A scanning lens for a microscopic imaging system

Abstract

The application discloses a scanning lens of a microscopic imaging system, which is composed of a diaphragm, a first lens with a negative focal length, a second lens with a positive focal length, a third lens with a positive focal length and a fourth lens with a negative focal length, and the whole system satisfies the following relations: arctan (HI / EFL) <=11.8°, 2.2<=|FS1 / EFL|<=2.9, 1.9<=|FS2 / EFL|<=2.2, 1.0<=|FS3 / EFL|<=1.3, 1.4<=|FS4 / EFL|<=1.7, the distance between the diaphragm and the first surface of the first lens is >=0.65*EFL, and the distance between the diaphragm and the image surface is <3*EFL, wherein HI is the half image height of the image surface, EFL represents the focal length of the whole scanning lens, FS1 is the focal length of the first lens, FS2 is the focal length of the second lens, FS3 is the focal length of the third lens, and FS4 is the focal length of the fourth lens, and the scanning lens has the advantages that the multi-piece lens structure with specific parameters eliminates various chromatic aberrations on the basis of realizing simultaneous scanning imaging in the case of multispectrum, the imaging quality is high, and the distortion is small.

Description

Technical Field

[0001] This invention relates to a microscopic imaging system, and more particularly to a scanning lens for a microscopic imaging system. Background Technology

[0002] Due to the limitations of traditional optics caused by light diffraction, confocal microscopy was proposed by Vin Minsky in 1957 to improve the ability of microscopes to observe tiny cells. In 1978, the German brothers Thomas and Christoph Cremer combined a scanning lens with a high-power laser, focusing all the laser energy into a point, scanning point by point, and synthesizing the pattern using computer processing. This solved the initial requirement of high-brightness energy for confocal microscopy. Because the observed samples are often rich in color, the scanning lens used in the microscopic imaging system must correct aberrations at the same level to allow simultaneous observation of samples of different colors. Currently, scanning lenses are most commonly used in the laser engraving industry. In most cases, a parallel beam of one wavelength is simply passed through the scanning lens to form a circular dot-shaped spot, as described in Chinese invention patent application CN114029609A. However, when such scanning lenses are used in microscopic imaging systems, different wavelengths of light beams will converge at different focal points due to the dispersion of the glass, resulting in different axial chromatic aberrations. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a scanning lens for a microscopic imaging system that can correct multicolor aberrations, while simultaneously meeting the specific structural and dimensional requirements of the microscopic system.

[0004] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a scanning lens in a microscopic imaging system, comprising an aperture stop, a first lens with a negative focal length, a second lens with a positive focal length, a third lens with a positive focal length, and a fourth lens with a negative focal length. The entire system satisfies the following relationships: arctan(HI / EFL)≤11.8°, 2.2≤|F S1 / EFL|≤2.9, 1.9≤|F S2 / EFL|≤2.2,1.0≤|F S3 / EFL|≤1.3, 1.4≤|F S4 / EFL|≤1.7, the distance between the aperture stop and the first surface of the first lens is ≥0.65*EFL, and the distance between the aperture stop and the image plane is <3*EFL, where HI is the half-image height of the image plane, EFL represents the focal length of the entire scanning lens, and FS1 F is the focal length of the first lens. S2 F is the focal length of the second lens. S3 F is the focal length of the third lens. S4 Let be the focal length of the fourth lens.

[0005] Compared with the prior art, the advantages of the present invention are that, through a multi-lens structure with specific parameters, multiple chromatic aberrations are eliminated while achieving simultaneous multispectral scanning imaging, resulting in high imaging quality and low distortion; the structure is compact, and sufficient structural space can be reserved on the incident light side, allowing for a wide range of adjustment of the telecentricity of the edge field of view; the distance between the aperture and the first surface of the first lens is ≥0.65*EFL, which facilitates assembly.

[0006] One preferred embodiment consists of 6 lenses: the first lens is a meniscus lens L1, the second lens is a cemented lens composed of a negative lens L2 and a positive lens L3, the third lens is a positive lens L4, and the fourth lens is a cemented lens composed of a positive lens L6 and a negative lens L7.

[0007] Among them, the negative lens L2 has a concave image side, the positive lens L3 is a biconvex lens, the positive lens L4 is a biconvex lens, the positive lens L6 is a biconvex lens, and the negative lens L7 is a biconcave lens.

[0008] The second preferred embodiment consists of 7 lenses: the first lens is a meniscus lens L1; the second lens is a cemented lens composed of a negative lens L2 and a positive lens L3; the third lens is a combination lens composed of a positive lens L4 and a positive lens L5; and the fourth lens is a cemented lens composed of a positive lens L6 and a negative lens L7.

[0009] Among them, the negative lens L2 has a concave image side, the positive lens L3 is a biconvex lens, the positive lens L4 is a biconvex lens, the positive lens L5 is a meniscus lens, the positive lens L6 is a biconvex lens, and the negative lens L7 is a biconcave lens.

[0010] In the above scheme, the third lens can be composed of one or more lenses, as long as the combined focal length is positive. However, considering the cost, one or two lenses are generally selected.

[0011] Preferably, the first lens is flint glass with a high refractive index and a low dispersion coefficient, the positive lens of the second, third, and fourth lenses is crown glass with a low refractive index and a high dispersion coefficient, and the negative lens of the fourth lens is flint glass with a high refractive index and a low dispersion coefficient.

[0012] The entire scanning lens system uses only one meniscus lens, and all of them are made of glass spherical lenses, which makes them easier to process and reduces processing costs. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the position of the scanning lens in the entire microscopic imaging system. The rear end is connected to the tube lens of the microscopic imaging system. The tube lens is mainly of two types: F200 and F180. The rear end is matched with the objective lens to form the microscopic imaging system.

[0014] Figure 2 This is a schematic diagram of the scanning lens structure in the microscopic imaging system of the present invention. In the figure, it is divided into 6 parts from left to right: the leftmost aperture G, the first lens S1, the second lens S2, the third lens S3, the fourth lens S4, and the rightmost imaging surface I.

[0015] Figure 3 This is a schematic diagram of the scanning lens according to Embodiment 1 of the present invention;

[0016] Figure 4 This is a graph showing the focal offset of the scanning lens at different wavelengths according to Embodiment 1 of the present invention.

[0017] Figure 5 This is a distortion curve diagram of the scanning lens at different wavelengths according to Embodiment 1 of the present invention;

[0018] Figure 6 This is a schematic diagram of the scanning lens according to Embodiment 2 of the present invention;

[0019] Figure 7 This is a graph showing the focal offset of the scanning lens at different wavelengths in Embodiment 2 of the present invention.

[0020] Figure 8 The distortion curves of the scanning lens at different wavelengths in Embodiment 2 of the present invention are shown.

[0021] Figure 9 This is a schematic diagram of the scanning lens according to Embodiment 3 of the present invention;

[0022] Figure 10 This is a graph showing the focal offset of the scanning lens at different wavelengths in Embodiment 3 of the present invention.

[0023] Figure 11 This is a distortion curve diagram of the scanning lens at different wavelengths according to Embodiment 3 of the present invention. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] Example 1: Structure as follows Figure 3 As shown, the specific parameters are listed in the table below.

[0026]

[0027] In this embodiment, the first surface is the aperture stop surface G, and the last surface is the imaging surface I. Light rays converge from the aperture stop surface through the scanning lens onto the imaging surface. In this embodiment, the focal length of the scanning lens is EFL = 60.08 mm, the half-image height is HI = 12.5 mm, and the corrected wavelength range is 400 nm to 700 nm. arctan(HI / EFL) = arctan(12.5 mm / 60.08 mm) = 11.75°. The distance between the first surface of the first lens S1 and the last surface of the fourth lens S4 is 58.27 mm, and the distance between the aperture stop surface G and the image surface I is 152.68 mm. The focal length of the first lens S1 is: F... S1 = -171.67mm; Focal length of second lens S2: F S2 =125.84mm; Focal length of the third lens S3: F S3 =70.68mm; Focal length of the fourth lens S4: F S4 = -96.29mm. Figure 4 This shows the deviation range of the image plane position under different wavelengths in this embodiment, and it can be seen that the deviation is small. Figure 5 The distortion of this embodiment is shown at short wavelength 400nm and long wavelength 700nm, respectively, and it can be seen that the distortion is relatively small.

[0028] Example 2: Structure as follows Figure 6 As shown, the specific parameters are listed in the table below.

[0029]

[0030] In this embodiment, the first surface is the aperture stop surface G, and the last surface is the imaging surface I. Light rays converge from the aperture stop surface through the scanning lens onto the imaging surface. In this embodiment, the focal length of the scanning lens is EFL = 50.05mm, the half-image height is HI = 9mm, and the corrected wavelength range is 400nm~700nm; arctan(HI / EFL) = arctan(9mm / 50.05mm) = 10.2°; the distance between the first surface of the first lens S1 and the last surface of the fourth lens S4 is 48.54mm, and the distance between the aperture stop surface G and the image surface I is 127.18mm; the focal length of the first lens S1 is: F S1 = -143.00mm; Focal length of second lens S2: F S2 =104.82mm; Focal length of the third lens S3: F S3 = 58.88mm; Focal length of the fourth lens S4: F S4 = -80.21mm. Figure 7 This shows the deviation range of the image plane position under different wavelengths in this embodiment, and it can be seen that the deviation is small. Figure 8 The distortion of this embodiment is shown at short wavelength 400nm and long wavelength 700nm, respectively, and it can be seen that the distortion is relatively small.

[0031] Example 3: Structure as follows Figure 9 As shown, the specific parameters are listed in the table below.

[0032]

[0033] In this embodiment, the first surface is the aperture stop surface G, and the last surface is the imaging surface I. Light rays converge from the aperture stop surface through the scanning lens onto the imaging surface. The focal length of the scanning lens in this embodiment is EFL = 60.02 mm, the half-image height is HI = 12.5 mm, and the corrected wavelength range is 400 nm to 700 nm. arctan(HI / EFL) = arctan(12.5 mm / 60.02 mm) = 11.76°. The distance between the first surface of the first lens S1 and the last surface of the fourth lens S4 is 57.95 mm, and the distance between the aperture stop surface G and the image surface I is 153.14 mm. The focal length of the first lens S1 is: F... S1 = -138.31mm; Focal length of second lens S2: F S2 =126.93mm; Focal length of the third lens S3: F S3 = 67.175mm; Focal length of the fourth lens S4: F S4 = -99.32mm. Figure 10 This shows the deviation range of the image plane position under different wavelengths in this embodiment, and it can be seen that the deviation is small. Figure 11 The distortion of this embodiment is shown at short wavelength 400nm and long wavelength 700nm, respectively, and it can be seen that the distortion is relatively small.

Claims

1. A scanning lens in a microscopic imaging system, characterized in that... The system consists of an aperture stop, a first lens with a negative focal length, a second lens with a positive focal length, a third lens with a positive focal length, and a fourth lens with a negative focal length. The first lens is a meniscus lens L1, the second lens is a cemented lens composed of a negative lens L2 and a positive lens L3, the third lens is a positive lens L4, and the fourth lens is a cemented lens composed of a positive lens L6 and a negative lens L7. The entire system satisfies the following relationships: arctan(HI / EFL) ≤ 11.8°, 2.2 ≤ |F|. S1 / EFL|≤2.9, 1.9≤|F S2 / EFL|≤2.2, 1.0≤|F S3 / EFL|≤1.3, 1.4≤|F S4 / EFL|≤1.7, the distance between the aperture stop and the first surface of the first lens is ≥0.

65. EFL, the distance between the aperture and the image plane is <3 EFL, where HI is the half-image height of the image plane, EFL represents the focal length of the entire scanning lens, and F... S1 F is the focal length of the first lens. S2 F is the focal length of the second lens. S3 F is the focal length of the third lens. S4 Let be the focal length of the fourth lens.

2. The scanning lens in a microscopic imaging system as described in claim 1, characterized in that... The negative lens L2 has a concave image side, the positive lens L3 is a biconvex lens, the positive lens L4 is a biconvex lens, the positive lens L6 is a biconvex lens, and the negative lens L7 is a biconcave lens.

3. The scanning lens in a microscopic imaging system as described in claim 1, characterized in that... The first lens is a meniscus lens L1, the second lens is a cemented lens composed of a negative lens L2 and a positive lens L3, the third lens is a combination lens composed of a positive lens L4 and a positive lens L5, and the fourth lens is a cemented lens composed of a positive lens L6 and a negative lens L7.

4. The scanning lens in a microscopic imaging system as described in claim 3, characterized in that... The negative lens L2 is a plano-concave lens, the positive lens L3 is a biconvex lens, the positive lens L4 is a biconvex lens, the positive lens L5 is a meniscus lens, the positive lens L6 is a biconvex lens, and the negative lens L7 is a biconcave lens.

5. A scanning lens in a microscopic imaging system as described in claim 1 or 3, characterized in that... The first lens is flint glass with a high refractive index and a low dispersion coefficient. The positive lenses in the second, third, and fourth lenses are crown glass with a low refractive index and a high dispersion coefficient. The negative lens in the fourth lens is flint glass with a high refractive index and a low dispersion coefficient.

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