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Hobby: Holography

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In the early 1960s Holography emerged as one of the most exotic uses of the unique light produced by lasers.  By the early 1970s it began to make the transition from scientist only to hobbyist.  At first it was to exploit it as an artistic medium but the amateurs that saw its potential quickly developed innovations of media and techniques that became main-stream.

By the mid 1990s the nascent “World Wide Web” had one or two Usenet newsgroups called alt.holography dedicated to the hobby.  Between this and a couple of “how-to” books published by the 1970s superstars of the San Francisco Holography Art movement everyone had access to the technology.

The hardware came available with affordable Kodak holography plates and the surplus lasers from copy machines made the hobby approachable to interested amateurs.  holo1

My holography table was built from the aft bulkhead of a 747 from Boeing Surplus which is a two-inch high honey-comb sandwiched between two aluminum sheets.  I added padding and bricks and placed it in my basement.

In the configuration seen in the pictures it is making a reflection hologram of some plaster whales.  One beam illuminates the whales, while the other illuminates the plate at the far right.

As yholo2ou can see, this is all stuff hacked together from scraps.

 

 

 

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Hobby: Rocketry

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The 1990’s was a wonderful time to be a hobbyist.

The contagious optimism of that time lent itself well to the enthusiasms of people and families [ 😦  mostly men and mostly white] who bonded in far flung disciplines that had always been the purview of “trained professionals”.

One of the hobbies that decade “launched” was high power rocketry.  There were always two reactions the first time anyone ever saw a launch of anything bigger than the “Estes”rockets you could buy at any hobby store:  Awe and fear that you could do more than take someone’s eye out.  To assuage such fears, the hobby community itself, the US rocketsFederal Aviation Administration and the Bureau of Alcohol, Tobacco and Firearms provided strict regulations around the storage, purchase and use of any rocket motors with a specific impulse above 36 Lb-seconds.  In order to better assure that the hobbyist would align with these regulations, hobbyists associations coordinate the launches and supply amateurs with the supplies and training they need.

In 1996 I passed my level 1 certification and my level 2 in 1997.  In order to be certified to level 3 (allowing launch of rockets with a specific impulse exceeding 1,150 Lb-seconds) it was traditional to build something novel into the design.  In those days before cell phones and micro-power electronics the favorite was altimeter-based parachute deployment.

EricalchMine was a pic-based system with a clunky altimeter and an enormous T-1 accelerometer but what I really wanted to study was what’s called the mach disks of the rocket’s exhaust.  This is actually a phenomena that reveals volumes about the sonics, plasma and nozzles of all jet and rocket propulsion.