Bartelized CCD Robo-Foucault

(Block 1 Proto-Type)

 

After finishing the Bino-Scope Bartelization, I thought it might be neat to Bartelize a Foucault platform, So I wrote a simple VB6 program (6 hours) and built a crude platform out of scraps (5 hours)  First test was performed today (08-04-2001) at the local mirror lab with GREAT results.

 

Here’s a pic of what I created.

 

 

Here’s a video showing the tester from various angles and doing its thing Motion.avi (1.5 Megs)

 

The tester is built from 2 identical platforms, one on top the other, positioned at 90 degrees.  Here’s a pic of the gear train used on both axis.

 

 

1)     200 step per revolution Stepper motor

2)     Circle Clamp

3)     1/8th inch ID – ½” OD rubber vacuum hose

4)     Threaded Oak block.

5)     Non-Threaded support Oak Block

6)     ¼ - 20 Threaded Rod

7)     Flywheel

8)     Roller blade bearing

 

The stepper motor is held in place by an Automotive circle clamp.  Beneath the motor I routed out a ½” wide 1 inch long, ½ deep grove.  I inserted a nail on the left edge of the board, below the motor, perpendicular and thru the routed grove.  The circle clamp is threaded below the nail then over the motor. 

 

The top platform (the one that moves) is supported at three points.  Two of the points are the threaded oak blocks and the third point is a roller blade bearing about 8 inches away from the threaded rod.  Gravity holds the roller bearing onto the Formica surface of the lower motor board.

 

To thread the Oak blocks, I simply drilled a hole slightly smaller than ¼” and chucked a piece of threaded rod in an electric drill.  The threaded rod was tapered on the end, and part of the length was sanded flat to help cut the threads.  Basically I forced the tapered section into the hole, got the treads to start,  and ran the electric drill in and out until the block started to smoke.  Then I put a little candle wax on the threads as a lubricant.  Worked really well.  Total backlash, as measured today with a micrometer, is only .0005”, which I attribute to the rubber hose coupling flexing.

 

Here’s a pic of the roller bearing support.

(yes, it just misses the screw head J)

 

(another view of the support bearing, which is from a previous AZ support project)

 

The whole contraption is controlled by the Mel Bartel’s scope drive board and hand pad, combined with a small Visual Basic 6 application I wrote (email me if your interested in a copy, but be-warned it has many caveats to its usage)

 

My handpad from Mel’s Scope drive system.

 

Screen Shot of the application I wrote.

 

The only user input (asides the hand pad) is adjustment of the slider bar, which controls the max speed of the steppers while slewing the platform.  Basically the red buttons on the hand pad do the to/away from mirror, and knife edge position, and the bottom toggle switch resets the counters to zero.

 

The whole thing is a joy to use.  The most notable improvement is the lack of wiggle while moving the platform. 

 

Not shown (yet) is the CCD camera I’m using.  It’s a 0.1 Lux Black and white analog security camera, from which I removed the previous wide angle lens and adapted the optical assembly from an OLD hand held cam corder.  This gives me Incredible zoom, I can get a 6” F8 to completely fill the 25” TV screen its displayed on.  This makes zonal measurements much easier!

 

Soon, I shall start playing with reading the CCD camera’s output into the computer, and having the computer do the zonal measurements for us.  (that ought to be a challenge J )

 

All in all I’m very happy with it.  I might not recommend its use for an at home ATMr as it’s a little overkill and doesn’t (yet) bring anything new to the table.  However, since I plan on using  it at the local ATM mirror lab, its appears its going to be worth its weight in gold.  The biggest advantage to this Foucault tester is it reduces mirror test time dramatically, even in its current state.

 

** If anyone would like to offer some ideas on how to measure mirror zones via software, I’d be ecstatic to hear from you!

As of 1/1/03 Real Time Automated Foucault code is now publicly available J

See the link to the left 11.2 J

 

Take Care

James Lerch