Angle/Angular Rate Sensor

Hi,

I was wondering if there is sensor to measure Angle/Angular rate at a distance of more than a few mm? I have been investigating Hall Effect and Inductive sensors but they all seem to be in the low mm maximum distance (air gap) range. I am not talking huge distances here but would like to be able to measure the angular rate from a distance of a few inches (maybe up to 12 inches) away. Is this possible? If so, could someone please point me to either a Hall Effect/Inductive Sensor which may be able to operate from that sort of distance or some other form of sensor which may meet this requirement?

Many Thanks.

It would be better if you could describe (or show a picture) of what it is that you are trying to measure.

Just saying angle/angular rate at a distance of 12" is not very helpfull.

JimB

Why not just measure the angular rate of the shaft (pivot)?

Laser tacho's can measure at a meter, do a google.

Thanks for your replies so far. I am trying to measure the rotational rate of a ball, be it a football, snooker/pool ball, tennis ball etc... The sensor needs to be contactless and needs to be able to measure the rotational rate whilst the ball is in linear motion. So whilst the ball is in the 'field of view' of the sensor it would some how need to measure the rotation. Because of this, I would imagine that the ball would not complete a full revolution therefore the sensor would need to be able to detect partial, degrees of revolution and calculate rpm from that. I would be quite happy if I needed to either mark the ball or possible embed some form of material (e.g small magnet) if this is needed to enable the sensor to operate. Hope this explains what I am trying to do.

@dr pepper - the laser tacho's look promising if a little expensive. Do yo think they would work for the above application?

Many Thanks.

If your thinking of something like whats done on tv in sports to measure the speed of a football or cricket ball, then as far as I know that is done by image processing rather than a black box, the video image is processed by software on a pc and rotational speed calculated from the image, you do of course need a high speed camera for such a thing.

A laser tacho would work but isnt practical, you'd need to keep the laser precisely aimed at the ball, something that the military can do very well, a little complex for an enthusiast however.

Many Thanks for your reply @dr pepper. A quick internet search has come up with the Hawk-Eye system which is I think is the system to which you are referring. It appears this used a collection of high-speed cameras to track the movement of the ball to then be able to predict where the ball would go. My application is slightly different to this in that I do not need to be able to track the ball or measure the spin over its full movement. I just need to measure the spin rate and/or spin angle at a specific instant in time. Take a snooker ball as an example - I would like to measure the spin immediately after the ball has left the cue. Clearly, to measure the spin, there will need to be a small amount of lateral movement for spin to occur. Hopefully, this would occur whilst still within the field-of-view of the sensor (whether it be laser/optical etc..) Does this sound feasible?

Many Thanks.