Pneumatic zoom holographic lens

Abstract

A pneumatic zoom holographic diffraction lens comprises a transparent glass tube used for loading gas and provided with a sealed bottom and a flexible substrate holographic lens attached to the end face of the glass tube. According to the developed pneumatic variable-focus holographic lens, the flexible substrate holographic lens located on the end face is subjected to convex or concave deformation through the change of the air pressure in the glass tube. The deformation process quickly changes along with the distance between the coaxial annular gratings in the material, so that the focal length of the holographic diffraction lens is quickly tuned, and a pneumatic zooming function is realized. Compared with Fresnel lens zooming caused by stretching and other mechanical means, the pneumatic zooming response speed is high, reversibility is achieved, and the method is quite suitable for the field of tunable spectral imaging and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of variable-focus diffraction lenses, and in particular relates to a pneumatic variable-focus holographic lens. Background Art

[0002] Tunable optical systems have important applications in three-dimensional biomedical imaging, hyperspectral imaging, advanced manufacturing and other fields. The core of designing tunable optical systems is to quickly adjust the three-dimensional spatial focus to achieve fast focusing. Designing and developing variable focus lenses has vital research significance and application value. For example, the spectral confocal measurement system can achieve fast axial scanning through a variable focus lens. Although there are many technologies to achieve variable focus of lenses, there are still certain problems. Finding new zoom technologies remains the focus of research.

[0003] As a diffraction lens recorded in an ultra-thin medium, the holographic lens provides an important way to reduce the size and weight of the device. Holographic lenses usually record holographic gratings inside photosensitive materials through the interference of coaxial divergent and converging spherical waves, thereby forming a diffraction lens. Holographic lenses provide an important basis for the development and application of diffraction optical elements, especially metal-based super lenses. The zoom of holographic lenses has also become a focus of research. The internal grating of the holographic lens is a series of concentric rings. If the spacing between the rings can be changed by mechanical means, the focus of the holographic lens can be tuned. However, the current tuning of the ring spacing is mainly achieved by mechanical stretching. A ring-shaped mechanical device is used to stretch the lens along the diameter direction to make it uniformly expand or shrink, thereby achieving diffraction zoom, which significantly affects the zoom speed. Therefore, new zoom methods used in holographic lenses need to be improved urgently. Summary of the invention

[0004] In order to solve the above problems, the present invention aims to provide a pneumatic variable focus holographic lens, characterized in that the pneumatic variable focus holographic lens is composed of the following parts: a bottom transparent sealed glass tube for loading gas and a flexible base holographic lens attached to the other end of the glass tube. The edge of the flexible base holographic lens and the transparent glass tube are pasted and mechanically pressed to maintain the overall airtightness of the glass tube. The glass tube is provided with a vent valve (17) and a deflation valve (18) for quickly and stably changing the air pressure in the tube.

[0005] The recording device of the holographic lens comprises the following parts: a laser (1), a first aperture (2), a first beam expansion and collimation system (3), a second aperture (4), a first reflector (5), a first broadband beam splitter prism (6), a second reflector (7), a second beam expansion and collimation system (8), a first converging lens (9), an adjustable aperture (10), a third reflector (11), a third beam expansion and collimation system (12), a second converging lens (13), a second broadband beam splitter prism (14), and a photosensitive recording material (15). The first reflector (5), the first broadband beam splitter prism (6), and the second reflector (7) are arranged in a row from left to right at a distance. The light beam emitted by the laser (1) passes through the beam expansion and collimation system and is then reflected by the first reflector (5). The light beam reflected by the second reflector (7) is converged by the second beam expansion and collimation system (8) and the first convergence lens (9), and then becomes a divergent spherical wave through the adjustable aperture (10), and is reflected to the photosensitive recording material (15) through the second broadband beam splitter prism (14) as one of the recording lights. The light beam reflected by the first broadband beam splitter prism (6) is reflected by the third reflector (11), and is passed through the third beam expansion and collimation system (12) and the second convergence lens (13) to form a convergent spherical wave. The convergent spherical wave is directly irradiated to the surface of the photosensitive recording material (15) through the second broadband beam splitter prism (14) as another recording light. A divergent spherical wave interferes with a convergent spherical wave to form a volume grating inside the photosensitive material, thereby realizing the recording of the holographic diffraction lens.

[0006] When the holographic diffraction lens is attached to the bottom sealed transparent glass tube, a sealed glass tube is formed. A certain amount of gas is passed into the glass tube to cause the holographic diffraction lens on the surface of the glass tube to bulge and expand, resulting in a change in the spacing of the annular grating stripes. This deformation causes the spacing of the grating stripes to change, causing a significant change in the focal length of the monochromatic light beam incident from the bottom of the transparent glass tube diffracted by the holographic lens. Through the rapid change of gas pressure, the flexible holographic diffraction lens can change the bulge deformation in real time, thereby realizing pneumatic rapid zoom. When broadband polychromatic light is used to read the pneumatic variable-focus holographic lens, significant spatial dispersion is generated in the axial direction of the holographic lens. Changes in air pressure will lead to significant changes in axial spatial dispersion, thereby providing a new lens with a high dispersion range and rapid zoom for the needs of equipment such as hyperspectral.

[0007] In order to achieve the rapid deformation response of the flexible substrate holographic lens caused by the change of air pressure inside the transparent glass tube, the overall morphology of the holographic lens with a thin center and thick edges is formed during the development process. The change of pressure is more likely to cause the flexible substrate to bulge and expand rapidly.

[0008] The recorded holographic diffraction lens is not limited to the type of holographic lens developed, and can be a coaxial point convergence lens or a line convergence lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The invention provides a process for attaching a pneumatic zoom holographic lens to a transparent glass tube.

[0010] Figure 2 The invention provides a pneumatic zoom process of a pneumatic zoom holographic lens.

[0011] Figure 3 The present invention provides a holographic lens recording device.

[0012] Figure 4 The present invention provides a holographic lens with a thin center and thick edges and a manufacturing process thereof.

[0013] Figure 5 A curve showing the change of the focal position of a pneumatic zoom holographic lens with pressure provided by the present invention.

[0014] Figure 6 The present invention provides a pneumatic zoom holographic lens dispersion spectrum displacement process at a fixed spatial position as the air pressure changes.

[0015] Figure 7 The invention provides a pneumatic zoom holographic lens dispersion spectrum, in which the peak wavelengths at three fixed positions shift linearly with the air pressure.

[0016] Figure 8 The present invention provides a test curve of the response speed of a pneumatic zoom holographic lens.

[0017] Fig. 9 The present invention provides a pneumatic zoom holographic lens response speed fitting curve and an acquired time constant. DETAILED DESCRIPTION

[0018] The following describes in detail a pneumatic zoom holographic lens and a pneumatic zoom process thereof provided by the present invention in conjunction with the accompanying drawings and specific embodiments.

[0019] like Figure 1 As shown, a process for developing a pneumatic zoom holographic lens is shown. The pneumatic zoom holographic lens is composed of the following parts: a bottom transparent sealed glass tube for loading gas and a flexible base holographic lens (16) attached to the other end of the glass tube. The edge of the flexible base holographic lens and the transparent glass tube are glued and mechanically pressed to maintain the overall airtightness of the glass tube. The glass tube is provided with a vent valve (17) and a deflation valve (18) for quickly and stably changing the air pressure in the tube.

[0020] like Figure 2As shown, a pneumatic zoom process of a pneumatic zoom holographic lens. When the holographic diffraction lens is attached to the bottom sealed transparent glass tube, a sealed glass tube is formed. A certain amount of gas is introduced into the glass tube to cause the holographic diffraction lens on the surface of the glass tube to bulge and expand, thereby causing the spacing of the annular grating stripes to change. The change in the spacing of the grating stripes caused by this deformation causes a significant change in the focal length of the monochromatic light beam incident from the bottom of the transparent glass tube diffracted by the holographic lens. Through the rapid change of gas pressure, the flexible holographic diffraction lens can change the bulge deformation in real time, thereby realizing pneumatic rapid zoom. When the pneumatic variable-focus holographic lens is read using broadband polychromatic light, significant spatial dispersion is generated in the axial direction of the holographic lens. Changes in air pressure will lead to significant changes in axial spatial dispersion, thereby providing a new lens with a high dispersion range and rapid zoom for the needs of equipment such as hyperspectral.

[0021] like Figure 3 As shown, the recording device of the holographic lens is composed of the following parts: a laser (1), a first aperture (2), a first beam expansion and collimation system (3), a second aperture (4), a first reflector (5), a first broadband beam splitter prism (6), a second reflector (7), a second beam expansion and collimation system (8), a first converging lens (9), an adjustable aperture (10), a third reflector (11), a third beam expansion and collimation system (12), a second converging lens (13), a second broadband beam splitter prism (14), and a photosensitive recording material (15). The first reflector (5), the first broadband beam splitter prism (6), and the second reflector (7) are arranged in a row from left to right at a distance. The light beam emitted by the laser (1) passes through the beam expansion and collimation system and is then reflected by the first reflector (5). The light beam reflected by the second reflector (7) is converged by the second beam expansion and collimation system (8) and the first convergence lens (9), and then becomes a divergent spherical wave through the adjustable aperture (10), and is reflected to the photosensitive recording material (15) through the second broadband beam splitter prism (14) as one of the recording lights. The light beam reflected by the first broadband beam splitter prism (6) is reflected by the third reflector (11), and is passed through the third beam expansion and collimation system (12) and the second convergence lens (13) to form a convergent spherical wave. The convergent spherical wave is directly irradiated to the surface of the photosensitive recording material (15) through the second broadband beam splitter prism (14) as another recording light. A divergent spherical wave interferes with a convergent spherical wave to form a volume grating inside the photosensitive material, thereby realizing the recording of the holographic diffraction lens.

[0022] like Figure 4 The figure shows a holographic lens with a thin center and thick edges and its manufacturing process provided by the present invention. In order to achieve a fast deformation response of the flexible substrate holographic lens caused by the change of air pressure inside the transparent glass tube, and to use the center of the holographic lens as the expansion center of the bulge, an overall morphology with a thin center and thick edges is formed during the manufacturing process of the holographic lens. Figure 4In the figure, (16) is a cross-sectional view of the photosensitive polymer for holographic lens, and (19) is a cross-sectional view of the mold substrate for preparing the photosensitive polymer. According to the mold with the convex shape, the polymer solution coated on the mold surface can form a morphology with a thin center and thick edges after drying. Therefore, during the pressure change in the glass tube, it is easier to cause the center of the flexible substrate to be the convex center, thereby achieving rapid convex expansion.

[0023] like Figure 5 As shown in the figure, the curve of the focus position of the pneumatic zoom holographic lens changes with pressure. During the pneumatic zoom process of the holographic lens, the focus moves as expressed by the spatial position of 633nm in the dispersion spectrum. As the pressure increases, the focus position moves significantly linearly and gradually moves away from the lens. The solid line is the linear fitting curve, and the symbols are experimental data. It can be seen that the movement process has good linearity.

[0024] like Figure 6 As shown in the figure, the dispersion spectrum of the pneumatic zoom holographic lens shifts with the change of air pressure at a fixed spatial position. It can be seen that with the increase of pressure, the dispersion spectrum has a significant red shift. The distance between this position and the holographic lens is 140mm.

[0025] Figure 7 As shown in the figure, the peak wavelength of the pneumatic zoom holographic lens dispersion spectrum at three fixed positions shifts linearly with the air pressure. At three fixed spatial positions, the peak wavelength of the extracted dispersion spectrum changes with the air pressure. As the air pressure increases, the three positions all show a linear peak wavelength shift. This plays an important role in the quantitative study of the spectral shift of dispersion.

[0026] Figure 8 As shown in the figure, the pneumatic zoom response speed test results. When the air pressure increases from 0.05Kpa to 4.00Kpa, the light intensity of the detector in the optical path changes significantly. The response time can be obtained through the change process.

[0027] Fig. 9 The pneumatic zoom response speed fitting results are shown in Figure 1. By fitting the change of light intensity in this process with an exponential function, the time constant of 28.58ms is obtained, which is the pneumatic zoom response speed of the holographic lens.

[0028] Embodiment 1:

[0029] The present embodiment provides a pneumatic zoom process of a pneumatic zoom holographic lens. The pneumatic zoom holographic lens is composed of a glass tube with a transparent bottom and a sealed end for loading gas, and a flexible substrate holographic lens (16) attached to the other end face of the glass tube. The edge of the flexible substrate holographic lens and the transparent glass tube are pasted and mechanically pressed to maintain the overall airtightness of the glass tube. The glass tube is provided with a vent valve (17) and a vent valve (18) for quickly and stably changing the air pressure in the tube. When the holographic diffraction lens is attached to the other end face of the glass tube with a transparent bottom and a sealed end, a closed glass tube is formed. The air pressure in the tube is controlled by the vent and vent valves on the side of the glass tube. A certain amount of gas is introduced into the glass tube, so that the holographic diffraction lens on the surface of the glass tube gradually bulges and expands with the center of the lens as the bulge point. This causes the spacing of the annular grating stripes of the holographic lens to change starting from the center. The change in the spacing of the grating stripes caused by the convex deformation causes a significant change in the focal length of the monochromatic light beam incident from the bottom of the transparent glass tube after diffraction by the holographic lens. Through the rapid tuning of the gas pressure, the flexible holographic diffraction lens can change the convex deformation in real time, thereby realizing pneumatic rapid zoom. When the pneumatic variable-focus holographic lens is read using broadband polychromatic light, significant spatial dispersion is produced in the axial direction of the holographic lens. Changes in air pressure will lead to significant changes in axial spatial dispersion, thereby providing a new lens with a high dispersion range and rapid zoom for the needs of hyperspectral equipment.

[0030] Embodiment 2:

[0031] This embodiment provides a process for developing a pneumatic variable-focus holographic lens. The development of the pneumatic variable-focus holographic lens is divided into two processes: writing the holographic lens into a flexible substrate photosensitive polymer, and attaching it to the end face of a transparent glass tube after writing. Figure 3 As shown. A beam of light emitted by a laser (1) passes through a beam expansion and collimation system and is then reflected by a first reflector (5). The light beam reflected by a second reflector (7) is converged by a second beam expansion and collimation system (8) and a first convergent lens (9), and then becomes a divergent spherical wave through an adjustable aperture (10), and is reflected to a photosensitive recording material (15) through a second broadband beam splitter prism (14) as one of the recording lights. The light beam reflected by the first broadband beam splitter prism (6) is reflected by a third reflector (11), and passes through a third beam expansion and collimation system (12) and a second convergent lens (13) to form a convergent spherical wave. The convergent spherical wave is directly irradiated to the surface of a photosensitive recording material (15) through the second broadband beam splitter prism (14) as another recording light. A divergent spherical wave interferes with a convergent spherical wave to form a volume grating inside the photosensitive material, thereby realizing the recording of a holographic diffraction lens.

[0032] The holographic lens is attached to a transparent bottom sealed glass tube, and is used to realize the development of a pneumatic zoom device. The edge of the flexible base holographic lens and the transparent glass tube are attached and mechanically pressed, so as to maintain the overall airtightness of the glass tube. At the same time, the bottom transparent sealed glass tube can allow the light beam to be normally transmitted to the holographic lens, so as to achieve the purpose of focusing through the diffraction of the holographic lens. The glass tube is provided with a vent valve (17) and an air release valve (18) for quickly and stably changing the air pressure in the tube.

[0033] Embodiment 3:

[0034] This embodiment provides a process for realizing the overall shape of a holographic lens with a thin center and thick edges. In order to realize the rapid convex or contraction deformation of the flexible substrate holographic lens caused by the change of air pressure inside the transparent glass tube. The overall shape of a thin center and thick edges is formed during the development of the holographic lens so that the center of the holographic lens can be used as the expansion center of the convexity. Figure 4 In the figure, (16) is a cross-sectional view of the photosensitive polymer for holographic lens, and (19) is a cross-sectional view of the mold substrate for preparing the photosensitive polymer. According to the mold with the convex shape, the polymer solution coated on the mold surface can form a morphology with a thin center and thick edges after drying. Therefore, during the pressure change in the glass tube, it is easier to cause the center of the flexible substrate to be the convex center, thereby achieving rapid convex expansion.

[0035] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0036] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A pneumatic zoom holographic diffraction lens, characterized in that: The pneumatic variable focus holographic lens consists of the following parts: a bottom transparent sealed glass tube for loading gas and a flexible base holographic lens attached to the other end of the glass tube. The edge of the flexible base holographic lens and the transparent glass tube are glued and mechanically pressed to maintain the overall airtightness of the glass tube. Ventilation and deflation valves are left on the side of the glass tube to quickly and stably change the air pressure in the tube.

2. According to claim 1, a pneumatic zoom holographic diffraction lens, characterized in that: The recording device of the holographic lens comprises the following parts: a laser (1), a first aperture (2), a first beam expansion and collimation system (3), a second aperture (4), a first reflector (5), a first broadband beam splitter prism (6), a second reflector (7), a second beam expansion and collimation system (8), a first converging lens (9), an adjustable aperture (10), a third reflector (11), a third beam expansion and collimation system (12), a second converging lens (13), a second broadband beam splitter prism (14), and a photosensitive recording material (15). The first reflector (5), the first broadband beam splitter prism (6), and the second reflector (7) are arranged in a row from left to right at a distance. After the laser (1) passes through the beam expansion and collimation system, it is reflected by the first reflector (5). The light beam reflected by the second reflector (7) is converged by the second beam expansion and collimation system (8) and the first convergence lens (9), and then becomes a divergent spherical wave through the adjustable aperture (10), and is reflected to the photosensitive recording material (15) through the second broadband beam splitter prism (14) as one of the recording lights. The light beam reflected by the first broadband beam splitter prism (6) is reflected by the third reflector (11), and is passed through the third beam expansion and collimation system (12) and the second convergence lens (13) to form a convergent spherical wave. The convergent spherical wave is directly irradiated to the surface of the photosensitive recording material (15) through the second broadband beam splitter prism (14) as another recording light. A divergent spherical wave interferes with a convergent spherical wave to form a volume grating inside the photosensitive material, thereby realizing the recording of the holographic diffraction lens.

3. According to claim 1, a pneumatic zoom holographic diffraction lens, characterized in that: When the holographic diffraction lens is attached to the bottom sealed transparent glass tube, a sealed glass tube is formed. A certain amount of gas is passed into the glass tube to make the holographic diffraction lens on the surface of the glass tube bulge and expand, resulting in a change in the spacing of the annular grating stripes. The change in the spacing of the grating stripes caused by this deformation causes a significant change in the focal length of the monochromatic light beam incident from the bottom of the transparent glass tube diffracted by the holographic lens. Through the rapid change of gas pressure, the flexible holographic diffraction lens can change the bulge deformation in real time, thereby realizing pneumatic rapid zoom. When broadband polychromatic light is used to read the pneumatic variable-focus holographic lens, significant spatial dispersion is generated in the axial direction of the holographic lens. Changes in air pressure will lead to significant changes in axial spatial dispersion, thereby providing a new lens with a high dispersion range and rapid zoom for the needs of equipment such as hyperspectral.

4. According to claim 1, a pneumatic zoom holographic diffraction lens, characterized in that: In order to achieve the rapid deformation response of the flexible substrate holographic lens caused by the change of air pressure inside the transparent glass tube, the overall morphology of the holographic lens with a thin center and thick edges is formed during the development process. The change of pressure is more likely to cause the flexible substrate to bulge and expand rapidly.

5. According to claim 1, a pneumatic zoom holographic diffraction lens, characterized in that: The recorded holographic diffraction lens is not limited to the type of the developed holographic lens, and can be a coaxial point convergence lens or a line convergence lens.

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