| ??? 05/05/09 03:52 Read: times |
#165050 - The reason I don't care ... Responding to: ???'s previous message |
Chico hasn't told us what he really wants to do.
Chico said:
I want to fix a mirror in the HDD head to deflect a laser, just direct driven, no gearboxes, as I need some speed ... That doesn't really tell us much, nor does it imply moving video fixed static graphics, or what. Retinal persistence is clearly no more than what's attained with the aid of phosphor, and probably less. That means that every square angstrom that is to be seen as illuminated has to have a certain intensity of light on it for a certain minimal amount of time. Does anyone know what that duration would be, say, for a bright, white wall? Laser power is definitely an issue. I don't know what sort of mirror is to be used on Chico's head actuator, but it doesn't have to be very large, nor need it be massive. The actuator can rotate the mirror over a range of, say, 40 degrees using the electronics on the HDD circuit board. We don't know how fast that can be used, but probably not fast enough for a complex graphic on a raster or on a stroked display. If the mirror is, say, 1.5 cm square, it should be adequate in size if it's fixed on the spindle of the actuator. Best performance will probably be reached with minimal mass but with best balance. If the heads are left in place, the balance is probably as good as it can get, but the mass is needlessly large. If that, namely, to fix a mirror in the HDD head to deflect a laser, is all he wants to do then he only has one degree of freedom. So long as the output power of his laser is not known, the speed requirement isn't readily discernible. When Chico lets us know what his inputs are, and what he's really trying to do, in some detail, perhaps we can stop all this speculation and address his problem. I imagine, however, that he's not reading much of this because it really doesn't address his interests/needs. Until the requirement for intensity is known, it can't be discussed. How many kW of laser power is required to produce a 33 ms uniformly persistent dot, as perceived by the human retina, when struck by the laser for 62 ns? ... at a distance of, say, 10 meters from the source, and the viewer ... on a matte-white painted wall? RE |
