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Rotor history

A project log for prism laser scanner

bringing additive manufacturing to the next level

hexastormHexastorm 07/06/2021 at 10:040 Comments

After my last post, @Gravis wondered if it would be any help to have a motor driver that compensated for being slightly out of balance?

In short I think so yes.

The prism rotor is a key component of the laser scanner. It might be good to go over the assumptions surrounding the rotor.
The project start with the assumption that it is not possible to get a laser grid. There are ways around this, e.g. laser with a DMD device. There is also research into nano-lasers; which could possible form a laser led screen. All these technologies have their limitations, due to cooling, diffraction or focusing of the laser. A way around this is moving the laser bundle either by mirrors or prisms.
Rotating prisms have a lower cross-scan error and require different optics then rotating mirrors.
The Netherlands is especially interested in lithography due to the regional importance of ASML.
The original prism can be seen in the image below. There are other images but this is the only image in the "public domain".
The original prism is relatively large, in the order of 20 cm and rotated using an air bearing.
It makes a lot of noise.



After studying the laser market for some time. I realized that if there is market for prism scanner with a plurality of bundles, there must be for a single. The rotor design present in laser printers is thought out extremely well. The current prism dimensions are simply based on these constraints. This probably needs to be changed in the future.
I could imagine the prisms are made smaller. This partly depends on manufacturing capabilities of the prism and the desired line length.
The prism could be lifted by an air-bearing or electromagnetic field. It could be kept in glass housing with a lower drag gas like Helium.
In such a configuration, I imagine that the position of the prism can be optimized during rotation.
I still need to look into how prisms are rotated by lasers. But I can imagine that a disk which can be rotated by an optical field can simply be attached to the prism.
Another option would be to add coils or magnets to the prism which would allow it to be rotated without contact.

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