Diagnostics and Resolution Optimization for Scanning Projection Stereolithography.

Abstract

The present disclosure relates to a system for performing scanning projection stereolithography. The system uses a light projector configured to generate a polymerization light signal that initiates polymerization of a photopolymerizable resin or material at a build surface. An optical subsystem collimates and focuses the polymerization light signal. The optical subsystem is movable relative to the build surface to optimize focus of the polymerization light signal at the build surface. An optical scanning subsystem directs the polymerization light signal received from the optical subsystem to selected X-axis and Y-axis locations on the build surface. A positioning subsystem positions the optical subsystem at a selected location relative to the build surface, the selected location being chosen to optimize focus of the polymerization light signal at a particular selected X / Y location on the build surface.

Description

[Technical field]

[0001] This application claims priority to U.S. Patent Application No. 17 / 729,140, ​​filed April 26, 2022, and claims the benefit of U.S. Provisional Application No. 63 / 179,761, filed April 26, 2021, the disclosures of which are incorporated herein by reference.

[0002] This invention was made with Government support under Contract No. DE-AC52-07NA27344 awarded by the U.S. Department of Energy. The U.S. Government has certain rights in this invention.

[0003] The present disclosure relates to scanning projection stereo lithography systems and methods, and more particularly to scanning projection stereo lithography systems and methods that utilize controllably positionable optical elements to eliminate or reduce the need for a flat image surface at the build plane, thereby providing significantly improved focusing accuracy at the build plane. [Background technology]

[0004] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0005] When doing scanning projection stereolithography, it is paramount to achieve the best focus, highest resolution, and smallest spot size. Stereolithography systems can only print features as small as the optical system can focus them. There are other techniques that affect the spot size, but they are secondary to the primary criterion, which is the resolution of the image of the Digital Micromirror Device ("DMD") or other Spatial Light Modulator ("SLM") at the build surface. Therefore, as with LAPuSL (Large Area Projection Microstereolithography) based stereolithography systems that direct the image of the SLM onto the build area, it is paramount to have the highest resolution image of the SLM on the build area.

[0006] The portion of the LAPuSL optical system that focuses the light onto the build surface is typically, but not exclusively, done by using a flat-field or F-theta lens after the scanning mirror. The purpose of the f-theta lens is to achieve a flat image field and to compensate for the distortion that occurs when light is directed at large angles off-axis through the lens. However, it is impossible to do this perfectly. In particular, the design goal was to design the f-theta lens to have a very flat in-focus field, so there is a compromise in image quality.

[0007] Thus, there remains a great need in the art for systems and methods that can eliminate or reduce the need for a flat image surface at the build plane when using scanning projection stereolithography systems. Summary of the Invention [Means for solving the problem]

[0008] This section provides a general overview of the disclosure and is not an exhaustive disclosure of the entire scope or all of its features.

[0009] In one aspect, the present disclosure relates to a system for performing scanning projection stereolithography. The system may include a light projector configured to generate a polymerization light signal that initiates polymerization of a photopolymerizable resin or material at a build surface. An optical subsystem may be included for collimating and focusing the polymerization light signal. The optical subsystem is movable relative to the build surface to optimize focus of the polymerization light signal at the build surface. An optical scanning subsystem may be included that is configured to direct the polymerization light signal received from the optical subsystem to selected X-axis and Y-axis locations on the build surface. A positioning subsystem may be included for positioning the optical subsystem at a selected location relative to the build surface, the selected location being chosen to optimize focus of the polymerization light signal at a particular selected X / Y location on the build surface.

[0010] In another aspect, the disclosure relates to a system for performing scanning projection stereolithography. The system may include a light projector configured to generate a polymerization light signal that initiates polymerization of a photoresist material at a build surface. A collimator may be included for collimating the polymerization light signal, and a focusing lens system may be included for focusing the polymerization light signal. At least one of the collimator or the focusing lens system is adjustable by movement along an axis relative to the build surface to optimize the focus of the polymerization light signal at the build surface. An optical scanning subsystem may be included configured to direct the polymerization light signal received from the collimator and focusing lens system to selected X-axis and Y-axis locations on the build surface. A focusing lens may be included, disposed downstream of the optical scanning subsystem and upstream of the build surface with respect to a direction of travel of the polymerization light signal from the light projector, to focus the polymerization light signal at the selected X-axis and Y-axis locations on the build surface. A positioning subsystem may be included for positioning at least one of the collimator or focusing lens at a selected location along the Z axis, the selected location being selected to optimize the focus of the polymerization light signal at a particular selected X-axis and Y-axis location on the build surface. A diagnostic subsystem may be included that utilizes a camera to image a portion of the polymerization light signal reflected from the build surface to observe polymerization occurring at the build surface during formation of the part.

[0011] In yet another aspect, the present disclosure relates to a method for performing scanning projection stereolithography. The method may include projecting a polymerization light signal toward a build surface, where the polymerization light signal can initiate polymerization of a photopolymerizable resin or material located on the build surface. The method may further include scanning the polymerization light signal to selected X-axis and Y-axis locations on the build surface. The method may further include collimating and focusing the polymerization light signal before the polymerization light signal reaches the optical scanning subsystem. The method may further include adjusting a position of the optical subsystem before the polymerization light signal reaches the optical scanning subsystem, and optimizing a focus of the polymerization light signal when the polymerization light signal reaches a specific X-axis and Y-axis location on the build surface.

[0012] Further scope of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0013] The drawings described herein are only for illustrative purposes of selected embodiments, not all possible embodiments, and are not intended to limit the scope of the present disclosure.

[0014] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a high-level block diagram of one embodiment of a system according to the present disclosure that utilizes dynamic adjustment of a collimator to reduce or eliminate the need for a flat image plane at the build plane. [Diagram 2] 2 is a high level flowchart of operations that may be performed using the system shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Exemplary embodiments will now be described in more detail with reference to the accompanying drawings.

[0017] The present disclosure relates to a system and method in which the required focus changes as a function of scan angle in a scanning projection stereolithography system are accommodated in one embodiment by dynamically mechanically adjusting the position of an optical component during the build operation phase, where the optical component in one embodiment is a collimator lens. This allows control of where the best image occurs. This greatly reduces the need for a very "flat" field from the optical system, thus removing one of the main difficult "tasks" from the optical system, namely providing a corrected focal plane.

[0018] The focus at various positions in the build plane can be adjusted mechanically, and in some embodiments dynamically mechanically. For example, the focus adjustment may be performed by electromechanical actuation, or by electrically adjustable lenses (e.g., ETL liquid lenses), or even by pneumatic actuators, or electro-optically, or possibly by a combination of two or more of the techniques described above, or by any other method suitable for adjusting optical components. By using one or more of the techniques described above, the optical design can be configured to give greater priority to improving the resolution. Using this system and method, i.e., mechanical compensation (dynamic or static) of the focus with an optical system optimized to use this mechanical focus adjustment, the resolution across the build plane can be significantly improved compared to a system that does not have active (i.e., real-time) adjustment. Thus, the present system and method is different from any other active control system, since it involves imaging an object (e.g., an SLM) over the scanned field and compensating to achieve the highest resolution.

[0019] FIG. 1 illustrates a system 10 according to one embodiment of the present disclosure. System 10 in this example provides dynamic control of the positioning of an optical element 14, in this example a collimator (hereinafter simply "collimator 14"), to eliminate the need for a calibrated focal plane. System 10 can include a light projector 12, such as a digital micromirror device ("DMD"), a spatial light modulator ("SLM") system, or any other suitable subsystem for projecting a patterned UV light image 12a (hereinafter simply "light signal 12a"). Light signal 12a forms a projected light pattern that is in a wavelength band capable of initiating polymerization, and has sufficient power (mW / cm2) to cause polymerization. 2 ) and sufficient flux (mJ / cm 2 ) The optical signal 12a may be pulsed, continuous, incoherent, or coherent.

[0020] The wavelength of the optical signal 12a can vary and can be within a range suitable for initiating polymerization of the photoresist used. In one embodiment, the wavelength of the optical signal 12a is selected to be about 405 nm. Other common wavelengths that may be used in photopolymerizable 3D printing are, for example but not limited to, 305 nm, 352 nm, 365 nm, 375 nm, 385 nm, 405 nm, 450 nm, 460 nm, and 470 nm. These wavelengths are the general center bands of the common light sources used. When they are produced by LED light sources, they usually have a bandwidth of about 20 nm to about 40 nm. The choice of light used depends on the requirements of the resin and possibly other factors related to the particular application. These aforementioned wavelengths span the wavelength range of 310 nm to 570 nm, although possibly further wavelengths outside this range may be used depending on the needs of the particular application.

[0021] The light projector 12 may be controlled by a processor-based electronic control system 16. The electronic control system 16 may include memory 18 (e.g., non-volatile memory, RAM, ROM, etc.) for containing control software 20. The control software 20 may include algorithms, correction files, look-up tables, and other data or files used to control manufacturing operations performed by the system 10. As further described in the following paragraphs, information collected during manufacturing operations may also be stored in the memory 18, as well as calibration information collected prior to using the system 10 to perform manufacturing operations.

[0022] 1 may further include a positioning subsystem 22, which may be, for example, a motorized stage or platform having motors (e.g., DC stepper motors) or other devices to provide highly controlled incremental movement of the collimator 14 and / or the galvanometer subsystem 16 and / or the pupil 27 and / or the focusing lens 28 along each of the X, Y, and Z axes. The positioning subsystem 22 may be controlled by the electronic control system 18 or may optionally include its own controller in communication with the electronic control system 18 (via a wired connection or wirelessly).

[0023] The system may further include a beam splitter 24 disposed downstream of the projector 12 for passing a portion of the optical signal 12a emitted from the projector 12 towards a galvanometer subsystem 26. The galvanometer subsystem 26 includes a pair of mirrors 26a and 26b for scanning the optical signal 12a in the X and Y planes. The scanned optical signal 12a is directed through an aperture stop (i.e., pupil) 27 to a focusing lens 28. In this example, the focusing lens 28 is not a flat-field lens, but operates similarly to an f-theta lens. The aperture stop 27 may be a small plate with an aperture of the desired diameter, in one example an aperture of 45 mm or so, formed in the axial center of the plate. However, in practice, the aperture stop may be of any practical size or shape, from a few mm to a few hundred mm in diameter. The size of the aperture is limited by the practical size of the scanning mirror and optics used. It should therefore be understood that the aperture size used in the aperture stop 27 may vary widely depending on the needs of a particular embodiment. One or more of collimator 14, galvanometer subsystem 26, aperture stop 27, and focusing lens 26 may be broadly considered as an optical subsystem for collimating and focusing optical signal 12a.

[0024] The focusing lens 28 focuses the optical signal 12a received from the galvanometer subsystem 26 onto a build plane 30. The build plane 30 can be understood as the surface on which the upper surface of the photopolymerizable material resides, and is typically contained within a reservoir or container. In this regard, it will be understood that the build plane 30 is actually disposed within a horizontal plane, but for purposes of explanation, FIG. 1 shows the build plane 30 and various components of the system 10 arranged side-by-side in a horizontal orientation to facilitate understanding of the operation of the system and the description of the various components of the system 10. The optical signal 12a is the optical signal used to activate selected portions of a layer of photopolymerizable resin to cure desired sections of the exposed photopolymerizable resin, which resides within the build plane as previously described, as is well understood in scanning projection stereolithography systems.

[0025] Stereolithography can also be performed in a bottom-up manner, where the photopolymerizing light is projected through an optically transparent substrate onto the bottom of a tank of photopolymerizable material. All of the techniques previously described for achieving optimized focus in the "top-down" method also apply to the bottom-up method.

[0026] The system 10 may further include a diagnostic subsystem 32 for monitoring the optical signal 12a at the build surface 30 and / or for controlling the focusing of the optical signal 12a by highly controlled movement of the collimator 14. The diagnostic subsystem 32 may include a flood illumination source 34 for generating an optical flood illumination signal to illuminate some or all of the build surface 30, an optical signal generating system 36, such as a laser (hereinafter simply "laser 34") for generating a laser optical signal 36a, and a camera 38 having an associated lens 38a. The diagnostic subsystem 32 may also include a movable stage or actuated optical element (e.g., a motorized stage or platform) 40 for moving a diagnostic focus control lens 42 along the X and Y axes in real time to keep the optical signals 36a and 38a focused at a specific location on the build surface 30. Mirrors or diffraction gratings 44, 46, and 48 may also form part of the diagnostic subsystem 32 to assist in directing the flood illumination light signal 34a (using mirror 42) and the laser diagnostic light signal 36a (using mirror 46) to the beam splitter 24.

[0027] The signals 34a and 36a may be combined to form a diagnostic light signal D1, which is reflected using a mirror 50 of the diagnostic subsystem 32 towards the diagnostic light focusing element lens 42. From there, the diagnostic light signal D1 is reflected by the beam splitter 24 to the galvanometer system 26 where it is steered onto the build surface 30 along with the polymerization light signal 12a. The diagnostic light signal D1, along with a portion of the polymerization light signal 12a, labeled 12a1 in FIG. 1, is reflected off the build surface 30 back to the diagnostic subsystem 32 where it is imaged by the camera 38. The camera 38 may provide digital information representing the image at the build surface 30 in real time to the electronic controller for analysis, as described in the following paragraphs. The laser light signal 36a is useful during a pre-operational calibration procedure to help determine the optimal X / Y location where the diagnostic focus control mirror 42 needs to be positioned to maintain optimal focus at various X / Y locations on the build surface 30. This feature is discussed further in the following paragraphs.

[0028] 1 thus provides two different optical paths: a first optical path, labeled with the reference character P1, along which the optical signal 12a from the light projector 12a travels to the build surface 30, and a second optical path, labeled with the reference character 52, along which a small reflected portion of the optical signal 12a, portion 12a1, travels back to the diagnostic subsystem 32. Optical path 52 partially overlaps path P1, but this does not affect the system operation in any way.

[0029] The flood illumination source 34 provides a light signal outside the range of wavelengths that cause polymerization of the photoresist material being used. The wavelength selected for the flood illumination signal 34a in one embodiment is approximately 630 nm (i.e., well longer than the 405 nm wavelength that causes polymerization of the photoresist material). It should be understood that the particular wavelength used to illuminate the build area for monitoring purposes must be outside the activation band of the photopolymerizable resin. For many common UV-activated resins, a 630 nm LED is well outside the wavelength range. 800 nm is also another common LED range that is well outside the activation wavelength. Thus, for example, a system operating at 365 nm for photopolymerization can use a 630 nm wavelength flood illumination signal, or optionally, a 800 nm wavelength flood illumination signal.

[0030] The laser 36 has a wavelength outside the photopolymerization band, which in one embodiment may be, for example, about 630 nm. In one embodiment, it is fiber coupled to a single mode fiber. The fiber output is focused via optics to the plane of the 405 nm polymerization light. In this way, the optimal focus position of the laser spot is used to locate the best focused photopolymerization plane using the non-polymerization wavelength of the laser.

[0031] The diagnostic focus control lens 42 is moved using the movable stage 40 to image the spot that the optical signal 12a is illuminating on the build surface 30. The optical laser signal 36a is used to establish a reference point at a known Z-axis location relative to the build surface 30 during a calibration operation. This Z-axis location can be stored in memory 18 for use by the control software 20. By using the diagnostic focus lens 42 to image the spot on the build surface 30 that the optical signal 12a is acting on, the laser 36 provides a focus check to help determine exactly where (i.e., at what Z-axis location relative to the build surface 30) the collimator 14 should be moved to maintain its optimum focus as the polymerization optical signal 12a strikes the build surface 30. To this end, a look-up table can be created during calibration and testing of the system 10 and stored in memory 18 for use by the electronic control system 10 and the software control module 20 during real-time use of the system 10. The look-up table may be a table of Z-axis position values ​​of the collimator 14 (and optionally the diagnostic focus control lens 42) as the polymerized light signal 12a is scanned to all X / Y points on the build surface 30 to achieve an optimal focus of the light signal 12a at each particular X / Y location on the build surface 30.

[0032] A unique feature of system 10 is the placement of aperture stop 27 on the scan lens side (i.e., “downstream”) of galvanometer system 26. This results in a consistent pupil position with respect to focusing lens 28, greatly easing the design of focusing lens 28 and greatly improving performance. When aperture stop 27 is positioned “upstream” of galvanometer mirrors 26a and 26b, the pupil presented to focusing lens 28 (or f-theta lens) is pivoted as galvanometer mirrors 26a and 26b scan along the X and Y axes. This makes the design of focusing lens 28 more difficult and generally results in poorer performance. However, one consequence of placing aperture stop 27 downstream of galvanometer system 26 is that collimator 14 can provide a slightly larger polymerized light beam 12a diameter to accommodate all angles of view without vignetting. However, the design of the collimator 14 is much easier to determine than the design of the focusing lens 28 (or the design of the f-theta lens) since the field it relays is small (i.e., approximately the same as the field of the light projector 12 (e.g., the DMD field; a DMD is typically on the order of only 1 cm x 1 cm or so). That is, by moving the aperture stop 27 downstream of the galvanometer mirrors 26a, 26b, the design burden is divided more evenly between the collimator 14 and focusing lens 28 portions of the overall system 10 design. A further consequence of this configuration is that the pupil (i.e., the opening of the aperture stop 27) is actually slightly overfilled with light, so that some of the light of the UV polymerization light signal 12a from the light projector 12 is discarded. However, this is a minimal drawback considering the significant advantages mentioned above that allow for a dramatic improvement in the design of the focusing lens 28 and thus an improvement in the overall system 10 resolution.

[0033] It should be understood that in connection with having the aperture stop 27 downstream of the galvanometer system 26, the galvanometer mirror sets are typically labeled as input and output. The output galvanometer mirror (which would be mirror 26a in FIG. 1) is typically slightly larger than the input galvanometer mirror (i.e., galvanometer mirror 26a in FIG. 1) to accommodate the turning of the light beam by the first galvanometer mirror. With the aperture stop 27 located downstream of the galvanometer system 26, it became advantageous to use the galvanometer system 26 "upside down" from its "normal" use (i.e., the larger galvanometer mirror 26a on the side next to the collimator 14). If the galvanometer mirror sets 26a and 26b were not used "upside down," a much smaller aperture would be used in the system 10, or the aperture stop 27 would be located on the collimator 14 side of the galvanometer system 26, which would make the design of the focusing lens 28 more difficult, as discussed above.

[0034] It should be understood that a "tessellated" system such as system 10 involves scanning across the build surface 30 with many high resolution image projections generated by light projector 12. These many image projections are scanned, or "tessellated," in a mosaic pattern to form a much larger image that is an assembly of many individual images. The best image for any location can be mapped into the build space in terms of both X and Y spatial location; where the image is preferably projected in mm (millimeters), and the exact Z axis spatial location of the focal positioning for collimator 14 and / or focusing lens 28 is noted for each X / Y location on the build surface 30. Thus, during the calibration process, this may be mapped with camera 38 being moved (manually or via a separate motorized stage) so that the camera is focused on the exact / desired Z axis location, typically the center of the build area. As collimator 14 is actively adjusted, the location of the collimator along the Z axis and the position of the X and Y galvanometer mirror pair (i.e., elements 26a and 26b) are recorded. Image quality is evaluated by projection of various patterns including line-pair measurements on MTF (Modulation Transfer Function). Here, the camera 38 is translated over the area of ​​the build surface 30, either by automatic means or manually. In this way, the exact voltages to the X, Y galvanometer mirrors 26a and 26b are recorded for the desired X / Y location in the build surface 30, together with the Z-axis focal position (in mm) of the collimator 14 and / or the focusing lens 28. This allows the generation of a correction file, for example in the form of the look-up table mentioned above, for use by the system 10 during operation. Thus, distortions and / or idiosyncrasies of the system are mapped and corrected. In this way, the correction file can be measured, recorded and then utilized to achieve the best performance of the system 10 (i.e. the best focus of the polymerization light signal 12a at each X / Y location on the build surface 30) and apply pre-corrections to the model of the 3D object to be printed.

[0035] The techniques described above can also be used to set up and qualify the diagnostic leg section 52 of the system 10. The camera 38 is focused across the entire field, either with a camera target on the stage or by focusing on a static target that covers the entire area of ​​the build surface 30. In this way, when the diagnostic light signal D1 is determined to be at a given X / Y location on the build surface, the particular X / Y location relative to the diagnostic focus control mirror 42 can be recorded.

[0036] The system 10, which in the above embodiment forms a large area projection microstereolithography (LAPuSL) system, can further be considered to incorporate two separate subsystems: a projection section or projection leg for optically projecting / imaging the polymerization light signal 12a onto the build surface 30 where polymerization occurs, and a diagnostic section (diagnostic subsystem 32) or "diagnostic leg" that images the build surface 30 partially along the same beam path as the polymerization optics. This is sometimes referred to as "co-linear diagnostics." Since the diagnostics are collinear, i.e., they proceed to the projected build surface 30 on the same beam path as the projection optics that they observe, diagnose, and image, they can be said to effectively "ride along" the projected polymerization light signal 12a. This allows for monitoring of the build surface 30 simultaneously with the projection of the polymerization light signal 12a onto the build surface.

[0037] The diagnostic leg 52 in FIG. 1 is typically connected to the projection leg P1 through some optics, such as the beam splitter 24 shown in FIG. 1, or optionally by a dichroic mirror or other suitable element. However, the system 10 is not limited to the use of such coupling optics positioned upstream of the scanning mechanism. Similarly, the system 10 is not necessarily limited to the use of a galvanometer scanning mirror pair, but may use other optical scanning subsystems, such as a scanning polygon mirror system, a Risley prism pair, an acousto-optical or electro-optical modulation system, etc. However, an advantage of the system 10 described herein is that the diagnostic leg 52 and the projection leg P1 are collinear, undergoing the same angular deflection from the scanner of the galvanometer system 26 and passing through focusing optics while stepping to the same X / Y location on the build surface 30. This feature then allows light from the build surface 30 produced by scattering, reflection, fluorescence, or any other mechanism to be observed by the camera 38 of the diagnostic subsystem 32.

[0038] The diagnostic leg 52 can be utilized both actively and passively to assist in setting up the system 10 for a normal print run, to observe and monitor the build surface 30 in real time while a print run is taking place, and to observe or diagnose aspects of the printing or performance of the system 10 after a print run is completed. The separation of the diagnostic functions of the system 10 into "active" and "passive" operations may be further understood and appreciated with a specific example. One example of an active diagnostic is to actively control the focus of the diagnostic to observe different focus positions or to compensate for different wavelengths. Another example is to project a light flood signal at a second wavelength to flood illuminate the build surface 30 with non-polymerizing light. This light reflecting from the build surface 30 may be observed by the camera 38, but is not limited to being observed only by a camera system. However, if a camera or other suitable imaging device is used, the build surface 30 may be resolved with high fidelity at this second wavelength band. Yet another example is to project a light signal at a second wavelength to induce fluorescence of portions within the build surface 30. The fluorescence from the build surface 30 can then be observed, for example and without limitation, by a camera system that can then resolve the fluorescence from the build surface 30 with high fidelity. Yet another example is to observe the fluorescence induced by the polymerization light (i.e., by the polymerization light signal 12a). Yet another example is to use a laser that projects a light beam to a small spot and is adjusted to be focused on the build surface to act as a reference to locate the exact build surface location. This can be done for initial setup / calibration of the system 10 and during the build process. Yet another example is to observe the polymerization light from the projection leg 52 with a collinear camera 38, both during the initial setup and during the build process as the part is manufactured.

[0039] Examples of passive diagnostic applications are numerous as well. For one, the camera 38 can be set to image the build area 30 with high fidelity. This can then be used to set the initial position of the build substrate on the build surface 30, observe the ongoing build, or observe parts within the build area with the flood illumination light previously described. Another example of passive diagnostics is observing the laser spot for focus, observing and monitoring fluorescence. In these examples, the camera 38 is integral and important to the diagnostics and overall setup of the system 10. Yet another example of passive diagnostics is that multiple cameras can be used, for example to image light signals at different wavelengths. Additionally, various types of filters can be actively or permanently employed to improve the observation of various aspects of the image made at the build surface 30. For example, the flood illumination can be turned on simultaneously with the polymerization light, but the flood illuminated light may be overwhelmed by the high intensity polymerization light and may not be distinguishable within the camera image. To accommodate this, a filter can be actively positioned within the camera to block the polymerization light, thereby allowing only the flood illumination light on the build surface 30 to be observed by the camera.

[0040] Thus, the present system 10 can determine and store the optimum focus position (i.e., optimum optical configuration) for every X / Y position on the build surface 30. The optimum focus position can be measured in advance and stored, for example, in a look-up table, spreadsheet, or other format of data file. As described above, the system 10 can use real-time diagnostics to monitor the build process and adjust the focus position on the fly as needed. However, this real-time focus position adjustment capability is not necessarily required for all applications of the system 10, although the system 10 nevertheless provides this capability, and it is anticipated that in some applications such real-time adjustment capability will still be advantageous and / or required.

[0041] It will also be appreciated that determining and selecting the optimum focus position for any X / Y location on the build surface 30 can generally be thought of as determining and selecting the highest contrast image position at each particular X / Y location on the build surface. This is important and is a key feature of the system 10. It will be appreciated that typically a projected image needs to be good (i.e. have sharp focus) over its entire projection area, such as an image projected onto a large screen in a movie theater where the entire image is projected at once. This involves a compromise in optical image quality so that all areas of the image are projected with "good enough" sharpness / focus. In the movie theater example above, this is sufficient since the customer would not be able to resolve differences or imperfections in focus / sharpness at different X / Y locations of the image being projected onto the screen. However, if one desires the highest resolution (i.e. approaching the diffraction limit) over a very large area, this becomes very difficult and expensive to achieve.

[0042] The system 10 and its optical system described above ensure that the best image is produced across the entire X / Y area of ​​the build surface 30 with little or no consideration of focus position. Normally, focus is typically the first feature or quality prioritized in an optical system. However, if one ignores it and instead creates the best image regardless of focus, no compromises need to be made and a much better image can be produced across a large area. System 10 achieves this by effectively "subdividing" a large projection layer into many separate smaller area projections. In contrast, in the movie theater example, it is not possible to adjust different parts of the image being projected onto the screen differently; rather, all areas of the image must be adjusted at once in one operation. System 10 removes this limitation and allows the focus to be adjusted for different X / Y locations across the area onto which the image is projected. Each of these smaller projections at separate X / Y locations is an opportunity to optimize the overall image quality by adjusting the focus as needed at each X / Y location on the build surface 30.

[0043] As a result, system 10 and its optics provide significantly improved image resolution across a large projection area (e.g., the entire build surface) than is achievable with typical prior art systems that have the dynamic adjustability capabilities that system 10 provides. Prior art systems do not provide this capability because they cannot project "sub-images" for different, separate X / Y locations on the build surface and then connect them together like a mosaic into a larger pattern. Thus, system 10 can provide high resolution over a large area, with focusing optimized at all X / Y locations across the entire image.

[0044] 2, a flow chart 100 is shown illustrating the major operations that can be performed using the system 10. In operation 102, a particular X / Y location on the build surface 30 is selected for operation (selection is typically made by the electronic control system 16). In operation 104, a Z-axis focus correction position signal for the collimator 14 is determined and applied by the positioning subsystem 22 to position the collimator and / or focusing lens along the Z-axis to achieve best focus at the current X / Y location. At the same time (or substantially at the same time, or thereafter, or possibly before operation 104), in operation 106, a position signal is determined and applied that is used to position the diagnostic focus control lens 42 to position the diagnostic focus control lens 42 to observe the polymerization action occurring at the selected X / Y location on the build surface 30. In operation 108, the build surface 30 is simultaneously or substantially simultaneously illuminated with both the polymerization light signal 12a and the diagnostic light signal D1 while the camera 38 is used to observe the action occurring at the X / Y location on the build surface 30. In this example, this observation / monitoring action using camera 38 occurs in real time, but need not occur in real time. In operation 110, a check is made to determine if the polymerization action is complete. If the answer to this check is no, operation 108 continues. If the answer to this check at operation 110 is yes, a check is made to determine if the scan for the entire build surface 30 is complete. If the answer to this check is no, the next X / Y location on the build surface 30 is selected for operation, as shown at operation 114, and operations 104 through 112 are repeated. If the check at operation 112 indicates that the scan for the build surface 30 is complete, operation is terminated for that particular layer of the part being manufactured using system 10.

[0045] The above description of the embodiments is provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment and, where applicable, can be interchangeable and used in selected embodiments even if not specifically shown or described. They can also be modified in various ways. Such modifications should not be considered as departures from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.

[0046] The exemplary embodiments are provided so that the disclosure will be complete and the scope will be fully conveyed to those skilled in the art. Many specific details are described, such as examples of specific components, devices, and methods, so that the embodiments of the present disclosure can be fully understood. It will be apparent to those skilled in the art that specific details need not be employed, and that the exemplary embodiments can be embodied in many different forms, none of which should be construed as limiting the scope of the present disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0047] The terminology used herein is for the purpose of describing specific exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may be intended to include the plural unless the context clearly dictates otherwise. The terms "comprises", "comprising", "including" and "having" are inclusive and thus specify the presence of stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. The method steps, processes and operations described herein should not be construed as necessarily requiring performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It should be understood that additional or alternative steps may also be employed.

[0048] When an element or layer is said to be "on", "engaged with", "connected to", or "coupled to" another element or layer, it may be directly on, engaged with, connected to, or coupled to the other element or layer, or there may be intervening elements or layers present. In contrast, when an element is said to be "directly on", "directly engaged with", "directly connected to", or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe relationships between elements should be interpreted similarly (e.g., "between" and "directly between", "adjacent" and "directly adjacent", etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0049] In this specification, terms such as first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or section from another region, layer, or section. As used herein, terms such as "first" and "second," and other terms denoting numerical values, do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer, or section discussed below may also be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0050] To describe the relationship of one element or feature to another as shown in the figures, spatially relative terms such as "inside," "outside," "lower," "below," "lower side," "upper," "upper" and the like may be used herein for ease of description. Spatially relative terms may be intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "below" other elements or features would be oriented "above" the other elements or features. Thus, the exemplary term "lower" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative language used herein would be interpreted accordingly.

[0051] Description of Various Embodiments of the Disclosure Embodiment 1: A system for performing scanning projection stereolithography comprising: an optical projector configured to generate a polymerization light signal that initiates polymerization of a photopolymerizable resin or material at a build surface; an optical system subsystem for collimating and focusing the polymerization light signal, the optical system subsystem being movable relative to the build surface to optimize a focus of the polymerization light signal at the build surface; an optical scanning subsystem configured to direct the polymerization light signal received from the optical system subsystem to selected X-axis and Y-axis locations on the build surface; and a positioning subsystem for positioning the optical system subsystem at a selected location relative to the build surface, the selected location being chosen to optimize focusing of the polymerization light signal at a particular selected X / Y location on the build surface.

[0052] Embodiment 2: The system of claim 1, wherein the optical subsystem comprises a collimator.

[0053] Embodiment 3: The system of claim 1, wherein the optical subsystem comprises a focusing lens.

[0054] Embodiment 4: The system of claim 1, wherein the optical subsystem comprises a collimator and a focusing lens.

[0055] Embodiment 5: The system of claim 1, wherein the optical subsystem includes a focusing lens, the focusing lens being disposed downstream of the optical scanning subsystem and upstream of the building surface with respect to the direction of travel of the polymerization light signal to focus the polymerization light signal at specific selected X-axis and Y-axis locations on the building surface.

[0056] Embodiment 6: The system of any one of claims 1 to 5, further comprising a diagnostic subsystem configured to optically monitor polymerization events occurring at selected X-axis and Y-axis locations on the build surface.

[0057] Embodiment 7: The system of any one of claims 1 to 5, further comprising: an optical component disposed in a path of the polymerization light signal to enable passage of the polymerization signal through the optical component; and a diagnostic subsystem configured to optically monitor polymerization occurring at selected X-axis and Y-axis locations on the building surface by receiving a portion of the polymerization light signal reflected from the optical component; the optical component enables a reflected portion of the polymerization light signal reflected from the building surface to be redirected through the optical component to the diagnostic subsystem.

[0058] Embodiment 8: The system of claim 6 or 7, wherein the diagnostic subsystem includes one or more cameras for imaging optical signals returning from the build surface to observe polymerization occurring at the build surface during formation of the part.

[0059] Embodiment 9: A system as described in any one of claims 6 to 8, wherein the diagnostic subsystem further includes a flood illumination source for producing an optical flood illumination signal, the optical flood illumination signal being passed through optical components and scanned onto the build surface by the optical scanning subsystem to flood-irradiate the build surface with flood illumination light, and the flood illumination light fails to initiate polymerization of the photopolymerizable resin on the build surface.

[0060] Embodiment 10: A system as described in any one of claims 6 to 9, wherein the diagnostic subsystem further includes a laser configured to provide a laser light signal directed onto the build surface to assist in determining a reference location relative to the build surface.

[0061] Embodiment 11: The system of claim 10, wherein the optical flood illumination signal and the laser optical signal are combined to form a diagnostic optical signal, and the diagnostic subsystem further includes a diagnostic focus control lens for receiving the diagnostic optical signal from the diagnostic subsystem and directing the diagnostic optical signal to the diagnostic focus control lens, the diagnostic focus lens is further configured to direct the diagnostic optical signal to the optical component, the optical component redirects the diagnostic optical signal to the optical scanning subsystem, and the optical scanning subsystem then scans the diagnostic optical signal onto the build surface at the same X-axis and Y-axis locations as the polymerization optical signal is directed.

[0062] Embodiment 12: The system of claim 11, wherein the diagnostic subsystem further comprises at least one of a movable stage or a motorized optical assembly for controllably positioning a diagnostic focus control lens such that the optical component directs the diagnostic light signal into an optical path along which the polymerization light signal travels.

[0063] Embodiment 13: A system described in any one of claims 1 to 12, wherein the optical scanning subsystem comprises a galvanometer subsystem.

[0064] Embodiment 14: The system of claim 13, wherein the galvanometer subsystem comprises first and second scanning mirrors configured to scan the polymerization light signal along the X and Y axes to specific selected X and Y axis locations on the build surface.

[0065] Embodiment 15: The system of claim 10, wherein the optical flood illumination signal comprises a first optical signal having a wavelength outside of a wavelength band capable of causing polymerization of a photopolymerizable resin or photopolymerizable material, and the laser optical signal comprises a second optical signal having a wavelength outside of a wavelength band capable of causing polymerization of a photopolymerizable resin or photopolymerizable material.

[0066] Embodiment 16: A system according to any one of claims 1 to 15, wherein the light projector comprises at least one of a spatial light modulator or a digital micromirror device.

[0067] Embodiment 17: The system of claim 5, further comprising an aperture stop component disposed between the optical scanning subsystem and the focusing lens to define a diameter of the polymerization light signal projected onto the build surface.

[0068] Embodiment 18: A system for performing scanning projection stereolithography, comprising: an optical projector configured to generate a polymerization light signal that initiates polymerization of a photoresist material at a build surface; a collimator for collimating the polymerization light signal, and a focusing lens system for focusing the polymerization light signal, wherein at least one of the collimator or the focusing lens system is adjustable by movement along an axis relative to the build surface to optimize a focus of the polymerization light signal at the build surface; and an optical scanning subsystem configured to direct the polymerization light signal received from the collimator and focusing lens system to selected X-axis and Y-axis locations on the build surface. a focusing lens disposed downstream of the light scanning subsystem and upstream of the build surface with respect to a direction of travel of the polymerization light signal from the light projector to focus the polymerization light signal at selected X-axis and Y-axis locations on the build surface; a positioning subsystem for positioning at least one of the collimator or the focusing lens at a selected location along the Z-axis, the selected location being selected to optimize focusing of the polymerization light signal at a particular selected X-axis and Y-axis location on the build surface; and a diagnostic subsystem including a camera for imaging a portion of the polymerization light signal reflected from the build surface to observe polymerization occurring at the build surface during formation of a part.

[0069] Embodiment 19: The system of claim 18, wherein the focusing lens is translated to locate a position of optimal focus / performance of the system, the optimal focus / performance being represented by the highest contrast image position at each particular X-axis and Y-axis location on the build surface.

[0070] Embodiment 20: The system of claim 18 or 19, further comprising a signal splitting element for passing the polymerization light signal through the signal splitting element as the polymerization light signal travels along a first optical path in a first direction toward the building surface, and for reflecting a portion of the polymerization light signal in a second direction opposite the first direction toward a camera of the diagnostic subsystem.

[0071] Embodiment 21: A system as described in any one of claims 18 to 20, wherein the diagnostic subsystem includes: a laser for generating a laser light signal; a diagnostic focus control lens for steering the laser light signal onto a signal splitting element so that the laser light signal can be steered towards and onto the building surface by the optical scanning subsystem; and a movable stage for moving the diagnostic focus control lens to assist in directing the laser light signal towards the signal splitting element.

[0072] Embodiment 22: A system as described in any one of claims 18 to 21, wherein the diagnostic subsystem further includes a flood illumination source for generating a flood illumination light signal, the flood illumination signal being steered by a diagnostic focusing lens towards a signal splitting element, which reflects the flood illumination light signal towards the optical scanning subsystem for subsequent scanning onto the building surface.

[0073] Embodiment 23: A method for performing scanning projection stereolithography, comprising: projecting a polymerization light signal toward a build surface, where the polymerization light signal can initiate polymerization of a photopolymerizable resin or photopolymerizable material located on the build surface; scanning the polymerization light signal to selected X and Y axis locations on the build surface; collimating and focusing the polymerization light signal before the polymerization light signal reaches an optical scanning subsystem; adjusting a position of an optical subsystem before the polymerization light signal reaches the optical scanning subsystem; and optimizing a focus of the polymerization light signal when the polymerization light signal reaches a specific X and Y axis location on the build surface.

[0074] Embodiment 24: The method of claim 23, wherein collimating or focusing includes using at least one of a collimator or a focusing lens.

[0075] Embodiment 25: The method of claim 23 or 24, further comprising monitoring operation of the polymerization light signal at the build surface.

[0076] Embodiment 26: The method of claim 25, wherein monitoring operation of the polymerization light signal at the build surface includes monitoring operation of the polymerization light signal at the build surface in real time using a diagnostic subsystem.

Claims

1. 1. A system for performing scanned projection stereolithography using multiple independent image projections to create tessellated images for each layer of a 3D part being formed, comprising: an optical subsystem having a collimator; a build surface forming an upper surface of the layer of photopolymerizable resin; an electronic controller having a memory including a correction / calibration file including a plurality of Z-axis position values ​​of the collimator as the polymerization light signal is scanned to a plurality of different X / Y axis locations within the build surface to achieve an optimal focus of the light signal at the build surface for each particular X / Y location; a light projector configured to generate a polymerization light signal to initiate polymerization of a layer of photopolymerizable resin present on the build surface; the optical system subsystem is configured to collimate and focus the polymerization light signal, is movable along the Z-axis and positionable to different predefined Z-axis positions relative to the top surface of the build surface and in accordance with information in a correction / calibration file that optimizes the Z-axis focus of the polymerization light signal at each of a plurality of predefined different X-axis and Y-axis locations on the build surface relative to the top surface of the build surface, the Z-axis being perpendicular to each of the X-axis and Y-axis, each of the predefined Z-axis positions corresponding to a particular location of the plurality of predefined different X-axis and Y-axis locations on the build surface, the predefined Z-axis positions being stored in the correction / calibration file along with the corresponding X-axis and Y-axis locations; an optical scanning subsystem configured to direct the polymerized optical signals received from the optical system subsystem to selected X-axis and Y-axis locations on the build surface in one of a mosaic pattern, or as a tessellated, plurality of individual image projections to form a larger image that is a collection of the plurality of individual image projections; and a positioning subsystem configured to access a correction / calibration file in the memory, obtain specific locations of Z-axis positions corresponding to X-axis and Y-axis locations on the surface to be printed, position the optical subsystem at selected locations of predefined Z-axis positions corresponding to X-axis and Y-axis locations on the top surface of the build surface to be printed, and create some of the multiple independent image projections used to compose a tessellated image on the surface of the build surface, while canceling distortions and idiosyncrasies of the system.

2. The system of claim 1 , wherein the optical subsystem comprises a focusing lens.

3. 2. The system of claim 1, wherein the optical subsystem further comprises a focusing lens, and at least one of the collimator or the focusing lens is moved along the Z axis to optimize focus at each of the X and Y axis locations printed.

4. 2. The system of claim 1, wherein the optical subsystem includes a focusing lens, the focusing lens being disposed downstream of the optical scanning subsystem and upstream of the building surface relative to a direction of travel of the polymerization light signal to focus the polymerization light signal at a specific selected X-axis and Y-axis location on the building surface.

5. 10. The system of claim 1, further comprising a diagnostic subsystem configured to optically monitor polymerization occurring at each of selected X-axis and Y-axis locations on the build surface being printed.

6. an optical component disposed in a path of the combined optical signal to enable passage of the combined signal therethrough; a diagnostic subsystem configured to optically monitor polymerization occurring at each of the selected X-axis and Y-axis locations on the build surface by receiving a portion of the polymerization light signal reflected from the optical component; and Further equipped with an optical component enabling a reflected portion of the polymerization light signal reflected from the build surface to be redirected through the optical component to a diagnostic subsystem; The system of claim 1 .

7. The system of claim 6 , wherein the diagnostic subsystem includes one or more cameras for imaging optical signals returning from the build surface to observe polymerization occurring at the build surface during formation of the part.

8. 8. The system of claim 7, wherein the diagnostic subsystem further includes a flood illumination source for producing an optical flood illumination signal, the optical flood illumination signal being passed through the optical components and scanned onto the build surface by the optical scanning subsystem to flood illuminate the build surface with flood illumination light, and the flood illumination light fails to initiate polymerization of the photopolymerizable resin at the build surface.

9. The system of claim 8 , wherein the diagnostic subsystem further comprises a laser configured to provide a laser light signal directed onto the build surface to assist in determining a reference location relative to the build surface.

10. the optical flood illumination signal and the laser optical signal are combined to form a diagnostic optical signal; the diagnostic subsystem further includes a diagnostic focus control lens for receiving the diagnostic light signal from the diagnostic subsystem and directing the diagnostic light signal to the diagnostic focus control lens, the diagnostic focus lens further configured to direct the diagnostic light signal to the optical component, which redirects the diagnostic light signal to the optical scanning subsystem, which then scans the diagnostic light signal onto the build surface at the same X-axis and Y-axis locations as the polymerization light signal is directed; The system of claim 9.

11. 11. The system of claim 10, wherein the diagnostic subsystem further comprises at least one of a movable stage or a motorized optical assembly for controllably positioning a diagnostic focus control lens such that the optical component directs the diagnostic light signal into an optical path traveled by the polymerization light signal.

12. The system of claim 1 , wherein the optical scanning subsystem comprises a galvanometer subsystem.

13. 13. The system of claim 12, wherein the galvanometer subsystem comprises first and second scanning mirrors configured to scan the polymerization light signal along the X and Y axes to specific selected X and Y axis locations on the build surface.

14. the optical flood illumination signal comprises a first optical signal having a wavelength outside a wavelength band capable of causing polymerization of a photopolymerizable resin or material; the laser light signal comprises a second light signal having a wavelength outside a wavelength band capable of causing polymerization of the photopolymerizable resin or material; The system of claim 9.

15. The light projector Spatial Light Modulator or Digital Micromirror Device The system of claim 1 , comprising at least one of:

16. The system of claim 4 , further comprising an aperture stop component disposed between the optical scanning subsystem and the focusing lens to define a diameter of the polymerization light signal projected onto the build surface.

17. 1. A system for performing scanned projection stereolithography to assist in the creation of a three-dimensional part, using multiple independent image projections to create tessellated images for each layer of a three-dimensional part being formed, comprising: a build surface forming an upper surface of the layer of polymerizable resin; an electronic control system including a memory; a collimator; the memory includes a correction / calibration file including a plurality of Z-axis position values ​​of the collimator as the polymerization light signal is scanned to a plurality of different X / Y axis locations within the build surface so that the collimator achieves an optimal focus of the light signal on the upper surface of the build surface for each particular X / Y location; a light projector configured to generate a polymerization light signal to initiate polymerization of the photoresist material at the build surface; The collimator is configured to collimate the polymerization light signal; an optical scanning subsystem configured to direct the polymerized optical signal received from the collimator to each of a plurality of predetermined X-axis and Y-axis locations on the build surface as a plurality of individual image projections in one of a mosaic pattern, or as a tessellated image, to form a larger image that is a collection of the plurality of individual image projections; a focusing lens disposed downstream of the optical scanning subsystem and upstream of the build surface relative to a direction of travel of the polymerization light signal from the optical projector for sequentially focusing the polymerization light signal at each of predetermined X-axis and Y-axis locations on the upper surface of the build surface to create a plurality of independent image projections required to create a tessellated image on the upper surface of the build surface; a positioning subsystem for positioning at least one of the collimator or focusing lens at a selected one of a plurality of different locations along the Z axis, each of the plurality of different Z axis locations being stored in a correction / calibration file and acquired by the positioning subsystem in response to a particular location of a predetermined X axis location and Y axis location to be printed, the selected one of the plurality of different Z axis locations being chosen to create one of a plurality of independent image projections having an optimal focus relative to the top surface of the build surface at the particular selected X axis location and Y axis location on the top surface of the build surface, while canceling distortions and idiosyncrasies of the system; and a diagnostic subsystem including a camera for imaging a portion of the polymerization light signal reflected from the build surface to observe polymerization occurring at the build surface during formation of the part.

18. 20. The system of claim 17, wherein the focusing lens is translated according to a selected Z-axis location obtained from a correction / configuration file to locate a position of optimum focus / performance of the system, the optimum focus / performance being represented by the highest contrast image position at each particular X-axis and Y-axis location on the build surface.

19. 20. The system of claim 17, further comprising a signal splitting element for passing the polymerization light signal therethrough as the polymerization light signal travels along a first optical path in a first direction toward the build surface and for reflecting a portion of the polymerization light signal in a second direction opposite the first direction toward a camera of the diagnostic subsystem.

20. The diagnostic subsystem: a laser for generating a laser light signal; a diagnostic focus control lens for steering the laser light signal onto the signal splitting element such that the laser light signal can be steered by the optical scanning subsystem towards and onto the build surface; a movable stage for moving the diagnostic focus control lens to assist in directing the laser light signal to the signal splitting element; 20. The system of claim 19, comprising:

21. The diagnostic subsystem: a flood illumination source for generating a flood illumination light signal, the flood illumination signal being steered by a diagnostic focusing lens towards a signal splitting element which reflects the flood illumination light signal towards an optical scanning subsystem for subsequent scanning onto the build surface; 21. The system of claim 20, further comprising:

22. 1. A method for performing scanning projection stereolithography, comprising: projecting a polymerization light signal toward the building surface, the polymerization light signal being capable of initiating polymerization of a photopolymerizable resin or material located on the building surface; scanning a polymerization light signal onto a build surface at selected X and Y axis locations; Collimating and focusing the polymerization optical signal before it reaches the optical scanning subsystem; adjusting a position of the optical subsystem before the polymerization optical signal reaches the optical scanning subsystem; optimizing the focus of the polymerization light signal when it reaches a particular X-axis and Y-axis location on the build surface; A method comprising:

23. 23. The method of claim 22, wherein collimating or focusing comprises using at least one of a collimator or a focusing lens.

24. Monitoring the operation of polymerization light signals at the build surface 24. The method of claim 22 or 23, further comprising:

25. 25. The method of claim 24, wherein monitoring operation of the polymerization light signal at the build surface comprises monitoring operation of the polymerization light signal at the build surface in real time using a diagnostic subsystem.

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