The prism scanner uses a BrushLess DC (BLDC) motor to spin the rotor.
How stators are winded can be seen in this video from Nide Group.
The BLDC external armature fusing machine is used for spot welding the wire and terminal of the BLDC rotor
I consider to simply buy these stators and pick and placing them on my own PCBs. It would simplify the wiring a lot and allow me to compress the technology further.
You can see the front and back of the motor pcb below. Note, that I use the NCB3111 and these are back in stock. I managed to find a new supplier so this is no longer an issue.
Copying this PCB in KiCad seems a trivial undertaking.
The back of the PCB can be seen below. The PCB is alluminum to simplify the transfer of heat. If the rotor is spin at too low speeds the board overheats and shuts it self down. A brass standoff seems to be pressed in the board from below and secured with a plastic ring. The hole on the right is for a plastic safety thing to fixate the rotor.
The rotor look as follows. You are looking at the bottom and can see the magnet. You can also "barely" see the six edges of the mirror. Here is video of making a similar DIY electric motor.
Came across this freely available article, basically information is stored efficiently by using color droplets. The method should require less energy and encoding should be more efficient as there are more options than black and white (binary).
Links with prism scanning are as follows; droplets can be placed on the substrate using laser induced forward transfer and reading the information using hyper spectral imaging and laser microscope, see hyper spectral chips from imec. Researchers so far used inkjet printing and a conventional microscope. Security is also not mentioned in the article but it could be an interesting method to place a hidden finger print.
The minimum viable product is
completely made out of PCBs. To show my gratitude to the
open-source community I added the logos of
a couple projects I use to
the laser head. Source code is available here.
Cross scan error of new prism with 1 arcminutes parallelism is shown below. A pixel in the image is 3 micron and the distance between lines is 111 microns.
A deviation of approx 0.1 mm is observed at distance, d, of 30 mm from prism, which implies planes are not planar within 9.8 arcminutes. New prisms reduce the cross scan error. The prisms are leveled within 1 micron prior to rotation and sides should be planar at 1 arc minutes (this is guaranteed by supplier) To ascertain the motor is the cause, one could monitor the height deviation of the prism while rotating using a laser distance sensor. Another option is to think about the results with the cylindical lenses. If it is assumed the prism is perfectly planar, the refracted rays remain parallel with the incident rays. The second cylindrical lens maps all parallel rays with the same angle to the same point in the focal plane. Ergo it filters any issues with the motor.
Use of cylindrical lenses proved to be highly beneficial, which implies these problems exist.
If higher accuracy is desired it can be resolved by; - using only a single facet - reducing the distance between the prism and the exposure plane - adding a cylindrical lens pair; this circularizes the laser bundle and filters out problems caused by rotation.
I improved the pitch (16-9-2021), fastest is to flip through this pdf. If you want to know more you can see it in the video! I copied format from NematX.
As said in my video, there are a lot of low hanging fruits.
The following improvements are made; - box is much smaller - photodiode flipped to opposite side (reduced size of box) - springs removed to adjust height photodiode and position first cylinder lens - added slit, simply clips all beams which are not refracted by prism
I changed the laser but want to move to a different housing, which is more compact and square.
In the image you can see the new photodiode board.
I attached an image of the new laser module, I want to use. It is more compact and has a cube housing
Anyhow will be on holiday coming weeks, so you'll need to wait for completion :-).
I aim to have a kit for sale at the end of September. I redesigned my boards due to the chip shortage. Luckily, I found a good alternative for the FPGA; the ICE40UP5K.
Design improved on the following points; - more modular; main board can be used for other applications - FPGA has a DSP which plays well with Bezier curves - FFC cables reduced number of wires used - two photodiodes are present, electronics can be used to test laser microscope
The photodiode board is not shown. Images are a straight from the bench. Main board got inspired by Upduino V3.
I attached images of the main board, motor board and the scanhead board (front and back)
A couple of years ago, Henner Zeller developed a laser direct imager called ldgraphy. In it he uses a circular mirror and a rotating polygon mirror;
Recently, I found out that Tecnica patented a very similar proces
They use this technology for selective laser sintering. It is very similar to Henner Zeller's idea but they did get patents (US10473915B2 and US9435998B1) Both ideas have a curved mirror but Tecnica hits the first mirror along the rotional axis. This is different from Zeller which hits orthogonal and as such "novel".
This is one of the drawings from the patent;
At first, i was a bit surprised Tecnica does not use pyramidal polygon scanning it would increase the duty cycle, see the figure below (source). I guess they face issues with the cross scan aberration.. Each facet is slightly different which produces error orthogonal to scanline (Zeller also noted this). By using one side this is fixed. It also reduces the tolerance of the curved mirror as it is hit a single spot and the deviations are constant. With a non uniform rotation speed, they might be able to increase the duty cycle. In selective laser sintering, the writing speed is typically lower.
Hexastorm
Links with prism scanning are as follows; droplets can be placed on the substrate using laser induced forward transfer and reading the information using hyper spectral imaging and laser microscope, see hyper spectral chips from 
In the image you can see the new photodiode board.
Recently, I found out that 