Re: ATM Bowed Flexure

["clement.focuser" <clement.focuser@verizon.net>]

Hello Vladimir,

> As I understand it, one side of the bow is fixed.
> At the middle you put lateral pressure via screw, and longitudinal
> extension of the free and is used
> for fine movement. How do you restrict movement of
> the free end of the bow to bi in longitudinal direction only,
> because there will be also component of the lateral trust
> ( same direction as screw pressure). This restriction must be
> such not to prevent smoothness of the movement. No jerks.

Both ends of the bow are restricted. I found it best to use the bowed
flexure with flexible bearings for the moveable stage. The simplest form of
a moveable stage would be a cantilevered beam. The flexible bearing could
then be a monolithic type or just a single milled or cut slot in solid
material. The ends of the flexible bow would then push up on the end of the
cantilevered beam. The nice part of this arrangement is that the compliance
of the cantilevered beam flexible bearings bears against the ends of the
flexible bow, which then push on the lead screw and eliminate backlash. Note
that flexible bow reduction can be stacked at right angles to get very large
reduction ratios. You are right, no jerks or stiction. The movement is
extremely smooth with what seems like infinite resolution.

> In the formula you mentioned " change in beam curve".
> What do you men by that. Could that be change in the
> radius of curvature?

I thought the bow approximated a triangle. The bow is the height of the
triangle and the length of the beam is the base.

Don Clement
Running Springs, California