens flares based on angular displacement. To do this, the camera was mounted horizontally on a 1.40m long bar. The camera end was free to rotate about a pivot located at the opposite end of the rod, above which a mirror was mounted. A linear micro-adjustment translation stage was placed below the camera end.
This calibration device was used to determine the change in pixel location of the center of the lens flares based on angular displacement. To do this, the camera was mounted horizontally on a 1.40m long bar. The camera end was free to rotate about a pivot located at the opposite end of the rod, above which a mirror was mounted. A linear micro-adjustment translation stage was placed below the camera end.
=== Video Analysis ===
=== Image Analysis ===
A high-speed (1200fps)video of the movement of the flare spot was then taken, and then analyzed using a fitting program. of the large number of images, a batching process was developed to aid in the video analysis. First, a built in Linux program, ffmpeg, separates the video into individual frames. Next, a program was developed to determine the center of th flare spot for each image. To find the location of the center of the flare, several lines of code were implemented:
[[Image:Screenshot.png|center|Matlab code used for image analysis]]
[[Image:Screenshot.png|center|Matlab code used for image analysis]]