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Construction of a Tabletop Michelson Interferometer (view source)
Revision as of 08:50, 17 December 2009
, 08:50, 17 December 2009no edit summary
== Estimating Camera Sensitivity ==
=== Estimating Camera Sensitivity ===
It is critical to understand the sensitivity of the camera to light from the interferometer, given the high intended image acquisition speed. The camera purchased for this setup, Casio EX-F1, has a movie frame rate capability of 1200 Hz. The following information allows an order of magnitude estimate of the sensitivity. (The camera uses a CMOS sensor. Note that lx=lm·m<sup>2</sup>)
It is critical to understand the sensitivity of the camera to light from the interferometer, given the high intended image acquisition speed. The camera purchased for this setup, Casio EX-F1, has a movie frame rate capability of 1200 Hz. The following information allows an order of magnitude estimate of the sensitivity. (The camera uses a CMOS sensor. Note that lx=lm·m<sup>2</sup>)
== Camera Calibration ==
== Camera Calibration ==
Analysis of videos taken of the vibraton of the diamond waffer can lead to information about both the frequency and the apmlitude of vibration. To perform simultaneous measurments of both parameters, a precise camera calibration was necessary.
Analysis of videos taken of the vibraton of the diamond waffer can lead to information about both the frequency and the apmlitude of vibration. To perform simultaneous measurments of both parameters, a precise camera calibration was necessary.
=== Calibration Set-Up ===
=== Calibration Set-Up ===
The following is an image of the device sed or the camera caibration:
The following is an image of the device sed or the camera caibration:
The parameters p(1) to p(6) are, in numerical order, (1) the amplitude of the function, (2) x location, (3)sigma x, (4) y location, (5) sigma y, and (6) an offset applied to eliminte background noise. The function takes user inputs as an initial guess, then loops the search process to find more accurate values for the parameters. Arbitrary values are chosen for p(1), p(3), p(5) and p(6) to begin, and are then readjusted based on the first output parameters. Typicall, the closer these fit parameters are to the true paramters, the better the functin is at defining p(2) an p(4).
The parameters p(1) to p(6) are, in numerical order, (1) the amplitude of the function, (2) x location, (3)sigma x, (4) y location, (5) sigma y, and (6) an offset applied to eliminte background noise. The function takes user inputs as an initial guess, then loops the search process to find more accurate values for the parameters. Arbitrary values are chosen for p(1), p(3), p(5) and p(6) to begin, and are then readjusted based on the first output parameters. Typicall, the closer these fit parameters are to the true paramters, the better the functin is at defining p(2) an p(4).
By knowing the change in pixel locaton betwen photos, as well as th angular displacment, a value for pixel change per mrad in the xdiection can be determined. This proess is then repeaed for the y direction. Once these tweo parameters are known, the video analyss can be used to fin both frequency nd amplitude.
By knowing the change in pixel locaton betwen photos, as well as th angular displacment, a value for pixel change per mrad in the xdiection can be determined. This proess is then repeaed for the y direction. Once these tweo parameters are known, the video analyss can be used to fin both frequency nd amplitude.
===Video analysis ===
The same process used for the calibration images can be used to analyze the motion of the center of the lens flair over im. Becaue of the number of images involved in a video at 1200 fps, a batching process was developed to automate the proces. First, a built in Linux program, ffmpeg, is used to separate the images from the video. Next, the automtion script is applied to the folder contaning the video stills. This script uses the same code as the image analysis, but loops the search pocess through a large group of imags.
INPUT MALAB CODE
* [[Interferograms]]
* [[Interferograms]]
* [[Analysis of heat equation for diamond mounting]]
* [[Analysis of heat equation for diamond mounting]]