System, method, optical assembly, and image projection system for use with a light source

Abstract

This invention includes an imaging projection system that can project five uniform illuminations onto a dimmer while maintaining a small point spread function. A Fourier optical system can be inserted between two homogenization structures such that the light output is uniform in both spatial and angular space as light passes through the system.

Description

Technical Field

[0001] The present invention relates to a method and / or system for spatial and / or angular homogenization of a light beam. Prior Technology

[0002] In the field of imaging projection, existing projectors are typically based on dimmer technology, such as various types of spatial dimmers, like light valves (LCD, DLP, or LCOS) or micromirror devices (DMD). The entire modulator, such as the light valve, illuminates as evenly as possible and blocks light where it is not needed. The disadvantages of this approach are: (1) for average video signals, a significant amount of light energy is wasted because the modulator discards all the light that is not needed for the image. (2) The ability to block light is not perfect, and a small amount of light still leaks into the image when it should be black. This reduces contrast because a completely black image is not actually completely black.

[0003] Currently, the expectation is for displays that can produce a greater dynamic range of contrast, including projection displays. This means darker black levels and higher peak brightness levels, which allows more detail to be distinguished in the dark or black areas of an image and to more fully represent very bright image highlights. However, a significant increase in average image brightness levels is not expected, as this would primarily force the eye to adapt to higher levels (which could be painful) without providing any perceived benefits in terms of dynamic range.

[0004] Typically, increasing the peak brightness level also increases the black or darkest illumination level. In a typical image, more information is encoded around this level, so losing detail in this way is highly undesirable. Alternatively, a cascade of two dimmers is proposed in US 5,978,142. While this method effectively reduces black leakage, it significantly impacts light transmission efficiency because losses in the first dimmer (e.g., imaging optics, mirrors, etc.) can easily reduce the peak brightness level by 50%.

[0005] Furthermore, in typical high dynamic range signals, the ratio between peak brightness levels and average brightness levels becomes larger, thus blocking a greater amount of light energy.

[0006] A more efficient implementation of HDR projectors could be one where only the second dimmer is a light valve type, and where the first dimmer only distributes or controls light where needed. For the same amount of illumination light input, such a solution provides a darker black level and a brighter peak white level. WO 2015 / 054797 proposes such an approach, where the first dimmer is based on a phase-modulated LCOS device.

[0007] Hoskinson and Stoeber describe a method in which analog MEMS devices are used as the first dimmer in their paper, "High-dynamic range image projection using an auxiliary MEMS mirror array," published in the Optical Society of America in 2008.

[0008] In a light-controlled projector, any light distribution at the location of the first dimmer can be converted into the desired light distribution at the second dimmer. However, it is still desirable for the light to be uniformly distributed on the first dimmer. This will distribute the heat load on the first dimmer and optimally utilize the device's resolution and optical spread (spread).

[0009] For a circular beam with a Gaussian distribution, the peak power lighting load on the first dimmer can be a multiple of the peak power lighting load with a uniform rectangular lighting profile. Figure 1A shows a circle representing the projection of a circular beam with a Gaussian distribution, fitted into a uniform 16:9 rectangle. The beam circle occupies only 44% of the total area of ​​the rectangle. This can cause local temperatures to far exceed the normal operating range of the device and / or significantly shorten its lifespan. It would be preferable if the light from the circular beam is uniformly distributed within the rectangle (as shown in Figure 1B).

[0010] While non-uniform illumination profiles can be calibrated and accounted for when calculating the required light control, the stability of the profiles will be crucial. For example, if multiple discrete laser sources are combined to illuminate a first dimmer, temperature differences or aging effects between the discrete laser sources could lead to unpredictable changes in the illumination distribution throughout the device's lifetime.

[0011] Therefore, preferably, the beams from multiple discrete laser sources are properly mixed such that each light source contributes equally and uniformly to all positions on the first dimmer. Another advantage is that this minimizes laser speckle effects in the image, especially if each primary color combination comes from lasers of slightly different wavelengths.

[0012] Furthermore, the angular spread of the illumination beam affects performance. Ideally, a laser beam is perfectly collimated, such that all parts of the beam propagate in the same direction. The optical system can then focus the beam onto a single focal point. However, real-world laser sources do not provide perfectly collimated beams; instead, they can exhibit some degree of divergence or angular spread around the propagation axis or optical axis. Therefore, when attempting to focus the beam, this light propagation will be visible as a blurred point around the optical axis. This spread can be referred to as the system point spread function (PSF).

[0013] In a light control system, the focal point can be located at an intermediate image plane, for example, at a stationary or moving diffuser located at a distance from the first dimmer. Due to beam divergence, the spot size on the intermediate image plane will be finite. The minimum size of the light-controlled beam spot at the intermediate image (and therefore in the final image) can then be a function of the angular spread at the first dimmer's location and the distance between the first dimmer and the intermediate image plane. In a typical configuration, the angular spread of the illumination from the first dimmer can be less than + / - 0.1°. The system PSF can also be used for a calibration step to calculate the true luminance level profile at the intermediate image. For multiple light sources, temperature differences or aging differences can alter the distribution of laser or light energy in angular space, thus changing the luminance distribution in the point spread function. Therefore, since the stability of the calibration step depends on the stability of the angular spread of the illumination light, it is desirable to minimize the effects of differences in characteristics such as temperature and aging.

[0014] Figure 2 illustrates a partially collimated light or laser beam 20 with an angular spread 21. It is reflected by a dimmer 22 to form an intermediate image on a moving diffuser 23 located at an intermediate plane 24. The beam spot on the moving diffuser 23 has a spread 25 around the ideal focal point 26 (at the optical axis). The spread 25 can be described using a point spread function. Figure 2 also includes incident beams 27 and 28, which have similar angular spreads and thus contribute to approximately the same PSF.

[0015] Figure 3 illustrates how angular and spatial light distribution can be altered through collimation (full arrow) or imaging (dashed arrow). If light is transmitted via an optical fiber and the light from the fiber is collimated onto the first dimmer, the angular brightness profile 31 of the light emitted from the fiber determines the spatial light distribution 32 on the phase modulator. The spatial distribution 30 of the light emitted from the fiber is transformed into an angular light distribution 33 on the phase modulator and can therefore be directly correlated with the shape of the point spread function. If the light at the fiber exit is imaged onto the phase modulator, the spatial uniformity 30 of the light will determine the spatial uniformity 32 of the light projected onto the phase modulator. The angular uniformity 31 of the light determines the angular uniformity 33 of the light projected onto the phase modulator, thereby determining the shape of the point spread function.

[0016] In both cases, the spatial and angular light distribution at the fiber optic exit is a key parameter.

[0017] When the illumination angle profile is smooth (e.g., Gaussian), the calibration of the imaging projection system can be improved. On the other hand, if the illumination angle profile is highly irregular, small differences in alignment between the actual and assumed PSF positions can produce large differences between the actual and assumed dimmer illumination. Ultimately, this results in significant errors in the final image. Figure 4A shows an example of a smooth brightness level profile, and Figure 4B shows an example of an irregular brightness level profile where the brightness level changes abruptly with the angle. These are only cross-sections; the requirement for smooth brightness level changes with angle applies in two dimensions. Summary of the Invention

[0018] The object of this invention is to provide a method and / or system for spatial and / or angular homogenization of a light beam.

[0019] In one embodiment of the invention, a system for providing a uniform light beam for use with a light source is provided. The system may include at least two homogenization structures, such as a first homogenization structure and a second homogenization structure, or at least a first homogenization structure and a second homogenization structure. Any or all of the homogenization structures may be, for example, optical fibers, each homogenization structure having an input (section) and an exit (section), i.e., each having an input plane and an exit plane. The system may also include a Fourier optical system having a first focus and a second focus. The light source, the first homogenization structure, the Fourier optical system, and the second homogenization structure may be placed adjacent to each other and continuously. The Fourier optical system may be positioned such that the exit (or exit plane) of the first homogenization structure coincides with the first focus of the Fourier optical system, and the input section (e.g., the input plane) of the second homogenization structure coincides with the second focus.

[0020] Alternatively or additionally, at least one of the two first homogenization structures and the second homogenization structure may include a cross-sectional region having a rectangular shape.

[0021] Additionally or alternatively, at least one of the first and second homogenization structures may have a cross-sectional area, and the dimmer may have an image area, and the aspect ratio of the cross-sectional area of ​​at least one of the first and second homogenization structures may be the same as the aspect ratio of the area of ​​the dimmer. The dimmer may be a spatial dimmer or a light valve, either of which may be transmissive or reflective.

[0022] Alternatively or additionally, the first homogenizing structure can be bent to have a bending radius. Alternatively or additionally, the first homogenizing structure can adopt different bending radii at different points in time.

[0023] Alternatively or additionally, at least one of the first homogenization structure and the second homogenization structure may be a conventional integrator. At least the first homogenization structure and the second homogenization structure may be conventional integrators. Furthermore, the system may include a diffuser, and the diffuser may be located between the light source and the first homogenization structure at a position where the light source can be placed.

[0024] In another embodiment of the invention, a method is provided for use with a light source to provide a uniform light beam. This method utilizes at least two homogenization structures, such as optical fibers, each homogenization structure having an input portion and an exit portion, such as an input plane and an exit plane; and utilizes a Fourier optical system having a first focal point and a second focal point. The method may include placing the light source, the first homogenization structure, the Fourier optical system, and the second homogenization structure adjacent to and continuously connected to each other. It may also include positioning the Fourier optical system such that the exit portion (or exit plane) of the first homogenization structure coincides with the first focal point of the Fourier optical system, and the input portion (e.g., the input plane) of the second homogenization structure coincides with the second focal point of the Fourier optical system.

[0025] Alternatively or additionally, at least one of the first homogenization structure and the second homogenization structure may have a cross-sectional region, and the method may include configuring the region into a rectangular shape.

[0026] Additionally or alternatively, at least one of the first homogenization structure and the second homogenization structure may have a cross-sectional region, and the dimmer may have an image region, wherein the method may include configuring the aspect ratio of a cross-sectional region of at least one of the first homogenization structure and the second homogenization structure to be the same as the aspect ratio of the region of the dimmer.

[0027] Alternatively or additionally, the method may include bending a first homogenizing structure with a bending radius. Alternatively or additionally, the bending radius may vary with frequency (i.e., vary periodically along the first homogenizing structure).

[0028] Additionally or alternatively, the method may include implementing at least one of the first homogenization structure and the second homogenization structure as a conventional integrator. Furthermore, a diffuser may be present, and the method may include placing the diffuser between the location of the light source and the first homogenization structure.

[0029] In another embodiment of the invention, an optical element is provided for use with a light source to provide a uniform light beam. The system may include at least two homogenization structures, such as optical fibers, each homogenizing structure having an input (section) and an exit (section), such as an input plane and an exit plane. The system may also include a Fourier optical system having a first focal point and a second focal point. The light source, the first homogenization structure, the Fourier optical system, and the second homogenization structure may be placed adjacent to each other and continuously. The Fourier optical system may be positioned such that the exit (e.g., the exit plane) of the first homogenization structure coincides with the first focal point of the Fourier optical system, and the input (e.g., the input plane) of the second homogenization structure coincides with the second focal point of the Fourier optical system.

[0030] Additionally or alternatively, at least one of the first homogenization structure and the second homogenization structure may include a cross-sectional region having a rectangular shape.

[0031] Additionally or alternatively, at least one of the first homogenization structure and the second homogenization structure may have a cross-sectional region, and the dimmer may have an image region, wherein the aspect ratio of the cross-sectional region of at least one of the first homogenization structure and the second homogenization structure may be the same as the aspect ratio of the region of the dimmer.

[0032] Alternatively or additionally, the first homogenization structure may be bent with a bending radius. Alternatively or additionally, the first homogenization structure may employ different bending radii at different points in time.

[0033] Alternatively or additionally, at least the first homogenization structure and the second homogenization structure may be conventional integrators. Alternatively or additionally, the optical element may include a diffuser, and the diffuser may be positioned between the light source and the first homogenization structure.

[0034] In another set of embodiments relating to an independent aspect of the invention, an image projection system for use with a light source is provided, the image projection system including a dimmer and a homogenization structure having an elongated shape and adapted to receive light from the light source and guide the light onto the dimmer, wherein the homogenization structure has a rectangular structure, such as a rectangular cross section, and one or more bends.

[0035] The homogenization structure may include a cross-sectional region with the shortest side, and each bending radius is at least 200 to 1000 times larger than the shortest length of that cross-sectional region.

[0036] A homogenized structure can have a rectangular cross-sectional region.

[0037] The homogenized structure may include a cross-sectional region having corners, wherein the shape of each corner is rounded with a radius of curvature.

[0038] The homogenization structure may have a cross-sectional area, and the dimmer may have an image area, and the aspect ratio of the cross-sectional area of ​​the homogenization structure is the same as the aspect ratio of the image area of ​​the dimmer.

[0039] In another aspect, the present invention provides a method for using with a light source and for diffusing light in an image projection system, the image projection system including a dimmer and a homogenization structure having an elongated shape and adapted to receive light from the light source and direct the light onto the dimmer, wherein the method includes bending the homogenization structure at one or more locations.

[0040] The homogenization structure may include a cross-sectional region having the shortest side, and the above method includes the step of configuring each bending radius to be at least 200 to 1000 times larger than the shortest length of the cross-sectional region.

[0041] The homogenization structure may have a cross-sectional region, and the above method includes configuring the cross-sectional region as a rectangle.

[0042] The homogenization structure may include a cross-sectional region having corners, and the above method includes configuring each corner into a rounded shape with a defined radius of curvature.

[0043] The homogenization structure may have a cross-sectional area, and the dimmer may have an image area. The method includes configuring the aspect ratio of the cross-sectional area of ​​the homogenization structure to be the same as the aspect ratio of the image area of ​​the dimmer.

[0044] definition

[0045] The Point Spread Function (PSF) describes the spread or blurring of light around the focal point on the surface of a beam due to beam divergence. The spatial distribution of the PSF describes the region of light spread on a physical surface. The angular distribution describes the different angles at which the beam strikes (illuminates) the physical surface.

[0046] "Optical fiber" can be a flexible fiber made of transparent materials such as glass, silicon dioxide, or plastic. The diameter of optical fiber is typically in the sub-millimeter range.

[0047] An "optical diffuser" or "diffuser" can be an optical component that can scatter light in any direction.

[0048] A "dimmer" can be an optical component capable of modulating a beam of light impacting (illuminating) it. One type of dimmer can be called an "amplitude modulator," which modulates the amplitude of the incident light. This can be achieved using technologies such as liquid crystal displays (LCDs), digital light processing (DLP) or liquid crystal on silicon (LCoS), digital micromirror devices (DMDs), or any other technology that can introduce controllable amplitude variations in the beam. Another type of dimmer can be called a "phase modulator," which modulates the phase of the incident light. This can be achieved using technologies such as LCoS, microelectromechanical systems (MEMS), or any other technology that can introduce controllable phase shifts in the beam.

[0049] A "homogenizing structure" is an optical component capable of homogenizing a light beam. It is typically elongated and has an inlet or input and an outlet or output. When a light beam is inserted into or input into the homogenizing structure, it is reflected on the inner walls of the structure. The reflection characteristics of the homogenizing structure depend on its geometry and the materials used to make it. For example, integrating rods made of fused silica or glass typically have a square or circular cross-section. Alternatively, it can be an optical fiber with a high-refractive-index core, whose rectangular, square, or hexagonal cross-section is surrounded by a low-refractive-index cladding material.

[0050] "Uniformity": For spatial light distribution, if the brightness level at each location is better than 70% of the average brightness level on the beam cross section, preferably better than 80%, then the brightness level can be said to be uniform.

[0051] For angular light distributions, the brightness observed from different angles within this range is uniform if it is constant or smooth (monotonic, without local maxima). For example, this could be a Gaussian distribution or a top-hat distribution with a steep rise and fall near the outermost edges. The ripple in the middle of the distribution is preferably less than 5%, or more preferably less than 2%.

[0052] A "Fourier transform optical system" is a system of optical components capable of transforming a light beam according to a Fourier transform. For example, if a light distribution in linear space is input into a Fourier system, the output can describe a similar light distribution in, for example, the frequency domain or angular space. Simple Explanation of the Diagram

[0053] Figures 1A and 1B show cross-sections of the illumination beam; Figure 2 shows an illumination beam with non-ideal collimation having spatial and angular extensions around the optical axis; Figure 3 shows how collimation or direct imaging of the beam affects its angular and spatial light distribution; Figures 4A and 4B show smooth and irregular brightness distribution profiles; Figure 5 shows four sub-light sources entering the homogenization structure; Figures 6A and 6B to 8A and 8B show embodiments of the invention including spatial and angular light distribution maps; Figures 9A and 9B show embodiments of the invention including angular light distribution maps; Figure 10 shows an embodiment of the invention including angular light distribution maps; Figure 11 shows an embodiment of the invention including spatial and angular light distribution maps; Figures 12 to 14 show embodiments of the invention including a two-stage homogenization structure system; and Figure 15 shows an embodiment of the invention including spatial and angular light distribution maps for a two-stage homogenization structure system. Implementation

[0054] The invention will be described with reference to specific embodiments and certain drawings, but the invention is not limited thereto but is limited only by the claims. The described drawings are illustrative and not restrictive. In the drawings, for illustrative purposes, the dimensions of some elements may be exaggerated and not drawn to scale. When the term "comprising" is used in this specification and patent applications, it does not exclude other elements or steps. Furthermore, the terms "first," "second," "third," etc., in the specification and patent applications are used to distinguish between similar elements and are not necessarily used to describe a sequence or temporal order. It should be understood that the terms thus used are interchangeable where appropriate, and the various embodiments of the invention described herein can operate in a different order than that described or illustrated herein.

[0055] According to an embodiment of the invention, the light control system may have a first dimmer illuminated by a beam providing a uniform rectangular spot and a smooth angular light distribution. When the light source comprises multiple discrete laser sources, these sources are preferably appropriately mixed. Ideally, each light source acts uniformly at every position on the first dimmer, and it acts uniformly across the entire angular range. In this way, the system can become less sensitive to power reduction (or failure) of a single light source. Furthermore, if beams with multiple wavelengths are superimposed, speckle patterns can be reduced by means of wavelength diversity.

[0056] The spatial distribution of illumination determines how light energy is distributed across different highlight regions in an image. If this spatial illumination profile changes, the light distribution across different highlights will fluctuate; for example, some highlight regions will become brighter, while others will become darker. Phase algorithms can be used on the light beam (light steering beam) to reduce sensitivity to non-uniform and / or varying input illumination beams. These phase algorithms can include mixing light from different locations. If each highlight region receives light from every location on the panel, the non-uniformity of the phase panel's illumination can be largely eliminated. However, more efficient phase algorithms (see WO 2015 / 184549) attempt to minimize steering angles and, for example, would preferably direct light from the upper right corner of the phase panel toward the highlights in the upper right corner of the central image. To enable the use of these more efficient algorithms, it is important to ensure uniform and stable illumination on the phase panel.

[0057] As shown in Figure 3, the angular light distribution determines the shape of the illumination light described by the point spread function on the intermediate image (which is equal to the shape of the minimum focused highlight). If the angular light distribution profile changes, the illumination light distribution within the point spread function also changes. This can lead to changes in high-frequency brightness levels, resulting in color variations in the RGB full-color system.

[0058] Ideally, the illumination light should be properly homogenized to deliver a stable light profile to the first dimmer in both the spatial and angular domains. The homogenization structure should provide this homogenization regardless of the characteristics of the light at its entry point. If multiple laser sources are coupled at its entry point, each laser source will preferably contribute equally to each position and angle at the phase modulator, thereby eliminating temperature differences and aging effects and minimizing laser speckle.

[0059] WO 2012 / 139634 discloses a method for improving the spatial and angular uniformity of a single laser source array, which discloses a system comprising two integrator stages. Each of the two integrator stages may have a diffuser in front of it, and the output of the first integrator stage can be imaged onto the diffuser in front of the second integrator stage.

[0060] For light-controlled projection systems, it is desirable to keep the point spread function small, as this allows for the resolution of small highlight features in the image. Therefore, the angular spread of the illumination beam incident on the first dimmer is preferably kept small. However, conventional homogenization structures, such as solid rod integrators or hollow tubes, can only properly blend the incident beam when the beam has sufficient angular spread and / or the integrator or tube is very long. Therefore, conventional rod integrators or tubes may not be suitable for light-controlled projection systems.

[0061] However, if the cross-section is small enough, a feasible angular extension can be achieved using an integrating rod of conventional length. For example, it can be about 100 times smaller than the size of the first dimmer. Then, the extension angle of + / -0.1° at the first dimmer can be converted to an extension angle of + / -10° at the homogenizing rod (integrator rod), which is sufficient to provide good integration over a finite length. For example, this length can be 50-100 times the height of the homogenizing rod. Assuming the height of the first dimmer is approximately 1 cm, the height of the homogenizing rod would be 100 μm (the minimum length could be 5 to 10 mm).

[0062] The homogenizing rod with the aforementioned small cross-section can be implemented using optical fibers with fused silica cores, for example, rectangular, square, or hexagonal cross-sections. For instance, Leoni offers multimode special-optical fibers (https: / / www.leoni-fiber-optics.com / en / products-and-services / fibers / multimode-special-optical-fibers / ). Custom (custom-made) cross-sections can be produced.

[0063] These optical fibers transmit the top cap intensity distribution at their output ends. The output can be imaged onto a first dimmer, and a uniform brightness level distribution can be achieved on the first dimmer (if the optical fiber has the same shape as the modulator).

[0064] An ideal rectangular optical fiber (i.e., an optical fiber with a rectangular cross-section) will reflect the angular light distribution at its input in both the horizontal and vertical directions, but will not result in angular homogenization. If multiple light sources are coupled at the input from different angles, the output image may include angular gaps between discrete light sources.

[0065] Implementation method one: optical fiber.

[0066] Figure 5 illustrates a light source comprising four sub-light sources 50 coupled at the entrance of an optical fiber 52 used in an embodiment of the invention from four different angles (e.g., three degrees relative to the normal or optical axis 51). The sub-light source beams overlap at the input (plane) 53. The sub-light source beams span an angle of + / -1.5 degrees, thus creating gaps in angular space. The light distribution at the input is non-uniform both spatially and angularly. Based on the above measurements, spatial and angular radiation maps were simulated. The results can be represented by spatial and angular radiation distribution charts, where the x-axis and y-axis extend in linear space and angular space, respectively. The intensity table on the right-hand side represents the radiation.

[0067] At input 53, light source 50 transmits a non-uniform illumination point, as shown in the spatial distribution diagram in Figure 6A. With the dimensions described above, the diameter of this point is approximately 20 μm. Figure 6B shows the corresponding angular light distribution, including gaps in the angular space, i.e., no radiation at these angles or directions.

[0068] The beams in Figures 5 and 6 can be input into a rectangular optical fiber with a cross-section of, for example, 160 x 90 μm and a length of 20 cm. Figures 7A and 7B show the spatial and angular radiation distributions at the output plane of the optical fiber, respectively. Therefore, the spatial distribution in Figure 7A exhibits good uniformity. However, the angular radiation distribution in Figure 7B shows that the non-uniform angular light distribution remains non-uniform. However, since the rectangular optical fiber reflects (reflects) the angular light distribution in both the horizontal and vertical directions, it mixes four sub-sources in the angular space. This means that if one of the sub-sources fails, the angular profile will at least remain stable.

[0069] Implementation method two, asymmetry.

[0070] The sub-light source or laser source at the input can be arranged at an asymmetrical angle. This may result in an overlap of the four angular profiles (or radiation distribution) at the output: a non-reflective (mirrored) input profile.

[0071] Only horizontal reflection (mirror image) input contours.

[0072] Only the input profile with vertical reflection (mirror image) has both horizontal and vertical reflection (mirror image) input profiles.

[0073] By taking this reflection (mirror image) effect into account, the gap in the angular space at the output can be reduced or eliminated. Care should also be taken to avoid generating significant overlap.

[0074] The sub-sources in Figure 5 can be coupled into a rectangular fiber at four discrete angles, which are asymmetrically distributed around the normal. The gaps in the angular light distribution graph can be chosen to be similar in size to the angular coverage of each input source. The angular light distribution obtained at the input can be seen in Figure 8A. Figure 8B shows the angular light distribution at the output. Different sub-images include the input angular light distribution in Figure 8A as well as the angular light distribution of the horizontal and / or vertical reflection (mirror) images. The resulting angular light distributions have no gaps. For a given angle, some overlap may still produce higher intensity.

[0075] However, since the mirrored images now have minimal overlap, the four light sources no longer mix in angular space. Each light source has its own four output points, and temperature differences or aging effects will cause variations in the angular light distribution.

[0076] Implementation method three: bending.

[0077] One embodiment of the invention can be advantageous because it introduces a controllable amount of diffusion to achieve beam mixing. The bending of the optical fiber can be used in conjunction with other embodiments of the invention, but this relates to a separate embodiment of the invention.

[0078] Because the cross-section of the fiber optic uniform beam is very small, conventional diffusers cannot be used. The diffuser's grain size needs to be much smaller than the fiber's cross-section, and the diffuser needs to be very close to the fiber inlet to prevent any light from escaping. Adding to the complexity is the extremely high power density.

[0079] The inventors discovered that controlled diffusion can be introduced into an optical fiber by slightly bending it. Due to the mirror (reflection) effect, bending in one direction will lead to a symmetrical increase in the distribution in angular space. Therefore, the final angular light distribution will be the incident angle light distribution plus or minus one degree.

[0080] By arranging rectangular optical fibers in a three-dimensional S-shape, diffusion can be increased along the x and y axes in angular space. The amount of diffusion around the horizontal axis can be chosen to be the same as or different from the amount of diffusion around the vertical axis.

[0081] Figure 9A illustrates how the exemplary optical fiber described above is bent with a bending radius of 10 cm in both the horizontal and vertical directions. Furthermore, using four sub-light sources as one of those in Figure 5, the angular light distribution at the output does not exhibit gaps, as shown in Figure 9B. The spatial light distribution (not shown here) also remains uniform. Moreover, the bending can vary over time (i.e., vibrate) to produce an effect equivalent to a moving diffuser. This reduces speckle effects in the output image.

[0082] Each time the optical fiber changes its bending direction, the diffusion angle increases. The amount of increased diffusion is a function of the bending radius. As with cascades of ordinary Gaussian diffusers, this effect is not cumulative, but is given by the square root of the sum of the squares of the individual diffusion angles, as shown in Equation 1.

[0083]

[0084] Figure 10 illustrates an exemplary embodiment of the invention, comprising (e.g., a rectangular) optical fiber 100, wherein the angles gradually evolve along a one-dimensional vertical S-curve of the fiber. Angular light distributions 101 to 107 at seven points (labeled "1" to "7") on the fiber from left to right are shown. After the straight fiber section at point 1, the initial angular light distribution 101 is the same as that emitted at the fiber inlet. At the beginning of the first bend at point 2, the light transitions from the straight fiber section to the bent fiber section, causing the reflection angle to increase, and the angular light distribution 102 begins to expand in one direction. As the light continues to propagate along the fiber with a constant bend radius and bend direction, the increase in angle caused by light reflected (reflected) on one side of the fiber is compensated by the decrease in angle caused by light reflected (reflected) on the other side of the fiber, and the overall angular distribution no longer expands. However, the effect of vertical mirroring at point 103 can be seen as the vertical gap beginning to fill. At point 104, the mirroring operation is complete (the vertical gap is filled). This effect is repeated whenever the bend direction changes, and the result corresponds to the result of adding an additional diffuser. From point 5 to point 6 and then to point 7, the effect of vertical diffusion can be gradually observed to increase. However, due to the square root law of equation (1), the effect of the fourth bend at point 7 is relatively small. The same type of S-shaped bend can also be applied in another direction to achieve horizontal diffusion.

[0085] It has been observed that whenever an optical fiber transitions from a straight section to a curved section, a certain amount of one-dimensional diffusion increases. The amount of diffusion can be related to the bending radius. Continuing to use the same bending radius and direction no longer affects the angular light distribution. However, bending the fiber back to a straight shape and then bending it in the opposite direction can further increase the amount of diffusion (albeit not linearly). Therefore, the desired amount of diffusion can be adjusted by controlling the fiber trajectory and bending radius.

[0086] The bending radius of an optical fiber can be 200 to 1000 times larger than its height; for example, a bending radius of 100 mm for a 0.1 mm fiber. The angle after the first bend (point 4) can be extended by approximately + / - 0.75 degrees. The angle after the full S-curve (point 7) can be extended by approximately + / - 1.5 degrees.

[0087] Implementation method four: rounded corners of the cross section.

[0088] Current fiber manufacturing processes may result in fibers with rounded cross-sectional corners, which thus possess a radius of curvature. Therefore, overfilling may be necessary to keep these rounded corners outside the effective area of ​​the first dimmer, leading to optical loss. Minimizing the rounding of the fiber cross-sectional corners can be expected to minimize this optical loss.

[0089] However, rounding the corners of the cross-section can introduce a radial mixing effect in angular space. Therefore, it may no longer be necessary to apply bending in both the horizontal and vertical directions to produce a complete diffusion effect. Introducing bending in any direction will be sufficient, and the rounded corners will provide radial mixing. For example, the radius of the rounded corners can preferably be less than 5% of the fiber width to minimize overfill. However, preferably, the radius is still large enough, for example, more than 1% of the fiber width, to introduce sufficient radial mixing over a finite length of 1-2 meters.

[0090] A single rectangular fiber with rounded corners can introduce blending at three levels: (1) spatial uniform blending on the rectangular cross-section, providing a uniform rectangle (possibly with rounded corners) at the output. (2) axial angular uniform blending by bending the fiber. The bending amount should be minimal enough to close the axial distance between adjacent laser diodes. (3) radial angular uniform blending possible due to the rounded corners of the cross-section, thereby eliminating gaps in the angular space between adjacent diodes in the radial direction.

[0091] Implementation method five: straight optical fiber.

[0092] In one exemplary embodiment, a straight optical fiber is provided, for example, having a cross-section of 315 x 166 μm, with rounded corners having a radius of, for example, 50 μm and a length of 1 meter.

[0093] Point light sources, such as lasers with a square angular profile of + / - 6.5 degrees in both the horizontal and vertical directions, are positioned to project light into an optical fiber. The point light source can be located, for example, at a distance of 300 μm before the fiber inlet, to illuminate a reduced area at the inlet, such as an area of ​​only 66 x 66 μm.

[0094] Figure 11 illustrates one embodiment of the invention, which includes the aforementioned optical fiber 110 and spatial and angular light distribution profiles 111 to 117 and 121 to 127, respectively, evolving at points 1 to 7. Points 1 to 7 are located at the fiber inlet and then at distances of 1 cm, 5 cm, 10 cm, 20 cm, 50 cm, and 100 cm from the fiber inlet, respectively. Table 1 summarizes the members (components) at each location.

[0095] Spatial uniformity 112 at point 1, 1 cm later, is not yet perfect. Similarly, the corresponding radial mixing shown in angular light distribution 122 is incomplete. At point 3, 5 cm later, spatial uniformity is almost perfect, and at point 4, 10 cm later, as seen in angular light distribution 124, radial mixing is also almost complete, achieving full coverage.

[0096] In this example, the corner rounding is relatively large (radius is 15% of the fiber width). However, since the amount of radial mixing is expected to be proportional to the radius / width ratio, and after 10 cm, we see that proper angular mixing, even at a ratio 10 times smaller (e.g., radius is 1.5% of the fiber width), is expected to provide sufficient radial mixing over a length of 1 meter.

[0097]

[0098] Implementation method six: two-stage homogenization, collimator.

[0099] Additionally or alternatively, in another embodiment of the invention, spatial and angular uniformity can be improved by implementing a two-stage homogenization solution comprising an "optical fiber" or "beam homogenizer" and a "Fourier transform optics (device)" or simply "Fourier optics (device)". Such Fourier optics (devices) can be used as a "converter" between angular space and linear space. The Fourier optics (devices) can be positioned such that the exit of the first homogenization structure coincides with the first focal point of the Fourier optics (device), and the input of the second homogenization structure coincides with the second focal point of the Fourier optics (device). At the exit of the first stage, good spatial uniformity can be obtained, but angular uniformity may not be optimal. The Fourier optics (devices) can transform the angular light distribution at the exit of the first homogenization stage into the spatial distribution at the entrance of the second homogenization stage; and vice versa (the spatial distribution at the exit of the first homogenization stage is transformed into the angular light distribution at the input of the second homogenization stage). The second stage stabilizes the non-uniformity in the spatial distribution and provides a uniform exit in space. This also maintains a uniform angular light distribution at its entrance, assuming the distribution is square or rectangular in shape with sufficiently sharp corners. Therefore, at the exit of the two-stage system, both spatial and angular uniformity are adequately guaranteed and virtually independent of input characteristics. Proper spatial and angular mixing of multiple light sources eliminates the problems of temperature differences or aging effects and provides optimal speckle reduction. In most cases, the natural divergence of (one or more) laser beams will be sufficient to achieve good mixing over a reasonable length of the first fiber stage. And no additional diffusion is needed, which would unnecessarily increase the optical spread of the laser beam. If the laser beam quality is too good, a small level of diffusion introduced by controlled bending of the first fiber stage or by placing a diffuser in front of the first homogenizer will be sufficient to achieve good mixing over a reasonable optical length of a few centimeters.

[0100] Fourier optics (devices) can be implemented, for example, using optical lens systems.

[0101] Patent application WO 2012 / 139634 discloses a dual homogenization structure solution. However, the optical lens system between the two stages is configured to image the exit of the first stage onto the entrance of the second stage, and a diffuser is placed before each stage.

[0102] Figure 12 illustrates one embodiment of the invention, which includes a system 130 with a dual homogenization structure solution and a Fourier lens 131. In this embodiment, the output from the second homogenization structure 136 can be extended and collimated onto a dimmer 138. A beam of light (not shown), such as a laser, originating from a light source 132, may be square and have a sub-light source 139, and passes through a focusing lens 133 and a static or moving diffuser 134 before entering the first homogenization structure 135, such as a rectangular homogenizer or optical fiber. The diffuser may have a relatively low angular extension and is preferably adapted in this respect to work with the first homogenization structure 135, such as a rectangular homogenizer or optical fiber. At the exit of the first homogenization structure 135, there is a Fourier optics component, such as a Fourier lens 131, and then the beam can enter the second homogenization structure 136, such as a square homogenizer or optical fiber, before being collimated onto the dimmer 138 by a collimating lens 137.

[0103] System 130 can be a light control system, wherein dimmer 138 is the first of two (or more) dimmers. Alternatively, system 130 can be a conventional single dimmer system, wherein dimmer 138 is the only dimmer.

[0104] If the first homogenization structure 135 is a rectangular homogenizing rod or optical fiber, its aspect ratio determines the ratio between the horizontal and vertical angles at the exit of the second stage. The collimating lens 137 following the two-stage integrator (or homogenization system) can convert or transform the horizontal and vertical angles into uniform rectangular points at the modulator 138. In this case, the first homogenization structure 135 is preferably rectangular, with the same aspect ratio as the modulator 138. The spatial uniformity at the exit of the second homogenization structure 136 determines the angular light distribution after collimation. The second homogenization structure 136 can be square to create a symmetrical PSF in the optical control system. For a single dimmer system, the square homogenization structure 136 can create and approximate a circular aperture in the optical path.

[0105] The minimum cross-section of the required second homogenization structure is determined by the angular subtense of the light source emitted in the first fiber. In a light-controlled system, this cross-section is preferably kept as small as possible to maintain the point spread function as small as possible.

[0106] While circular or hexagonal point spread functions may be preferred, it is impossible to use circular or hexagonal cross-sectional geometries for the second homogenization structure because only rectangular or square fibers will maintain the angular light distribution generated in the first stage. Furthermore, circular cross-sectional geometries do not produce the desired spatial uniformity.

[0107] In the case of implementing the second homogenization structure using optical fiber, rounding at the corners of the cross-section is undesirable because radial mixing would interfere with the requirements for maintaining the horizontal and vertical angular light distribution at the input of this stage. Therefore, it is desirable to limit the corner rounding to the minimum achievable limit and to limit the length of the second stage to the minimum length required to obtain sufficient spatial mixing.

[0108] Implementation method seven: two-stage homogenization and imaging.

[0109] Figure 13 illustrates another embodiment of the invention, wherein the second homogenization structure 146 may be rectangular, while the first homogenization structure 145 may be square. A light beam (not shown), such as a laser, originating from a light source 142, may be rectangular and have a sub-light source 149, passing through a focusing lens 143 and a static or moving diffuser 144 before entering the first homogenization structure. The static or moving diffuser 144 may have a low-angle extension and is preferably adapted to work in conjunction with the first homogenization structure. In this embodiment, the output from the second homogenization structure 146 can be directly imaged onto a dimmer 148 via an imaging lens 147.

[0110] For a system with light control (including at least two dimmers), the first homogenization structure 145 can then determine the shape of the point spread function in the intermediate image. For a single dimmer system, the first homogenization structure 145 can create and approximate a circular aperture in the optical path. The first homogenization structure 145 is preferably square or hexagonal in shape.

[0111] The second homogenization structure can provide radial (angular light distribution) mixing, and this second homogenization structure includes optical fibers with rounded corners. It can also convert square or hexagonal angular light distributions into more desirable circular distributions.

[0112] If the light source array is, for example, circular or square, rounded corners in the cross-section of the first homogenization structure can be tolerated. Then, a circular light spot will be present at the entrance of the second homogenization structure, which can match the shape of the second homogenization structure (e.g., rectangular), but will result in unused system optical spread.

[0113] Alternatively, the laser array can have a rectangular shape and an aspect ratio suitable for the dimmer. To maintain the rectangular angular distribution profile, the first homogenization structure should preferably be square, and the degree of corner rounding and fiber length should be minimized.

[0114] Implementation method eight: two-stage conventional homogenization structure.

[0115] In another embodiment of the invention, a two-stage homogenization or integration (homogenization) system is provided, comprising two conventional integrators, such as fused silica rods or hollow light tubes ("integrators"), preceding a diffusion element (or "diffuser"), and including intermediate imaging (Fourier) optics and a dimmer. The "integrator" can be a "homogenization structure". This arrangement can be similar to the one shown in Figures 12 or 13.

[0116] Examples of conventional integrators could be hollow light channels (https: / / materion.com / - / media / files / precision-optics / data-sheets-2012 / light-tunnel-data-sheet.pdf?la=en&hash=1B2EE007DE55470622DCA2D0A90842D6EDD0C01A) or solid rods (https: / / www.newport.com / f / light-pipe-homogenizer).

[0117] An array of laser sources can be focused into a first square integrator. A second integrator can have a rectangular cross-sectional aspect ratio that matches that of the dimmer. Fourier optics can be placed between the integrators to convert the angular light distribution at the output of the first homogenization structure into the spatial light distribution at the entrance of the second homogenization structure (and similarly, the uniform spatial light distribution at the exit of the first homogenization structure can be converted into a uniform angular light distribution at the entrance of the second homogenization structure).

[0118] To utilize all available optical extension at the entrance of the second homogenization structure, the angle of light coupling from the laser array is ideally also asymmetrically distributed. This can be achieved if the laser array is arranged as a rectangle with the same aspect ratio as the dimmer, and the first homogenization structure is a square. In this way, the angular light distribution of the incident light is maintained, which is not the case for, for example, a hexagonal rod.

[0119] Furthermore, a static or moving diffuser can be placed before the first homogenization structure to enable good mixing with minimal rod length. The static or moving diffuser can have a low-angle extension and is preferably adapted to work with the first homogenization structure. However, a diffuser is not required before the second homogenization structure.

[0120] The cross-section of the first homogenization structure determines the system aperture, where the system aperture becomes square instead of circular. If the physical aperture in the illumination system or projection lens is circular, the aforementioned square system aperture should be fitted into this circular aperture. Optical loss caused by unused optical spread can be compensated for by improved fitting of the beam at the homogenizer entrance and elimination by the second diffuser. Overall, optical spread is better utilized, and more laser diodes can be coupled into the system, or the system's focal length ratio (aperture number) can be increased, which further improves the projector's contrast and reduces the size of the optical components.

[0121] In a preferred embodiment, the physical system apertures in the lighting system and projection lens are also square.

[0122] Advantageously, the mixing of individual light sources, such as laser diodes, in the array is nearly perfect in both the spatial and angular domains. For example, wavelength diversity for speckle reduction can be enabled by using only one light source, such as a laser diode, for each wavelength. Using the method of WO 2012 / 139634, a small number of light sources, such as laser diodes, would necessitate a very strong diffuser to close the angular gap between light sources, such as laser diodes, with the same wavelength. A strong diffuser would increase the PSF diameter, which is undesirable in a light-controlled system. It should be noted that, in order to achieve optimal speckle reduction via angular diversity, it is recommended to move or vibrate the diffuser located before the first homogenization structure.

[0123] Implementation method nine: two-stage, fiber homogenization structure.

[0124] Figure 14 illustrates one embodiment of the invention, which includes a system 150 having a first homogenization structure 151, such as a rectangular optical fiber, with a cross-section of, for example, 160 x 90 μm. The system 150 may further include a second homogenization structure 152, such as a square optical fiber, with a cross-section of, for example, 175 x 175 μm. A Fourier lens 153, such as a fused silica sphere lens, is located between the two homogenization structures, for example, with a diameter of 0.5 mm. The lengths of both optical fibers can be, for example, 30 mm.

[0125] Figure 15 shows the corresponding spatial light distributions 161 to 165 and angular light distributions 171 to 175, respectively. The light source 180 can be a four-light source arrangement as shown in Figure 5. The inlet 181 and outlet 182 of the first homogenization structure 190 are further shown. The inlet 184 and outlet 185 of the second homogenization structure 191 are further shown.

[0126] At the entrance 181 of the first homogenization structure 190, the spatial distribution 161 is, for example, a square illumination point of 40 μm, which does not completely fill the cross-section of the rectangular optical fiber. The corresponding angular light distribution 171 shows four discrete angles associated with the four light sources.

[0127] At the exit 182 of the first homogenization structure 190, the spatial distribution 162 is a uniform fill corresponding to the rectangular fiber cross-section. However, the corresponding angular light distribution 172 remains at four discrete angles. This is because the symmetrical angular profile maintains a horizontal position, while the vertical mirror does not function.

[0128] As light passes through the spherical lens 183, as indicated by the arrows, the spatial and angular profiles exhibit a "switching position" (with some slight distortion and blurring). Thus, at the entrance 184 of the second homogenization structure 191, the spatial distribution 163 is now distributed at four discrete locations, and the corresponding angular light distribution 173 is homogeneous within a filled rectangle.

[0129] At the exit 185 of the second homogenization structure 191, the spatial distribution 164 is a uniform square profile, and the angular light distribution 174 is a filled rectangle identical to the entrance angular distribution 173 (because there is no horizontal and vertical mirror effect). In the case where the second homogenization structure is an optical fiber with rounded corner sections, the final spatial and angular distributions will be represented as 165 and 175, respectively.

[0130] Therefore, the gaps in the angular profile present at the input are closed without introducing any diffusion. Due to the spherical aberration of the Fourier lens, some blurring may be observed near the edges.

[0131] Even if only one of the four light sources is activated, the angular and spatial output distribution remains unchanged. This is also true when the angle at which a single light source is coupled is modified. Therefore, the setup described in Figure 15 provides a stable angular and spatial distribution profile even when the spatial and / or angular light distribution at the input changes.

[0132] Therefore, if the inputs from different primary colors of the light source are different, the present invention can provide uniform illumination for each dimmer and a uniform point spread function for each primary color. The optimal common point spread function that can be achieved is limited by the primary color with the largest optical spread.

[0133] Although the present invention has been described above with reference to specific embodiments, this is for illustrative purposes and not for limiting the invention. Those skilled in the art will understand that various modifications and different combinations of the disclosed features are possible without departing from the scope of the invention.

[0134] 1~7: points

[0135] 20: Laser Beam

[0136] 21: Angle Expansion

[0137] 22: Dimmer

[0138] 23: Mobile Diffuser

[0139] 24: Intermediate Plane

[0140] 25: Extension

[0141] 26: Ideal Focus

[0142] 27, 28: Incident beam

[0143] 30: Spatial distribution, spatial uniformity

[0144] 31: Angular brightness profile and angular uniformity

[0145] 32: Spatial light distribution, spatial uniformity

[0146] 33: Angular light distribution, angular uniformity

[0147] 50: Light source, sub-light source

[0148] 51: Optical Axis

[0149] 52, 100: Fiber optic

[0150] 53: Input

[0151] 101, 102: Angular light distribution

[0152] 103: points

[0153] 111~117, 121~127: Angular light distribution, angular light distribution profile

[0154] 130: System

[0155] 131: Fourier lens

[0156] 132: Light source

[0157] 133: Focusing lens

[0158] 134: Static diffuser, mobile diffuser

[0159] 135: First homogenization structure

[0160] 136: Second homogenization structure, homogenization structure

[0161] 137: Collimating Lens

[0162] 138: Dimmer, Modulator

[0163] 139: Sub-source

[0164] 142: Light Source

[0165] 143: Focusing Lens

[0166] 144: Static diffuser, mobile diffuser

[0167] 145: First homogenized structure

[0168] 146: Second homogenization structure

[0169] 147: Imaging Lens

[0170] 148: Dimmer

[0171] 149: Sub-source

[0172] 150: Rectangular fiber optic system

[0173] 151: First homogenization structure

[0174] 152: Second homogenization structure

[0175] 153: Fourier lens

[0176] 161~165: Spatial light distribution, spatial distribution

[0177] 171~175: Angular light distribution, entrance angular distribution, angular distribution

[0178] 180: Light source

[0179] 181, 184: Entrance

[0180] 182, 185: Exports

[0181] 183: Spherical lens

[0182] 190: First homogenized structure

[0183] 191: Second homogenization structure

Claims

1. A system for providing a uniform light beam for use with a light source, the system comprising: At least one first homogenization structure and one second homogenization structure, each having an inlet and an outlet; and a Fourier optical system having a first focal point and a second focal point, wherein the light source, the first homogenization structure, the Fourier optical system, and the second homogenization structure are positioned adjacent to and continuously connected to each other, wherein the Fourier optical system is positioned such that the outlet of the first homogenization structure coincides with the first focal point of the Fourier optical system, and the inlet of the second homogenization structure coincides with the second focal point of the Fourier optical system, wherein at least one of the first and second homogenization structures includes a cross-sectional region having a plurality of corners, wherein the shape of each corner is rounded with a radius of curvature, and wherein at least one homogenization structure includes a cross-sectional region having a shortest side, each radius of curvature being at least 200 to 1000 times larger than the length of the shortest side of the cross-sectional region.

2. The system as described in claim 1, wherein the first homogenization structure and the second homogenization structure are optical fibers.

3. The system as claimed in claim 1, wherein at least one of the first homogenization structure and the second homogenization structure includes a cross-sectional region having a rectangular shape.

4. The system as claimed in claim 1, wherein at least one of the first homogenization structure and the second homogenization structure has a cross-sectional region, and a dimmer has an image region, wherein the aspect ratio of the cross-sectional region of at least one of the first homogenization structure and the second homogenization structure is the same as the aspect ratio of the image region of the dimmer.

5. The system as described in claim 1, wherein the first homogenization structure is bent at a bending radius.

6. The system as described in claim 5, wherein the first homogenization structure employs different bending radii at different time points.

7. The system as claimed in claim 1, wherein at least one of the first homogenization structure and the second homogenization structure is a conventional integrator.

8. The system as described in claim 7, further comprising a diffuser disposed between the light source and the first homogenization structure.

9. The system as claimed in claim 1, wherein the radius of curvature of each corner is less than 5% of the width of the corresponding homogenization structure and greater than 1% of the width of the corresponding homogenization structure.

10. A method for use with a light source to provide a uniform light beam, the method being adapted to a system comprising: at least one first homogenization structure and a second homogenization structure, each having an inlet and an outlet, wherein at least one of the first and second homogenization structures includes a cross-sectional region having a plurality of corners, wherein the shape of each corner is rounded with a radius of curvature, and the at least one homogenization structure includes a cross-sectional region having the shortest side; and a Fourier optical system having a first focal point and a second focal point, the method comprising the following steps: The light source, the first homogenization structure, the Fourier optical system, and the second homogenization structure are placed close together and continuously; the Fourier optical system is positioned such that the exit of the first homogenization structure coincides with the first focal point of the Fourier optical system, and the entrance of the second homogenization structure coincides with the second focal point of the Fourier optical system; and each bending radius is configured to be at least 200 to 1000 times larger than the length of the shortest side of the cross-sectional region of the homogenization structure.

11. The method as described in claim 10 further includes the step of: implementing the first homogenization structure and the second homogenization structure as optical fibers.

12. The method as described in claim 10, wherein at least one of the first homogenization structure and the second homogenization structure has a cross-sectional region that is rectangular in shape.

13. The method of claim 10, wherein at least one of the first homogenization structure and the second homogenization structure has a cross-sectional region, and a dimmer has an image region, the method comprising configuring the aspect ratio of the cross-sectional region of at least one of the first homogenization structure and the second homogenization structure to be the same as the aspect ratio of the image region of the dimmer.

14. The method as described in claim 10 further includes the step of bending the first homogenization structure with a bending radius.

15. The method as described in claim 14, wherein the bending radius varies with frequency.

16. The method as described in claim 10 further includes the step of: implementing at least one of the first homogenization structure and the second homogenization structure as a conventional integrator.

17. The method of claim 16, wherein the system further includes a diffuser, and the method further includes placing the diffuser between the light source and the first homogenization structure.

18. An optical element used with a light source and providing a uniform light beam, the optical element comprising: At least one first homogenization structure and one second homogenization structure, each having an inlet and an outlet, at least one of the first and second homogenization structures including a cross-sectional region having a plurality of corners, each corner being rounded with a radius of curvature, and at least one homogenization structure including a cross-sectional region having a shortest side, each radius of curvature being at least 200 to 1000 times larger than the length of the shortest side of the cross-sectional region; a Fourier optical system having a first focal point and a second focal point, the light source, the first homogenization structure, the Fourier optical system, and the second homogenization structure being positioned close to and continuously on each other, wherein the Fourier optical system is positioned such that the outlet of the first homogenization structure coincides with the first focal point of the Fourier optical system, and the inlet of the second homogenization structure coincides with the second focal point of the Fourier optical system.

19. The optical element as claimed in claim 18, wherein the first homogenization structure and the second homogenization structure are optical fibers.

20. The optical element as claimed in claim 18, wherein at least one of the first homogenization structure and the second homogenization structure includes a cross-sectional region having a rectangular shape.

21. The optical element as claimed in claim 18, wherein at least one of the first homogenization structure and the second homogenization structure has a cross-sectional region, and a dimmer has an image region, wherein the aspect ratio of the cross-sectional region of at least one of the first homogenization structure and the second homogenization structure is the same as the aspect ratio of the image region of the dimmer.

22. The optical element as claimed in claim 18, wherein the first homogenization structure is bent at a bending radius.

23. The optical element as claimed in claim 22, wherein the first homogenization structure employs different bending radii at different time points.

24. The optical element as claimed in claim 18, wherein at least one of the first homogenization structure and the second homogenization structure is a conventional integrator.

25. The optical element as claimed in claim 18 further includes a diffuser disposed between the light source and the first homogenization structure.

26. An image projection system for use with a light source, comprising: a dimmer and a homogenization structure having an elongated shape and adapted to receive light from the light source and direct the light onto the dimmer, wherein, The homogenization structure has a rectangular structure and one or more bends. The homogenization structure includes a cross-sectional region having a plurality of corners, wherein the shape of each corner is rounded with a radius of curvature, and wherein the cross-sectional region has a shortest side, and the radius of each bend is at least 200 to 1000 times larger than the length of the shortest side of the cross-sectional region.

27. The image projection system as described in claim 26, wherein the homogenization structure has a rectangular cross-section.

28. The image projection system of claim 26, wherein the homogenization structure has a cross-sectional region and the dimmer has an image region, the aspect ratio of the cross-sectional region of the homogenization structure being the same as the aspect ratio of the image region of the dimmer.

29. The image projection system as claimed in claim 26, wherein the homogenization structure is adapted to use different bending radii at different time points, or the homogenization structure is adapted to use bending radii that vary with frequency.

30. The image projection system of claim 26, comprising: a light source; at least one first homogenization structure and a second homogenization structure, wherein the first homogenization structure and the second homogenization structure each have an inlet and an outlet; a Fourier optical system having a first focal point and a second focal point, wherein the light source, the first homogenization structure, the Fourier optical system, and the second homogenization structure are positioned adjacent to and continuously connected to each other, wherein... The Fourier optical system is positioned such that the exit of the first homogenization structure coincides with the first focal point of the Fourier optical system, and the entrance of the second homogenization structure coincides with the second focal point of the Fourier optical system.

31. A method for using with a light source and diffusing light in an image projection system, the image projection system including a dimmer and a homogenizing structure having an elongated shape and adapted to receive light from the light source and direct the light onto the dimmer, the homogenizing structure including a cross-sectional region having a plurality of corners, wherein the cross-sectional region has a shortest side, wherein, The method includes bending the homogenized structure at one or more locations, the method includes configuring each corner into a rounded shape defining a radius of curvature, and the method further includes configuring each bending radius to be at least 200 to 1000 times larger than the length of the shortest side of the cross-sectional region.

32. The method as described in claim 31, wherein the homogenization structure has a rectangular cross-sectional region.

33. The method of claim 31, wherein the homogenization structure has a cross-sectional region and the dimmer has an image region, the method further comprising the steps of: configuring the aspect ratio of the cross-sectional region of the homogenization structure to be the same as the aspect ratio of the image region of the dimmer.

34. The method as described in claim 31, wherein the homogenization structure employs different bending radii at different time points.

35. The method as described in claim 34, wherein the bending radius varies with a frequency.

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