🚀 go-pugleaf

In article <2110@puff.cs.wisc.edu> boettche@gumby.cs.wisc.edu (Michael Boettcher) writes:
>A bar magnet, or another electro-magnet is mounted on a pivot, with a
>mirror on the opposite end.  The polarity of the magnet end within the
>fields of the four outer magnets would be the same.  The inner magnet,
>connector, and mirror would all be very low mass, for low inertia.

>Michael Boettcher                 boettche@gumby.cs.wisc.edu

Mechanical control of the mirror as described above can be difficult. 
Following is what I would try:
 

                     reflected beam 
                              .
 ----------                     .     / (mirror)
          I                       .  /
  Laser     . . .  beam . . . . . ..x 
          I                        /
 ----------                       /



Mirror is rotating freely at very high speed, around a shaft centered at x.
Any speed above 1800 rpm (30 revolutions/sec) should be adequate.
We can track the position of the mirror by an optocoupler and
a circular grid attached to the shaft. 

Laser is off most of the time. Whenever mirror comes to the desired
angle, we pulse the laser on. Since mirror is revolving at very high
speed, the pulsed beam appears continously on to the eye. 

Advantage of this method: All electronical; position of the mirror is not 
controlled mechanically. Mirror can rotate at any speed and no 
calibration is necessary. 

Disadvantages: 1)Angle of the beam can be changed only in a 2-D plane.
2) Can you turn the laser on-off in the desired interval? 

-=-
Bulent Abali
Ohio State Univ., Dept.of Electrical Eng.
2015 Neil Av. Columbus, Ohio 43210
abali@baloo.eng.ohio-state.edu