Comment on Video about laser interferometer design and use – replace superconducting gravimeters
Counting Atoms with the Doppler Effect – Heterodyne Interferometer by Sam Zeloof at http://sam.zeloof.xyz
https://www.youtube.com/watch?v=vPu6lN9yJOY
Sam,
I sent you an email about using this to replace the network of superconducting gravimeters with something more people can afford. You have several orders of magnitude available to you by very small adjustments. SGs cost several hundred thousand and are only single axis. Here is my explanation of what is going on – https://hackaday.io/project/164550-low-cost-time-of-flight-gravimeter-arrays
I finally understand the gas lasers and the linear interferometer range of possibilities from your video. I have been reading and studying related things for more than 50 years now. I really appreciate your clarity and insight. With people like you and your smarter brother, there is hope for the future.
Thank you for pointing me to Sam GoldWasser at https://repairfaq.org/sam/lipm/lipm.htm
I never knew anyone who made their own MEMS devices at home. Maybe you can try the MEMS gravimeters. I wrote you a little about that.
Richard Collins, Director, The Internet Foundation
At about minute 14 you talk about storm fronts. Any accelerometer or gravimeter is affected by the changing gravitational potential from weather systems. There are direct forces from infrasound, wind, diffusion of atoms. And electron flows and radiation field changes. Seismometer networks are also good detectors for storms and weather. Gravimeter arrays can be used to image the atmosphere. I sent you a note about that kind of gravimeter array. There is a group working on part of that, called ATMAC – Atmospheric attraction computation service. But they are just one group working with the superconducting gravimeter array.
Atmacs – Atmospheric attraction computation service. Here is their basic approach to estimating. It is very crude but works for their purposes. http://atmacs.bkg.bund.de/docs/computation.php
The Japan earthquake registered on both the broadband seismometer array, and the superconducting gravimeter array. So movement of the earth from seismic waves changing the density of voxels in, on and near the earth change the gravitational potential. The gradient of the potential is what the gravimeters (an accelerometer sensitive enough to measure the sun moon tidal signal can be called a gravimeter, my rule). are measuring. There are groups working on “earthquake early warning”. I put some notes on that at GravityNotes.Org. There are LIGO groups who also work on earth-based signals, and lots of low frequency electromagnetic signals for imaging the atmosphere and earth interior. Lots going on. But the world needs low cost, time of flight gravimeter arrays.
The reason you need time of flight and three axis (or direction of arrival) is to resolve the location of the source. The array can determine where the signal is coming from and determine if it is man-made (cars, people, trucks, trains, planes) or natural (ocean waves, seismic waves, electromagnetic, infrasound, ocean currents, river currents, atmospheric rivers, atmospheric currents, magnetic, electromagnetic. It seems like a lot, but there are only about 40 basic technologies and then everyone names their stuff based on the frequencies and power levels.
For the Internet Foundation, I try to keep track of all these groups to watch how they merge and grow. New industries of the future are forming now, and usually have roots that go back many decades. It is not hard to find them, and trace out their futures. Not hard, just tedious. I get impatient because I want to tell some of them to hurry up, you are almost there.
Richard Collins, Director, The Internet Foundation
