Illumination optical system optimization design method with high energy utilization rate and high uniformity

Abstract

The invention discloses an optimal design method of an illumination optical system with high energy utilization rate and high uniformity. The illumination optical system is mainly composed of a laser light source, a collimation and beam expansion lens group, a fly lens array unit, a relay lens group, a TIR prism group and a DMD. The optimization design method comprises the following steps: determining the optimal size of the fly-eye lens array through DMD parameters; the optimal parameters of the TIR prism group are calculated through the total reflection law and the Snell law, and the optimal deflection angle of the TIR prism group is analyzed through simulation; and the optimal deflection angle of the DMD is calculated based on the Scheimpflug principle. According to the method, the optimal relation between the uniformity and the energy utilization rate of the illumination system in the laser target simulator is determined, the uniformity and the energy utilization rate of the system are improved while the size of the system is reduced, and a research thought is provided for design of the target simulator or target scene simulation.

Description

Technical Field

[0001] The invention belongs to the field of lighting optical system design, and in particular relates to an optimization design method for a lighting optical system with high energy utilization and high uniformity. Background Art

[0002] The lighting system is the key to the laser target simulator. A lighting system with high energy utilization and high uniformity can make the simulator's projection system also have excellent projection effects and high energy utilization, thereby reducing heat dissipation pressure. Therefore, a lighting system with high energy utilization and uniformity is a key issue in the design of the laser target simulator's optical system.

[0003] In order to increase the receiving range, non-imaging optical devices are needed to effectively expand and collimate the laser beam, which will also increase the overall size of the system. Therefore, how to strike a balance between uniformity, energy utilization and system size is a challenging task in lighting system design. Summary of the invention

[0004] In order to solve the problems of low energy utilization and poor uniformity of the illumination optical system of the existing laser target simulator, the present invention provides an optimization design method for the illumination optical system with high energy utilization and high uniformity, and determines the optimal size of a fly-eye lens array (FELA) through DMD parameters to improve the energy utilization of the system; adopts a TIR prism group to reduce the back intercept and reduce the system size, and calculates the optimal parameters of the TIR prism group through the total reflection law and Snell's law, and determines the optimal incident angle of the illumination light beam entering the TIR prism group through simulation analysis, that is, the optimal deflection angle of the TIR prism group, so as to improve the energy utilization; calculates the optimal deflection angle of the DMD based on the Scheimpflug principle, solves the problem of image plane deformation caused by the insertion of the TIR prism group, and improves the uniformity of the system.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A method for optimizing and designing an illumination optical system with high energy utilization and high uniformity, wherein the illumination optical system mainly consists of a laser light source, a collimating beam expansion lens group, a fly-eye lens array unit, a relay lens group, a TIR prism group, and a DMD; an illumination light beam emitted by the laser light source passes through the collimating beam expansion lens group so that the illumination light beam completely covers a display chip, and then is homogenized by a fly-eye lens array and then emitted to the relay lens group, and then is converged and formed by the relay lens group and vertically incident on the TIR prism group, and then is uniformly irradiated on the DMD after being totally reflected by the TIR prism group, and a DMD off-state light beam is derived from a projection system, and the DMD is used to simulate a scene target;

[0007] The optimization design method comprises the following steps:

[0008] S1. Determine the optimal size of the fly-eye lens array through DMD parameters;

[0009] S2, calculating the optimal parameters of the TIR prism group by the total reflection law and Snell's law, and analyzing the optimal deflection angle of the TIR prism group by simulation;

[0010] S3. Calculate the optimal deflection angle of DMD based on the Scheimpflug principle.

[0011] Furthermore, the fly-eye lens array uses two rows of fly-eye lens arrays of equal size. The first row of fly-eye lens arrays subdivides the illumination beam into fine beams, and the second row of fly-eye lens arrays re-image the fine beams and emit them to the front surface of the relay lens group.

[0012] Furthermore, the step S1 comprises:

[0013] The fly-eye lens array is composed of several fly-eye lens units arranged in an array. According to the working principle of the fly-eye lens, the parameters of the fly-eye lens array include the focal length f2 of the relay lens group, the size h of the illumination surface, the focal length f1 of the fly-eye lens, and the size D1 of the fly-eye lens unit. The relationship between the above parameters is as follows:

[0014]

[0015] In the formula, the illumination surface size h is the DMD target surface size; the relay system focal length f2 is obtained by the F number of the illumination optical system and the aperture of the relay lens group; the length and width ratio of the fly-eye lens array and the DMD chip are consistent, and the number of units of the fly-eye lens array, the array form and the size of the fly-eye lens unit are determined according to the size of the DMD chip;

[0016] After determining the number of fly-eye lens units, substitute it into the above formula to solve the focal length f1 of the fly-eye lens;

[0017] Then, the curvature radius R of the fly-eye lens unit in the fly-eye lens array is obtained according to the following formula:

[0018]

[0019] Where n is the refractive index of the fly's eye lens material.

[0020] Furthermore, the TIR prism group is composed of a triangular prism G1 and a triangular prism G2, the triangular prism G1 includes an S1 surface, an S2 surface and an S3 surface, and the triangular prism G2 includes an S4 surface, an S5 surface and an inclined surface arranged parallel to the S2 surface.

[0021] Furthermore, the step S2 comprises:

[0022] S21. Determine the design conditions to be met by the TIR prism group;

[0023] S22. Calculation of critical angles of TIR prism group;

[0024] S23. Obtain the optimal deflection angle of the TIR prism group through LightTools simulation.

[0025] Furthermore, in step S21, the TIR prism group must meet three design conditions:

[0026] 1) The light beam of the illumination system enters the TIR prism group, and is evenly irradiated onto the DMD after being totally reflected at the S2 surface of the triangular prism G1;

[0027] 2) When the light beam reflected by the DMD passes through the TIR prism group, the off-state light beam is fully reflected away from the projection system, while the on-state light beam enters the projection system vertically;

[0028] 3) The length of each face and the overall thickness of the triangular prism must be greater than the size of the illumination beam.

[0029] Furthermore, the step S22 includes:

[0030] The glass material used in the TIR prism group is Chengdu Guangming H-K9L glass, whose refractive index is 1.5168. According to the total reflection theorem, the reflection angle ∠C of the light beam on the S2 surface of the triangular prism G1 is calculated using the following formula:

[0031]

[0032] Where n H-K9L is the refractive index of the material of the S2 surface of the triangular prism G1;

[0033] According to Snell's law, the value of θ1 can be obtained:

[0034]

[0035] Where θ1 is the incident angle of the light reflected from the S2 surface of the triangular prism G1 to the S3 surface; θ DMD It is twice the deflection angle of DMD; n air is the refractive index of air;

[0036] Then, through geometric relationships, all angles of the TIR prism group are calculated:

[0037]

[0038] Since the diameter of the illumination beam is larger than the size of the DMD chip, the length of each face of the triangular prism G1 and the triangular prism G2 is designed according to the size of the DMD chip.

[0039] Furthermore, the step S3 comprises:

[0040] The angle between the optical axes of the illumination optical system and the projection system is expressed by the formula:

[0041]

[0042] In the illumination optical system, the object plane is the light source and the image plane is the DMD;

[0043] The optimal deflection angle of DMD The formula is:

[0044]

[0045] In the formula, is the angle between the optical axis of the incident illumination beam and the projection system; β is the magnification of the optical system, β = D DMD / D0, D0 is the effective emission aperture of the laser.

[0046] The present invention has the following advantages:

[0047] The present invention provides an optimization design method for an illumination optical system with high energy utilization and high uniformity, and determines the optimal size of a fly-eye lens array (FELA) through DMD parameters to improve the energy utilization of the system;

[0048] The TIR prism group is used to reduce the back intercept and the system size, making the overall structure of the system compact. At the same time, the optimal parameters of the TIR prism group are calculated by the total reflection law and Snell's law, and the optimal incident angle of the illumination beam entering the TIR prism group, that is, the optimal deflection angle of the TIR prism group, is determined by simulation analysis to improve energy utilization and improve uniformity while ensuring that the energy utilization rate does not change much.

[0049] The optimal deflection angle of the DMD is calculated based on the Scheimpflug principle to solve the image deformation problem caused by the insertion of the TIR prism group and further improve the uniformity of the system.

[0050] The present invention determines the optimal relationship between the uniformity and energy utilization of the illumination system in the laser target simulator, improves the uniformity and energy utilization of the system while reducing the size of the system, and provides a research idea for the design of the target simulator or the simulation of the target scene. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0052] Figure 1 This is a diagram of the optical system composition of the laser target simulator used in the embodiment of the present invention;

[0053] Figure 2 is a light path diagram of the illumination optical system described in an embodiment of the present invention;

[0054] Figure 3 Schematic diagram of the fly eye lens array (FELA) described in an embodiment of the present invention;

[0055] Figure 4 The shape of the illumination spot described in the embodiment of the present invention;

[0056] Figure 5 Schematic diagram of optical path analysis of a TIR prism assembly described in an embodiment of the present invention;

[0057] Figure 6 Schematic diagram of the effect of the incident angle of a light beam on the surface uniformity and energy utilization efficiency of a DMD in a TIR prism assembly described in an embodiment of the present invention;

[0058] Figure 7 A schematic diagram of the angle between the optical axes of the illumination optical system and the projection system in an embodiment of the present invention;

[0059] Figure 8 This is the effect of the deflection angle of the DMD on the surface uniformity and energy utilization described in the embodiment of the present invention. DETAILED DESCRIPTION

[0060] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0061] In the present invention, unless otherwise clearly stipulated and limited, a first feature being “on” or “under” a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them.

[0062] In the description of this embodiment, terms such as "up", "down", "left", and "right" and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0063] Example

[0064] The present embodiment is a method for optimizing the design of an illumination optical system with high energy utilization and high uniformity. The illumination optical system is mainly composed of a laser light source, a collimating and expanding lens group, a fly-eye lens array, a relay lens group, a TIR prism group and a spatial light modulator (DMD); the illumination light beam emitted by the laser light source passes through the collimating and expanding lens group so that the illumination light beam completely covers the display chip; then, the illumination light beam is homogenized by the fly-eye lens array and then emitted to the relay lens group, after the light beam is converged and formed by the relay lens group, it is vertically incident on the TIR prism group, and after total reflection occurs in the TIR prism group, it is uniformly irradiated on the DMD, and the DMD off-state light beam is derived from the projection system; the DMD is used to simulate scene targets.

[0065] The optimization design method comprises the following steps:

[0066] S1. Determine the optimal size of the fly-eye lens array (FELA) through DMD parameters to improve the energy utilization of the system:

[0067] The fly eye lens array is composed of a number of fly eye lens units arranged in an array. The characteristics of the fly eye lens array (FELA) are uniform illumination of the working plane, compact design, beam shaping, and easy use. In this embodiment, the fly eye lens array uses two rows of fly eye lens arrays (FELA) of equal size. The first row of FELA subdivides the illumination beam into fine beams, and the second row of FELA re-images the fine beams and then emits them to the front surface of the relay lens group.

[0068] The optimal size of the fly-eye lens array (FELA) is calculated as:

[0069] According to the working principle of the fly-eye lens, the parameters of the fly-eye lens array include the focal length f2 of the relay lens group, the size of the illumination surface h, the focal length f1 of the fly-eye lens, and the size D1 of a single fly-eye lens unit. The relationship between the above parameters is expressed by the following formula:

[0070]

[0071] In the formula, the illumination surface size h is the DMD target surface size; the relay system focal length f2 can be obtained by the F number of the illumination optical system and the aperture of the relay lens group. This embodiment uses a DMD with a resolution of 1920×1080 and a pixel size of 10.8um. ​​In order to keep consistent with the aspect ratio of the DMD chip, this embodiment uses 16×9 fly eye lens units, each of which is 1.5mm×2.67mm in size; the fly eye lens material is H-QK3L, and the refractive index is 1.487.

[0072] After determining the number of fly-eye lens units, substitute it into the above formula to solve the focal length f1 of the fly-eye lens.

[0073] Then, the curvature radius R of a single fly-eye lens unit in the fly-eye lens array can be obtained:

[0074]

[0075] Where n is the refractive index of the fly's eye lens material.

[0076] In this embodiment, Figure 4 As shown, by analyzing the shape change of the illumination spot, it can be known that after the fly-eye lens array splits the light beam, it has been shaped into a rectangular light spot that meets the size of the illumination surface through the relay lens group.

[0077] S2. The optimal parameters of the TIR prism group are calculated by the total reflection law and Snell's law, and the optimal deflection angle of the TIR prism group is analyzed by LightTools simulation, so that the overall structure of the system is compact and the uniformity is improved under the premise of ensuring that the energy utilization rate does not change much:

[0078] like Figure 5 As shown, in this embodiment, the TIR prism group is composed of a triangular prism G1 and a triangular prism G2, the triangular prism G1 includes an S1 surface, an S2 surface, and an S3 surface, and the triangular prism G2 includes an inclined surface arranged parallel to the S2 surface, and an S4 surface and an S5 surface. When light is incident vertically to the S1 surface of the triangular prism G1, the light will enter the prism along the original direction and will be totally reflected on the S2 surface, thereby changing the propagation direction of the light. This total reflection process can effectively reduce the loss of light and improve the efficiency of light energy use.

[0079] S21. Determine the three design conditions that the TIR prism assembly must meet:

[0080] 1) The light beam of the illumination system enters the TIR prism group, and is evenly irradiated onto the DMD after being totally reflected at the S2 surface of the triangular prism G1;

[0081] 2) When the light beam reflected by the DMD passes through the TIR prism group, the off-state light beam is fully reflected away from the projection system, while the on-state light beam enters the projection system vertically;

[0082] 3) The length of each face and the overall thickness of the triangular prism should be greater than the size of the illumination beam. This ensures that the beam is completely reflected in the prism without leakage or loss. The prism size cannot be much larger than the beam size to ensure maximum energy utilization and thus optimize the performance of the optical system.

[0083] S22. Calculation of key angles of TIR prism set:

[0084] In this embodiment, the glass material used in the TIR prism group is H-K9L glass from Chengdu Guangming, and its refractive index is 1.5168. The value of the reflection angle ∠C can be obtained by the following formula according to the total reflection theorem:

[0085]

[0086] To ensure that the illumination beam is totally reflected at the S2 surface of the G1 prism, ∠C = 42.05°. The deflection angle of the DMD is ±12°, so θ DMD =24, the value of θ1 can be obtained according to Snell's law:

[0087]

[0088] Where θ1 is the incident angle of the light reflected from the S2 surface of the triangular prism G1 to the S3 surface; n air is the refractive index of air.

[0089] Then, through geometric relationships, all angles of the TIR prism group are calculated:

[0090]

[0091] Wherein, θ2 is the left base angle of the triangular prism G1; θ3 is the obtuse angle of the top of the triangular prism G1; θ4 is the right base angle of the triangular prism G1; θ5 is the refraction angle of the light from the triangular prism G1 to the triangular prism G2; θ6 is the obtuse angle of the triangular prism G2.

[0092] In this embodiment, since the diameter of the illumination beam is larger than the size of the DMD chip, the length of the S1 surface of the prism G1 is 35mm, and the length of the S3 surface is 50mm. Considering the refraction range of the off-state beam, the length of the S4 surface of the prism G2 is 65mm, and the length of the S5 surface is 40mm. The optical path analysis and design results are shown in Figure 1. Figure 5 shown.

[0093] S23. Obtain the optimal deflection angle of the TIR prism group through LightTools simulation:

[0094] After simulation verification, when the TIR prism group is deflected by 8° to 12°, the illumination beam will be totally reflected inside the prism and will not deviate too much from the projection lens group. Therefore, it is only necessary to analyze the optimal illumination uniformity and energy utilization of the DMD surface when the TIR prism group is deflected within 8° to 12°. Figure 6 As shown. Figure 6 From the curve analysis, it can be seen that as the TIR prism deflects within the angle range of 8° to 11°, the illumination uniformity on the DMD surface shows an overall upward trend. However, when the prism deflection angle enters the range of 11° to 12°, the illumination uniformity begins to decline. During the entire deflection process, although the change in energy utilization is not significant, when the TIR prism group reaches 11° deflection, the energy utilization is 61.38%, and the illumination uniformity on the DMD surface reaches the optimal level, up to 92.91%.

[0095] S3, based on the Scheimpflug principle, the optimal deflection angle of DMD is calculated to solve the image plane deformation problem caused by the insertion of the TIR prism group, and further improve the uniformity of the system:

[0096] The angle between the optical axes of the illumination system and the projection system combined with the mathematical formula and relationship between the axial magnification and the vertical magnification can be expressed as:

[0097]

[0098] In the formula, It is the angle between the tangent plane at any point on the object plane and the plane perpendicular to the optical axis; is the angle between the tangent plane corresponding to the image point and the plane perpendicular to the optical axis, such as Figure 7 As shown; β is the magnification of the optical system.

[0099] In the laser target simulator illumination system, the object plane is the light source, the image plane is the DMD, D0 = 4 mm is the effective emission aperture of the laser, β = D DMD / D0, get the angle between the optical axis of the incident illumination light and the projection system The optimal deflection angle of DMD Expressed as a formula:

[0100]

[0101] Therefore, in this embodiment, the illumination system is modified to deflect the DMD angle by 4.244°.

[0102] Through simulation analysis, when the DMD deflection is between -2° and 5.6°, the illumination beam can effectively remain within the S4 surface of the triangular prism G2 of the TIR prism group and the projection lens group. When the deflection of the TIR prism group is fixed at 11°, the illumination effect of the DMD under the deflection of -2° to 5.6° is analyzed. Figure 8 As shown in the figure, when the DMD deflection is between -2° and 0° and between 0° and 2°, the surface uniformity decreases significantly, especially when the deflection is between -2° and -1.4°, the energy utilization rate also decreases significantly. When the deflection angle increases to 2° to 4.244°, the uniformity gradually increases. However, when the deflection angle exceeds 4.244°, the uniformity drops sharply, especially when it exceeds 5°, the energy utilization rate also drops significantly. Comprehensive analysis shows that according to the Scheimpflug principle, when the DMD deflection angle is 4.244°, the illumination uniformity reaches 96.93%, and the energy utilization rate is 60.05%, which is close to the ideal value of 61.62%. This result proves the effectiveness and feasibility of the proposed method.

[0103] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for optimizing the design of an illumination optical system with high energy utilization and high uniformity, characterized in that: The illumination optical system mainly consists of a laser light source, a collimating beam expansion lens group, a fly-eye lens array unit, a relay lens group, a TIR prism group and a DMD; the illumination light beam emitted by the laser light source passes through the collimating beam expansion lens group so that the illumination light beam completely covers the display chip, and then is emitted to the relay lens group after being homogenized by the fly-eye lens array, and then is converged and formed by the relay lens group and vertically incident on the TIR prism group, and is evenly irradiated on the DMD after being totally reflected by the TIR prism group, and the DMD off-state light beam is derived from the projection system, and the DMD is used to simulate scene targets; The optimization design method comprises the following steps: S1. Determine the optimal size of the fly-eye lens array through DMD parameters; S2, calculating the optimal parameters of the TIR prism group by the total reflection law and Snell's law, and analyzing the optimal deflection angle of the TIR prism group by simulation; S3. Calculate the optimal deflection angle of DMD based on the Scheimpflug principle.

2. The method for optimizing the design of an illumination optical system with high energy utilization and high uniformity as claimed in claim 1, characterized in that: The fly-eye lens array uses two rows of fly-eye lens arrays of equal size. The first row of fly-eye lens arrays subdivides the illumination beam into fine beams, and the second row of fly-eye lens arrays re-image the fine beams and then emit them to the front surface of the relay lens group.

3. The method for optimizing the design of an illumination optical system with high energy utilization and high uniformity according to claim 1, characterized in that: The step S1 comprises: The fly-eye lens array is composed of several fly-eye lens units arranged in an array. According to the working principle of the fly-eye lens, the parameters of the fly-eye lens array include the focal length f2 of the relay lens group, the size h of the illumination surface, the focal length f1 of the fly-eye lens, and the size D1 of the fly-eye lens unit. The relationship between the above parameters is as follows: In the formula, the illumination surface size h is the DMD target surface size; the relay system focal length f2 is obtained by the F number of the illumination optical system and the aperture of the relay lens group; the length and width ratio of the fly-eye lens array and the DMD chip are consistent, and the number of units of the fly-eye lens array, the array form and the size of the fly-eye lens unit are determined according to the size of the DMD chip; After determining the number of fly-eye lens units, substitute it into the above formula to solve the focal length f1 of the fly-eye lens; Then, the curvature radius R of the fly-eye lens unit in the fly-eye lens array is obtained according to the following formula: Where n is the refractive index of the fly's eye lens material.

4. The method for optimizing the design of an illumination optical system with high energy utilization and high uniformity according to claim 1, characterized in that: The TIR prism group is composed of a triangular prism G1 and a triangular prism G2. The triangular prism G1 includes an S1 surface, an S2 surface, and an S3 surface. The triangular prism G2 includes an S4 surface, an S5 surface, and an inclined surface arranged parallel to the S2 surface.

5. The method for optimizing the design of an illumination optical system with high energy utilization and high uniformity as claimed in claim 4, characterized in that: The step S2 comprises: S21. Determine the design conditions to be met by the TIR prism group; S22. Calculation of critical angles of TIR prism group; S23. Obtain the optimal deflection angle of the TIR prism group through LightTools simulation.

6. The method for optimizing the design of an illumination optical system with high energy utilization and high uniformity as claimed in claim 5, characterized in that: In step S21, the TIR prism group must meet three design conditions: 1) The light beam of the illumination system enters the TIR prism group, and is evenly irradiated onto the DMD after being totally reflected at the S2 surface of the triangular prism G1; 2) When the light beam reflected by the DMD passes through the TIR prism group, the off-state light beam is fully reflected away from the projection system, while the on-state light beam enters the projection system vertically; 3) The length of each face and the overall thickness of the triangular prism must be greater than the size of the illumination beam.

7. The method for optimizing the design of an illumination optical system with high energy utilization and high uniformity as claimed in claim 5, characterized in that: The step S22 comprises: The glass material used in the TIR prism group is Chengdu Guangming H-K9L glass, whose refractive index is 1.5168. According to the total reflection theorem, the reflection angle ∠C of the light beam on the S2 surface of the triangular prism G1 is calculated using the following formula: Where n H-K9L is the refractive index of the material of the S2 surface of the triangular prism G1; According to Snell's law, the value of θ1 can be obtained: Where θ1 is the incident angle of the light reflected from the S2 surface of the triangular prism G1 to the S3 surface; θ DMD It is twice the deflection angle of DMD; n air is the refractive index of air; Then, through geometric relationships, all angles of the TIR prism group are calculated: Since the diameter of the illumination beam is larger than the size of the DMD chip, the length of each face of the triangular prism G1 and the triangular prism G2 is designed according to the size of the DMD chip.

8. The method for optimizing the design of an illumination optical system with high energy utilization and high uniformity as claimed in claim 1, characterized in that: The step S3 comprises: The angle between the optical axes of the illumination optical system and the projection system is expressed by the formula: In the illumination optical system, the object plane is the light source and the image plane is the DMD; The optimal deflection angle of DMD The formula is: In the formula, is the angle between the optical axis of the incident illumination beam and the projection system; β is the magnification of the optical system, β = D DMD / D0, D0 is the effective emission aperture of the laser.

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