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• when mirrors do not follow law of reflection

  Hexastorm • 09/15/2023 at 10:24 • 0 comments

  Laser scanning via mirrors is of relevance to prism scanning, being an alternative. For mirrors it is assumed angle in is angle out (law of reflection). Still, this is not always valid. The following article on arxiv goes into depth on the latteral shift and angular shift known as goos hanchen effect and imbert federov effect. It is seems to be simple consequence of Fresnel equations.
  

  Aberration is small but you would have to account for distance to substrate  and also compound both effect. Details in article
  

  https://arxiv.org/pdf/2308.10940.pdf

• 3D printing of ultra-high viscosity resin by a linear scan-based vat photopolymerization system

  Hexastorm • 09/07/2023 at 16:33 • 2 comments

  Last july, an article was published in Nature for a new high viscosity vat printing method, https://doi.org/10.1038/s41467-023-39913-4
  This method is depicted below, the figure is copied from the article.
  

  It uses four rollers to apply a new layer to 3d print a part. The article comes with some cool videos and equations describing the mechanism.

  The method, and this is not mentioned in Nature is not entirely new, see patent EP2272653A1. The only difference i can see from a legal perspective is recoater number 2. I also remember it is not a true vat method. Resin went to a waste box, see number 23.  I think the Admatec machine is a spinoff from this concept. It also uses a a rotating foil, coated with a blade and the remainder is put into a left over box.
  

  Furthermore, in my white paper on reprap,  i claim the usage of a foil with my Prism scanner.  I made two drawings to protect up and down projection.
  

  
  

  I think the authors of the nature article should consider the following  two patents;
       US8777602B2 (recoater patent)

  Loophole might be not using recoater. 
  

       US9939633B2  (scanlab, EOS subsidiary patent, reflecting lens)

  Their reflecting lens seems very similar to scanlab. The authors mention the 3SP patent, so I did not include it.
  

• Flipping a PCB motor using a ferrite sheet

  Hexastorm • 08/30/2023 at 14:04 • 2 comments

  I use a sliding bearing. This keeps costs low and ensures the prism is kept in a given plane. A challenge is that the prism falls if this sliding bearing is flipped 180 degrees.  This is fixed by adding a ferrite sheet on the back of my PCB.

  Materials used flexible ferrite sheet MHLL5040-200 Laird, Magnets MKSA-8x5-ZW-N45 i.e. 8x5 mm, neodium 45 with a black epoxy coating.
  I think that ferrite instead of neodium is possible if the whole contraption was made better.  Ferrite is typically 2-7 times less strong. If the distance would be decreased a bit, which is still possible, ferrite should work.
  

• Brief update

  Hexastorm • 08/10/2023 at 16:08 • 0 comments

  Two changes;

     -  Layout Hexastorm.com changed and is now more in line with look and feel of Hackaday.
        Website is generated using Quarto

    -  Decided to further perfect engine, moved from 4 to 8 magnets.  The magnets have a black coating
       which aligns better with the overal design Hexastorm.
  

• Laser prism scanning with Bessel like beams

  Hexastorm • 07/14/2023 at 13:21 • 0 comments

  I made a presentation on how laser prism scanning might use Bessel like beams. I outline how they are created and how they might be used in combination with laser prism scanning. This due to recent interest to startups like Inphocal.
  

• Rendering laserscanner

  Hexastorm • 06/28/2023 at 21:13 • 0 comments

  Rendering the laserscanner in Blender.

  File is here https://cdn.hackaday.io/files/21933938381472/assembly_compact.7z
  

• Structured Light

  Hexastorm • 06/23/2023 at 23:20 • 0 comments

  Claim 1:

  -  I claim the use of two lenses which in combination focus light into a structured optical beam. Between these lenses there is a prism which   can rotate so that a scanline can be formed. The first lens focuses the light parallel to the scanline and the second lens focuses the light   orthogonal to the scanline.

  Claim 2:

  - The optical system of claim one, wherein the focal length of both lenses are different such that they circularize the light source. 

  Claim 3:

    - The optical system of claim one, wherein each of these lenses is similar to an axicon.  The difference with a normal axicon, is that each individual axicon focuses the light in one dimension and not two as a normal axicon. The light is just propagated and not diverted along the other axis. Only the combination focuses the light along two axes, one orthogonal and one parallel to the scanline.

  Claim 4:

    - The optical system as outlined in any of these above claims and in an applications outlined on (https://reprap.org/wiki/Open_hardware_fast_high_resolution_LASER)  or https://hackaday.io/project/21933-prism-laser-scanner

  Claim 5:

  An optical systems similar to claim one, which is used in an optical tweezer or laser microscope.

  I adapted this blog as it contained inconsistencies;

    CERN provided more information here https://ventureconnect.cern/index.php/structured-laser-beam-slb
                                          
  

  https://indico.cern.ch/event/707301/contributions/3073255/attachments/1699704/2736949/CESP_Structured_Laser_Beam.v1.pdf             
  

  Background
   
  

  In the laser prism scanner, so far Gaussian beams are used.  An alternative would be to use a Bessel beam. An advantage of a Bessel beam is that they have a longer depth of field as compared to a Gaussian beams for a given focus size. A true Bessel beam is non diffracting.
  True Bessel-beams are not possible as they require infinite energy.  Bessel beams can be approximated and then called structured light.
  These structured light beams are less diffractive than Gaussian beams.
  
  A Gaussian beam is created by focusing light into a point.  Structured light is created by focusing light along a line. This is denoted by Bessel beam in the figure below.
  

  Recently, companies such as ASML, Europe's most valuable tech firm according to BBC,  started to support laserscan startups such as Inphocal which use structured light.  Inphocal is based on intellectual property from Cern (WO2019211391A1) Inphocal received funding from HighTechXL, NWO, DeeptechXL and the European Union.

  CERNs contributions to Kicad are highly appreciated. WO2019211391A1 feels incomplete. In short it outlines an improved version of the axicon. This new lens produces a beam which better approximates a Bessel beam and diffracts less. I can understand this due to the greater design freedom as the shape seems mathematically more general to me, but still I would be interested to see the actual differences backed up by optical simulations.  The authors from CERN do not provide this. CERN furthermore does not really goes into the difficulties which arise by scanning a laser bundle.  I can imagine Inphocal uses a galvo scanner from scanlabs and does not have a challenge with cross scan errors.  Galvo scanner are slower than polygon scanners.

  In specific, the authors do not outline how the movement orthogonal to the scanline can be mitigated if a Bessel beam is scanned by a prism. Given my experience with cylindrical lenses and Gaussian beams. I propose a similar solution for Bessel beams.

  For Gaussian beams,  my solution is outlined below;

  
  
  

  Light diverges from a laser diode and is collimated by an aspherical lens. The first cylindrical lens focuses...

  Read more »

• Realistic laser laser scanner in blender

  Hexastorm • 06/17/2023 at 21:51 • 0 comments

  The laser prism scanner can be simulated in blender, I am working on the cylinder lenses.
  
  In the following image you see a 1 mm laser spot displaced by prism and reflected by a mirror to a photo diode.
  

  I

  The laser ray is visualized by adding an atmosphere to the volume

  In the last figure a laser deflected by a tilted prism is shown. It impinges on a white sheet.

• Laser Prism Scanner Summary

  Hexastorm • 04/12/2023 at 12:51 • 0 comments

  I made a summary video of my laser prism scanner work.
  This should save you time if you are interested in the topic.

  0:00 - Intro 
  1:35 - Process 
  2:58 - Applications 
  5:00 - Optics: prism more accurate than mirrors 
  5:59 - Optics: displacements caused by prisms 
  7:44 - Optics: rotating polygon mirrors vs rotating prisms 
  10:45 - Optics: position photodiode 
  11:59 - Optics: advanced prism designs
  13:16 - Aberrations: how measurements are made
  14:23 - Aberrations: cross scan error versus jitter
  16:08 - Aberrations: mounting
  16:56 - Aberrations: solutions to mounting
  18:44 - Aberrations: prism imperfections
  20:09 - Aberrations: solutions to scan errors
  21:18 - Aberrations: vibrations
  22:34 - Aberrations: prism mounting using Ricoh motor
  24:04 - Aberrations: new mounting solution
  26:04 - Aberrations: new mounting solution (Freecad view)
  26:57 - Aberrations: measurement cross scan errors
  29:07 - Validation, result of exposures
  29:59 - Positive feedback
  31:20 - Negative feedback
  33:48 - Outlook
  35:08 - Origins laser prism scanning
  37:08 - Challenges with thick laser prism scanners

• A reply to "The state of open-source in 3D printing in 2023"

  Hexastorm • 04/04/2023 at 08:18 • 0 comments

  In the blog state of open source, Prusa complains about cheap 1:1 clones who do not honor the open source ethos and as remedy suggests altering the license.

  
  The most successful companies, e.g. Microsoft and Apple, in the world are closed source.
  Still closed source seems not to work for a number of technologies; operating systems (Linux) and programming languages (Python).
  In the nature of the firm, Coase argues that the main reason to establish a firm is to avoid some of the transaction costs of using the price mechanism.
  Open source lowers the transaction costs for inbound innovation. Information is more readily available to outsiders and less asymmetric. As a result, the technology grows.
  I think open-source is best suited for "highly" complex products with an initial weak product market fit. It works better for software than hardware. As hardware is harder to reproduce. This leaves the question of monetization.
  Open source software is now monetized by cloud providers who earn money by running it in the cloud.
  Examples are Github, Amazon Web Services or DataBricks.
  It is also monetized by software developers who tailor the software for specific business needs.
  They enjoy large benefits by the fact it is open source. As they can simple hop companies and sell the same knowledge again. A problem with proprietary software is that the new firm or client of the developer would also require a license.
  
  

  In your blog you also give an example of solar panels. One example for all is solar panels – the original inventions and processes were gradually copied by Chinese companies. After that, with the help of state subsidies and tax breaks, they drove all competition out of the market within a few years. Today, you have virtually no chance of buying a non-Chinese-made solar panel.
  I agree with your assessment that this makes solar panel manufacturing less profitable. It might also be a reason for a government to intervene using tariffs.
  Still, an entrepreneur can still make money. Once the solar panel becomes free, the challenges becomes getting it on your roof. You might also need advice on how to best place your solar panel. It is very hard for the Chinese to compete with a Dutch solar installation company given the fact they are in China.
  They can also not work in the Netherlands due to regulations.  If China makes printers for free, you might need to alter your workforce or firm. I still see a lot of ways of making money.
  
  Moving back to the Prusa firm. I would not alter your open source approach but better look at how it can provide unique value. Your company actually pursues a mixed strategy. Part is closed and part is open.
  It is impossible to make a firm a completely "open".  I would not focus on changing the relation between Europe and China or the patent system. These things are external to your company and not under your control.
  You can make it easier for external parties to add new tools to your printer.
  You could give these external parties a slice of the profit.  Goal here is to really think outside of the box and look at your relation with the customer.
  As example, there is a Dutch company called Swapfiets, who offers bikes via a subscription service instead of selling them. This has been hugely successful. I would not advice you to offer a subscription service. Still, it shows that the way you interact with the external parties can be a key differentiator.
  If you control the most popular design of the printer, you should still be able to make money simply as you decide which parts end up in the next printer.
  A successful open source approach, requires more thought than simply putting the source code on the web.
  This was done by Lulzbot and not successful.
  
  

  Finally, I partly disagree with your view on patents.
  I believe like you and the Economist that the patent system is broken.  From experience, I believe that most patent applications are a failure.
  Still, you should patent given the opportunity. If you have a lot of...

  Read more »

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