Uniform light illumination system

Abstract

The invention provides a uniform light illumination system, which comprises a rotational symmetry free-form surface lens used for refracting and reflecting non-uniform light beams diverged by a light source in all directions and then redirecting and distributing the non-uniform light beams to obtain uniform light beams; and the light bar is used for carrying out multiple total reflection on the uniform light beam so as to carry out homogenization treatment and form a uniform illumination light field.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of optical illumination technology, and in particular to a uniform light illumination system. BACKGROUND

[0002] In the illumination device, the uniformity and energy density of the illumination light field are the core performance indicators. When a light rod is used as a uniform light device, in order to meet the requirement of uniform light field distribution on the exit surface, more sufficient light field mixing needs to be realized by increasing the number of total reflections of light in the light rod. However, the increase of the number of total reflections directly leads to the increase of the length of the light rod, which not only increases the system volume, but also intensifies the energy loss due to the lengthening of the light transmission path. SUMMARY

[0003] In view of the above problems, the present disclosure provides a uniform light illumination system to at least partially solve the above technical problems.

[0004] The present disclosure provides a uniform light illumination system, comprising: a rotationally symmetric free-form lens for refracting and reflecting the non-uniform light beams emitted in various directions by the light source to reorient and distribute the light beams, thereby obtaining a uniform light beam; and a light rod for performing multiple total reflections on the uniform light beam to perform uniformization processing, thereby forming a uniform illumination light field.

[0005] According to the embodiments of the present disclosure, the curvature of the rotationally symmetric free-form lens is related to the energy correspondence relationship between the light intensity distribution of the light source and the target surface illumination distribution.

[0006] According to the embodiments of the present disclosure, the light source comprises a light-emitting diode light source; and the reorienting and distributing the non-uniform light beams emitted in various directions by the light source by the rotationally symmetric free-form lens comprises: the rotationally symmetric free-form lens uses the non-uniform curvature of each point on the surface to perform dual regulation of the spatial angle and energy density on the non-uniform light beam emitted by the light-emitting diode light source, thereby obtaining a uniform light beam, and adjusting the divergence angle of the uniform light beam to obtain a parallel uniform light beam.

[0007] According to the embodiments of the present disclosure, the uniform light illumination system can further comprise: a coupling mirror group arranged on the light path between the rotationally symmetric free-form lens and the light rod, for coupling the adjusted uniform light beam to the light rod.

[0008] According to an embodiment of the present disclosure, the coupling mirror set comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens; the first lens is used for preliminary collimation and aberration pre-correction of the uniform light beam; the second lens is used for compression and chromatic aberration preliminary correction of the light beam output by the first lens; the third lens is used for aberration main correction of the light beam output by the second lens and ensures that the light beam is parallel to the optical axis; the fourth lens is used for light beam shaping and uniformity optimization of the light beam output by the third lens; and the fifth lens is used for focusing and optical axis alignment of the light beam output by the fourth lens, focusing the light beam to the incident end surface of the light rod and entering the light rod at a certain angle.

[0009] According to an embodiment of the present disclosure, the first lens, the second lens, the third lens, the fourth lens and the fifth lens are independently installed and have air gaps therebetween.

[0010] According to an embodiment of the present disclosure, the curved surface shapes of the first lens, the second lens, the third lens, the fourth lens and the fifth lens are respectively double-convex lens, meniscus lens, meniscus lens, double-convex lens and plano-convex lens; and the first lens, the second lens, the third lens, the fourth lens and the fifth lens all adopt spherical lenses.

[0011] According to an embodiment of the present disclosure, the light rod is a rectangular cross-section light rod, and the cross-section area of the light rod can match the required illumination area and the magnification of the coupling mirror set.

[0012] According to an embodiment of the present disclosure, the light rod is a fused quartz light rod.

[0013] According to an embodiment of the present disclosure, the incident end surface and the exit end surface of the light rod are both formed with a broadband anti-reflection coating.

[0014] The uniform illumination system provided by the present disclosure has at least the following technical effects:

[0015] The system adopts a unique two-stage uniform light architecture, the first-stage uniform light adopts a rotationally symmetric free-form surface lens to preliminarily adjust and optimize the light field distribution of the light source, the second-stage uniform light completes the final uniformization treatment through a uniform light rod, and high-quality uniform light effect is realized through the cooperative matching of the rotationally symmetric free-form surface lens and the light rod, forming a highly uniform illumination light field. The two-stage uniform light architecture greatly reduces the number of total reflections required in the light rod through the pre-modulation effect of the front rotationally symmetric free-form surface lens, significantly reduces the mixing complexity required in the light rod, and enables the length of the light rod to be significantly shortened, thereby not only ensuring the light field uniformity but also making the system structure more compact and reliable, and reducing the manufacturing cost and maintenance difficulty.

[0016] The system is composed of a rotationally symmetric freeform lens with precise wavefront control ability, a coupling mirror group with diffraction transfer function performance close to the diffraction limit, and a fused quartz light rod manufactured by ultra-precision machining process. This combined design not only meets the strict requirements for illumination uniformity and imaging quality, but also improves the stability and economy of the system, providing a reliable illumination solution.

[0017] The curvature of the rotationally symmetric freeform lens is determined based on the energy correspondence between the light intensity distribution of the light source and the target surface illumination distribution. It can be adaptively designed for different needs and can redirect and distribute the non-uniform light emitted by the light source after refraction and reflection, thereby achieving high uniformity of illumination effect in the target area.

[0018] The coupling mirror group adopts a double-telecentric optical path structure composed of multiple lenses. By designing the curvature shape and arrangement distance of each lens, it can completely and distortionlessly transfer the preliminarily homogenized light field to the incident end surface of the rectangular light rod in a compact space. By designing the curvature shape and arrangement position of each lens, the unique non-cemented spherical lens group design effectively eliminates spherical aberration and distortion problems during imaging. The coupling mirror group adopts a fully separated structure, with all lenses independently installed and leaving an air gap in the middle, avoiding the stress problem caused by temperature changes in cemented lenses. Thanks to the double-telecentric optical path structure, this coupling mirror group can ensure that the light is transmitted at the best angle, maintaining high imaging clarity and making the light energy distribution more uniform, while greatly reducing the difficulty of precision machining. This design not only improves the stability of the optical system, but also enables the light to enter the subsequent optical components with allowable optical interface parameters.

[0019] A rectangular cross-section light rod is used as a secondary homogenization device, which minimizes transmission loss while ensuring sufficient homogenization reflection times by precisely controlling the aspect ratio. A broadband anti-reflection coating is applied to the incident and exit end surfaces of the light rod using ultraviolet band antireflection film technology, significantly reducing reflection loss. This design optimizes the balance between reflection times and transmission efficiency, ensuring that the light field uniformity meets the requirements and maintaining high energy transmission efficiency, ultimately achieving simultaneous improvement of illumination image uniformity and energy density. The rectangular light rod structure combined with precision optical polishing process provides stable and reliable uniform light field output for the system.

[0020] The optical homogenization component of the system has a simple structure, only including three core components of a free-form surface lens, a coupling mirror group and a rectangular light rod, has few requirements for external devices, and is simple to debug and maintain. The optical system has a significant cost advantage, does not need to build a complex and precise optical platform, and effectively optimizes the volume and running energy consumption of the instrument. The system can be quickly installed through a standard optical interface, and can be directly connected to common optical interfaces to form a seamless optical connection with front and rear optical modules, thereby significantly reducing the use threshold. The system is designed in a modular manner, and each optical component can be independently replaced, so that the system can be flexibly adapted to various homogenization requirements, thereby significantly reducing the system modification cost. The system has high stability and does not need to be frequently calibrated during long-term use. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 A structural diagram of a homogenization illumination system according to one embodiment of the present disclosure is schematically shown.

[0023] Figure 2 A real model diagram of a rotationally symmetric free-form surface lens according to an embodiment of the present disclosure is schematically shown.

[0024] Figure 3 A structural diagram of a homogenization illumination system according to another embodiment of the present disclosure is schematically shown.

[0025] Figure 4 A structural diagram of a homogenization illumination system according to still another embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that the description is merely exemplary, and is not intended to limit the scope of the present disclosure. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present disclosure. However, it will be apparent to one skilled in the art that one or more embodiments can be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques have been omitted to avoid unnecessarily obscuring the concept of the present disclosure.

[0027] Figure 1 A structural diagram of a homogenization illumination system according to one embodiment of the present disclosure is schematically shown.

[0028] As Figure 1 shown, the homogenization illumination system of the present embodiment can include a rotationally symmetric free-form surface lens 1 and a light rod 3.

[0029] The rotationally symmetric free-form surface lens 1 is used to refract and reflect the non-uniform light beams emitted in various directions by the light source F to reorient and distribute the light beams to obtain uniform light beams.

[0030] The light rod 3 is used to perform multiple total reflections on the uniform light beams to perform homogenization processing to form a uniform illumination light field.

[0031] According to an embodiment of the present disclosure, the light homogenization illumination system is a two-stage light homogenization system for high uniformity and high energy density. The first stage uses a rotationally symmetric free-form surface lens to perform preliminary adjustment and homogenization processing on the light field distribution of the light source F, and the second stage performs final homogenization processing through a light homogenization rod to form a highly uniform illumination light field.

[0032] Since there is a difference between the illumination area of the first stage and the illumination area of the second stage of the system, a coupling mirror group is introduced to match the optical interface sizes of the two.

[0033] The working process of the system is as follows: the non-uniform light beams generated by the light source F become uniform light beams after being reoriented and distributed by the rotationally symmetric free-form surface lens 1, and the uniform light beams are subjected to multiple total reflections inside the light rod 3 to obtain homogenization processing, thereby emitting light beams with uniform illumination light fields.

[0034] In some embodiments, the curvature of the rotationally symmetric free-form surface lens 1 is related to the energy correspondence relationship between the light intensity distribution of the light source and the target surface illuminance distribution.

[0035] Figure 2 An actual model diagram of the rotationally symmetric free-form surface lens according to an embodiment of the present disclosure is schematically shown.

[0036] As shown in Figure 2 The design of the rotationally symmetric free-form surface lens 1 is based on the energy correspondence relationship between the light intensity distribution of the light source and the target surface illuminance distribution. In the design process, the refraction or reflection law of light is used to accurately redistribute the energy of the incident light rays emitted from the light source, so that the expected illuminance distribution is formed on the target surface. To achieve uniform illumination, a partial differential equation set describing the light redistribution law needs to be established, which essentially reflects the conservation relationship between the light flux emitted by the light source and the desired illuminance on the target surface. By solving this nonlinear partial differential equation set by numerical methods, the coordinate information of a series of key points on the free-form surface can be obtained. These discrete points describe the geometric shape of the surface, and the surface fitting technology (such as spline interpolation or least squares fitting) is used to construct these discrete points into a continuous and smooth free-form surface profile. Finally, the rotationally symmetric free-form surface lens 1 can refract and reflect the non-uniform light rays emitted by the light source to reorient and distribute the light rays, thereby achieving high uniformity of illumination in the target area.

[0037] The rotationally symmetric freeform lens 1 designed based on the above method can reorient and distribute the non-uniform light beams emitted in various directions by the light source after refraction and reflection, which can include: efficiently collecting the light rays emitted in various directions by the light source with a large-angle divergence angle. The non-uniform curvature of each point on the surface is used to perform dual regulation of the spatial angle and energy density on the non-uniform light beam emitted by the illumination light source, such as a light-emitting diode light source, to obtain a uniform light beam, and adjust the divergence angle of the uniform light beam to obtain a parallel uniform light beam. The light source can include a light-emitting diode light source.

[0038] Figure 3 A structural diagram of the light homogenization system according to another embodiment of the present disclosure is schematically shown.

[0039] As shown in Figure 3 , the light homogenization system can include a coupling mirror set 2. The coupling mirror set 2 is arranged on the optical path between the rotationally symmetric freeform lens 1 and the light rod 3, and is used to adjust and couple the uniform light beam to the light rod. The uniform light beam passes through the coupling mirror set 2, so that the adjusted uniform light beam matches the optical interface size of the light rod 3 and is smoothly incident into the light rod 3.

[0040] Figure 4 A structural diagram of the light homogenization system according to another embodiment of the present disclosure is schematically shown.

[0041] As shown in Figure 4 , in some embodiments, the coupling mirror set 2 can include: a first lens 21, a second lens 22, a third lens 23, a fourth lens 24, and a fifth lens 25.

[0042] The first lens 21 is used to preliminarily collimate and aberration pre-correct the uniform light beam.

[0043] The second lens 22 is used to compress the light beam output by the first lens and preliminarily correct chromatic aberration.

[0044] The third lens 23 is used to perform main correction of aberration on the light beam output by the second lens and ensure that the light beam is parallel to the optical axis.

[0045] The fourth lens 24 is used to perform beam shaping and uniformity optimization on the light beam output by the third lens.

[0046] The fifth lens 25 is used to focus and align the optical axis of the light beam output by the fourth lens, focus the light beam to the incident end surface of the light rod, and enter the light rod at a certain angle.

[0047] Further, the first lens 21, the second lens 22, the third lens 23, the fourth lens 24, and the fifth lens 25 are independently installed and have air gaps between each other. This method can avoid the stress problem caused by temperature changes of the cemented lens.

[0048] In some embodiments, the curved surface shapes of the first lens 21, the second lens 22, the third lens 23, the fourth lens 24, and the fifth lens 25 are a double convex lens, a meniscus lens, a meniscus lens, a double convex lens, and a plano-convex lens, respectively. By calculating the curved surface shape and the arrangement distance of each lens, the light field that has been preliminarily homogenized is completely and distortionlessly transmitted to the incident end face of the rectangular light rod in a compact space. For example, the distances between the first lens 21, the second lens 22, the third lens 23, the fourth lens 24, and the fifth lens 25 are 43.4 mm, 9.23 mm, 0.78 mm, 32.56 mm, and 18.41 mm, respectively.

[0049] In some embodiments, the first lens 21, the second lens 22, the third lens 23, the fourth lens 24, and the fifth lens 25 are all spherical lenses. The spherical lenses have significant advantages in cost, processing feasibility, system stability, and the like.

[0050] In some embodiments, the light rod 3 is a rectangular cross-section light rod, and the cross-sectional area of the light rod can be matched with the required illumination area and the magnification of the coupling lens group. The rectangular cross-section light rod is used as the second-stage light homogenization device, and high-efficiency light homogenization is achieved by balancing the number of reflections and energy loss. The light rod works based on the total internal reflection principle, and by controlling the aspect ratio, the number of sufficient light homogenization reflections is ensured while the transmission loss is minimized. For example, the aspect ratio of the rectangular cross-section light rod is 17:14.

[0051] It should be noted that the specific values of the distances between the first lens 21, the second lens 22, the third lens 23, the fourth lens 24, and the fifth lens 25 and the aspect ratio of the rectangular cross-section light rod listed above are for more clearly illustrating the present disclosure, and are not used to limit the present disclosure.

[0052] In some embodiments, the light rod 3 is a fused quartz light rod manufactured by an ultra-precision machining process. The rectangular cross-section light rod structure is matched with a precision optical polishing process to form a stable total internal reflection light path, providing a stable and reliable uniform light field output for the system.

[0053] In some embodiments, the incident end face and the exit end face of the light rod 3 are both formed with a broadband anti-reflection coating. For example, an ultraviolet band anti-reflection film technology can be used to coat a broadband anti-reflection coating on the incident end face and the exit end face of the light rod, significantly reducing the reflection loss and ensuring efficient transmission in the ultraviolet band, and finally achieving a high-uniformity and high-energy-density illumination light field output.

[0054] In one example of the present disclosure, the light uniformity achieved by the light uniformity system using only the light bar is consistent with the light uniformity achieved by the light uniformity system provided by the present embodiment when the length of the light bar is 264 mm, and the corresponding image plane energy density of the light uniformity system using only the light bar is 157 mW / cm 2 , which is 27.4% lower than the corresponding image plane energy density of the light uniformity system provided by the present embodiment. This also shows that the light uniformity system provided by the present embodiment can improve the image plane energy density while reducing the volume. It should be noted that the length of the light bar and the energy density mentioned above are only used to verify the performance of the light uniformity system of the present embodiment, and are not used to limit the length of the light bar of the present disclosure.

[0055] The above describes embodiments of the present disclosure. However, these embodiments are only for illustrative purposes, and are not intended to limit the scope of the present disclosure. Although each embodiment is described above separately, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various alternatives and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A homogenizing illumination system, characterized in that, The application relates to a rotating symmetry free curved surface lens and a light rod. The rotating symmetry free curved surface lens is used for refracting and reflecting a non-uniform light beam emitted by a light source in all directions to reorient and distribute the light beam to obtain a uniform light beam. The light source comprises a light emitting diode light source.

2. The homogenizing illumination system of claim 1, wherein, The rotating symmetry free curved surface lens is used for refracting and reflecting a non-uniform light beam emitted by a light source in all directions to reorient and distribute the light beam to obtain a uniform light beam.

3. The homogenizing illumination system of claim 1, wherein, The rotating symmetry free curved surface lens is used for refracting and reflecting a non-uniform light beam emitted by a light source in all directions to reorient and distribute the light beam to obtain a uniform light beam. The application further relates to a coupling mirror group. The coupling mirror group is arranged on an optical path between the rotating symmetry free curved surface lens and the light rod and is used for adjusting and coupling the uniform light beam to the light rod.

4. The light uniformization system of claim 1, wherein, The coupling mirror group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens. The first lens is used for primary collimation and aberration pre-correction of the uniform light beam.

5. The homogenizing illumination system of claim 4, wherein, The second lens is used for compression and primary chromatic aberration correction of the light beam output by the first lens. The third lens is used for main aberration correction of the light beam output by the second lens and ensures that the light beam is parallel to the optical axis. The fourth lens is used for light beam shaping and uniformity optimization of the light beam output by the third lens. The fifth lens is used for focusing and optical axis alignment of the light beam output by the fourth lens, focuses the light beam to an incident end surface of the light rod and enters the light rod at a certain angle. The first lens, the second lens, the third lens, the fourth lens and the fifth lens are independently installed and have air gaps therebetween. The first lens, the second lens, the third lens, the fourth lens and the fifth lens are spherical lenses. The light rod is a rectangular cross-section light rod, and the cross-section area of the light rod can match the required illumination area and the magnification of the coupling mirror group.

6. The homogenizing illumination system of claim 5, wherein, The light rod is a fused quartz light rod.

7. The homogenizing illumination system according to claim 5 or 6, characterized in that The incident end surface and the exit end surface of the light rod are formed with a broadband anti-reflection coating. ​ 8. The light uniformization system of claim 1, wherein, ​ 9. The light uniformization system of claim 1, wherein, ​ 10. The light homogenization system of claim 1 or 9, wherein, ​

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