Explaining galvo Optical deflection

[bsancken]

Could some one please explain in simple terms what the optical deflection is and means and how it would come into play in an laser projector.. I searched the forum and the bits that I have read are abit confusing.

Thanks!..

[Things]

Probably just a marketing term for scan angle, as in, how big the galvo's can project an image at certain distances.

[bsancken]

I guess the part I'm confused about is that it says for example one galvo says 50kpps at 5 degrees optical deflection but it says 30kpps at 20 degrees optical deflection.... So what does that mean exactly?? (In simple terms please, I've got alotta things goin on now and my brain is a little scattered so much thanks for keepin it simple!!)

[laserist]

If the mirror moves 10 degrees mechanically according to your little bitty protractor, a laser beam reflecting off the mirror moves 20 degrees. It's that old angle of incidence equals angle or reflection thing. So calling out "optical deflection" just defines the terms. Rotating the mirror takes work - doubling the angle requires more work and there's an upper limit to how much work you can do per second - so the number of points drops. TANSTAAFL

[planters]

If you approach this from an optoo-mechanical point of view then "points" will drive you a little crazy. Following on laserist's explanation, the performance of a scanner is limited by physical laws. Trying to move a mirror faster and farther(greater angles) will require more work and generates greater forces and these properties are not linear. In other words, doubling the scanned angle within the same small time period will quadruple the instantaneous energy required and the average power demanded of the power supply/driver will increase 8 times! You can imagine what must be required of the mechanical properties of the scanner components as the speed/ angle increase. So, in practical, real world systems the interplay of these requirements will limit the performance of a scanner system and the "points" designation is an attempt to represent the relative performance of different scanners by comparing how they are able to display an image. If all the systems were HONESTLY compared and the specs could be trusted then higher KPPS is better. Rather look for reviews of performance by those experienced with several models and without a financial stake and stay a little skeptical of manufacturer's claims.