Imaging lens for a dlp 3d printing system

Abstract

The invention relates to an imaging lens for digital light processing 3D printing system. The lens comprises 8 lenses, which are in turn passed after reflection from a digital micromirror array: meniscus 1, convex lens 2, biconvex lens 3, concave lens 4, biconvex lens 5, convex lens 6, biconvex lens 8. The invention uses optical engineering principles to design a customized imaging lens for DLP 3D printing system, which has the advantages of structural symmetry, clear imaging and high degree of freedom. In addition to improving the imaging quality of the DLP 3D printing system, the structural printing precision can be further improved, the application range is wide, and the customizability of related products is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of 3D printing systems, and belongs to the technical field of optical lenses, in particular to an imaging lens for a DLP 3D printing system. BACKGROUND

[0002] With the continuous development of 3D printing technology, digital light processing technology (DLP) is considered a promising additive manufacturing technology due to its low cost, high accuracy, fast manufacturing speed, and material versatility. The previous point-to-point photopolymerization method is converted into 2D plane projection curing, which greatly improves the printing speed and improves the structural quality, showing great potential in microfluidic, tissue engineering, biomedical micro devices and other application fields.

[0003] In order to improve the overall performance of the DLP 3D printing system and increase its application, the optimization combination of optical and hardware configuration is necessary. Most of the existing DLP 3D printing systems use multipurpose commercial optical elements, however, the problem with such commercial optical elements is that the matching degree is not high, and the size and structural accuracy of the 3D printer is limited by the characteristics of these elements. Therefore, the DLP 3D printing technology still needs to be further improved to overcome its current limitations, and it is necessary to develop optical components that are suitable for DLP systems. SUMMARY

[0004] The purpose of the present application is to design and develop a customized imaging lens based on DLP 3D printing technology, which has the characteristics of miniaturization, low dispersion, low cost and high resolution, and can be customized for DLP 3D printing system, improve the XY direction size accuracy, and manufacture high resolution 3D microstructure.

[0005] The present application realizes high-quality imaging of the light reflected by the digital micromirror array in the DLP 3D printing system through the imaging lens of the present application.

[0006] The lens includes 8 lenses, arranged in order from the direction of light incidence: concave-convex lens 1, double convex lens 2, convex-concave lens 3, convex-concave lens 4, concave-convex lens 5, concave-convex lens 6, double convex lens 7, and convex-concave lens 8, each lens is arranged on a central axis.

[0007] In the lens, four different types of optical glass materials can be used, type H-LAK52, H-LAK4L, H-LAK53B and ZF7, the optical glass type of each lens: the concave-convex lens 1 is H-LAK52 type, the biconvex lens 2 is H-LAK4L type, the convex-concave lens 3 is H-LAK53B type, the convex-concave lens 4 is ZF7 type, the concave-convex lens 5 is ZF7 type, the concave-convex lens 6 is H-LAK53B type, the biconvex lens 7 is H-LAK4L type, and the convex-concave lens 8 is H-LAK52 type.

[0008] Compared with the existing integrated DLP projector which is limited in application, the imaging lens provided by the present application eliminates stray light and outputs good imaging effect through reasonable matching of each lens and optimization of each parameter, and has significant advantages in high degree of freedom customization and reduction of equipment size. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a structural schematic diagram of an embodiment of the present application.

[0010] Figure 2 is a spatial frequency curve diagram of an embodiment of the present application.

[0011] Figure 3 is an energy distribution schematic diagram of a focal spot of an embodiment of the present application.

[0012] Figure 4 is a field curvature and distortion curve diagram of an embodiment of the present application.

[0013] Figure 5 is an optical path difference curve diagram of an embodiment of the present application.

[0014] Figure 6 is a curve diagram of spatial frequency variation caused by design data modification of the present application. DETAILED DESCRIPTION

[0015] In order to facilitate understanding of the present application, the present application is further described below in combination with the drawings and embodiments.

[0016] The imaging lens design for the DLP 3D printing system of the present application adopts the principle of ray tracing, and realizes high-quality imaging effect through optimization design by changing the thickness and spacing between lenses, and the material of the lenses.

[0017] Figure 1The structural schematic diagram of an embodiment of the present application is composed of eight lenses. Among them, lenses 1, 5 and 6 are concave-convex lenses, lenses 2 and 7 are convex lenses, and lenses 3, 4 and 8 are convex-concave lenses. The left end of lens 1 in the figure is the schematic position of the object, and the right side of lens 8 is the schematic position of the image. After the light is reflected by the DMD, it enters the imaging lens, passes through lenses 1 to 8 in sequence from left to right, reaches the imaging plane, and induces the photosensitive material in the sample pool of the DLP 3D system to undergo photopolymerization reaction according to imaging. The lens material adopts four kinds of optical glass materials, and the corresponding glass material models are H-LAK52 type, H-LAK4L type, H-LAK53B type and ZF7 type respectively. The material sequence of the lens is H-LAK52→H-LAK4L→H-LAK53B→ZF7→ZF7→H-LAK53B→H-LAK4L→H-LAK52.

[0018] In an embodiment of the imaging lens for the DLP 3D printing system of the present application, the relevant parameters and arrangement of each lens are shown in the following table (unit: millimeter).

[0019]

[0020] Figure 2 The figure is the spatial frequency curve of an embodiment of the present application. In the figure, the horizontal axis is the spatial frequency, and the vertical axis is the amplitude of the optical transfer function. The eight curves in the figure are the spatial frequency curves of the meridian and sagittal planes at 0 field, 0.577 field 5 millimeters, 0.816 field 7.07 millimeters, and the meridian and sagittal planes at full field 8.66 millimeters, and the wavelength range is 398 nanometers to 412 nanometers. In the figure, at the spatial frequency of 228 lines per pair, the amplitude of the optical transfer function is greater than 0.4 when the object side resolution is 2.2 microns.

[0021] Figure 3 The figure is the energy distribution schematic diagram of the focal spot of an embodiment of the present application. In the figure, the horizontal axis is the spot radius, and the vertical axis is the relative intensity. In the figure, the energy of the focal spot is greater than 50% within a radius of 0.9 microns. In addition to the diffraction limit, the four curves in the figure are the energy distribution schematic diagrams of the focal spots at 0 field, 0.577 field 5 millimeters, 0.816 field 7.07 millimeters, and full field 8.66 millimeters.

[0022] Figure 4 The figure is the field curvature and distortion curve of an embodiment of the present application. The left half of the figure is the field curvature curve, the horizontal axis is the field curvature value, and the vertical axis is the field value, and the field is from 0 field to full field 8.66 millimeters. The right half of the figure is the distortion curve, the horizontal axis is the distortion percentage, and the vertical axis is the field value, and the field is from 0 field to full field 8.66 millimeters.

[0023] Figure 5The optical path difference curve diagram of the replication imaging lens of the present application eliminates aberration for three ultraviolet lights with wavelengths of 398 nm, 405 nm and 412 nm respectively, and the light with a parallel light 0 degree angle of incidence. The wavelength unit in the diagram is microns. The upper left diagram in the diagram is the optical path difference curve diagram of 0 field of view, the upper right diagram is the optical path difference curve diagram of 0.577 field of view at 5 mm, the lower left diagram is the optical path difference curve diagram of 0.816 field of view at 7.07 mm, and the lower right diagram is the optical path difference curve diagram of full field of view at 5 mm.

[0024] In the above embodiment of the present application, the design values are a set of optimal data obtained after optimization. If any one data in the specific design size table of the lens is modified, the obtained spatial frequency curve diagram will change greatly. Figure 6 The spatial frequency curve diagram obtained after the vertex distance of the lens surface No. 4 in the specific design size table of the lens is reduced by 0.05 mm.

[0025] The replication imaging objective lens of the DLP-based light-curing biological 3D printing system designed by using the above special method meets the special requirements of the DLP light-curing biological 3D printing system on the replication imaging objective lens. The specific indicators that can be achieved by the embodiment of the present application are as follows:

[0026] 1. The object field of view of the lens is 17.32 mm, which can meet the size of the used DMD, image the projection area, and meet the requirements of the system on the imaging area.

[0027] 2. The numerical aperture of the lens is 0.15, which is a larger numerical aperture based on the coordination of the spatial positions of the imaging part and the illumination part, is conducive to collecting the projection light and its diffraction spots, and improves the imaging resolution and the uniformity of the image light intensity.

[0028] 3. The image side working distance of the lens is 100 mm, which meets the spatial position requirements of the objective lens and the printing plane installation assembly under the condition of equal proportion imaging.

[0029] 4. The object side resolution is less than 2.2 microns, various aberrations are well corrected, the optical transfer function meets the requirements in the resolution range, and the imaging resolution of the system is improved.

Claims

1. An imaging lens for a DLP 3D printing system, characterized in that, The lens consists of 8 lenses, arranged in the following order from the direction of light incidence: a concave-convex lens 1 with positive optical power, a biconvex lens 2 with positive optical power, a convex-concave lens 3 with positive optical power, a convex-concave lens 4 with negative optical power, a concave-convex lens 5 with negative optical power, a concave-convex lens 6 with positive optical power, a biconvex lens 7 with positive optical power, and a convex-concave lens 8 with positive optical power. All lenses are arranged on a central axis. The features are as follows: the average radius of the object-side surface of the concave-convex lens 1 is 372 mm, the average radius of the image-side surface is 83.4 mm, and the central thickness is 4.242 mm; the average radius of the object-side surface of the biconvex lens 2 is 139.67 mm, the average radius of the image-side surface is 308.93 mm, and the central thickness is 17.109 mm; the average radius of the object-side surface of the convex-concave lens 3 is 56.192 mm, the average radius of the image-side surface is 111.17 mm, and the central thickness is 16.721 mm; the average radius of the object-side surface of the convex-concave lens 4 is 349.9 mm, the average radius of the image-side surface is 36.392 mm, and the central thickness is 25.001 mm. The average radius of the object side of the concave-convex lens 5 is 36.392 mm, the average radius of the image side is 349.9 mm, and the center thickness is 25.001 mm; the average radius of the object side of the concave-convex lens 6 is 111.17 mm, the average radius of the image side is 56.192 mm, and the center thickness is 16.721 mm; the average radius of the object side of the biconvex lens 7 is 308.93 mm, the average radius of the image side is 139.67 mm, and the center thickness is 17.109 mm; the average radius of the object side of the convex-concave lens 8 is 83.4 mm, the average radius of the image side is 372 mm, and the center thickness is 4.242 mm.

2. The imaging lens according to claim 1, characterized in that, Four different types of optical glass materials are used: H-LAK52, H-LAK4L, H-LAK53B, and ZF7. The optical glass types of each lens are as follows: Concave-convex lens 1 is H-LAK52, biconvex lens 2 is H-LAK4L, convex-concave lens 3 is H-LAK53B, convex-concave lens 4 is ZF7, concave-convex lens 5 is ZF7, concave-convex lens 6 is H-LAK53B, biconvex lens 7 is H-LAK4L, and convex-concave lens 8 is H-LAK52.

3. The imaging lens according to claim 1, characterized in that, The total length is 353.52694 mm, the diameter is 56.4 mm, the effective focal length is 159.876 mm, the lens field of view is 17.32 mm, the lens numerical aperture is 0.15, the lens object-side working distance is 99.998 mm, the lens image-side working distance is 99.446 mm, the resolution is less than 1.5 micrometers, and the magnification is -1.

4. The imaging lens according to claim 1, characterized in that, The specific design dimensions and arrangement of each lens are shown in the table below. The units for radius of curvature, vertex spacing and surface radius are all millimeters. The variation range of the following structural dimensions is ±0.02mm.

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