Patent Description:
Digital masking is a technology which may be used to form patterns on a photo-sensitive material without a physical photomask (i.e., maskless lithographic processing), and is thus applicable to fields like 3D printing.

As shown in <FIG>, a conventional projector for 3D printing includes a light source and a digital micromirror device (DMD) chip. The DMD chip may convert light provided by the light source into an image by controlling rotation of each micro mirror thereof between two specific angles (usually having a difference of approximately <NUM> degrees therebetween) which respectively represent on and off states, so as to create an optical image projection onto a photo-curable material placed on a movable printer bed (not shown). By variation of the image projected on the photo-curable material and movement of the printer bed, a printed 3D object may thus be formed.

However, the DMD chip has a maximum optical power input limit, which limits intensity of light outputted by the projector and thus the speed of 3D printing.

<CIT> discloses a projecting display system including a light source which produces light which is spatially modulated by a number of spatial light modulators. <CIT> deals with a method and apparatus for creating a three-dimensional object by generating a cross-sectional pattern of energy of an object to be formed at a selected surface of a medium capable of altering its physical state in response to the energy projected or transmitted onto the selected layer. <CIT> relates to a 3D printing system, in particular to a 3D printing system that employs digital light processing (DLP). <CIT> concerns digital projection equipment and techniques for enhancing characteristics of electronic projection systems.

Therefore, the disclosure provides a digital masking system (i.e., a maskless lithographic processing system) according to claim <NUM>, a pattern imaging apparatus according to claim <NUM> and a digital masking method (i.e., a maskless lithographic processing method) according to claim <NUM> that can alleviate at least one of the drawbacks of the prior art.

According to one aspect of the disclosure, the digital masking system includes a pattern imaging apparatus and a supporting structure for supporting at least one layer of a material (i.e., a photo-sensitive material). The pattern imaging apparatus includes multiple light sources, a group of imaging devices, and a combiner. The light sources are configured to provide a group of light components that have substantially the same wavelength spectrum respectively to the imaging devices. Each of said imaging devices has a maximum power input limit. Each of the light components has a power smaller than or equal to the maximum power input limit, and a sum of the powers of the light components is greater than the maximum power input limit of each of said imaging devices. The imaging devices convert the light components provided by said light sources respectively into a group of light beams each representing a same image, and provide the light beams to said combiner. The combiner is disposed to receive, combine and redirect the light beams provided by said imaging devices toward said at least one layer of the material supported by the supporting structure in such a way that the images represented by the light beams completely overlap each other on the at least one layer of the material. Said combiner has a plurality of combiner elements, each having a pair of connection surfaces opposite to each other, and a plurality mount surfaces each of which connects the connection surfaces. For each of said combiner elements, one of said connection surfaces thereof is connected to one of said connection surfaces of another one of said combiner elements, and said combiner elements are connected in series. Said imaging devices are disposed such that each of the light beams is provided into said combiner through an individual one of said mount surfaces of said combiner elements, and said combiner redirects and outputs the light beams from a terminal one of said connection surfaces of said combiner elements that are connected in series.

According to another aspect of the disclosure, the pattern imaging apparatus is proposed for patterning a material (i.e., a photo-sensitive material), and includes multiple light sources, a plurality of imaging devices, and a combiner. The light sources are configured to provide a group of light components that have substantially the same wavelength spectrum respectively to the imaging devices. Each of said imaging devices has a maximum power input limit. Each of the light components has a power smaller than or equal to the maximum power input limit, and a sum of the powers of the light components is greater than the maximum power input limit of each of said imaging devices. The imaging devices are disposed to respectively receive and convert the light components provided by said light sources respectively into a group of light beams each representing an same image, and provide the light beams to said combiner. The combiner is disposed to receive, and combine and redirect the light beams provided by said imaging devices into a single light beam output that is projected toward said at least one layer of the material supported by the supporting structure in such a way that the images represented by the light beams completely overlap each other on the at least one layer of the material. Said combiner has a plurality of combiner elements, each having a pair of connection surfaces opposite to each other, and a plurality mount surfaces each of which connects the connection surfaces. For each of said combiner elements, one of said connection surfaces thereof is connected to one of said connection surfaces of another one of said combiner elements, and said combiner elements are connected in series. Said imaging devices are disposed such that each of the light beams is provided into said combiner through an individual one of said mount surfaces of said combiner elements, and said combiner redirects and outputs the light beams from a terminal one of said connection surfaces of said combiner elements that are connected in series.

According to the disclosure, the digital masking method includes: by multiple light sources, providing a plurality of light components that have substantially the same wavelength spectrum respectively to multiple imaging devices, wherein each of the light components has a power smaller than or equal to a maximum power input limit of each of the imaging devices, and a sum of the powers of the light components is greater than the maximum power input limit of each of the imaging devices; by the imaging devices, receiving and converting the light components provided by the light sources respectively into a plurality of light beams each representing a same image, and providing the light beams to a combiner; and by the combiner, receiving, combining and redirecting the light beams provided by the imaging devices toward at least one layer of a material (i.e., a photo-sensitive material) in such a way that the images represented by the light beams completely overlap each other on the at least one layer of the material. The combiner has a plurality of combiner elements, each having a pair of connection surfaces opposite to each other, and a plurality mount surfaces each of which connects the connection surfaces. For each of the combiner elements, one of the connection surfaces thereof is connected to one of the connection surfaces of another one of the combiner elements, and the combiner elements are connected in series. The providing the light beams to the combiner includes, by the imaging devices, providing each of the light beams into the combiner through an individual one of the mount surfaces of the combiner elements. The receiving, combining and redirecting the light beams includes, by the combiner, redirecting and outputting the light beams from a terminal one of the connection surfaces of the combiner elements that are connected in series.

Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment(s) with reference to the accompanying drawings, of which:.

It is further noted herein that the term "light," "light beam," "light component," or the like as used throughout this disclosure is not limited to ultra violet (UV) light, and may also mean electromagnetic radiation/wave of any wavelength.

Referring to <FIG>, a first embodiment of the digital masking system according to this disclosure is exemplarily applied to a 3D printer system. In the embodiment, the digital masking system includes a pattern imaging apparatus <NUM>, a supporting structure <NUM> on which a printed 3D object is to be supported and formed from a photo-sensitive material, a motor apparatus <NUM> coupled to the supporting structure <NUM> for enabling movement thereof, and a computer <NUM> coupled to the pattern imaging apparatus <NUM> and the motor apparatus <NUM> for controlling operations thereof according to printing parameters and printing files inputted by a user. It is noted that the photo-sensitive material used in 3D printing may vary depending on the to-be-used printing technology, and this disclosure is not limited in this respect. For example, the photo-sensitive material may be a solidifiable/photo-curable resin for stereo lithography technology (SLA), digital light processing (DLP), or PolyJet™ technology, sinterable powder of, for example, metal, ceramic, polymer or nylon, for selective laser sintering (SLS) technology, an adhesive like polyvinyl Acetate (PVA) for selective deposition lamination (SDL) technology, or solidifiable powder of, for example, polyamide (PA12), for HP Multi Jet Fusion technology developed by Hewlett-Packard. In an ordinary patterning process, the photo-sensitive material may be a photo-sensitive substrate. In this embodiment, the supporting structure <NUM> may for instance be immersed in a tank filled with the photo-curable resin in liquid state. In the present disclosure, the pattern image or the resultant pattern image may correspond to a single layer of the printed 3D object when the digital masking system is applied to 3D printing, which is formed while the supporting structure <NUM> (see <FIG>) is disposed at a fixed position relative to, e.g., the tank of the photo-sensitive material. With successive patterning operations in cooperation with movement of the supporting structure <NUM>, multiple patterned layers of solidified photo-sensitive material that are stacked together may form the printed 3D object.

The pattern imaging apparatus <NUM> is configured to generate a patterning light beam that forms a pattern. Examples of suitable techniques to deliver the patterning light beam may include, but are not limited to, spatial light modulators (SLMs), projection units on the basis of digital light processing (DLP®), digital mirror device (DMD®), liquid crystal display (LCD), image light amplifier (ILA®), liquid crystal on silicon (LCoS), silicon X-tal reflective display (SXRD™), etc., light valves, microelectromechanical systems (MEMS), and laser systems. In this embodiment, the pattern imaging apparatus <NUM> is a projector realized using DLP technology, and includes a DLP controller <NUM>, a light source device <NUM>, a plurality of imaging devices <NUM> which are digital micromirror device (DMD) chips <NUM>, a lens unit <NUM>, a combiner <NUM>, and a housing <NUM> (e.g., an outer projector shell that forms an appearance of the projector). The DLP controller <NUM>, the light source device <NUM>, the imaging devices <NUM>, the lens unit <NUM> and the combiner <NUM> are mounted on the housing <NUM>, where the expression "mounted on the housing <NUM>" means, but is not limited to, being accommodated within the housing <NUM> or being indirectly mounted to the housing via, for example, an internal frame (i.e., the components <NUM>-<NUM> may not be directly connected to the housing). The lens unit <NUM> may include one or more lenses, and/or other components such as mechanical focusing devices, but this disclosure is not limited in this respect.

The DLP controller <NUM> is configured to control operations of the DMD chips <NUM> according to instructions from the computer <NUM>.

The light source device <NUM> is configured to provide a plurality of light components respectively to the DMD chips <NUM>. In this embodiment, the light source device <NUM> includes a single light source <NUM> to emit light, and a light separation structure <NUM> (e.g., bifurcating tubes, dichroic filters, etc.) disposed to receive and separate the light emitted by the light source <NUM> into the light components. In one embodiment, the light source device <NUM> may include a plurality of light sources each emitting light that serves directly as a respective light component to be provided to a respective one of the DMD chips <NUM>, and the separation structure <NUM> may be omitted in such case. As exemplified in <FIG>, the pattern imaging apparatus <NUM> includes two DMD chips <NUM> and two light sources <NUM> for providing the light components respectively to the DMD chips <NUM>. In one embodiment, multiple light sources <NUM> and the separation structure <NUM> may be used in a mixed manner to provide the light components, and this disclosure is not limited in this respect. It is noted that the light source device <NUM> may provide UV light, infrared light, visible light and/or microwave, etc., and this disclosure is not limited thereto. In this embodiment, the light source device <NUM> provides light components all having one and the same or similar wavelength spectrum to the DMD chips <NUM>.

Each of the DMD chips <NUM> receives and converts the respective one of the light components into a respective light beam representing an image. The term "image" herein represents a group of pixels respectively corresponding to all of the smallest imaging elements of the imaging device <NUM> (e.g., the micro mirrors of a DMD chip), so an image represented by a light beam covers a maximum patternable area of the corresponding DMD chip, and includes both of a patterned area (for example, see "pattern" in part (a) of <FIG>) and a pattern-less area (for example, the "pattern image" excluding the "pattern" in part (a) of <FIG>). The DMD chips <NUM> are arranged such that the light beams from the DMD chips <NUM> are projected toward the photo-curable resin to form the images represented thereby on the photo-curable material through the lens unit <NUM>. Since each of the DMD chips <NUM> has a maximum power input limit to prevent damage due to overheating, the printing speed would be limited if only one DMD chip <NUM> is used for patterning. In order to increase the printing speed, the combiner <NUM> is used in this embodiment to receive and combine multiple light beams, which are converted from the light components having the same or approximately/substantially the same wavelength spectrum, into a single light beam output (i.e., the patterning light beam) with greater intensity while the images represented by the light beams are identical. Combination of multiple light beams into a single light beam refers to redirecting the light beams to have the same or approximately/substantially the same traveling path, so that the images represented thereby are formed on the same or approximately/substantially the same region. After the single light beam output passes through the lens unit <NUM>, the images represented by the light beams completely overlap and are aligned with each other on the photo-curable resin to form a pattern. In this configuration, although power of each of the light components is smaller than or equal to the maximum power input limit, the power of the light components combined may be greater than the maximum power input limit, so as to enhance light intensity of the pattern projected onto the photo-curable resin, leading to greater printing speed, which may exceed the limit otherwise imposed by the maximum power input limit of each DMD chip <NUM>. It is noted that examples of suitable techniques to deliver the light beams include, but are not limited to, spatial light modulators (SLMs), projection units on the basis of Digital Light Processing (DLP®), DMD®, LCD, ILA®, LCOS, SXRD, etc., light valves, MEMs, and laser systems.

<FIG> respectively illustrate two exemplary implementations of the first embodiment, in which the pattern imaging apparatus <NUM> includes three sets of the light source <NUM> and the imaging device <NUM> in <FIG>, and five sets of the light source <NUM> and the imaging device <NUM> in <FIG>. In <FIG> and the following figures and descriptions, the term "pattern image" refers an image which contains a complete pattern (e.g., the island-like portion shown in <FIG>, <FIG>, <FIG> and <FIG>) and which is represented by the light beam output(s) generated by the digital masking system, wherein the digital masking system may include one or more pattern imaging apparatuses <NUM>. The pattern image covers a maximum patternable area of the digital masking system (i.e., an area consisting of the maximum patternable area(s) of all pattern imaging apparatus(es) <NUM>). In this embodiment, since the digital masking system includes only one pattern imaging apparatus <NUM>, and the light beams generated by the imaging devices <NUM> are combined into a single light beam output, the pattern image is the same or approximately/substantially the same as the image represented by the respective light beam.

<FIG> illustrate another exemplary implementation of the first embodiment, in which the pattern imaging apparatus is exemplified as a projector that includes seven sets of the light source <NUM> and the imaging device <NUM>. <FIG> show internal components of the pattern imaging apparatus <NUM> viewed from different angles. The internal components include three light combination modules that are stacked together one by one. <FIG> shows a single light combination module that includes a combiner element <NUM> (e.g., an optical prism-based component, such as a dichrioc prism, an X-cube, etc.) and at least two imaging devices <NUM> mounted to the combiner element <NUM>. The combiner element <NUM> has a pair of connection surfaces (top and bottom surfaces in <FIG> opposite to each other, and a plurality mount surfaces (side surfaces in <FIG> each of which connects the connection surfaces. Each imaging device <NUM> can be mounted to one of the mount surfaces for providing the respective light beam into the combiner element <NUM> therefrom. The connection surface of the combiner element <NUM> can be used for connection with the connection surface of another combiner element <NUM>, an imaging device <NUM>, or the lens unit <NUM>, etc. As a result, multiple combiner elements <NUM> can be connected together in series. In <FIG>, each combiner element <NUM> is an optical prism cube mounted with two imaging devices <NUM> at two opposite mount surfaces thereof. The top one of the light combination modules further includes an additional imaging device <NUM> mounted to the upper connection surface (while the lower connection surface is mounted with the combiner element <NUM> of the middle one of the light combination modules). For the bottom one of the light combination modules, the combiner element <NUM> is mounted with the lens unit <NUM> on the connection surface thereof for providing the light beam output resulting from the combination of the light beams from the seven imaging devices <NUM> thereto. Use of the light combination module may enable the pattern imaging apparatus <NUM> to have any number of sets of the imaging devices <NUM> and the light sources <NUM> as desired. For example, the pattern imaging apparatus <NUM> having an even number of the imaging devices may be realized with one light combination module or multiple light combination modules that are stacked together, where each light combination module has two imaging devices <NUM> as shown in <FIG>; and the pattern imaging apparatus <NUM> having an odd number of the imaging devices may be realized with one light combination module or multiple light combination modules stacked together, where each light combination module has two imaging devices <NUM> mounted to the mount surfaces of the corresponding combiner element <NUM>, and a terminal light combination module has an additional imaging device <NUM> mounted to the connection surface of the corresponding combiner element <NUM>, as shown in <FIG>. Such structure benefits in terms of cost and package size. It is noted that, in the implementation shown in <FIG>, each set of the light source <NUM> and the imaging device <NUM> is implemented using DLP technology, in which the light source <NUM> emits light to the corresponding imaging device <NUM> (a DMD chip <NUM>) directly, and the imaging device <NUM> reflects the light into the corresponding combiner element <NUM> based on the desired pattern. Referring to <FIG>, another exemplary implementation of the pattern imaging apparatus (a projector) of the first embodiment is shown to be similar to <FIG>, and differs in that each set of the light source <NUM> and the imaging device <NUM> in <FIG> is implemented using LCD technology, in which light provided by the light source <NUM> passes through the corresponding imaging device <NUM> (an LCD panel <NUM>) based on the desired pattern, and enters the corresponding combiner element <NUM>. Referring to <FIG>, yet another exemplary implementation of the pattern imaging apparatus (a projector) of the first embodiment is shown to be similar to <FIG>, and differs in that each set of the light source <NUM> and the imaging device <NUM> in <FIG> is implemented using LCoS technology, in which each imaging device <NUM> may include an optical component (e.g., a polarizing beam splitter <NUM>) and an LCoS chip (including an LCoS panel <NUM>). Light emitted by the light source <NUM> passes through a polarizing surface of the optical component, reflects off the LCoS panel <NUM> of the LCoS chip based on the desired pattern, and reflects off a reflective surface of the optical component to enter the corresponding combiner element <NUM>.

It is noted that each implementation exemplified in this disclosure includes the lens unit <NUM>, which may include a focusing lens designed based on a focal distance and focal area required for the specific application, and the combiner <NUM> for speeding up curing of the photo-sensitive material by combining the light beams from the imaging devices <NUM> into a single light beam output, but the lens unit <NUM> and/or the combiner <NUM> may be omitted from the figures for the sake of clarity.

Referring to <FIG>, the pattern imaging apparatus <NUM> according to this disclosure may be realized using liquid crystal display (LCD) technology. In this case, the light source device <NUM> (see <FIG>) includes a single light source <NUM>, and the light separation structure <NUM> includes, for example but not limited to, two dichroic mirrors <NUM> to separate light emitted by the light source <NUM> into three light components respectively for three LCD panels <NUM> (i.e., the imaging devices <NUM> in this case). Then, the LCD panels <NUM> convert the light components into light beams each representing an image, and the light beams are combined together by the combiner <NUM> (e.g., a prism).

Referring to <FIG>, the pattern imaging apparatus <NUM> according to this disclosure may be realized using reflecting masking technology, which is exemplified as liquid crystal on silicon (LCoS) technology herein. In this embodiment, the light source device <NUM> (see <FIG>) includes a single light source <NUM>, and the light separation structure <NUM> includes, for example but not limited to, three dichroic mirrors <NUM> to separate light emitted by the light source <NUM> into three light components respectively for three LCoS devices (i.e., the imaging devices <NUM>) each including an LCoS panel <NUM> and a polarizing beam splitter <NUM>. Then, the LCoS panels <NUM> convert the light components into light beams each representing an image, and the light beams are combined together by the combiner <NUM> (e.g., a prism).

Referring to <FIG>, a second embodiment of the digital masking system according to this disclosure is shown to include six sets of the imaging devices <NUM> and the light sources <NUM> (with one imaging device <NUM> and one light source <NUM> composing one set) within a single pattern imaging apparatus <NUM> to generate two light beam outputs, one of which is provided by three of the six sets in cooperation with a combiner (not shown), and the other one of which is provided by the other three of the six sets in cooperation with another combiner (not shown). Each light beam output represents a respective image portion of a pattern image. The two portions of the pattern image are projected on the photo-sensitive material at adjacent positions, and are non-overlapping or slightly overlapping with each other to constitute the pattern image.

In a third embodiment of the digital masking system according to this disclosure, as shown in <FIG>, the pattern imaging apparatus <NUM> may include different types of the imaging devices <NUM>, such as a DMD chip <NUM>, an LCD panel <NUM> and an LCoS device <NUM>+<NUM> to cooperate with a combiner <NUM> in one assembly for providing a single light beam output. Such embodiment may provide better process control for different lights, photo-sensitive materials or varying processes.

Referring to <FIG>, a fourth embodiment of the digital masking system according to this disclosure is exemplified to include multiple light sources <NUM> within the pattern imaging apparatus <NUM> to provide the light components with multiple wavelength spectrums, wherein the light components with different wavelength spectrums may have different effects on the photo-sensitive material(s). This aspect is not covered by the claims. In <FIG>, this is simply implemented by providing different light sources <NUM> for different imaging devices <NUM>. Depending on the design, provision of the light components may be implemented in various manners. For example, the light sources <NUM> of the light source device <NUM> (see <FIG>) may be a combination of a mercury lamp (which emits light with a wide wavelength spectrum, meaning high intensity regions or peaks are widely distributed/dispersed in terms of wavelength) with dichroic filters splitting the light into light components with wavelengths of <NUM> and <NUM>, and a laser light source providing a light component in the infrared range. In a case that more energy is needed for a specific wavelength spectrum, there may be more than one light source <NUM> that emits light with that f spectrum, as exemplified in <FIG>. In <FIG>, three light sources <NUM> are used to emit light with a primary wavelength of <NUM>, and cooperate with two other light sources that emit light with primary wavelengths of <NUM> and <NUM>, the corresponding imaging devices <NUM>, and a combiner (not shown) to generate a single light beam output that forms a pattern image on the photo-sensitive material.

<FIG> exemplifies a fifth embodiment of the digital masking system which includes four pattern imaging apparatuses <NUM>, each having a housing <NUM>, a combiner <NUM> mounted to the housing <NUM>, and three sets of the light sources <NUM> and the imaging devices <NUM> mounted to and disposed within the housing <NUM>. For each pattern imaging apparatus <NUM>, the three sets of the imaging devices <NUM> and the light sources <NUM> cooperate with the corresponding combiner <NUM> to provide completely overlapping images to serve as one of a total of four portions of the pattern image, and the light sources <NUM> may emit light with either the same wavelength spectrum to obtain three times the light intensity of a single light source <NUM>, or with different wavelength spectrums based on application requirements.

Referring to <FIG>, in a sixth embodiment of the digital masking system according to this disclosure, the imaging devices <NUM> of the pattern imaging apparatus <NUM> are precisely arranged relative to each other with a specific offset to cause image shifting, such that at least some of the images formed on the photo-sensitive material overlap each other except for edge portions thereof, resulting in higher pixel density of the pattern image. In <FIG>, the pattern imaging apparatus <NUM> is exemplified to include four imaging devices <NUM> each providing the same image with four pixels. The imaging device <NUM>(<NUM>) is arranged such that the image provided thereby is <NUM>/<NUM> pixel (in length or width, which are usually the same) to the right of the image provided by the imaging device <NUM>(<NUM>). The imaging device <NUM>(<NUM>) is arranged such that the image provided thereby is <NUM>/<NUM> pixel to the downward of the image provided by the imaging device <NUM>(<NUM>). The imaging device <NUM>(<NUM>) is arranged such that the image provided thereby is <NUM>/<NUM> pixel to the left of the image provided by the imaging device <NUM>(<NUM>). As a result, a resultant pattern image with higher pixel density (e.g., twenty-five pixels in <FIG>) is obtained, which may lead to a smoother edge in the X-Y direction. Furthermore, the image shifting may also enhance grayscale control due to pixel blending, which may result in a smoother surface in the Z direction for the final printed 3D object when the digital masking system is applied to 3D printing. It is noted that the imaging devices <NUM> may be arranged relative to each other in any of the six degrees of freedom in order to obtain the desired image shifting, and this disclosure is not limited to the exemplary implementations described herein. In <FIG>, the imaging devices <NUM> are rotated relative to each other for acquiring a smoother edge of the printed 3D object. The concept of the sixth embodiment may be combined with the concept of other embodiments, such as multiple wavelength spectrums of light introduced in the fourth embodiment, to achieve various applications as desired, and details for which will be omitted herein for the sake of brevity.

The pattern imaging apparatus <NUM> may also be applied to patterning only a single layer of the photo-sensitive material. As exemplified in <FIG>, the photo-sensitive material may be, for example, a photo resist layer formed on a substrate (e.g., a silicon wafer). The pattern imaging apparatus <NUM> includes multiple imaging devices <NUM> cooperating with the combiner <NUM> and the lens unit <NUM> to project the single light beam output onto the photo-sensitive material, so as to form a desired pattern thereon. Parts of the photo-sensitive material that are irradiated by the pattern area of the image represented by the light beam output may be solidified, and the other parts of the photo-sensitive material that correspond to pattern-less area of the image represented by the light beam output (e.g., the parts that are not irradiated) remain in the original state, thereby completing maskless exposure. After the subsequent development and etching process, the substrate is formed with the desired pattern.

In summary, the digital masking system according to this disclosure includes multiple imaging devices <NUM> configured therein to achieve higher light intensity, higher resolution, and/or higher pixel density of the (resultant) pattern image. Since the multiple imaging devices <NUM> are robustly configured within the housing <NUM> of the digital masking system <NUM> during the manufacturing process, high assembly precision of the devices (e.g., imaging devices <NUM>, light source device <NUM>, etc.) may be achieved (e.g., with a nanoscale tolerance), leading to high precision in image positioning (e.g., image overlapping, image shifting, etc.). In addition, since the imaging devices <NUM> are small in size and are close to each other within the digital masking system <NUM>, distortion among the images provided by different imaging devices may be minimized.

In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiment(s). It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to "one embodiment," "an embodiment," an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects.

Claim 1:
A pattern imaging apparatus (<NUM>) for using light to pattern at least one layer of a photo-sensitive material, comprising multiple light sources (<NUM>), a plurality of imaging devices (<NUM>) and a combiner (<NUM>), wherein:
each of said imaging devices (<NUM>) has a maximum power input limit;
said light sources (<NUM>) are configured to provide a plurality of light components that have substantially the same wavelength spectrum respectively to said imaging devices (<NUM>);
each of the light components has a power smaller than or equal to the maximum power input limit, and a sum of the powers of the light components is greater than the maximum power input limit of each of said imaging devices (<NUM>);
said imaging devices (<NUM>) convert the light components provided by said light sources (<NUM>) respectively into a plurality of light beams each representing a same image, and provide the light beams to said combiner (<NUM>); and
said combiner (<NUM>) combines and redirects the light beams provided by said imaging devices (<NUM>) toward the at least one layer of the photo-sensitive material in such a way that the images represented by the light beams completely overlap each other on the at least one layer of the photo-sensitive material;
wherein said combiner (<NUM>) has a plurality of combiner elements (<NUM>), each having a pair of connection surfaces opposite to each other, and a plurality mount surfaces each of which connects the connection surfaces;
wherein for each of said combiner elements (<NUM>), one of said connection surfaces thereof is connected to one of said connection surfaces of another one of said combiner elements (<NUM>), and said combiner elements (<NUM>) are connected in series; and
wherein said imaging devices (<NUM>) are disposed such that each of the light beams is provided into said combiner (<NUM>) through an individual one of said mount surfaces of said combiner elements (<NUM>), and said combiner (<NUM>) redirects and outputs the light beams from a terminal one of said connection surfaces of said combiner elements (<NUM>) that are connected in series.