16 hours ago •
Finished PCB for start of scanline detector. The main cape will also be changed. The laser diode driver will be moved from the cape to the scanhead. This is probably better and will make it easier to detach the scanhead as it is a unit with its own electronics.
7 days ago •
Let's quickly read, Inkjet Technolgy for Digital Fabrication, IAN M. Hutchings. There are various ways to create droplets such as Continuous Inkjet and Drop On Demand (DOD).
A well known challenge with DOD technologies are the limits with respect to viscosity. Continuous inkjet allows for higher viscosity but the stream has to be broken up into droplets and droplets need to be selected.
In Continuous Inkjet generation an electric field can be used to position the droplets, see Sweet 1965.
Rejected droplets can be put in a container and reused.
This requires a conductive ink. For non-conductive inks, Kodak has explored alternative selection techniques to select the droplets via air. A patent on droplet selection can be found here US8544974.
The liquid stream has to be forced to break up into droplets when the liquid stream leaves the nozzle. As man, you might recall from peeing that the stream doesn't break up into droplets immediately when the liquid leaves the nozzle.
A way for doing this is via a piezoelectric effect or heating. The droplets can be detected by a stroboscope and a camera.
I claim that the Hexastorm is used to force the break up of droplets in a continuous inkjet head using heating. I claim that the Hexastorm is used to detect the position of one or more droplets.
I then claim that the Hexastorm is used as a selection mechanism to evaporate certain droplets or push them away by colliding them with another droplet generated with laser induced forward transfer.
I claim that the Hexastorm is used to emit a droplet from one stream via LIFT and then merge it into another droplet.
Likewise, I claim the same things for a drop on demand system where droplets are ejected by acoustic energy, piezoelectric effect or thermal effect. Again the Hexastorm can be used to detect the position of droplets, see if nozzles are clogged and calibrate the inkjet head by checking the position of droplets either upon the substrate or in the air.
Light can be used to cure liquids so they become conductive via so called flash curing. In some novel conductive inks nano-particles are dissolved. The solvent is used to lower the viscosity and facilitate transportation in the head. If the ink is on the substrate, the solvent must be removed which is done via flash curing.
They could also cure UV inks and vary the dosage per ink using optical coherence tomography. Or use OCT to check wether the conductive ink is fully cured.
Anyway, what might be of interest to the reader is the work of Georg von Hippel from the MIT Sloan school of Management.
At the moment, l I am a bit done with creating prior art and will move back to building the scanner!
07/15/2019 at 18:21 •
Prior art is of huge importance to the open-hardware movement. It prevents that certain markets become locked for 20 years by patent law.
Let's generate some prior art with patents. I claim all the claims generated by rewriting all patents in the world which use the concept of scanning mirror and do not mention the concept of scanning prism. I make these claims by rewriting the scanning mirror patent but now using the concept of scanning prism. I think these new claims would be obvious for a Person Having Ordinary Skill in the Art (PHOSITA), familiar with my work and familiar with the patent. The total of these claims and other prior art describe the legal application limits of transparent polygon scanning.
Let's provide some examples;
Example 1: US7892474
This is an interesting patent it describes something like Continuous 3D printing. Could explain why Carbon didn't outline the figure 3 option.
Claim 1 reads "... comprising the step of solidifying a photo-polymerizable material by means of mask exposure of a build area or partial build area in a building plane via electromagnetic radiation from a digital light processing/digital micromirror device projection system ..."
using transparent prism creates prior art not under patent let's reformulate
"... comprising the step of solidifying a photo-polymerizable material by means of refraction exposure of a build area or partial build area in a building plane via electromagnetic radiation from a transparent polygon scanner device projection system ..."
Example 2: US9079355B2
The first reflective polygon scanner in photo-polymerization was described by the Institute of Physical and Chemical Research (RIKEN) in 1997.
RIKEN did, however, not describe the combination of a laser diode and reflective polygon scanner.
Shuji Nakamura of Nichia discribed the blue diode laser in 1996. Envisitontec patented the combination of polygon scanner, laser diode and 3D printing in 2011. This was a smart legal move.
Claim 1 reads:
"... and deactivatable ultraviolet laser diode and a rotating polygonal mirror ..."
using transparent prism creates prior art not under patent let's reformulate
" ... and deactivatable ultraviolet laser diode and a tranparent polygon scanner ..."
Example 3: EP3233499B1
Laser induced forward transfer can be used to generate droplets with laser light. The earliest description I could find date back to 2004.
Poeitis patented this process for bio-printing in 2015. In this video, it is describes how laser-assisted bioprinting works. The process is also shown in figure 1 and 2 of the patent.
From the video it can be concluded that a transparent polygon scanner can be used to shoot with a laser pulse on a disk so a droplet is emitted. This can be used in bioprinting, 3D printing or used in the semiconductor industry to deposit resist, glue, polymer or ink etc.
A microfluidic chips with multiple channels could be made and the transparent polygon could be used to send a laser pulse to the disk and select the channel from which the droplet is emitted.
Example 4: US900887
Compact, low dispersion, and low aberration optics scanning system. I claim the same in this patent but then with a moving transparent prism.
Example 5: US6850363
Arthur Ashkin, nobel laureate, invented the optical tweezer with Gerard Monrou and Donna Strickland.
This patent describes optical tweezer in a laser scanning microscope using a scanning mirror. I claim an optical tweezer made by a scanning transparent prism or galvo transparent prism.
07/13/2019 at 10:09 •
UV Light can be used to disinfect the material flowing in tubes. Infrared laser light can be used to heat specific particles/cells/droplets if the tube is made from glass. Here is a market report on UV disinfection equipment. A company active in UV disinfection is uvo3. Transparent polygon scanning can be used in vibrometery, which can be used to measure fluid flows in glass tubes using laser doppler velocimetry. Laser galvo scanning interferometry can be used for flow velocity measurements through disturbing interfaces. Likewise a transparent polygon scanner can be used to measure flow in chemical processes.
Ideally, the glass tube is square to minimize a lensing effect.
Furthermore, an interesting option would to polymerize particles in the tube, or sintering takes place in the tube. MIT patented this process in US7709554, but used a DMD projector and not a transparent polygon scanner. In addition, I claim the case the walls of the tube are created from Teflon AF. This could for instance done on a micro-fluidic chip which would again be produced by a transparent polygon scanner. One could simply use the setup outlined here and use a transparent polygon instead of a galvo scanner. If this is not sufficient I would make the tube square and sufficient porous by laser engraving the tube with a transparent polygon scanner and C02 laser, where i spin the prism at a relatively low speed and possibly use an auxiliary bundle to fix the timing.
The speckle pattern can be measured which is created by shining in the tube. This process can for example be is used in the food industry to measure the dairy viscosity in a glass tube. You could walk around in the garden with a handheld Hexastorm and measure the biological status of a plant.
The detector could be a CCD/CMOS camera at the same side or opposite side of the plant leaf or glass tube. Possibly, the transparent polygon scanner is under an angle so the reflected light does not fully transmit back to the polygon scanner but can be measured by another device at the same edge of the tube, like a CMOS/CCD chip/grating light valve with appropriate lens.
The laser is pulsed and the time of flight is measured. This allows one to both record the amplitude and time phase spectrum of the material under measurement. Incidentally, I claim that gasses are flowing in the tubes or that that tracers are applied to the particles in the tube.
07/12/2019 at 18:31 •
In my previous post, I outlined how transparent polygon scanner can be used for detecting eye diseases.
Logically, a transparent polygon scanner can also be used in 3D glasses. Reflective polygon scanners are used for creating a screen in a laser TV. It is harder to use scanning mirrors in fibers because the reflected light has a different angle than the incident light. By scanning prisms the transmitted light does have the same angle as the incident light.
Colors are created in a laser TV by coupling three lasers of different wavelength and optical power in the same bundle. At 50000 RPM and six sides the line rate is in the order of 5000 Hz. If you project a 1000 lines with a 1000 pixels the refresh rate would be 5 Hz at 1 megapixel.
Let's look into multiple options of improving this;
Option 1: Optical transformation
Project a 1000 lines with 4000 pixels and transform it into 2000 lines at 2000 pixels using optical transformations provided by a combination of lenses, mirrors or surface waves.
Option 2: Miniaturization
Scale down the size of the prism, using possibly transparent conductors (e.g. indium tin oxide ITO). Place the prism in a fluid to reduce the influence of vibrations or into a gas for a low drag. Due to the down scaling it will be much easier to balance and spin the prism. The angular momentum drops due to lower mass and radius, which implies lower energies at a fixed RPM. The fastest spinning disk ever made at 600 million RPM is also small.
The following options are foreseen;
1. Laser Light emitted from a fiber which is collimated by a lens. The light is then focused by a cylinder lens parallel to the prism rotation plane. The light is subsequently focused by a cylinder lens orthogonal to the rotation plane. The line is converted into a plane by moving the light in a second direction via a piezo-actuated tube actuator. A photo-diode in the image plane detects the start of a scan line.
2. Laser Light emitted from a fiber which is directly focused by a lens. The laser light is refracted through a rotating transparent prism. This creates a line. This light is then refracted again through a rotating transparent prism or a tilt-able prism. This creates a plane. In the plane there is a photo-diode which detects the start of the line for each line.
I claim that in the configurations the rotation of the prism is monitored by monitoring an auxiliary laser bundle with a photodiode that refracts through the rotating or titl-able prism.
I claim that that lenses are are added after the laser bundle is focused onto a 2D plane to transform it so it is more suitable for the eye.
I also claim the use of a plurality of transparent polygon fiber scanning displays to create one image.
Get hold of a Magic leap Glass and replace Magic Leap core technology; the fiber scanning display, see patent US10260864B2 with the Transparent Polygon Fiber Scanning Display (TPFSD). Couple in the light to the eye via WaveOptics as provided by companies like Enhanded World.
Possibly, the TPFSD must be placed on a static underground as the rotation is affected by vibrations.
I claim the trade mark on Hexa Glass for virtual reality glasses which use a rotating prism to move laser bundles.
07/12/2019 at 12:30 •
In the following, I would like to outline how transparent polygon scanning can be used to save lives. I again aim to create prior art to extend the freedom of use of transparent polygon scanning.
Optical Coherence Tomography (OCT) is an imaging technique that uses low-coherence light to measure samples based upon the principle of light interference. It is used in the medical industry to detect cancer in tissues and diseases in eyes, e.g. the Cylite of Hewlett Packard. OCT is typically used to obtain information from a sample. In 3D printing it has been used to verify a print. For example, Photoncontrol used Optical Coherence Tomography and Raman spectroscopy to test the quality of bio-printed tissue, see 1. A startup, called Inkbit from MIT, is using it to create samples accurately. They print droplets with an inkjet head and then verify the position of these droplets using among others OCT.
OCT has also been used to detect the adhesion between layers in a 3D printing process, see Non-destructive testing of layer-to-layer fusion of a 3D print using ultrahigh resolution optical coherence tomography.
Due to the interest in this area, I decided to elaborate upon how OCT can be used in combination with a transparent polygon scanner. I claim that in figure 2 a transparent polygon scanner is used instead of a galvo scanner. I claim that in the optical path of the Hexastorm a beam splitter is placed after the aspherical lens and before the first cylindrical lens to enable the scanner for optical coherence tomography. I claim the use of a transparent polygon scanner for wavefront measurement in Ophthalmology and Optometry. The vertical measure of an eye ball, generally less than the horizontal, is about 24 mm. The current scan head has a scanline of maximum 24 mm, making it already close to dimensions required for eye ball measurement. I claim that possibly two transparent polygon scanners are used in ophthalmology and optometry, to move the bundle in two directions.
An OCT enabled transparent polygon scanner might also be useful for 3D printing. Imagine that a small percentage of the bundle is scattered to the reference mirror and most of it used to go to the sample. It will then be possible to sinter powders or polymerize liquids at the sample location. A small portion of the beam will be reflected and refract back to the beam splitter and interfere with the reference beam at the photo-detector.
This allows one to measure the photo-polymerization or sintering process during printing. I can imagine this is especially useful if the layer height is less than the wavelength. I can also imagine that this is useful during a process akin to Hexaforming (see previous post). A hand held device could be used to check the skin of a patient. An application would be laser surgery, such as eye surgery (Carl Zeiss Meditech) or tattoo removal and laser hair removal.
The transparent polygon scanner could also be useful in a Raman microscope as galvo's are used by NanoPhoton. In two-photon point-scanning microscopy,temporal focussing can be used to increase the image rate for a transparent polygon scanner similar to a galvo setup. Another option is in vivo imaging with HiLo microscropy but then a transparent polygon scanner. Further possibility is Field-portable quantitive lenssless microscopy based on translated speckle illumation on sub-sampled ptychographic phase retrieve using a transparent polygon scanner. Or A New Method of Creating High-Temperature Speckle Patterns and Its Application in the Determination of the High-Temperature Mechanical Properties of Metals with a transparent polygon scanner.
Another option is laser scanning fluorence microscopy with a transparent polygon scanner instead of a scanning mirror. The dichroic mirror could be positioned between the first cylinder lens and the aspherical lens. If a pinhole is added before the camera, we have just created a transparent polygon scanning confocal microscope, see video.
Another option is edge radius measurement, with a transparent polygon scanner.
07/11/2019 at 12:47 •
Recently, Carbon's 3D valuation exceeded 2.4 billion USD . This provided me with inspiration to again look at its intellectual property and create prior art to facilate circumventions of its patent.
Carbon has a technique which it denotes as Continuous Liquid Interface Processing (CLIP) . Carbon uses a Digital Micro-mirror Device (DMD) to illuminate a photopolymer through an oxygen-permeable window made of a fluorpolymer such as Teflon AF. Teflon AF can be sourced from Biogeneral . Nasa described how a teflon AF sheet can be made. A supplier of chemicals can be found here .
The permeation of oxygen through the window creates a persistent liquid interface, nicknamed "dead zone", where photopolymerization is inhibited between the window and the polymerizing part. Oxygen inhibition was an effect that was already shown to play a role by Denkari et al. in 2006 for silicon release coating invented by John Hendrik, see US7052263 (B2) . The "dead zone" in silicone release coating is so small that a peeling is needed to release the part from the transparent window. Hessel Maaldrink sped up the process by adding a force feedback sensor EP2043845B1 . Using Teflon AF and a polyuerethane Tumbleston et al. 2015 where able to extend the "dead zone" to approximately 30 micrometers. As such the part does not have to be peeled of from the optical window during the process and stair stepping is minimized. This allows for the production of flexible parts. Furthermore, the "dead zone" speeds up the viscous flow between two parallel plates, part and window, for the application of a new layer, see WO2014126837A2 , improving the print speed.
I will now try to create prior art and formulate a work around for the Carbon patent to extend the freedom of application of the transparent polygon scanner marketed as Hexastorm.
After studying the WO application of CLIP, I noticed that the European patent is different from the US patent. In the European patent EP2956823B1 claim one states ".. irradiating said build region through said optically transparent member to form a solid polymer from said polymerizable liquid while also concurrently advancing carrier away ..".
As such, I claim irradiating said build region with for example a transparent polygon scanner while not concurrently advancing away the part, but discretely. The part is exposed and moves after a full exposure. Moving during an exposure is also not possible as Hexastorm exposes a line and not a plane.
DMDs have a pattern/pixel rate of up to 20 kHz. Laser diodes can achieve a refresh rate up to 100 MHz. At 50.000 RPM and six sides, a transparent polygon scanner exposes at line rates of 5000 Hz. With a laser diode, the refresh rate is so much higher that it might be possible to alter the polymerization over much smaller distances. Stair stepping would be minimized even though the part is moved discretely.
If it is not possible, the procedure would still allow for the production of flexible parts.
The US patent, US 9216546B2, is wider in scope as claim one specifies "A method of forming a three-dimensional object, comprising the steps ...". The formulation using "steps" in US patent differs from "concurrently" in the European patent.
In the US the process is also under patent if the part is not moved during exposure. Carbon as a result markets its technology as "digital light synthesis technology", although Continuous Liquid Interface Processing (CLIP) seems more accurate in the European union.
Key in the US patent is that parts are produced upside down and moved away from a build surface which is not air. This is peculiar as the original patent by Hull in 1986 specifies both up and down projection in figure 3 and 4 respectively.
As such, I claim the use of oxygen-inhibition in down projection, where the top is up, using a transparent polygon scanner. Again, the fast exposure of a laser diode might minimize stair stepping and the "dead zone" will simplify coating. Additionally, using air instead of a teflon AF layer reduces costs.
After studying the following literature, dip and blade coating patent US5651934 of Charles Hull, flows in thin film coating by Christian Kushel, Zerphyr coating as described in US6159311, curtain coating as described in EP0928242 and the book Liquid Film coating by Kistler, I claim the following.
1. Firstly, the use of "dead zone" in 3D printing to facilitate the coating of liquids in down projection photo-polymerization where the top of the part is up. I will now explain this.
Boundary conditions during coating are important. A part solidified up to air provides a non-consistent liquid // solid boundary condition. During for example blade coating the coater can collide with the part. A dead-zone would prevent this and create a more consisting wetting of the substrate during for example Zephyr coating as it is entirely liquid.
2. Secondly, I claim that an array of transparent polygon scanners is integrated in the Zephyr blade. I claim that possibly in the Zephyr blade a Teflon AF film is partly applied between the liquid and air interface. I claim that in the Zephyr blade the pressure of the air is monitored. I claim that an opening is provided to actively supply liquid to the Zephyr blade using a pumping mechanism.
3. Thirdly, I claim that the teflon AF film or part moves parallel to the plane of illumination and not only orthogonal as in the CLIP patent. Transfer substrates are used by Admatec , Carima and TNO EP2272653. Especially, I look at the figure provided at the front page of US2012007287. I claim that the film in this figure denoted by 10 is teflon AF and the exposure module denoted by 9 is an array of transparent polygon scanners.
I label the process which fall under my claims and not under Carbon's claims as Hexaforming.
06/21/2019 at 15:32 •
The proof of concept module was hard to build. I used shims of 100 micrometers and a tweezer to set the height of the laser. In the next module the build procedure is simplified so it is easier to scale the amount of single bundle transparent polygon scanners in the world from 1 to 10, and make a 10x improvement.
The procedure is as follows; set height laser, set horizontal position laser by first cylindrical lens, set height diode.. Other components still need to be added an whole system needs testing.
06/18/2019 at 21:31 •
I want to simplify the fabrication of a scan head. I disassembled the head so I could reuse the components. A colleague advised me to glue the lenses with CAF3 (silicon glue) to the plastic posts. This was good advice, lenses were very easy to take off. I was worried that i had to order the components anew.
Components are ready for the next iteration. Some remaining glue can still be seen.
06/14/2019 at 15:35 •
As always, I would like to generate some prior art to extend room of operation. The following concerns the situation that multiple scan heads are used in a single machine. For an example see Kleo which uses 288 bundles by Carl Zeiss.
If multiple scan heads are used, a challenge is to align these heads. The position of the laser in each head has to be known exactly.
One way of doing this is by moving a camera under the scan heads and collecting position information per laser. The laser would project directly onto the CCD / CMOS chip and its position would be determined. This is however expensive as it requires an extra stage with camera. The chip has a finite size of for example 5x5 mm and has to be moved.
Another solution of doing this would be to add a bar from diffuse glass, e.g. opal glass. The light would be scattered in this bar and reach the edges of it. At the edge of this bar there would be a photodiode. The bar could be made of opal glass. One might think that this bar must be narrow so the position can be detected up to 10 micrometers accurate in one direction. The current photodiode used to calibrate the laser is, however, also not narrow. You can simply use the rising edge of the signal recorded by the photo-diode used to monitor the diffuse opal bar.
The stage upon which the scan head is mounted then moves in orthogonal direction to this bar.
By turning on the laser and moving it over the bar. The position can be determined exactly in that direction. It might be needed to add a cap-around the bar to minimize stray light. This is also done for the photo-diode in the scanhead.
Still, I need two dimensional information. I also need to know the position of the laser diode at the bar.
To do this I could use multiple photodiodes along edges of the bar. They would all measure a signal if the laser hits the bar. The signals will, however, arrive at different points in time. This allows one to determine the position of the laser along the bar.