| ??? 01/29/09 15:08 Read: times |
#161822 - Yes, faster is better in this case Responding to: ???'s previous message |
Per Westermark said:
The problem with scanning like a TV is that the laser needs quite high intensity, since it has to scan a significant area. If you use them in a darkened room, you have considerable flexibility. If drawing in X-Y, then you normally don't have time for any feedback loop. You just calibrate the system manually to know what analog values that represents the two ends of a movement, and then drive a voice coil run as fast as possible. The big thing here is speed - not precision - since you must be able to do a full trace within a very limited time to get your eyes to see a static drawing. The primary advantage of using the rotating mirror approach is that you can time the horizontal sweep "open-loop". Most people who tries this uses voice coils from loudspeakers, since they are designed for very high speed and reasonably good linearity. This depends on what you mean by "high-speed." I tend to think of "high-speed" as meaning > ~10 MHz. Speaker voice coils operate at audio frequency, i.e. < 25 KHz. I suppose that's why I like those relatively fast (>20 MHz) one-clockers. RE |
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| more info | 01/01/70 00:00 | |
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| harder than I thought | 01/01/70 00:00 | |
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