Anyone know of any reference that discusses the methods of measuring distances both small and large and the electronics behind them? I want a method to measure with mil to sub mill accuracy over a few inches. My initial thought was to use high freq sound pulses since this would be a cheap way but after doing some calculations it seems that it might be impossible, or at least very difficult without precise sensors(piezo's might work but still a problem of determining when the sound is "heard"). Speed in measuring is not really an issue either(can take a few seconds if necessary).
I'm a bit afraid of using light because it seems it would require relatively expensive devices and techniques. BTW, I need a wireless method but the device itself can be wired(so it can compare the speed with that of a wired EM signal).
Any ideas where I can look for more info on this? The main reason for this is to get around having to manufacture very precise positioning parts. Obviously if the cost of "remote" position sensing is more than that of just manufacturing the parts then its not worth it.
Also note that I suppose that I could have many sensors(I was thinking 4 to6) that have super-mil accuracy but take some statistical average to get a better result.
In fact I don't care much about the relative position but only the change in position.
I just found this site:
Which seems to say that the ultrasonic method might work... It also gives two other methods. I'm going to read more about it but a book would probably be much nicer.