prism laser scanner

I like to keep a record of related ideas I cross over on the web and the involvement of the Netherlands in laser scanning with prisms. 

Related Ideas

Various hackers have been active in the field of laser scanning microscopes. There is a project
on Hackaday (BlueBeam).  A Swiss hacker space, Gaudilabs build one.
Most are based on components of DVD drives (link to a tear down).
Loetlabor also did an exceptional write down of DVD-based laser scanning microscopy.
They even used a FPGA core to control the laser.
Scanning this literature, I found the following figure;

It shows how the focus is obtained using a four channel photo-diode. One targeted at 850 can be found here Vishay K857PE.  It could be nice to integrate this concept in the laser head. Possible areas would the current place of the photo-diode. Another option would be to place a beam splitter on the point where the laser is colimated, i.e. after the first aspherical lens and before the first cylinder lens.

All this thinking about imaging, made me think of another point of improvement.
Using the camera of an optical mice to record or track the laser beam.
Optical Mice, have camera's which are 30x30 pixels, e.g. ADNS-9500 S9500. The price is in the order of 3 dollars.  The camera's might be large enough to image the spot formed by the laser.
At the moment, I use a CMOS camera from Arducam (OV9281) . These are great but much more expensive (in the order of a 100 dollars). Circuit boards are available for this chip.
Another point of improvement, possible with this chip might be to use it to track the position of the laser head.  A second laser, infrared, would shine on the substrate.  This substrate could be the platform used for printing or the underside of the top of the box that is used to enclose the printer.
Via speckle the position of the laser head can be actively tracked.
Finally, MIT made a nice video of the LaserFactory One. I really like the video. It shows, how extrusion and lasers might be combined one day.  Note, MIT doesn't use laser scanning and moves the bundle using a gantry.

Netherlands

The Netherlands is relocating more assets to laser scanning. Recently, AMSystems got featured by TNO,
in it's line up of 25 spinoffs.   AMSystems, as far as I know, aims to build a laser scanner with a plurality of laser bundles per prism.  They adapted their European patent.
Hexastorm no longer falls under the main claim, as it uses a single bundle, which is really good news.

The Netherlands also supports/is founder of some affiliated startups.
Keiron Technologies, is basically a laser startup which uses laser scanning in combination with laser induced forward transfer. They are affiliated with TNO.
Inphocal is using a Bessel beam in laser scanning.  There is also a startup using Bessel beams for communication known as Aircision.
TNO is also setting up a new startup in STED lithography.

All these startups, including AMsystems, are related to HighTechXL.  I think it is very possible, one or more will use or are using prism scanning.
I have looked for patents but so far did not find a lot.

It has been a while, the last months I worked on adding motion control to the FPGA.
I ended up starting from scratch. I wanted to move from migen to nmigen and structure the FPGA code better.
A proof of concept is seen in the very rough video below;

Motors are sampled at 1 MHz. The circuit operates at 50 MHz.  The system can account for; jerk, acceleration and velocity. 

The software consists out of the following elements;
   * SPI command interface  (receives command and words, copied from Luna)          
   *  Transactionalized FIFO (buffers instruction in sram, copied from luna)
   * SPI parser (basically an extension of SPI command interface, with specifics for my                            
                        project)
   *  Dispatcher; picks up commands from the FIFO buffer and dispatches instructions to                            
                          actual hardware
    * Polynomial integrator: creates pulse train for stepper motors; basically you send the                        
                                           coefficients for the polynomial and the number of ticks in a segment.

Code is available online, it was quite a lot of work. Especially the boring stuff which "should be easy" took a long time. Thanks go out to Kate Temkin and her work on Luna.

Made a video of the alignment procedure with new updated tool chain. I moved away from the PRU of the Beaglebone to the FPGA and replaced the ueye camera with an arducam. This sounds easy but still took me a year :-).

Recently, I was reading upon the character-by-character reconstruction of the BioNTech/Pfizer SARS-CoV-2 Vaccine .
Most of us, will end up with this in their bloodstream so I thought it was rather interesting. It turns out there was a startup which produced DNA using laser printing . Austen Heinz gives a good presentation of this process below, scroll to time 10.24 min

The startup Cambrian Genomics was founded by Mr. Heinz in 2014. The startup no longer exists and seems to have faced many difficulties. They did manage to raise over 10 million USD. Austen Heinz committed suicide at the age of 31 on May 24, 2015.
His patents are still around, see US 10,822,605 B2 which got awarded in November 2020.
As there are still people funding the patents, there must be people working on it. I looked into the patents for details on the required accuracies. You need optics which provide an accuracy of around 1 micron.  This accuracy could be possible with prisms, if you have a reasonable budget. Process uses laser induced forward transfer or laser catapulting.

Quote from patent;

Methods of using emulsion-PCR derived beads by the present assignee have been based on the fact that the bead itself serves as a decent ablation substrate for the approx 1 microJoule nanosecond laser pulse used to induce transfer.
Beads from 1 to 10 micrometers are easily and specifically ejected by focusing light into their plane.
Although ejection optics disclosed by the present assignee can target features as small as 600 nm, it is desirable to generate slightly larger, more disperse 1 micron clusters for use with initial prototyping.

I have made an assembly design of the laser scanner in Freecad using the new assembly 4 workbench.

I am really happy with this workbench. It really helps with the open-hardware concept of the project; without these tools it would not be possible to give other people the ease of use to adapt and add their modifications.  Companies like Prusa Research are open source but not open-hardware as they don't provide access to the assembly drawings. They might do that in the future with these new tools.

As described on Hackaday and Sci-hub, a new volumetric printing method has been described which uses two colors.
A light sheet with a 375 nm laser diode and DLP projection between 450-700 nm.

The prism scanner can also be used to accomplish this. Basically, you can intersect the projection of the prism scanner with a laser sheet or line.  The prism scanner could operate at 550 nm and the light sheet at 375 nm. It would allow you to solidify resin at the intersection and not at the top of the resin bath.

Note that if you project a resin bath from above (say from air). The top surface of this resin bath is NOT even. In fact it is wobbly, due to all sorts of surface effects. This would be circumvented by this new technology, as the top of the resin bath is not solidified.  An alternative for this would be to use a process akin to Continuous Liquid Interface Processing (CLIP) (here you also don't solidify the top due to oxygen interaction).
Back to Xolo, they might infringe patent US10843410B2, there seems to be no patent in Europe... The patents claims something very similar to what Xolo is doing.

Austin Russell is the world's youngest self made billionaire at age 25. Mr. Russell founded Luminar Technologies, trades a Nasdaq under LAZR, a company which builds Lidar scanners for cars.
Luminar's lidar scanners use a combination of a rotating polygon mirror with a galvo mirror. The laser source uses a wavelength of 1550 nm. This allows one to use a higher laser power without risking damaging the retina.
Luminar currently has a good patent position in the US market and a very weak one in the European market.

Pulsed laser for Lidar system: US 10520602 B2, US10012732B2
Group of patents which protect the laser source used in a Lidar system. Luminar seems to have a monopoly on using laser sources between 1400-1600 nm and repetition rates up to 100 MHz.
In Europe patents were filed under the numbers, EP3411660A1 up to A4. These have all been rejected due to lack of novelty. Personally, I think it is strange the US patents got accepted.
There was already prior by Trimble, see my earlier post, this system also operates a wavelength of 1600 nm and has an even larger scanning range. It was announced at Intergeo in 2016.

Low profile lidar scanner with polygon mirror: US10571567B2
Patent which protects a certain embodiment which uses a rotating polygon mirror with a galvo mirror.
No patent seems to have been filed in Europe.

Group of software patents; US10627521B2, US10209359B2, US10254762B2
There is a collection of US patents which protects scan patterns, adaptive pulse patterns and monitoring the vibration of the car to improve the scan patterns. Software is not directly patentable in Europe.

Plurality of digital converters; US10267918B2
Still pending in Europe under a different title under number EP3602128A1-A4, search report requires amendment before April 2021. It seems likely that it will result in some sort of patent.

Pulse Encoding; US10545240B2 
Still pending in Europe, search report was not positive see EP3602112A1

Summary
I have looked into a lot of patents of Luminar Technologies, but couldn't find a single one which is accepted in Europe yet. Most patents are rejected, maybe one or two will be accepted in a much weaker form.  So far, building and selling your own car Lidar scanner in Europe still seems possible in the US, a non-free nation with respect to Lidar scanning, you would face many legal problems

Finished new controller board for laser scanner and can now stream data via a ringbuffer to prism scanner. No more micro-controllers from now on but only FPGAs :-). Thanks to Claire Wolf, Migen and Litex team. Code can be found here.

On Tuesday 3 November 2020, I gave a talk on coloring textiles with lasers. Lasers allow you to locally tune the diffusion of a colorant into the textile by applying heat. My aim is to reduce waste and create a more sustainable world with this technology and promote my prism scanner :-). You can watch the video here.

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I created an open-hardware project and got part of my inspiration while working for the Dutch State (TNO). The core idea is that a laser bundle is moved by rotating a prism.  The Dutch state got a patent for a plurality of laser bundles but not for a single laser bundle. For the printed circuit board application, it founded LDI Systems in 2015. This failed and they wasted multiple million tax dollars. I only spent 10K dollars on a working system and paid taxes. I thought they would leave it there. But TNO requested another subsidy from the Dutch government (NWO) to pump 45K euro into a new company AM systems BV for the 3D printing application. I have contacted NWO in this regard as I don't see how the original issues can be solved.  I also wonder how much "own" money is brought in (company is largely owned by the Dutch State). A company is not subject to tender law but the government is.  As such the company might be use to circumvent it. I am also not aware of employees in this company and know they contacted an optical consultancy. My work is free within the constraints provided by the typical licenses MIT and GPL. But I think is strange the state is still sponsoring this project. Hackaday gave me 3K and the Dutch states gives a chosen business developer 45K to explore their failed project. That's not really fair and in that sense the state it is sponsoring "closed hardware".
Often the government throws away the result if unsuccessful, if it was open source one could at least learn something. Anyhow, I filed an official complaint and have talked to NWO.

Links are no longer online, you can still find it in Google Cache. NWO stated it updated its website.