Patent Publication Number: US-2023134032-A1

Title: High Speed Light Valve System

Description:
RELATED APPLICATION 
     The present disclosure is part of a non-provisional patent application claiming the priority benefit of U.S. Patent Application No. 63/107,310, filed on Oct. 29, 2020, which is incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to operation of high speed light valve systems. More particularly, use of electron emission and novel architecture suitable for high speed operation is described. 
     BACKGROUND 
     High power laser systems able to operate at high fluence for long durations are useful for additive manufacturing and other applications that can benefit from use of patterned high energy lasers. Unfortunately, many existing high power laser systems needed for additive manufacturing or other applications cannot operate at full speed due to relatively slower operation of light valves. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise specified. 
         FIG.  1 A  illustrates an example of a high speed reflective light valve (RLV) for metal additive manufacturing; 
         FIG.  1 B (i) illustrates an example of a high speed electron beam addressed RLV (EBA-RLV); 
         FIG.  1 B (ii) illustrates an example of an embodiment to an EBA-RLV incorporating an electron beam array; 
         FIG.  1 B (iii) illustrates an example of an embodiment of an EBA-RLV incorporating a photoconducting separating layer; 
         FIG.  1 C  illustrates an example of a high-speed directly coupled self-emissive display addressed RLV (e-RLV); 
         FIG.  1 D (i) illustrates an example of a high-speed dual photoconductor LV 
         FIG.  1 D (ii) illustrates an example of a high-speed dual photoconductor LV utilizing fringe field switching; 
         FIG.  1 E  illustrates an example of a high-speed LV utilizing in-plane switching; 
         FIGS.  1 F (i) and  1 F(ii) together illustrate an example of an architecture for high speed LV system (HSLV unit)  100 F(i) and its timing  100 F(ii); 
         FIG.  1 F (iii) illustrates an example of use of multi-point LVs switches for the high speed LV system of  FIG.  1 F (i); 
         FIG.  1 G  illustrates an example of an architecture using an array of HSLV units; 
         FIG.  2    illustrates a block diagram of a high fluence light valve based additive manufacturing system supporting a beam dump, a high speed light valve, and a heat engine; 
         FIG.  3    illustrates a high fluence high speed light valve based additive manufacturing system; 
         FIG.  4    illustrates another embodiment of a high fluence high speed light valve based additive manufacturing system; and 
         FIG.  5    illustrates another embodiment of a high fluence high speed light valve based additive manufacturing which incorporates a switchyard approach for recovery and further usage of waste energy. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the accompanying drawings that form a part thereof, and in which is shown by way of illustrating specific exemplary embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the concepts disclosed herein, and it is to be understood that modifications to the various disclosed embodiments may be made, and other embodiments may be utilized, without departing from the scope of the present disclosure. The following detailed description is, therefore, not to be taken in a limiting sense. 
     In the following disclosure, an additive manufacturing system includes a high power laser to form a high fluence laser beam. A 2D patternable light valve having a structure responsive to electron emission is positioned to receive and pattern light received from the high power laser. 
     Light valve (LV) technology is limited in ability to switch pixel speeds. In some described embodiments discussed herein: 
     The use of described LVs in a metal additive manufacturing system (M-AM LV) system allows for a large increase (&gt;1000× over conventional LVs) in speed by changing to materials that can support fast switching times such as LiNbO3, BBO, KDP or K*DP; 
     The use of described LVs in a M-AM LV system allows reduced complexity of while allowing for &gt;10-1000× improvement (over existing LV M-AM systems) in frame speed; 
     The use of described LVs in a M-AM system allows for speed improvements due to the ability to use fringe field switching (FFS) in a LV system while reducing complexity. This reduction is due to reduced thickness of the LEOL when using Fringe field switching with an expected speed increase of 4-10× (over existing LV M-AM systems); 
     The use of described LVs in a M-AM LV allows for In-plane switching to be realized in a LV with its commensurate speed increase due to a thickness reduction of it LEOL layer, such speed increase are similar to that of Fringe Field (4-10×) but at a reduced complexity over that required in FFS; 
     The use of described LVs in a M-AM LV system allows for the use of PI cells to be used in a binary tree with slow patterning LVs and timewise slicing the output of the 2N LVs into a sequence resulting in an Nx improvement in overall frame speed over conventional M-AM LV systems; 
     The use of described LVs in a M-AM LV system allows for an improvement in speed by using a solid state scanning (SSS) non-patterning LV to select an array of 1D or 2D slow LVs with speeds dependent on number of set angles that the SSS can attain. Such a system also allows for random access sequencing of the slow patterning LVs. 
       FIG.  1 A  illustrates an example of a speed reflective light valve (RLV)  100 A for metal additive manufacturing. The RLV ( 110 A) is composed of a top Transparent Conductive Oxide (TCO,  120 A) which is deposited to the top of a photoconductor ( 130 A). A high reflective mirror ( 140 A) is deposited to the bottom of  130 A and is &gt;99.9% reflective for 990-1070 nm light and &gt;75% reflective for 265-500 nm light. An alignment or impedance layer is deposited onto the interior side of  140 A and is used to interface to a linear electro-optic (LEO,  160 A). Another alignment or impedance layer ( 170 A) is used to interface to  160 A and is attached to the bottom TCO ( 180 A), which is deposited onto the supporting substrate ( 190 A). 
     A low fluence patterned write beam ( 200 A) at λ2 passes through  120 A, and into  130 A causing  130 A to reduce its resistance in a circuit composed of  120 A,  130 A,  140 A,  150 A,  160 A,  170 A and terminating at  180 A. This electrical circuit is controlled by an external controller not shown. The change in resistance in  130 A mirrors the intensity pattern in  200 A and permits the non-patterned electric field seen at  120 A to become a patterned field at  140 A. This patterned field is also imposed across  160 A which causes a change in this material&#39;s birefringence as seen by a high fluence laser beam (HFL,  210 A) entering  110 A. The high fluence beam ( 210 A) is at λ1 and travels from right to left entering  110 A by passing through  190 A,  180 A,  170 A before it interacts with the patterned birefringence of  160 A. The patterned birefringence of  160 A imposes the pattern in  200 A onto  210 A as it passes through  160 A. The HFL passes through  160 A and  150 A before reflecting off  140 A and again passes through  160 A,  170 A,  180 A, and  190 A before leaving  110 A as a patterned HFL in the form of  220 A. The double pass through  160 A requires that  160 A is structured so that the double pass imposes the pattern that was on  200 A onto  210 A. Because the full effect of  160 A is felt in a double pass method, its physical distance can be reduced by &gt;50% allowing the speed to be increased by &gt;4× over that of a standard transmissive LV. The patterned HFL beam ( 220 A) passes through a beam pattern separator ( 230 A) allowing the desired pattern  240 A to be re-imaged into the print chamber while the unwanted pattern (not shown for clarity) is sent to either a beam dump or a switchyard system. 
     In the case where  200 A is not present, an unpatterned HFL beam ( 250 A) enters  110 A and passes through  190 A,  180 A,  170 A,  160 A,  150 A, reflects off of  140 A and again transits  150 A,  160 A,  170 A,  180 A and  190 A before leaving the  110 A as an unpatterned HLF beam  260 A. Upon striking  230 A, it is fully rejected (as  270 A) into either a beam dump or into a switchyard system such as later discussed with respect to  FIG.  5   . 
       FIG.  1 B (i) illustrates an example of a high-speed electron beam addressed RLV (EBA-RLV)  100 B(i). EBA-RLV  100 B 9 ( i ) is composed of a secondary emission grid ( 115 B(i)) which collects negative charges which either are scattered off the surface of the structured via array ( 120 B(i)), emit from  120 B(i) from a ballistic charge, or are pulled off as a function of  120 B(i)&#39;s voltage.  115 B(i) allows  120 B(i) to a charge ‘pixel’ defined by the electron beam to have a positive, neutral or negative charge and allows the pixel to be better defined than those systems without such a screen. The via layer ( 120 B(i)) can be structured by being made of anisotropic matrix in which platelet conductive particles are scattered throughout its volume, a silicon or polymer based electrical via array commonly used in microelectronics as a fanout interlayer, or flex layer with similar arrangements of microscopic or nanoscopic through conduction paths. Attached to  120 B(i) is a High Reflective Mirror (HRM,  130 B(i)) which is &gt;99% reflective for 990-1070 nm light. Attached to  130 B(i) is an alignment or impedance layer ( 140 B(i)) which sets up the orientation of the Linear Electro-Optic layer ( 150 B(i)). An additional alignment/impedance layer ( 160 B(i)) aids in defining the orientation of  150 B(i). A Transparent Conductive Oxide (TCO,  170 B(i)) terminates  110 B(i)&#39;s electrical circuit composed of  115 B(i),  120 B(i),  130 B(i),  140 B(i),  150 B(i), and  160 B(i). A supporting substrate ( 180 B(i)) provides stability for 110B(i). 
     The electron source which defines a pixel in  110 B(i) is generated by an electron gun (can also be a tunneling electron source, a Spindt type cold cathode emitter or similar electron beam generator) which emits a stream of free electrons ( 200 B(i)). Deflection and focusing structures allow the beam to be swept in the “x” ( 210 B(i)) and “y” ( 220 B(i)) directions across the face of  115 B(i), which in tandem with  115 B(i) defines charged pixels in  120 B(i) and varying voltage fields across  150 B(i). Modulating the strength of  200 B(i) along with the waveform imposed on  115 B(i) allows for gray scale imagery to be imposed on  150 B(i). The current and voltage control for  190 B(i) is conveyed to  190 B(i) by way of control line  230 B(i) from the electron beam electronics module ( 270 B(i)). Likewise, the control of the voltage waveform for  210 B(i) and  220 B(i) are conveyed by control lines  240 B(i) and  250 B(i), respectively from  260 B(i) (X-Y deflection driver) controlled by  270 B(i). In addition,  270 B(i) controls the voltage and current waveform of  115 B(i) by way of  280 B(i) control line.  270 B(i) is controlled by the LV electronics module ( 290 B(i)) which also controls the voltage waveform of  170 B(i) by way of  300 B(i) control line. 
     Operation of  110 B(i) as a light valve requires that an unpatterned high fluence beam ( 310 B(i)) enters  110 B(i) by passing through  180 B(i),  170 B(i),  160 B(i),  150 B(i)  140 B(i) and reflecting off  130 B(i) before traversing  140 B(i),  150 B(i),  160 B(i),  170 B(i) and exiting  180 B(i). The charge image that is deposited by the raster scanning  200 B(i) across  115 B(i) and  120 B(i) is transferred as a voltage image across  150 B(i). This voltage image acts upon  150 B(i) causing its optical response to change. The optical response of  150 B(i) is usually a change in its birefringence but can also be a phase change, spectral, scattering, absorption, or reflection response as seen by  310 B(i). The voltage image imposes an optical response image on  150 B(i), the double passage of  310 B(i) through  150 B(i) imposes that image onto  310 B(i) changing it to a patterned HFL beam ( 320 B(i)).  320 B(i) passes out of  110 B(i) and strikes the beam pattern separator ( 330 B(i)) which splits the desired pattern image ( 370 B(i)) from the undesired image. The desired image ( 370 B(i)) is relayed to the print chamber while the undesired image (not shown) goes to either a beam dump or a switchyard system. 
     In the situation where an unpatterned HLF beam ( 340 B(i)) enters  100 B(i) where there is no image presented by the electron beam system, this light is not affected and not patterned by  110 B(i) and exits unpatterned ( 350 B(i)) and upon striking  330 B(i), is diverted into  360 B(i) as it is sent to either a beam dump or a switchyard system. The frame rates of an EBA-RLV system can exceed E6 frames per second and would be likely limited by the switch time of  150 B(i) than the capabilities of the scanning electron beam electronics. 
       FIG.  1 B (ii) illustrates an example of an embodiment to an EBA-RLV  100 B(ii) incorporating an electron beam array. Light valve  110 B(ii) is activated by a 2D addressable electron emitters ( 120 B(ii)) which contain rows and columns of separately addressable field emitters ( 125 B(ii)) in an active matrix arrangement. Activation of one such emitter ( 125 B(ii)) allows electron emission ( 127 B(ii)) to be locally deposited onto  110 B(ii) so that a charged pixel ( 130 B(ii)) is generated and a modification of the LEO layer within  110 B(ii)) is affected. The row and column addressing of  120 B(ii) is controlled by an electron beam array driver( 160 B(ii)) and is conveyed to  120 B(ii) by control lines  140 B(ii) (column control lines) and  150 B(ii) (row control lines). A LV electronics controls  160 B(ii) including the voltage waveform imposed on the TCO inside  110 B(ii) via the control line  180 B(ii). As described in  FIG.  1 B , an incoming unpatterned HFL ( 190 B(ii)) enters  110 B(ii) and leaves as a patterned HFL ( 200 B(ii)) wherever an electron beam pixel has been activated.  200 B(ii) is split by beam pattern separator ( 210 B(ii)) into the desired patterned HFL beam ( 220 B(ii)), which is imaged to the print chamber, and an undesired pattern that goes into a beam dump or a switchyard system. If an unpatterned HFL beam ( 230 B(ii)) enters  110 B(ii) where there is no electron beam pixel is activated, it will leave  110 B(ii) as an unpatterned HFL beam ( 240 B(ii)) and be totally rejected by  210 B(ii) and be directed to either a beam dump or a switchyard system as  250 B(ii). The frame rate of a 2D addressable EBA-RLV is limited by the array drivers, typically in the E2 frames per second. 
       FIG.  1 B (iii) illustrates an example of an embodiment to an EBA-RLV  100 B(iii). incorporating a photoconducting separating layer between the gate anode and the tip entrance and making the base of the cathode emission array transparent to a write beam. This effectively converts a EBA-RLV into an optically addressed EBA-RLV as shown in  110 B(iii). The EBA-RLV ( 110 B(iii)) components is described in  FIG.  1 B . In this embodiment the scanning electron beam is replaced by an optically addressed cold cathode emitter array ( 113 B(iii)) which includes a photoconductor ( 120 B(iii)) separating the anode from the tip support structure. In this embodiment, a patterned write beam ( 115 B(iii)) at λ2 passes through  113 B(iii) and activates the photoconductor  125 B(iii) allowing the tip directly below  125 B(iii) to emit a stream of electrons ( 127 B(iii)) which creates a patterned charged area ( 130 B(iii)) within  110 B(iii) that mirrors the pattern in  115 B(iii). The charged pattern transfers a voltage from the outside of  110 B(iii) to across the LEO layer within  110 B(iii). The control lines  140 B(iii),  150 B(iii), and  153 B(iii) which control the voltage waveforms impressed onto the cold cathode array, the photoconductor anode layer, and the secondary emission grid within  110 B(iii), respectively. The electron beam array electronics ( 155 B(iii)) control the waveforms on  140 B(iii),  150 B(iii), and  153 B(iii) and works in conjunction with the LV electronics ( 157 B(iii)) which also controls the waveform delivered to the TCO inside  110 B(iii) via control line  160 B(iii). 
     The desired pattern is imposed onto the HFL beam by initially having an unpatterned HFL beam ( 170 B(iii)) enter  110 B(iii) and interact with the LEO that has been activated by  115 B(iii) by way of  126 B(iii),  127 B(iii) and  130 B(iii). The LEO impresses the same pattern as that inherent in  115 B(iii) onto  170 B(iii) and upon reflection off  110 B(iii)&#39;s HRM, leaves  110 B(iii) as a patterned HFL beam ( 180 B(iii)). The patterned HFL beam ( 180 B(iii)) strikes the pattern separator ( 190 B(iii)) and the desired beam ( 200 B(iii)) is relayed to the print chamber while the unwanted pattern goes into either a beam dump or a switchyard system. As is in prior cases, an unpatterned HFL beam ( 210 B(iii)) entering  110 B(iii) in an area not activated, the beam reflects of the HRM inside  110 B(iii) and leaves the EBA-RLV still unpatterned as  220 B(iii) where it is fully rejected by  190 B(iii) and becomes  230 B(iii) which goes into either a beam dump or a switchyard system. The benefit of  100 B(iii) is that the frame rate is dependent on the speed at which  115 B(iii) and the LEO material can be switched and in the case for LiNbO3 as the LEO material and a fast DLP system as the source for  115 B(iii),  100 B(iii) is limited to the 50-100 KHz frame rate limitation inherent in the DLP system. 
       FIG.  1 C  illustrates an example of a high-speed directly coupled self-emissive display addressed RLV (e-RLV)  100 C. The RLV ( 110 C) is directly coupled to a self-emissive display ( 130 C) operating at λ2. The optical coupling between  130 C and  110 C is performed by either a lenslet array ( 120 C), an aperture array or by similar proximity focusing (butt coupling the surface of  130 C directly to a thin photoconductor layer within  110 C). The self-emissive display can be an OLED, an array of LEDs (driven as a display), a microLED display or any variety of surface emitting displays that can emit at λ2 (being in the 265 nm to 500 nm band). The light emitted by a set of pixels which form a patterned beam ( 140 C) within the  130 C causes the photoconductor element in direct contact or coupled via  120 C to transfer the voltage on the outside of  110 C to be across the LEO layer inside  110 C and impose a change to the LEO&#39;s optical properties as described above. The self-emissive display is controlled by a high-speed display drive ( 160 C) through the control lines  150 C while  110 C is controlled by LV electronics ( 170 C) as described previously. An unpattern HFL beam ( 189 C) enters  110 C, passing through the LEO layer in the region which is affected by  150 C which is addressed by  140 C. The image imposed by  140 C is transferred to  180 C through the action of  150 C on the LEO layer and as  180 C reflects of the HRM layer inside  110 C and passes through the LEO layer and the intermediate layers, it exits as a patterned HFL beam,  190 C. The desired pattern ( 200 C) in  190 C is separated out by the action of the beam pattern separator ( 190 C) which is then imaged to the print chamber. The undesired pattern (not shown) reflects off of  195 C and is imaged into a beam dump or into a switchyard system. In the case where there is no pattern or light emitted from  130 C, an unpatterned HFL beam  210 C, travels through  110 C and does not exit patterned by the action of the LEO as there is no activation from  130 C; it leaves  130 C as an unpatterned HFL beam ( 220 C) and is totally rejected by  195 C and is imaged either into a beam dump or a switchyard system as waste light ( 230 C). The frame rate attainable by  100 C is dependent on the LEO layer inside  110 C as well as the switching speed of  130 C, both typically &gt;1000 frames per second. 
       FIG.  1 D (i) illustrates an example of a high-speed dual photoconductor LV (DPCLV)  100 D(i). The DPCLV includes a top Transparent Conductive Oxide (TCO,  120 D(i)), a top photoconductor layer (PC,  130 D(i)), a top impedance/alignment layer (IML,  150 D(i)), a top linear electro-optic layer (TLEOL,  160 D(i)), an intermediate layer group ( 170 D(i), shown in more detail in  340 D(i)), a bottom LEOL (B-LEOL,  180 D(i)), a bottom IML ( 190 D(i)), a bottom PC layer ( 210 D(i)), and a bottom TCO ( 220 D(i)). 
     The DPCLV system ( 110 D(i)) works by the dual action of two counterpropagating patterned write beams, both at λ2, that come into  110 D(i) from the right ( 230 D(i)) and from the left ( 240 D(i). The patterned write beam entering  110 D(i) from the right ( 230 D(i)) activates  130 D(i) to form a patterned voltage image inside  130 D(i) which is transferred into  160 D(i) through the response by the T-LEOL to this patterned voltage variation ( 270 D(i)). Likewise, the patterned write beam entering  110 D(i) from the left ( 240 D(i)) performs the same transfer into the B-LEOL by way of  260 D(i) and  280 D(i). A unpatterned HF 1  beam ( 300 D(i)) at λ1 enters  110 D(i), passing through and interacting with the pattern response of  270 D(i) and  260 D(i), leaving  110 D(i) as a patterned HFL beam  310 D(i) through its interacts with these two LEOLs. Similarly, in areas of  110 D(i) that are not patterned by  230 D(i) and  240 D(i), an unpatterned HFL beam ( 320 D(i)) passes through  110 D(i) without being affected by the LEOLs becoming  330 D(i)—a sill unpatterned HFL beam. The patterned  310 D(i) is imaged to the print bed after passing through a beam pattern separator (not shown) with the desired image going on to the bed while the undesired pattern as well as  330 D(i) are rejected and are imaged into a beam dump or into a switchyard system such as discussed with respect to  FIG.  5   . 
     The intermediate layer group ( 170 D(i)) within  110 D(i) is shown in detail as  340 D(i). This structure acts an intermediate support for  160 D(i) and  180 D(i) and is composed of an intermediate Top IML ( 350 D(i)), an intermediate top TCO ( 260 D(i)), a intermediate support layer ( 370 D(i)), an intermediate bottom TCO layer ( 380 D(i)), and a intermediate bottom IML ( 390 D(i)). 
     Due to the reduction in the LEOLs to half or less than that of a standard transmissive LV, the switching speed can be increased by &gt;4× over that of a standard high-speed transmissive LV. 
       FIG.  1 D (ii) illustrates an example of a high-speed dual photoconductor LV 100 D(ii) utilizing fringe field switching. A fringe field switching LEOL system uses different types of linear electro-optic materials in which the material&#39;s optical properties (notably, its birefringence) is activated by electric field gradients. These gradients are due to fringe fields between two adjacent activated regions. The fringe fields are typically higher in local field strength and have a larger effect on the LOELs; consequently, the LEOL thicknesses can be dramatically reduced with a commensurate increase in frame rate as the square of the thickness reduction over normally operating LVs. In this embodiment, the fringe fields are created by using a dual photoconductor concept introduced in  FIG.  1 D . An exemplary of fringe field DPCLV is depicted in  110 D(ii) and is composed of a top TCO ( 120 D(ii)), a top photoconductor ( 130 D(ii)), a top IML ( 140 D(ii)), a LEOL ( 150 D(ii)), a bottom IML ( 160 D(ii)), a bottom photoconductor ( 170 D(ii)) and a bottom TCO ( 175 D(ii)). 
     A patterned write beam (at λ2)  180 D(ii) enters  110 D(ii) from the left and imposes a voltage pattern ( 200 D(ii)) inside  130 D(ii). A second patterned write beam (carrying the same image,  190 D(ii)) enters from the right and enters  110 D-I slightly displaced from being collinear and counterpropagating with  180 D(ii) and imposes a voltage pattern ( 210 D(ii)) inside  170 D(ii). The fringe fields inside  150 D(ii) created by the offset between the two voltage patterns ( 200 D(ii) and  210 D(ii)) actuate the LEO inside  150 D(ii) to create a pattern optical response in  150 D-I depicted as  250 D(ii) (details of the voltage fringe fields in  130 D(ii) and  170 D(ii) were left out for clarity). A unpatterned HFL beam ( 240 D(ii)) enters  110 D(ii) and the optical response pattern in  250 D(ii) is imposed onto  240 D(ii) so that upon leaving  110 D(ii), the HFL beam becomes patterned ( 260 D(ii)) with the same spatial imagery contained in both  180 D(ii) and  190 D(ii). The desired pattern within  260 D(ii) is imaged to the print chamber while its undesired pattern is imaged into a beam dump or into a switchyard system such as discussed with respect to  FIG.  5   . 
     The two write beams ( 180 D(ii) and  190 D(ii)) do not have to carry the same imagery, fringe fields will be set up regardless of the imagery presented on each channel; the response on  240 D(ii) will be as described above but with the final pattern imposed on  260 D(ii) being a convolution of the two images contained in  180 D(ii) and  190 D(ii). Additionally,  150 D(ii)&#39;s response to the fringe fields created by  200 D(ii) and  210 D(ii) depends on both fields being present in the same time interval. The overlap in time of  180 D(ii) and  190 D(ii) provides an additional speed improvement and is dependent on the relaxation times of  150 D(ii) and the two photoconductors ( 130 D(ii) and  170 D(ii)), providing a fast LV. 
     In the case where there is one write beam or an absence of both write beams ( 180 D(ii) and  190 D(ii)) and an unpatterned HFL beam ( 270 D(ii)) enters  110 D-I, no pattern optical response is contained in  150 D(ii) and  270 D(ii) leaves  110 D(ii) as an unpatterned HFL beam ( 280 D(ii)) that will be imaged into a beam dump or into a switchyard system such as discussed with respect to  FIG.  5   . 
       FIG.  1 E  illustrates an example of a high-speed LV  100 E utilizing in-plane switching. LV  110 E is composed of a top TCO ( 120 E), a photoconductor ( 130 E), a top IML ( 140 E), a LEO layer ( 150 E), a bottom IML ( 160 E) and a supporting substrate ( 170 E). The  150 E is composed of a material which reacts to fringe fields and is typically an electrically controlled birefringent liquid crystal (ECB-LC) that has been vertically aligned (VA). An in-plane LC system can be extremely thin, but this condition places the need for the LCs in this class of device to have a very large birefringence to allow a sufficient contrast ratio to be practical. Since the frame speed of an LC based LV goes as the square of the thickness reduction over nominal LVs, the frame speed can be 1-2 orders larger than nominal. 
     The activation of  110 E originate with two patterned write beams ( 180 E and  190 E), both operating at λ2 and entering  110 E from the left, passing into  130 E where they generate two voltage patterns ( 200 E and  210 E) within  130 E. The field interference pattern between  200 E and  210 E generates in-plane fringe fields between the two patterns just past  140 E and into  150 E, represented by  220 E. The in-plane fringe fields modify the LEO material within  150 E ( 230 E) according to the interference field  220 E and imposes an optical response within  230 E that mirrors the images contained in  180 E and  190 E. 
     A HFL beam ( 240 E) enters  110 E from the left and interacts with a patterned section of  150 E caused by in-plane switching between two similarly created interference as described above (depicted as  250 E), the details of its presentation to  150 E is omitted for clarity. The pattern optical response in  150 E ( 250 E) imposes the pattern onto  240 E and it leaves as a patterned HFL beam ( 260 E) with the desired portion of this patterning continuing to the print chamber and the undesired portion going into a beam dump or into a switchyard system. In the case where on or both write beams are absent, an unpatterned HFL beam ( 270 E) interacts with an unpatterned  150 E volume leaving  110 E still unpatterned as  280 E and is imaged either into a beam dump or into a switchyard system such as discussed with respect to  FIG.  5   . 
       FIGS.  1 F (i) and  1 F(ii) together illustrate an example of an architecture for high speed LV system (HSLV unit)  100 F(i) and its timing  100 F(ii). In this schematic layout, there are high speed areal LV (aka as PI-cell) switches and low speed patterning LVs, there is also supporting optics to realize this architecture which is omitted for clarity. An unpatterning HFL beam ( 110 F(i)) enters  100 F(i) and is switched by PI cell  120 F(i) into one of two possible paths/channels, either  130 F(i) or  240 F(i). Assume that  120 F(i) switched the incoming  110 F(i) into  130 F(i) channel, the unpatterned HF(i)L beam enters the 2nd tier of unpatterned PI cell ( 140 F(i)) which can put the  130 F(i) into one of two paths/channels, either  150 F(i) or into  160 F(i). Assume that  140 F(i) was activate so that unpatterned HFL beam on  130 F(i) is switched into the  150 F(i) channel. The unpatterned HFL beam,  150 F(i), enters a patterning LV  170 F(i) and gets patterned during time slot t1. The patterned HF(i)L beam leaves  170 F(i), travelling along path  190 F(i) where it is switched into  220 F(i) by a non-patterning 3rd tier PI cell ( 210 F(i)). The patterned HFL beam travels along  220 F(i) and into the 4th tier non-patterning PI cell ( 230 F(i)) which integrates the various signals onto channel  340 F(i) where it is imaged to the print chamber in time slot t1. 
     Similarly, the paths that take the unpatterned HFL from  110 F(i), through  120 F(i) and into  130 F(i), through  140 F(i) and into  160 F(i) which allows the unpatterned HFL beam to be patterned by the patterning LV  180 F(i) at time t2. The output of  180 F(i) travels along  200 F(i) into  210 F(i) which places the patterned HFL beam  200 F(i) onto  220 F(i) which again allows  230 F(i) integrates that image onto  340 F(i) in time slot t2 to be sent to the print chamber. 
     In a similar manner the initial unpatterned HFL beam can be sent to patterning LV  280 F(i) (at time t3) by way of PI cell,  250 F(i), along the paths  240 F(i) and  260 F(i). The patterned HFL result from  280 F(i) travels along  300 F(i) and is integrated into  340 F(i) (at time slot t3) by way of PI cells,  320 F(i) and  230 F(i), along paths  300 F(i) and  330 F(i). In a similar fashion, the unpatterned HFL beam can be patterned by the patterning LV  290 F(i) in time slot t4 by traversing  240 F(i) and  270 F(i) through PI cell  250 F(i). The integration of the patterned HFL output from  290 F(i) ( 310 F(i)) into  340 F(i) in time slot t4 is accomplished by traversing paths  310 F(i) and  330 F(i) and passing through  320 F(i) and finally  230 F(i). The sequence coming out of  230 F(i) patterned HFL beams originating from patterns placed onto it by  170 F(i),  180 F(i),  280 F(i), and  290 F(i) in time slots t1, t2, t3, and t4, respectively thus creating a 4× improvement over a the frame rate that could be achieved if only one patterning LV were used. 
     The timing sequence is demonstrated in  350 F(i) where  360 F(i) is the timing sequence of  120 F(i) (the 1st tier of PI cell). The 2nd tier of PI cell ( 140 F(i) and  250 F(i)) has timing diagrams depicted in  370 F(i) and  420 F(i), respectively. The slow patterning LVs ( 170 F(i),  180 F(i),  280 F(i) and  290 F(i)) have timing diagrams of  400 F(i),  410 F(i),  430 F(i) and  440 F(i), respectively. The 3rd tier of PI cells ( 210 F(i) and  320 F(i)) having timing diagrams depicted in  380 F(i) and  450 F(i), respectively. The 4th tier of PI cell ( 230 F(i)) has a timing diagram depicted in  390 F(i). The timing diagram of the output of the high-speed LV system (channel  340 F(i)) is depicted in  460 F(i). Comparing the frame rate ( 480 F(i)) of an individual patterning LV (seen as a dotted box around the timing of  400 F(i)) and comparing that to the frame rate for the LV system (dotted box  490 F(i)), it can be seen that the LV system has a frame rate that is 4× faster for a 2-tier up/down system. This architecture allows for 2N speed improvement over single LV systems where N is the number of tiers of PI cells prior/post to the patterning LVs in the system. This architecture requires that the PI cells be &gt;4× the switching speed of the slow patterning LVs. The arrangement depicted in  100 F(i) is a unit of a high-speed binary switch LV system. 
       FIG.  1 F (iii) illustrates an example of use of multi-point LVs switches  100 F(ii) for the high speed LV system of  FIG.  1 F (i). A single high-speed multi-point non-patterning LV switch is used for both input and output gates that feed into/out of a 1D or 2D array of slow patterning LVs. An unpatterned HFL beam ( 110 F(i)) enters a multi-point scanning/staring LV ( 120 F(i)) and is scanned to any one of an array of slow patterning LVs depicted as  160 F(i). on either side of  160 F-I is a prismatic array that takes the angled unpatterned HFL ( 130 F(i)) and straightens it out so as to optimize the spatial resolution of any one patterning LV in  160 F(i). Since each patterning LV is at a precise position with respect to  120 F-I,  150 F(i) can be a static array of prismatic components. The HFL gets patterned by any one patterning LV within  160 F(i) at a time slot ti before passing through another prismatic array ( 170 F(i)). The second prismatic array ( 170 F(i)) deflects the patterned HFL beam ( 180 F(i)) into the second non-patterning high-speed multi-point LV which is set up to redirect  180 F(i) into the output channel of  100 F(i) to form one part of the train of patterned pulses imaged to the print chamber. While  130 F(i) and  180 F(i) represents the 1st channel into and out of (respectively) the pattern LV array, the last channel into and out of this array is represented by  140 F(i) and  190 F(i) (respectively). 
     There are several different ways for the channel selection to be performed with this arrangement, sequential from the 1st channel ( 130 F(i)/ 180 F(i)) to the last ( 140 F(i)/ 190 F(i)) or any variation there in including not starting with  130 F(i)/ 180 F(i) or ending with  140 F(i)/ 190 F(i). The frame speed improvement of this method over that of a standard (single) LV system is equal to the number of unique and controllable pointing directions that  120 F(i)/ 200 F(i) can perform (Mx). Additionally, this method requires  120 F(i)/ 200 F(i) is Mx faster than any on of the slow patterning LVs in  160 F(i), where M is equal to the number of unique addressable directions that  120 F(i)/ 200 F(i) can attain. The arrangement of  100 F(i) is a unit of a high-speed multi-point switch LV system. 
       FIG.  1 G  illustrates an example of an architecture using an array of HSLV units  100 G. Note that while a schematic for the binary high-speed architecture ( 110 G) is used illustrated, multi-point embodiments can also be used. The binary switched LV system contains a non-patterning high speed areal LV switch (exemplified by  120 G) and a slow patterning LV (exemplified by  130 G). A 3D representation of  110 G is depicted in  140 G where  150 G and  160 G equates to  120 G and  130 G, respectively. An end-view of  140 G is depicted in  170 G where  180 G and  190 G equates to  120 G and  130 G, respectively. This unit cell of the high-speed LV system can be arrayed ( 200 G) in which  210 G represents one such unit. The arraying of  170 G into  200 G allows the concept of high-speed LV systems to be extended in space to realize a high speed areal printing engine, an alternative architecture for switchyard such as discussed with respect to  FIG.  5   , or a solid state scanning system. 
     A wide range of lasers of various wavelengths can used in combination with the described phase change light valve system. In some embodiments, possible laser types include, but are not limited to: Gas Lasers, Chemical Lasers, Dye Lasers, Metal Vapor Lasers, Solid State Lasers (e.g. fiber), Semiconductor (e.g. diode) Lasers, Free electron laser, Gas dynamic laser, “Nickel-like” Samarium laser, Raman laser, or Nuclear pumped laser. 
     A Gas Laser can include lasers such as a Helium-neon laser, Argon laser, Krypton laser, Xenon ion laser, Nitrogen laser, Carbon dioxide laser, Carbon monoxide laser or Excimer laser. 
     A Chemical laser can include lasers such as a Hydrogen fluoride laser, Deuterium fluoride laser, COIL (Chemical oxygen-iodine laser), or Agil (All gas-phase iodine laser). 
     A Metal Vapor Laser can include lasers such as a Helium-cadmium (HeCd) metal-vapor laser, Helium-mercury (HeHg) metal-vapor laser, Helium-selenium (HeSe) metal-vapor laser, Helium-silver (HeAg) metal-vapor laser, Strontium Vapor Laser, Neon-copper (NeCu) metal-vapor laser, Copper vapor laser, Gold vapor laser, or Manganese (Mn/MnCl 2 ) vapor laser. Rubidium or other alkali metal vapor lasers can also be used. A Solid State Laser can include lasers such as a Ruby laser, Nd:YAG laser, NdCrYAG laser, Er:YAG laser, Neodymium YLF (Nd:YLF) solid-state laser, Neodymium doped Yttrium orthovanadate(Nd:YVO 4 ) laser, Neodymium doped yttrium calcium oxoborateNd:YCa 4 O(BO 3 ) 3  or simply Nd:YCOB, Neodymium glass(Nd:Glass) laser, Titanium sapphire(Ti:sapphire) laser, Thulium YAG (Tm:YAG) laser, Ytterbium YAG (Yb:YAG) laser, Ytterbium:2O 3  (glass or ceramics) laser, Ytterbium doped glass laser (rod, plate/chip, and fiber), Holmium YAG (Ho:YAG) laser, Chromium ZnSe (Cr:ZnSe) laser, Cerium doped lithium strontium (or calcium)aluminum fluoride(Ce:LiSAF, Ce:LiCAF), Promethium 147 doped phosphate glass(147Pm +3 :Glass) solid-state laser, Chromium doped chrysoberyl (alexandrite) laser, Erbium doped anderbium-ytterbium co-doped glass lasers, Trivalent uranium doped calcium fluoride (U:CaF 2 ) solid-state laser, Divalent samarium doped calcium fluoride(Sm:CaF 2 ) laser, or F-Center laser. 
     A Semiconductor Laser can include laser medium types such as GaN, InGaN, AlGaInP, AlGaAs, InGaAsP, GaInP, InGaAs, InGaAsO, GaInAsSb, lead salt, Vertical cavity surface emitting laser (VCSEL), Quantum cascade laser, Hybrid silicon laser, or combinations thereof. 
       FIG.  2    illustrates use of a high speed light valves such as disclosed herein in an additive manufacturing system  200 . A laser source  202  directs a laser beam through a laser preamplifier and/or amplifier  204  into a high speed light valve  206 . After patterning, light can be directed into a print bed  210 . In some embodiments, heat or laser energy from laser source  202 , laser preamplifier and/or amplifier  204 , or an high speed light valve  206  can be actively or passively transferred to a heat transfer, heat engine, cooling system, and beam dump  208 . Overall operation of the light valve based additive manufacturing system  200  can controlled by one or more controllers  220  that can modify laser power and timing. 
     In some embodiments, various preamplifiers or amplifiers  204  are optionally used to provide high gain to the laser signal, while optical modulators and isolators can be distributed throughout the system to reduce or avoid optical damage, improve signal contrast, and prevent damage to lower energy portions of the system  200 . Optical modulators and isolators can include, but are not limited to Pockels cells, Faraday rotators, Faraday isolators, acousto-optic reflectors, or volume Bragg gratings. Pre-amplifier or amplifiers  204  could be diode pumped or flash lamp pumped amplifiers and configured in single and/or multi-pass or cavity type architectures. As will be appreciated, the term pre-amplifier here is used to designate amplifiers which are not limited thermally (i.e. they are smaller) versus laser amplifiers (larger). Amplifiers will typically be positioned to be the final units in a laser system  200  and will be the first modules susceptible to thermal damage, including but not limited to thermal fracture or excessive thermal lensing. 
     Laser pre-amplifiers can include single pass pre-amplifiers usable in systems not overly concerned with energy efficiency. For more energy efficient systems, multi-pass pre-amplifiers can be configured to extract much of the energy from each pre-amplifier  204  before going to the next stage. The number of pre-amplifiers  204  needed for a particular system is defined by system requirements and the stored energy/gain available in each amplifier module. Multi-pass pre-amplification can be accomplished through angular multiplexing or polarization switching (e.g. using waveplates or Faraday rotators). 
     Alternatively, pre-amplifiers can include cavity structures with a regenerative amplifier type configuration. While such cavity structures can limit the maximum pulse length due to typical mechanical considerations (length of cavity), in some embodiments “white cell” cavities can be used. A “white cell” is a multi-pass cavity architecture in which a small angular deviation is added to each pass. By providing an entrance and exit pathway, such a cavity can be designed to have extremely large number of passes between entrance and exit allowing for large gain and efficient use of the amplifier. One example of a white cell would be a confocal cavity with beams injected slightly off axis and mirrors tilted such that the reflections create a ring pattern on the mirror after many passes. By adjusting the injection and mirror angles the number of passes can be changed. 
     Amplifiers are also used to provide enough stored energy to meet system energy requirements, while supporting sufficient thermal management to enable operation at system required repetition rate whether they are diode or flashlamp pumped. Both thermal energy and laser energy generated during operation can be directed the heat transfer, heat engine, cooling system, and beam dump  208 . 
     Amplifiers can be configured in single and/or multi-pass or cavity type architectures. Amplifiers can include single pass amplifiers usable in systems not overly concerned with energy efficiency. For more energy efficient systems, multi-pass amplifiers can be configured to extract much of the energy from each amplifier before going to the next stage. The number of amplifiers needed for a particular system is defined by system requirements and the stored energy/gain available in each amplifier module. Multipass pre-amplification can be accomplished through angular multiplexing, polarization switching (waveplates, Faraday rotators). Alternatively, amplifiers can include cavity structures with a regenerative amplifier type configuration. As discussed with respect to pre-amplifiers, amplifiers can be used for power amplification. 
     In some embodiments, thermal energy and laser energy generated during operation of system  200  can be directed into the heat transfer, heat engine, cooling system, and beam dump  208 . Alternatively, or in addition, in some embodiments the beam dump  208  can be a part of a heat transfer system to provide useful heat to other industrial processes. In still other embodiments, the heat can be used to power a heat engine suitable for generating mechanical, thermoelectric, or electric power. In some embodiments, waste heat can be used to increase temperature of connected components. As will be appreciated, laser flux and energy can be scaled in this architecture by adding more pre-amplifiers and amplifiers with appropriate thermal management and optical isolation. Adjustments to heat removal characteristics of the cooling system are possible, with increase in pump rate or changing cooling efficiency being used to adjust performance. 
       FIG.  3    illustrates an additive manufacturing system  300  that can accommodate high speed light valves as described in this disclosure. As seen in  FIG.  3   , a laser source and amplifier(s)  312  can include resonance based light valves and laser amplifiers and other components such as previously described. As illustrated in  FIG.  3   , the additive manufacturing system  300  uses lasers able to provide one or two dimensional directed energy as part of a laser patterning system  310 . In some embodiments, one dimensional patterning can be directed as linear or curved strips, as rastered lines, as spiral lines, or in any other suitable form. Two-dimensional patterning can include separated or overlapping tiles, or images with variations in laser intensity. Two-dimensional image patterns having non-square boundaries can be used, overlapping or interpenetrating images can be used, and images can be provided by two or more energy patterning systems. The laser patterning system  310  uses laser source and amplifier(s)  312  to direct one or more continuous or intermittent energy beam(s) toward beam shaping optics  314 . After shaping, if necessary, the beam is patterned by a laser patterning unit  316  that includes either a transmissive or reflective light valve, with generally some energy being directed to a rejected energy handling unit  318 . The rejected energy handling unit can utilize heat provided by active of cooling of light valves. 
     Patterned energy is relayed by image relay  320  toward an article processing unit  340 , in one embodiment as a two-dimensional image  322  focused near a bed  346 . The bed  346  (with optional walls  348 ) can form a chamber containing material  344  (e.g. a metal powder) dispensed by material dispenser  342 . Patterned energy, directed by the image relay  320 , can melt, fuse, sinter, amalgamate, change crystal structure, influence stress patterns, or otherwise chemically or physically modify the dispensed material  344  to form structures with desired properties. A control processor  350  can be connected to variety of sensors, actuators, heating or cooling systems, monitors, and controllers to coordinate operation of the laser source and amplifier(s)  312 , beam shaping optics  314 , laser patterning unit  316 , and image relay  320 , as well as any other component of system  300 . As will be appreciated, connections can be wired or wireless, continuous or intermittent, and include capability for feedback (for example, thermal heating can be adjusted in response to sensed temperature). 
     In some embodiments, beam shaping optics  314  can include a great variety of imaging optics to combine, focus, diverge, reflect, refract, homogenize, adjust intensity, adjust frequency, or otherwise shape and direct one or more laser beams received from the laser source and amplifier(s)  312  toward the laser patterning unit  316 . In one embodiment, multiple light beams, each having a distinct light wavelength, can be combined using wavelength selective mirrors (e.g. dichroics) or diffractive elements. In other embodiments, multiple beams can be homogenized or combined using multifaceted mirrors, microlenses, and refractive or diffractive optical elements. 
     Laser patterning unit  316  can include static or dynamic energy patterning elements. For example, laser beams can be blocked by masks with fixed or movable elements. To increase flexibility and ease of image patterning, pixel addressable masking, image generation, or transmission can be used. In some embodiments, the laser patterning unit includes addressable light valves, alone or in conjunction with other patterning mechanisms to provide patterning. The light valves can be transmissive, reflective, or use a combination of transmissive and reflective elements. Patterns can be dynamically modified using electrical or optical addressing. In one embodiment, a transmissive optically addressed light valve acts to rotate polarization of light passing through the valve, with optically addressed pixels forming patterns defined by a light projection source. In another embodiment, a reflective optically addressed light valve includes a write beam for modifying polarization of a read beam. In certain embodiments, non-optically addressed light valves can be used. These can include but are not limited to electrically addressable pixel elements, movable mirror or micro-mirror systems, piezo or micro-actuated optical systems, fixed or movable masks, or shields, or any other conventional system able to provide high intensity light patterning. 
     Rejected energy handling unit  318  is used to disperse, redirect, or utilize energy not patterned and passed through the image relay  320 . In one embodiment, the rejected energy handling unit  318  can include passive or active cooling elements that remove heat from both the laser source, light valve(s), and amplifier(s)  312  and the laser patterning unit  316 . In other embodiments, the rejected energy handling unit can include a “beam dump” to absorb and convert to heat any beam energy not used in defining the laser pattern. In still other embodiments, rejected laser beam energy can be recycled using beam shaping optics  314 . Alternatively, or in addition, rejected beam energy can be directed to the article processing unit  340  for heating or further patterning. In certain embodiments, rejected beam energy can be directed to additional energy patterning systems or article processing units. 
     In one embodiment, a “switchyard” style optical system can be used. Switchyard systems are suitable for reducing the light wasted in the additive manufacturing system as caused by rejection of unwanted light due to the pattern to be printed. A switchyard involves redirections of a complex pattern from its generation (in this case, a plane whereupon a spatial pattern is imparted to structured or unstructured beam) to its delivery through a series of switch points. Each switch point can optionally modify the spatial profile of the incident beam. The switchyard optical system may be utilized in, for example and not limited to, laser-based additive manufacturing techniques where a mask is applied to the light. Advantageously, in various embodiments in accordance with the present disclosure, the thrown-away energy may be recycled in either a homogenized form or as a patterned light that is used to maintain high power efficiency or high throughput rates. Moreover, the thrown-away energy can be recycled and reused to increase intensity to print more difficult materials. 
     Image relay  320  can receive a patterned image (either one or two-dimensional) from the laser patterning unit  316  directly or through a switchyard and guide it toward the article processing unit  340 . In a manner similar to beam shaping optics  314 , the image relay  320  can include optics to combine, focus, diverge, reflect, refract, adjust intensity, adjust frequency, or otherwise shape and direct the patterned light. Patterned light can be directed using movable mirrors, prisms, diffractive optical elements, or solid state optical systems that do not require substantial physical movement. One of a plurality of lens assemblies can be configured to provide the incident light having the magnification ratio, with the lens assemblies both a first set of optical lenses and a second sets of optical lenses, and with the second sets of optical lenses being swappable from the lens assemblies. Rotations of one or more sets of mirrors mounted on compensating gantries and a final mirror mounted on a build platform gantry can be used to direct the incident light from a precursor mirror onto a desired location. Translational movements of compensating gantries and the build platform gantry are also able to ensure that distance of the incident light from the precursor mirror the article processing unit  340  is substantially equivalent to the image distance. In effect, this enables a quick change in the optical beam delivery size and intensity across locations of a build area for different materials while ensuring high availability of the system. 
     Article processing unit  340  can include a walled chamber  348  and bed  344  (collectively defining a build chamber), and a material dispenser  342  for distributing material. The material dispenser  342  can distribute, remove, mix, provide gradations or changes in material type or particle size, or adjust layer thickness of material. The material can include metal, ceramic, glass, polymeric powders, other melt-able material capable of undergoing a thermally induced phase change from solid to liquid and back again, or combinations thereof. The material can further include composites of melt-able material and non-melt-able material where either or both components can be selectively targeted by the imaging relay system to melt the component that is melt-able, while either leaving along the non-melt-able material or causing it to undergo a vaporizing/destroying/combusting or otherwise destructive process. In certain embodiments, slurries, sprays, coatings, wires, strips, or sheets of materials can be used. Unwanted material can be removed for disposable or recycling by use of blowers, vacuum systems, sweeping, vibrating, shaking, tipping, or inversion of the bed  346 . 
     In addition to material handling components, the article processing unit  340  can include components for holding and supporting 3D structures, mechanisms for heating or cooling the chamber, auxiliary or supporting optics, and sensors and control mechanisms for monitoring or adjusting material or environmental conditions. The article processing unit can, in whole or in part, support a vacuum or inert gas atmosphere to reduce unwanted chemical interactions as well as to mitigate the risks of fire or explosion (especially with reactive metals). In some embodiments, various pure or mixtures of other atmospheres can be used, including those containing Ar, He, Ne, Kr, Xe, CO 2 , N 2 , O 2 , SF 6 , CH 4 , CO, N 2 O, C 2 H 2 , C 2 H 4 , C 2 H 6 , C 3 H 6 , C 3 H 8 , i-C 4 H 10 , C 4 H 10 , 1-C 4 H 8 , cic-2,C 4 H 7 , 1,3-C 4 H 6 , 1,2-C4H6, C 5 H 12 , n-C 5 H 12 , i-C 5 H 12 , n-C6H 14 , C 2 H 3 Cl, C 7 H 16 , C 8 H 18 , C 10 H 22 , C 11 H 24 , C 12 H 26 , C 13 H 28 , C 14 H 30 , C 15 H 32 , C 16 H 34 , C 6 H 6 , C 6 H 5 —CH 3 , C 8 H 10 , C 2 H 5 OH, CH 3 OH, iC 4 H 8 . In some embodiments, refrigerants or large inert molecules (including but not limited to sulfur hexafluoride) can be used. An enclosure atmospheric composition to have at least about 1% He by volume (or number density), along with selected percentages of inert/non-reactive gasses can be used. 
     In certain embodiments, a plurality of article processing units or build chambers, each having a build platform to hold a powder bed, can be used in conjunction with multiple optical-mechanical assemblies arranged to receive and direct the one or more incident energy beams into the build chambers. Multiple chambers allow for concurrent printing of one or more print jobs inside one or more build chambers. In other embodiments, a removable chamber sidewall can simplify removal of printed objects from build chambers, allowing quick exchanges of powdered materials. The chamber can also be equipped with an adjustable process temperature controls. In still other embodiments, a build chamber can be configured as a removable printer cartridge positionable near laser optics. In some embodiments a removable printer cartridge can include powder or support detachable connections to a powder supply. After manufacture of an item, a removable printer cartridge can be removed and replaced with a fresh printer cartridge. 
     In another embodiment, one or more article processing units or build chambers can have a build chamber that is maintained at a fixed height, while optics are vertically movable. A distance between final optics of a lens assembly and a top surface of powder bed a may be managed to be essentially constant by indexing final optics upwards, by a distance equivalent to a thickness of a powder layer, while keeping the build platform at a fixed height. Advantageously, as compared to a vertically moving the build platform, large and heavy objects can be more easily manufactured, since precise micron scale movements of the ever changing mass of the build platform are not needed. Typically, build chambers intended for metal powders with a volume more than ˜0.1-0.2 cubic meters (i.e., greater than 100-200 liters or heavier than 500-1,000 kg) will most benefit from keeping the build platform at a fixed height. 
     In one embodiment, a portion of the layer of the powder bed may be selectively melted or fused to form one or more temporary walls out of the fused portion of the layer of the powder bed to contain another portion of the layer of the powder bed on the build platform. In selected embodiments, a fluid passageway can be formed in the one or more first walls to enable improved thermal management. 
     In some embodiments, the additive manufacturing system can include article processing units or build chambers with a build platform that supports a powder bed capable of tilting, inverting, and shaking to separate the powder bed substantially from the build platform in a hopper. The powdered material forming the powder bed may be collected in a hopper for reuse in later print jobs. The powder collecting process may be automated and vacuuming or gas jet systems also used to aid powder dislodgement and removal. 
     Some embodiments, the additive manufacturing system can be configured to easily handle parts longer than an available build chamber. A continuous (long) part can be sequentially advanced in a longitudinal direction from a first zone to a second zone. In the first zone, selected granules of a granular material can be amalgamated. In the second zone, unamalgamated granules of the granular material can be removed. The first portion of the continuous part can be advanced from the second zone to a third zone, while a last portion of the continuous part is formed within the first zone and the first portion is maintained in the same position in the lateral and transverse directions that the first portion occupied within the first zone and the second zone. In effect, additive manufacture and clean-up (e.g., separation and/or reclamation of unused or unamalgamated granular material) may be performed in parallel (i.e., at the same time) at different locations or zones on a part conveyor, with no need to stop for removal of granular material and/or parts. 
     In another embodiment, additive manufacturing capability can be improved by use of an enclosure restricting an exchange of gaseous matter between an interior of the enclosure and an exterior of the enclosure. An airlock provides an interface between the interior and the exterior; with the interior having multiple additive manufacturing chambers, including those supporting power bed fusion. A gas management system maintains gaseous oxygen within the interior at or below a limiting oxygen concentration, increasing flexibility in types of powder and processing that can be used in the system. 
     In another manufacturing embodiment, capability can be improved by having an article processing units or build chamber contained within an enclosure, the build chamber being able to create a part having a weight greater than or equal to 2,000 kilograms. A gas management system may maintain gaseous oxygen within the enclosure at concentrations below the atmospheric level. In some embodiments, a wheeled vehicle may transport the part from inside the enclosure, through an airlock, since the airlock operates to buffer between a gaseous environment within the enclosure and a gaseous environment outside the enclosure, and to a location exterior to both the enclosure and the airlock. 
     Other manufacturing embodiments involve collecting powder samples in real-time from the powder bed. An ingester system is used for in-process collection and characterizations of powder samples. The collection may be performed periodically and the results of characterizations result in adjustments to the powder bed fusion process. The ingester system can optionally be used for one or more of audit, process adjustments or actions such as modifying printer parameters or verifying proper use of licensed powder materials. 
     Yet another improvement to an additive manufacturing process can be provided by use of a manipulator device such as a crane, lifting gantry, robot arm, or similar that allows for the manipulation of parts that would be difficult or impossible for a human to move is described. The manipulator device can grasp various permanent or temporary additively manufactured manipulation points on a part to enable repositioning or maneuvering of the part. 
     Control processor  350  can be connected to control any components of additive manufacturing system  300  described herein, including lasers, laser amplifiers, optics, heat control, build chambers, and manipulator devices. The control processor  350  can be connected to variety of sensors, actuators, heating or cooling systems, monitors, and controllers to coordinate operation. A wide range of sensors, including imagers, light intensity monitors, thermal, pressure, or gas sensors can be used to provide information used in control or monitoring. The control processor can be a single central controller, or alternatively, can include one or more independent control systems. The controller processor  350  is provided with an interface to allow input of manufacturing instructions. Use of a wide range of sensors allows various feedback control mechanisms that improve quality, manufacturing throughput, and energy efficiency. 
     One embodiment of operation of a manufacturing system supporting use of a high speed light valve suitable for additive or subtractive manufacture is illustrated in  FIG.  4   . In this embodiment, a flow chart  400  illustrates one embodiment of a manufacturing process supported by the described optical and mechanical components. In step  402 , material is positioned in a bed, chamber, or other suitable support. The material can be a metal plate for laser cutting using subtractive manufacture techniques, or a powder capable of being melted, fused, sintered, induced to change crystal structure, have stress patterns influenced, or otherwise chemically or physically modified by additive manufacturing techniques to form structures with desired properties. 
     In step  404 , unpatterned laser energy is emitted by one or more energy emitters, including but not limited to solid state or semiconductor lasers, and then amplified by one or more laser amplifiers. In step  406 , the unpatterned laser energy is shaped and modified (e.g. intensity modulated or focused). In step  408 , this unpatterned laser energy is patterned by a high speed light valve, with energy not forming a part of the pattern being handled in step  410  (this can include use of a beam dump as disclosed with respect to  FIG.  2    and  FIG.  3    that provide conversion to waste heat, recycling as patterned or unpatterned energy, or waste heat generated by cooling the laser amplifiers in step  404 ). In step  412 , the patterned energy, now forming a one or two-dimensional image is relayed toward the material. In step  414 , the image is applied to the material, either subtractively processing or additively building a portion of a 3D structure. For additive manufacturing, these steps can be repeated (loop  416 ) until the image (or different and subsequent image) has been applied to all necessary regions of a top layer of the material. When application of energy to the top layer of the material is finished, a new layer can be applied (loop  418 ) to continue building the 3D structure. These process loops are continued until the 3D structure is complete, when remaining excess material can be removed or recycled. 
       FIG.  5    is one embodiment of an additive manufacturing system that includes a high speed light valve and a switchyard system enabling reuse of patterned two-dimensional energy. An additive manufacturing system  520  has an energy patterning system with a laser and amplifier source  512  that directs one or more continuous or intermittent laser beam(s) toward beam shaping optics  514 . Excess heat can be transferred into a rejected energy handling unit  522  that can include an active light valve cooling system as disclosed with respect  FIG.  2   ,  FIG.  3   , and  FIG.  4   . After shaping, the beam is two-dimensionally patterned by an energy patterning unit  530  based on resonance based material, with generally some energy being directed to the rejected energy handling unit  522 . Patterned energy is relayed by one of multiple image relays  532  toward one or more article processing units  534 A,  534 B,  534 C, or  534 D, typically as a two-dimensional image focused near a movable or fixed height bed. The bed can be inside a cartridge that includes a powder hopper or similar material dispenser. Patterned laser beams, directed by the image relays  532 , can melt, fuse, sinter, amalgamate, change crystal structure, influence stress patterns, or otherwise chemically or physically modify the dispensed material to form structures with desired properties. 
     In this embodiment, the rejected energy handling unit has multiple components to permit reuse of rejected patterned energy. Coolant fluid from the laser amplifier and source  512  can be directed into one or more of an electricity generator  524 , a heat/cool thermal management system  525 , or an energy dump  526 . Additionally, relays  528 A,  528 B, and  528 C can respectively transfer energy to the electricity generator  524 , the heat/cool thermal management system  525 , or the energy dump  526 . Optionally, relay  528 C can direct patterned energy into the image relay  532  for further processing. In other embodiments, patterned energy can be directed by relay  528 C, to relay  528 B and  528 A for insertion into the laser beam(s) provided by laser and amplifier source  512 . Reuse of patterned images is also possible using image relay  532 . Images can be redirected, inverted, mirrored, sub-patterned, or otherwise transformed for distribution to one or more article processing units.  534 A-D. Advantageously, reuse of the patterned light can improve energy efficiency of the additive manufacturing process, and in some cases improve energy intensity directed at a bed or reduce manufacture time. 
     Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. It is also understood that other embodiments of this invention may be practiced in the absence of an element/step not specifically disclosed herein.