Optical energy collection and imaging system and method based on PVG optical contraction pupil

Abstract

The invention discloses an efficient optical energy collection and imaging system and method based on PVG optical pupil contraction, and belongs to the technical field of optical imaging and infrared detection. The system comprises a pupil dilation unit, a polarizer holographic grating (PVG), an optical waveguide device and a detector unit. The pupil contraction unit reduces the aperture of an incident light beam to improve the energy density; the PVG realizes high-efficiency light beam diffraction regulation and control through the design of a fixed period and a Bragg dip angle, and breaks through the limitation of a traditional F number; the optical waveguide expands the beam aperture through multiple total internal reflection, and the luminous flux is improved; the detector receives the light beam and generates a high-resolution image. By combining Zemax simulation optimization parameters, the problems that a traditional system depends on a large lens and is large in size and low in luminous flux are solved, and the system has the advantages of being compact in structure, high in energy collection efficiency and high in resolution imaging and is suitable for infrared detection and uncooled infrared imaging scenes.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging and infrared detection technology, and in particular to an optical energy collection and imaging system and method based on PVG optical miosis. The system aims to improve the compactness, light flux, and imaging quality of the optical system through waveguides and an innovative PVG structure, thereby achieving efficient energy collection and imaging. Background Art

[0002] Optical imaging and infrared detection technologies are widely used in modern science and technology, encompassing fields ranging from remote sensing and night vision to security surveillance. However, existing infrared imaging systems often rely on large lens systems to achieve beam focusing and pupil reduction. This traditional design not only increases system size and weight but also poses significant challenges to optical performance, especially in scenarios requiring high energy collection and high-resolution imaging.

[0003] Polarization volume holographic gratings (PVGs) are gaining increasing attention in optical devices due to their unique polarization selectivity and diffraction efficiency. PVGs enable efficient beam manipulation and adaptability to varying wavelengths and incident angles, transcending the limitations of conventional lens f-numbers. This feature frees optical systems from the constraints of a specific light-receiving area, enabling high light flux collection while maintaining system compactness. Because the diffraction angle and diffraction efficiency of PVGs can be optimized through specific design parameters, PVGs are widely used in systems requiring high light flux and efficient energy collection.

[0004] In recent years, with increasing demands for compactness and portability in optical systems, optical waveguide technology has gradually become a crucial tool in optical system design. By combining PVG with an optical waveguide, the system not only achieves beam pupil expansion and multiple reflections within a small footprint, but also further improves light flux collection efficiency, enabling the system to exhibit superior performance in multi-band optical applications. In this design, the light beam undergoes initial diffraction control through the PVG before entering the optical waveguide for multiple reflections and expansion, thereby maintaining efficient beam transmission while reducing reliance on large lenses.

[0005] To accurately simulate and optimize the performance of PVG in optical waveguide systems, computer simulation tools such as Zemax are typically used to build simulation models of the PVG and waveguide. Ray tracing and diffraction calculations allow the propagation path of the light beam through the PVG and waveguide to be observed, and diffraction angles and waveguide parameters to be optimized to ensure optimal energy transfer efficiency during beam transmission. The C++ programming language excels in efficient computation and model optimization, making it particularly well-suited for these computationally intensive simulation applications.

[0006] In summary, traditional infrared imaging systems rely on large lenses to achieve light beam focusing, which has the problems of large size and low light flux. Although the polarization volume holographic grating (PVG) has high diffraction efficiency, it is difficult to break through the F-number limitation when combined with the traditional optical path. Although optical waveguide technology can reduce the size of the system, the light energy utilization rate is insufficient when used alone. Based on the understanding of these technical challenges, the present invention proposes a new optical pupil reduction system that combines PVG and optical waveguide. In this system, the light beam is regulated by PVG to maximize the utilization of the received light energy, and the pupil is expanded by the optical waveguide device, and finally a high-resolution image is generated on the detector. This system can not only achieve high light flux collection in a miniaturized design, but also improve the quality and efficiency of infrared imaging through advanced optical design optimization, meeting the current needs of optical energy collection and high-resolution imaging. Summary of the Invention

[0007] The present invention aims to effectively combine pupil reduction and pupil expansion technologies by combining PVG and waveguide, so that the light beam is focused and enters the PVG structure, and then the pupil is expanded and multiple reflections are achieved through the optical waveguide to achieve efficient energy collection and imaging. The PVG structure is uniquely designed and has a lateral periodicity of P X and the Bragg period P B The Bragg tilt angle φ can be adjusted between 20° and 60°, allowing the system to adapt to a variety of optical application scenarios at different wavelengths.

[0008] Technical solution:

[0009] A high-efficiency optical energy collection and imaging system based on PVG optical miosis, comprising:

[0010] 1. Miotic unit: reduces the incident beam aperture and optimizes beam focusing, allowing the beam to enter the PVG system more efficiently.

[0011] 2. Polarization Volume Holographic Grating (PVG) Structure: This grating structure design breaks through the limitation of the traditional lens F number, making the light receiving area theoretically infinite. X and the Bragg period P B The Bragg tilt angle φ can be adjusted from 20° to 60° to achieve efficient diffraction of multi-wavelength light. The grating period is 800 nanometers to 1 micron.

[0012] 3. Optical waveguide device: Using materials with a refractive index ≥1.9, combined with a two-dimensional pupil expansion design, it supports multiple reflections of the light beam in the waveguide, expands the light beam exit aperture, increases the luminous flux, and thus effectively enhances the light energy collection efficiency.

[0013] 4. Detector unit: Located at the exit of the optical waveguide, it is used to receive the light beam transmitted in the waveguide and generate a high-resolution image.

[0014] Preferably, the miotic unit has a focal length of 50 to 100 mm, a diameter of 10 mm, and a light beam incident angle of 0°.

[0015] Preferably, the Bragg tilt angle of the PVG is 45°, the grating period is 800 nanometers, and the thickness is 2 micrometers.

[0016] Preferably, the optical waveguide device has a width of 10 to 20 mm, a length of 50 to 100 mm, and a thickness of 1 mm.

[0017] Preferably, the operating wavelength of the system is 8 microns, which is suitable for infrared band detection and uncooled infrared imaging.

[0018] The present invention also provides a design method for an optical energy collection and imaging system based on PVG optical miosis, comprising the following steps:

[0019] Step 1: Set the light source parameters through Zemax simulation, including the beam type as parallel light, wavelength as 8 microns, light source power as 5 watts, and beam incident angle as 0°;

[0020] Step 2: In the non-sequential mode (NSC mode) of Zemax, the geometric models of the miotic unit, PVG, and optical waveguide were constructed. The focal length of the miotic unit was set to 50-100 mm, the diameter was 10 mm, the width of the optical waveguide was 10-20 mm, and the length was 50-100 mm.

[0021] Step 3: Execute with precision of 10 -6 Ray tracing to simulate the propagation path of light beams in the system;

[0022] Step 4: Based on the simulation data, adjust the Bragg tilt angle of the PVG within the range of 20° to 60°, the grating period within the range of 800 nanometers to 1 micron, and optimize the optical waveguide dimensions.

[0023] Step 5: Verify system performance to ensure that the PVG diffraction efficiency is ≥90% and the luminous flux is increased by ≥2.41 times.

[0024] Preferably, the optimization of the PVG parameters in step 4 includes:

[0025] By adjusting the Bragg tilt angle to 45° and the grating period to 800 nanometers, the high diffraction efficiency at an 8-micron wavelength is matched;

[0026] The grating period and waveguide size are iteratively optimized based on the simulation results to ensure that the number of total internal reflections of the light beam in the optical waveguide is ≥5 times.

[0027] Preferably, the optimization of the optical waveguide includes:

[0028] Use materials with a refractive index of ≥1.9 to ensure that the light energy utilization rate of multiple total internal reflections is ≥99%;

[0029] Through simulation, the waveguide width is adjusted to 10-20 mm, the length is 50-100 mm, and the thickness is 1 mm.

[0030] The present invention also provides an optical energy collection and imaging method, based on the above system, comprising the following steps:

[0031] Step A: Focusing a parallel beam of 8 micron wavelength at an incident angle of 0° through a miotic unit;

[0032] Step B: Use PVG to perform polarization control and diffraction modulation on the light beam, with a Bragg tilt angle of 45° and a grating period of 800 nm;

[0033] Step C: Expanding the beam aperture to 20 mm by ≥5 total internal reflections in the optical waveguide;

[0034] Step D: The detector receives the expanded light beam and generates a high-resolution image with a spot concentration of ≤0.1mm;

[0035] Step E: In combination with the design method described in claims 6 to 8, optimize the system parameters through Zemax simulation.

[0036] Preferably, the performance verification of the method includes:

[0037] Measure the incoherent illuminance distribution of the entrance and exit pupils, and calculate the luminous flux increase by ≥2.41 times;

[0038] The system resolution was evaluated by the detector imaging results to ensure that the spot diameter was ≤0.1 mm and the imaging signal-to-noise ratio was ≥30 dB.

[0039] Beneficial Effects: By incorporating optical waveguide technology, this system effectively controls the light propagation path and improves light flux collection efficiency. By optimizing the design parameters of a fixed-period PVG, this system overcomes the limitations of traditional lens F-numbers and significantly improves the energy efficiency of the light beam. Furthermore, by integrating Zemax simulation methods, the system optimizes the light propagation path within the PVG and waveguide, significantly improving imaging quality and system efficiency. This system design maintains a compact structure while being suitable for high-resolution infrared imaging applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a system structure diagram in Zemax provided in the implementation of the present invention, 1 is a holographic lens, 2 is a paraxial lens, 3 is a holographic grating, 4 is a rectangular light source, and 5 is a detection unit.

[0041] Figure 2A schematic diagram of the PVG grating structure is provided for the implementation of the present invention, showing the basic structural parameters of the PVG, including the lateral period, Bragg period and Bragg tilt.

[0042] Figure 3 This is the Zemax simulation model of the system, including the layout of the light source, holographic lens, and PVG components.

[0043] Figure 4 This is a flow chart in Zemax provided in the implementation of the present invention.

[0044] Figure 5 This is a color diagram of human pupil imaging provided in a specific embodiment of the present invention.

[0045] Figure 6 Comparison diagram of incoherent light illumination of entrance and exit pupils obtained in a specific embodiment of the present invention: (a) incoherent light illumination of entrance pupil; (b) incoherent light illumination of exit pupil. DETAILED DESCRIPTION

[0046] The present invention will be further explained below with reference to the accompanying drawings and a specific embodiment.

[0047] This embodiment provides a design method for an optical energy collection and imaging system based on PVG optical miosis. The design method uses a PVG miosis and waveguide structure, combined with Zemax simulation, to achieve efficient energy collection and imaging. The design method specifically includes the following steps:

[0048] Step 1: Set the key parameters of the incident light;

[0049] In the Zemax simulation environment, the light source is set as a rectangular light source to meet the special requirements of the PVG optical system:

[0050] Beam type: A parallel light source is used to ensure that the direction of light remains consistent as it propagates through the system.

[0051] Wavelength: Set to 8 microns, which meets the infrared band requirements of this system and ensures that the system works at the specified wavelength.

[0052] Light source power: Set to 5 watts to ensure that the system can obtain sufficient light flux to achieve high-efficiency energy collection and imaging.

[0053] Beam incident angle: Set to 0° so that the beam enters the miotic unit vertically to avoid beam loss caused by angle deviation.

[0054] Step 2: Define the geometry of the optical components and the miotic unit parameters;

[0055] In Zemax's non-sequential mode (NSC mode), the geometric model of the optical components is constructed one by one to achieve the best focusing effect of the optical system:

[0056] Miotic unit focal length: set to 100 mm to ensure that the light beam can be effectively focused after passing through the miotic unit and maintain stable transmission in the waveguide.

[0057] Diameter of the miotic unit: set to 10 mm to adapt to the size of the incident light beam, ensuring that the light beam can effectively pass through the miotic unit during the focusing process and reduce optical losses.

[0058] Waveguide Dimensions: The waveguide width is set to 20 mm and the length is set to 100 mm, so that the light beam can achieve multiple reflections in the waveguide and expand the output aperture. This size design ensures high light flux transmission while maintaining a compact structure.

[0059] Step 3: Set the diffraction parameters of the polarization volume holographic grating (PVG);

[0060] Specific parameters are adjusted on the PVG grating to ensure efficient beam steering at specific wavelengths and angles:

[0061] Bragg tilt angle: set to 45°, which meets the optimal incident condition of the light beam on the PVG and helps achieve the high diffraction efficiency required by the system.

[0062] Grating period: Set to 800 nanometers to match the 8 micron wavelength and ensure the system achieves high diffraction efficiency at this wavelength.

[0063] Grating efficiency optimization: Based on the set Bragg tilt angle and grating period, Zemax was used to fine-tune the grating angle to optimize the system's beam diffraction effect. Final diffraction efficiency measurements showed that the PVG efficiency reached over 90% under this setting.

[0064] Step 4: Design the optical waveguide system and define the material properties;

[0065] The optical waveguide device uses a high refractive index material (refractive index of about 1.9) to ensure efficient total internal reflection:

[0066] Material selection: Using high refractive index optical glass can maintain the energy of the light beam during multiple reflections and reduce loss.

[0067] Waveguide geometry: Specific width is 20 mm and length is 100 mm to ensure that the light beam can be reflected multiple times inside the waveguide and expand the beam exit aperture at the exit. The thickness is set to 1 mm to adapt to the propagation path of the light beam inside the waveguide.

[0068] Total internal reflection condition: The reflectivity of the waveguide interface is configured to be 99% to ensure efficient energy utilization during the transmission of the light beam inside the waveguide.

[0069] Step 5: Perform ray tracing simulation;

[0070] Enable high-precision ray tracing in your Zemax simulation to ensure accurate beam propagation throughout the system:

[0071] Tracking Accuracy: Set to 10 -6 , in order to better simulate the transmission path and behavior of light beams in complex optical systems.

[0072] Beam Path Analysis: This comprehensive observation of the beam's path through the miotic unit, PVG, and waveguide ensures that its reflection, diffraction, and transmission in each component meet design expectations. Simulation results show that after passing through the PVG, the beam smoothly enters the waveguide and forms the desired imaging effect at the detector.

[0073] Step 6: Calculate the diffraction efficiency and luminous flux;

[0074] A detector unit is set at the exit of the waveguide to evaluate the optical performance of the system:

[0075] Detector setup: The detector surface is set to 20 mm wide to receive all beams after the waveguide pupil is expanded. It is located close to the waveguide outlet to ensure measurement accuracy.

[0076] Diffraction efficiency measurement: The light intensity distribution captured by the detector shows that the diffraction efficiency of PVG exceeds 90%, meeting the requirements for efficient beam control.

[0077] Luminous flux measurement: The system's luminous flux is measured based on the light intensity captured by the detector. Simulation results show that the system can efficiently collect and transmit light beams, meeting the expected energy collection and imaging performance.

[0078] Step 7: Optimize system design;

[0079] Based on the simulation results, Zemax optimization tools were used to further adjust key parameters to maximize the system light throughput and ensure high-resolution imaging quality:

[0080] Bragg tilt fine-tuning: Fine adjustments are made based on 45° to optimize the diffraction efficiency of the light beam on the PVG and ensure that the light beam can achieve optimal multiple reflections in the waveguide.

[0081] Iterative optimization of grating period and waveguide dimensions: The PVG grating period and waveguide geometry were adjusted through multiple iterations to ensure optimal system performance at an 8-micron wavelength. The final results showed that with a 100-mm focal length and 20-mm waveguide width, the system can maintain stable imaging quality at high light flux.

[0082] Taking into account multiple factors such as light flux, diffraction efficiency, and energy transmission efficiency, the overall performance of the system is improved through parameter adjustment. Ultimately, the system can achieve maximum light flux in a small volume while maintaining high-resolution imaging quality.

[0083] like Figure 3 The system optical path diagram shows the beam's propagation path through the various optical components. After passing through the miotic unit, the beam enters the PVG grating and undergoes multiple reflections before reaching the waveguide. The Zemax 3D view clearly demonstrates the beam's propagation through the various components. High-precision tracking is used during the simulation to ensure a stable beam path and optimize energy collection and transmission efficiency.

[0084] Figure 5 The image of the pupil, obtained on the detector after processing by the optical system, is shown. The color map shows the distribution of the luminous flux, demonstrating that the imaging effect of the light beam after passing through the PVG and waveguide structure is excellent, with a clear and concentrated light spot, demonstrating the system's high-resolution imaging performance, suitable for infrared detection and high-precision imaging.

[0085] Figure 6 A comparison of the system's entrance and exit pupil incoherent illumination is shown: (a) Entrance pupil incoherent illumination: This shows the energy distribution of the beam at the entrance pupil, verifying the effectiveness of the initial miosis and PVG treatment of the beam. The luminous flux is 7 lumens, with a unit area flux of 0.0175 lumens / mm². (b) Exit pupil incoherent illumination: The exit pupil luminous flux is 3.7 lumens, and the unit area flux increases to 0.042 lumens / mm². Compared to the entrance pupil, the illumination distribution at the exit pupil is more uniform, demonstrating the system's energy distribution advantage. The significant light energy concentration at the exit pupil indicates that the system's energy collection efficiency has been significantly improved through the adjustment of the optical waveguide and PVG. The energy collection efficiency at the exit pupil is approximately 2.41 times higher than that at the entrance pupil. This gain demonstrates the effectiveness of combining PVG with the optical waveguide in optimizing energy distribution and improving system efficiency.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An optical energy collection and imaging system based on PVG optical miosis, characterized in that: include: The miotic unit is used to reduce the incident light beam aperture and focus it, thereby increasing the energy density of the beam; a polarization volume holographic grating (PVG) configured to diffraction-modulate a light beam, wherein the PVG has a Bragg tilt angle of 20° to 60° and a grating period of 800 nm to 1 μm; The optical waveguide device uses a material with a refractive index of ≥1.9, which supports multiple total internal reflections of the light beam to expand the output aperture; The detector unit, located at the exit of the optical waveguide, receives the light beam and generates a high-resolution image.

2. The system according to claim 1, wherein: The miotic unit has a focal length of 50 to 100 mm, a diameter of 10 mm, and a light beam incident angle of 0°.

3. The system according to claim 1, wherein: The PVG has a Bragg tilt angle of 45°, a grating period of 800 nanometers, and a thickness of 2 micrometers.

4. The system according to claim 1, wherein: The optical waveguide device has a width of 10 to 20 mm, a length of 50 to 100 mm, and a thickness of 1 mm.

5. The system according to claim 1, wherein: The system has an operating wavelength of 8 microns and is suitable for infrared band detection and uncooled infrared imaging.

6. A design method for an optical energy collection and imaging system based on PVG optical miosis, characterized in that: The following steps are involved: Step 1: Set the light source parameters through Zemax simulation, including the beam type as parallel light, wavelength as 8 microns, light source power as 5 watts, and beam incident angle as 0°; Step 2: In the non-sequential mode (NSC mode) of Zemax, the geometric models of the miotic unit, PVG, and optical waveguide were constructed. The focal length of the miotic unit was set to 50-100 mm, the diameter was 10 mm, the width of the optical waveguide was 10-20 mm, and the length was 50-100 mm. Step 3: Execute with precision of 10 -6 Ray tracing to simulate the propagation path of light beams in the system; Step 4: Based on the simulation data, adjust the Bragg tilt angle of the PVG within the range of 20° to 60°, the grating period within the range of 800 nanometers to 1 micron, and optimize the optical waveguide dimensions. Step 5: Verify system performance to ensure that the PVG diffraction efficiency is ≥90% and the luminous flux is increased by ≥2.41 times.

7. The design method according to claim 6, characterized in that: The optimization of the PVG parameters in step 4 includes: By adjusting the Bragg tilt angle to 45° and the grating period to 800 nanometers, the high diffraction efficiency at an 8-micron wavelength is matched; The grating period and waveguide size are iteratively optimized based on the simulation results to ensure that the number of total internal reflections of the light beam in the optical waveguide is ≥5 times.

8. The design method according to claim 6, characterized in that: The optimization of the optical waveguide includes: Use materials with a refractive index of ≥1.9 to ensure that the light energy utilization rate of multiple total internal reflections is ≥99%; Through simulation, the waveguide width is adjusted to 10-20 mm, the length is 50-100 mm, and the thickness is 1 mm.

9. An optical energy collection and imaging method, based on the system according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step A: Focusing a parallel beam of 8 micron wavelength at an incident angle of 0° through a miotic unit; Step B: Use PVG to perform polarization control and diffraction modulation on the light beam, with a Bragg tilt angle of 45° and a grating period of 800 nm; Step C: Expanding the beam aperture to 20 mm by ≥5 total internal reflections in the optical waveguide; Step D: The detector receives the expanded light beam and generates a high-resolution image with a spot concentration of ≤0.1mm; Step E: In combination with the design method described in claims 6 to 8, optimize the system parameters through Zemax simulation.

10. The method according to claim 9, characterized in that Performance verification of the method includes: Measure the incoherent illuminance distribution of the entrance and exit pupils, and calculate the luminous flux increase by ≥2.41 times; The system resolution was evaluated by the detector imaging results to ensure that the spot diameter was ≤0.1 mm and the imaging signal-to-noise ratio was ≥30 dB.

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