ImageJ measurement of spring constant
In this exercise, you will setup imageJ, download a movie sequence and find the mean square deviation of a bead in the movie
- Download GW's bead finder routine
- Place this into the plugins/Analyze folder of ImageJ
- Restart ImageJ
- load the image sequence as 8-bit gray scale.
- draw a box around the region of interest
- Now select Plugins > Analyze > Bead Find
- Adjust threshold (varies from .1 to .99 -- try a few) and select generate boundary image
- You should get a new set of images that look like a dark donut
- Once you get this, close the windows that you generated
(except the original video) and rerun Bead_Find with your good
- Copy and paste the x-y values generated into logger pro
- Plot the x-y data as a trajectory -- compare to a random walk
- Plot a histogram of N vs x and N vs y
- Fit a gaussian to the histogram. You may need to adjust your binning to get a good-looking gaussian.
- What is xave and what is the average value of x2?
- What are the units?
- How will you calibrate the setup?