Ultraviolet dual-band exposure lens

Abstract

This invention discloses a dual-band ultraviolet exposure lens, comprising a front lens group, an aperture stop, and a rear lens group. The aperture stop is located between the front and rear lens groups. The front lens group includes, in sequence, a first lens (a biconvex lens), a second lens (a plano-convex lens), a third lens (a concave-convex lens), and a fourth lens (a plano-concave lens). The rear lens group includes, in sequence, a fifth lens (a concave-convex lens) and a sixth lens (a plano-convex lens). Through the above design, the dual-band ultraviolet exposure lens of this invention can simultaneously accommodate laser light sources in both 375nm and 405nm bands, and has a simple structure, high transmittance, low distortion, and low object-image telecentrism.

Description

Technical Field

[0001] This invention relates to optical lenses, and more particularly to a dual-band ultraviolet exposure lens for micro-nano lithography. Background Technology

[0002] Existing ultraviolet binocular telecentric lenses generally only operate in narrow bands with a single light source, such as 375 nm or 405 nm single band. The few lenses that can achieve dual bands have complex structures and a large number of lenses, which leads to a decrease in lens transmittance. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a dual-band ultraviolet exposure lens that is compatible with both 375nm and 405nm laser light sources, and has a simple structure, high transmittance, low distortion, and small object-image telecentricity.

[0004] One of the objectives of this invention is achieved through the following technical solution:

[0005] A dual-band ultraviolet exposure lens includes a front lens group, an aperture stop, and a rear lens group. The aperture stop is located between the front lens group and the rear lens group. The front lens group includes a first lens, which is a biconvex lens; a second lens, which is a plano-convex lens; a third lens, which is a concave-convex lens; and a fourth lens, which is a plano-concave lens. The rear lens group includes a fifth lens, which is a concave-convex lens; and a sixth lens, which is a plano-convex lens.

[0006] Furthermore, the front of the front lens group is in the object direction, and the rear of the rear lens is in the image direction; or the front of the front lens group is in the image direction, and the rear of the rear lens is in the object direction.

[0007] Furthermore, the radius of curvature of the first lens near the object surface is greater than the radius of curvature near the image surface.

[0008] Furthermore, the second lens has a convex surface near the object side and a flat surface near the image side.

[0009] Furthermore, the third lens has a convex surface near the object side and a concave surface near the image side.

[0010] Furthermore, the radius of curvature of the convex surface is smaller than the radius of curvature of the concave surface.

[0011] Furthermore, the fourth lens has a planar surface near the object side and a concave surface near the image side.

[0012] Furthermore, the fifth lens has a concave surface near the object side and a convex surface near the image side.

[0013] Furthermore, the radius of curvature of the convex surface is smaller than the radius of curvature of the concave surface.

[0014] Furthermore, the sixth lens has a convex surface near the object side and a flat surface near the image side.

[0015] Compared with existing technologies, the ultraviolet dual-band exposure lens of this invention can be compatible with laser light sources in both 375nm and 405nm bands at the same time, and has a simple structure, high transmittance, low distortion, and small object telecentricity. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the ultraviolet dual-band exposure lens of the present invention;

[0017] Figure 2 for Figure 1 A schematic diagram of the optical path of a dual-band ultraviolet exposure lens;

[0018] Figure 3 for Figure 1 The dual-band MTF diagram of the ultraviolet dual-band exposure lens with light source wavelengths of 375nm and 405nm.

[0019] Figure 4 for Figure 1 Image telecentricity curve of a dual-band ultraviolet exposure lens;

[0020] Figure 5 for Figure 1 Image point diagram of a dual-band ultraviolet exposure lens when the light source wavelength is 375nm;

[0021] Figure 6 for Figure 1 Image point diagram of a dual-band ultraviolet exposure lens when the light source wavelength is 405nm;

[0022] Figure 7 for Figure 1 Image point diagram of the ultraviolet dual-band exposure lens when the light source wavelengths are 375nm and 405nm;

[0023] Figure 8 for Figure 1 Field curvature diagram of a dual-band ultraviolet exposure lens;

[0024] Figure 9 for Figure 1 Distortion image of a dual-band ultraviolet exposure lens.

[0025] In the diagram: 10, front lens group; 11, first lens; 12, second lens; 13, third lens; 14, fourth lens; 20, aperture stop; 30, rear lens group; 31, fifth lens; 32, sixth lens; 40, seventh lens; 50, lens protective glass. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or it can be fixed through another intermediate component. When a component is said to be "connected to" another component, it can be directly connected to the other component or it may be fixed through another intermediate component. When a component is said to be "set on" another component, it can be set directly on the other component or it may be set through another intermediate component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] Please see Figures 1 to 2 The present invention provides an ultraviolet dual-band exposure lens comprising a front lens group 10, an aperture 20, a rear lens group 30, a seventh lens 40, and a lens protective glass 50.

[0030] The aperture stop 20 is located between the front lens group 10 and the rear lens group 30. The object side can be located in front of the front lens group 10, and the image side can be located behind the rear lens group 30, such as... Figure 1 and Figure 2 As shown. At this time, the seventh lens 40 is located between the object side and the front lens group 10, and the lens protective glass 50 is located between the object side and the seventh lens 40.

[0031] If the object side is located behind the rear lens group 30 and the image side is located in front of the front lens group 10, the order of the lens arrangement remains unchanged, and the lens is flipped 180 degrees. Taking the first lens 11 as an example, the first lens 11 is a biconvex lens. When the object side is in front of the front lens group 10 and the image side is behind the rear lens group 30, the radius of curvature of the surface of the first lens 11 close to the object side is greater than the radius of curvature of the surface close to the image side. If the object side is located behind the rear lens group 30 and the image side is located in front of the front lens group 10, after the first lens 11 is flipped 180 degrees, the radius of curvature of the surface of the first lens 11 close to the object side is still greater than the radius of curvature of the surface close to the image side. That is, whether the object side is in front of the front lens group 10 or behind the rear lens group 30, the range of the radius of curvature of the lens facing the object side is the same. Correspondingly, the range of the radius of curvature of the lens facing the image side is the same.

[0032] The front lens group 10 includes a first lens 11, a second lens 12, a third lens 13, and a fourth lens 14. The first lens 11, the second lens 12, the third lens 13, and the fourth lens 14 are arranged in sequence. The first lens 11 is a biconvex lens. The radius of curvature of the surface of the first lens 11 close to the object side is greater than the radius of curvature of the surface close to the image side. The second lens 12 is a plano-convex lens. The surface of the second lens 12 close to the object side is convex, and the surface close to the image side is flat. The third lens 13 is a meniscus lens. The surface of the third lens 13 close to the object side is convex, and the surface close to the image side is concave. The radius of curvature of the convex surface is less than the radius of curvature of the concave surface. The fourth lens 14 is a plano-concave lens. The surface of the fourth lens 14 close to the object side is flat, and the surface close to the image side is concave.

[0033] The rear lens group 30 includes a fifth lens 31 and a sixth lens 32 arranged in sequence. The fifth lens 31 is a meniscus lens. The surface of the fifth lens 31 close to the object side is concave, and the surface close to the image side is convex. The radius of curvature of the convex surface is less than the radius of curvature of the concave surface. The sixth lens 32 is a plano-convex lens. The surface of the sixth lens 32 close to the object side is convex, and the surface close to the image side is flat.

[0034] The seventh lens 40 is a protective glass, and both sides are flat. Both sides of the lens protective glass 50 are flat.

[0035] It should be noted that for the descriptions of the above first lens 11, second lens 12 to seventh lens 40, the first, second, etc. are only naming methods for distinguishing lenses and do not represent the arrangement order.

[0036] Preferably, the range of the radius of curvature R of the ultraviolet dual-band exposure lens is as follows:

[0037] Object side of the first lens 11: 220 mm < R < 270 mm, image side of the first lens 11: 80 mm < R < 115 mm;

[0038] Object side of the second lens 12: 25 mm < R < 50 mm, image side of the second lens 12: infinity;

[0039] Object side of the third lens 13: 20 mm < R < 40 mm, image side of the third lens 13: 70 mm < R < 95 mm;

[0040] Object side of the fourth lens 14: infinity, image side of the fourth lens 14: 8 mm < R < 25 mm;

[0041] Object side of the fifth lens 31: 28 mm < R < 35 mm, image side of the fifth lens 31: 17 mm < R < 27 mm;

[0042] Object side of the sixth lens 32: 115 mm < R < 135 mm, image side of the sixth lens 32: infinity.

[0043] The above lenses are made of materials such as flint glass or crown glass.

[0044] The following is an illustration with specific embodiments. The parameters of the exposure lens are as shown in the following table:

[0045]

[0046]

[0047] Optical detection is performed on the above ultraviolet double - band exposure lens. As Figure 3 shown, it is the double - band MTF graph of the ultraviolet double - band exposure lens with light source wavelengths of 375 nm and 405 nm, which represents the transfer function of the exposure lens. It can be seen from Figure 3 that it reaches the diffraction limit.

[0048] Figure 4 is the image - side telecentricity curve graph of the ultraviolet double - band exposure lens. The abscissa represents the field of view, and the ordinate represents the telecentricity. It can be obtained from the graph that the telecentricity curve at the image - side center of the exposure lens is within 0.2 mrad, having very good telecentricity. Figure 5 Spot diagram of the ultraviolet double - band exposure lens when the light source wavelength is 375 nm. Figure 6 is the spot diagram of the ultraviolet double - band exposure lens when the light source wavelength is 405 nm. Figure 7 is the spot diagram of the ultraviolet double - band exposure lens when the light source wavelengths are 375 nm and 405 nm. Figure 8 is the field curvature graph of the ultraviolet double - band exposure lens. It can be seen from the graph that the field curvature aberration is small. Figure 9 is the distortion graph of the ultraviolet double - band exposure lens. In the graph, the abscissa represents the distortion magnitude, and the ordinate represents the change in the field of view. It can be seen from the graph that the distortion is one in one hundred thousand and two in one hundred thousand, so the distortion is small.

[0049] Through the above specific embodiments, it can be seen that the ultraviolet dual-band exposure lens of the present invention can be compatible with laser light sources in both 375nm and 405nm bands at the same time, and has a simple structure, high transmittance, low distortion, and small object telecentricity.

[0050] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These are all equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of these fall within the protection scope of the present invention.

Claims

1. A dual-band ultraviolet exposure lens, comprising a seventh lens, a front lens group, an aperture stop, and a rear lens group arranged sequentially, wherein the aperture stop is located between the front lens group and the rear lens group, characterized in that: The front lens group consists of four lenses arranged in sequence: a first lens, a second lens, a third lens, and a fourth lens; the first lens is a biconvex lens, the second lens is a plano-convex lens, the third lens is a concave-convex lens, and the fourth lens is a plano-concave lens; the rear lens group consists of two lenses arranged in sequence: a fifth lens and a sixth lens; the fifth lens is a concave-convex lens, and the sixth lens is a plano-convex lens. The parameters of the exposure lens are shown in the table below:

2. The ultraviolet dual-band exposure lens according to claim 1, characterized in that: The front of the front lens group is in the object direction, and the rear of the rear lens is in the image direction; or the front of the front lens group is in the image direction, and the rear of the rear lens is in the object direction.

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