A short-distance detection short-wave infrared telescope

Abstract

The present invention discloses a short-wave infrared telescope for short-distance detection, which is a coaxial transmissive optical system with a working wavelength range of 1000nm to 2500nm. It includes a window glass and eight spherical lenses. Along the light incident direction, they are successively the first plane window plate, the second negative meniscus lens, the third positive meniscus lens, the fourth positive meniscus lens, the aperture stop, the fifth positive biconvex lens, the sixth negative meniscus lens, the seventh positive biconvex lens, the eighth negative biconvex lens, and the ninth positive biconvex lens. The present invention is applicable to the short-wave infrared band of 1000nm to 2500nm; applicable to short detection distances of 1050mm to 1500mm; has a large viewing angle and a small system volume; the image-space telecentric system makes the image plane illumination uniform and is easy to be spliced with the spectrometer splitting system; within the range of -10°C to 40°C, the imaging quality is close to the diffraction limit; the processing and manufacturing costs are low; the energy utilization rate is high, the light-gathering ability is strong, and the thermal adaptability is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of optics, and particularly relates to a short-distance detection short-wave infrared telescope. Background Art

[0002] With the development of technology, infrared systems are widely used in civilian, military, and national defense fields. Short-wave infrared refers to the infrared band with a wavelength range of 1000nm - 2500nm. It can provide information that cannot be carried by visible light, low-light night vision, mid-wave, and long-wave infrared, making the presentation of details more prominent. It can be widely used in industrial multispectral imaging analysis, resource remote sensing, infrared astronomy, transportation, medical treatment, public security, and other fields.

[0003] Currently, most domestic infrared lenses use aspherical surfaces, with relatively complex structures and systems. The system has a large volume, high weight, and poor thermal stability. Therefore, it is particularly important to develop a telescopic lens suitable for a short-wave infrared spectrometer system. Summary of the Invention

[0004] In view of the deficiencies of the existing technology, the present invention provides an anastigmatic image-space telecentric lens for short-distance detection, with high imaging quality, good thermal stability, small volume, applicable to a spectrometer system, and operating in the short-wave infrared band.

[0005] To achieve the above object, the present invention provides a short-distance detection short-wave infrared telescope. The telescope is a transmissive optical system; the structure of the optical system is a coaxial structure; all lenses of the telescope are spherical surfaces; along the light incident direction, there are successively a first plane window, a second negative meniscus lens, a third positive meniscus lens, a fourth positive meniscus lens, an aperture stop, a fifth positive double convex lens, a sixth negative meniscus lens, a seventh positive double convex lens, an eighth negative double convex lens, and a ninth positive double convex lens; the chief ray in the image space is parallel to the optical axis and perpendicularly incident on the image plane; along the light incident direction, the focal lengths of the respective lenses correspond to f1, f2, f3, f4, f6, f7, f8, f9, f 10 , and their normalized values relative to the telescope focal length f are respectively f’1 = 0, -2.5 ≤ f’2 ≤ -1.5, 7 ≤ f’3 ≤ 8, 7 ≤ f’4 ≤ 8, 0.5 ≤ f’6 ≤ 1.5, -4.0 ≤ f’7 ≤ -3.0, 0.4 ≤ f’8 ≤ 1, -0.8 ≤ f’9 ≤ -0.2, 0.3 ≤ f’ 10 ≤ 1.

[0006] Furthermore, the lens materials of the telescope include any three of chalcogenide glass, quartz series, and fluorides.

[0007] Furthermore, along the light incident direction, the refractive indices of the respective lenses correspond to n1, n2, n3, n4, n6, n7, n8, n9, n 10, the corresponding value ranges are 1.5 ≤ n1 ≤ 2.0, 2.0 ≤ n2 ≤ 3.0, 2.0 ≤ n3 ≤ 3.0, 2.0 ≤ n4 ≤ 3.0, 1.2 ≤ n6 ≤ 1.7, 1.2 ≤ n7 ≤ 1.7, 2.0 ≤ n8 ≤ 3.0, 2.0 ≤ n9 ≤ 3.0, 2.0 ≤ n 10 ≤ 3.0.

[0008] Furthermore, the working wavelength band of the telescope is 1000nm - 2500nm, the working temperature range is -10°C - 40°C, and the applicable detection distance range is 1050mm - 1500mm.

[0009] Furthermore, the maximum field of view angle of the telescope is 35.6°.

[0010] Furthermore, the maximum relative aperture of the telescope is F / 3.0.

[0011] Furthermore, the maximum focal length of the lens in the telescope is 15mm.

[0012] Furthermore, the telescope is applicable to a detector resolution of 640×512 and a pixel size of 30μm×30μm.

[0013] Furthermore, the telescope is small in size, with a total system length of 62mm, the maximum aperture of the lens in the system is less than 14.50mm, and the maximum aperture of the first planar window is less than 15.0mm.

[0014] Furthermore, the telescope has an image-space telecentric characteristic.

[0015] Compared with the prior art, the advantages of the present invention are as follows: The telescope provided by the present invention is applicable to the wavelength band of 1000nm - 2500nm, the applicable temperature range is -10°C - 40°C, the applicable distance range is 1050mm - 1500mm, and it has an image-space telecentric property, making it relatively easy to be combined with a spectroscopic system to form a spectrometer system. The system is small in size and low in weight, with a total length of 62mm; in the full wavelength band and at temperatures from -10°C to 40°C, MTF > 0.85 @ 16.7lp / mm, the radius of the blur spot is less than the radius of the Airy disk, and the image quality is close to the optical diffraction limit; it can be applied to fields such as non-destructive testing, industrial multispectral imaging analysis, resource remote sensing, and infrared astronomy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of the short-distance detection short-wave infrared telescope provided in Embodiment 1 of the present invention;

[0017] Figure 2 is a modulation transfer function curve diagram (cut-off frequency 16.7lp / mm) of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1050mm and -10°C;

[0018] Figure 3 The modulation transfer function curve diagram (cut-off frequency 16.7 lp / mm) of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1500 mm and -10°C;

[0019] Figure 4 The modulation transfer function curve diagram (cut-off frequency 16.7 lp / mm) of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1050 mm and 20°C;

[0020] Figure 5 The modulation transfer function curve diagram (cut-off frequency 16.7 lp / mm) of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1500 mm and 20°C;

[0021] Figure 6 The modulation transfer function curve diagram (cut-off frequency 16.7 lp / mm) of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1050 mm and 40°C;

[0022] Figure 7 The modulation transfer function curve diagram (cut-off frequency 16.7 lp / mm) of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1500 mm and 40°C;

[0023] Figure 8 The spot diagram of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1050 mm and -10°C;

[0024] Figure 9 The spot diagram of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1500 mm and -10°C;

[0025] Figure 10 The spot diagram of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1050 mm and 20°C;

[0026] Figure 11 The spot diagram of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1500 mm and 20°C;

[0027] Figure 12 The spot diagram of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1050 mm and 40°C;

[0028] Figure 13 The spot diagram of the telescope provided in Embodiment 1 of the present invention at a detection distance of 1500 mm and 40°C;

[0029] Figure 14 The field curvature and distortion diagram of the telescope provided in Embodiment 1 of the present invention;

[0030] Figure 15 This is the relative illuminance diagram of the telescope provided in Embodiment 1 of the present invention. Detailed implementation manners

[0031] The present invention will be further described below with reference to the drawings and through specific embodiments.

[0032] Embodiment 1

[0033] This embodiment provides athermalized image-space telecentric telescope in the short-wave infrared band. The telescope is a transmissive optical system with a coaxial structure. It operates in the short-wave infrared band of 1000nm - 2500nm, has a detection distance of 1050mm - 1500mm, an operating temperature range of -10°C to 40°C, a focal length of 15mm, an F / # of 3.0, a full field of view of 35.6°, is applicable to a detector resolution of 640×512, and a pixel size of 30μm.

[0034] Refer to the attached Figure 1 It is a schematic diagram of the short-wave infrared telescope provided in this embodiment. The telescope is a transmissive optical system; the structure of the optical system is a coaxial structure; all the lenses of the telescope are spherical surfaces; along the light incident direction, there are successively a first planar window plate 1, a second negative meniscus lens 2, a third positive meniscus lens 3, a fourth positive meniscus lens 4, an aperture stop 5, a fifth positive double convex lens 6, a sixth negative meniscus lens 7, a seventh positive double convex lens 8, an eighth negative double convex lens 9, a ninth positive double convex lens 10, and an image plane 11. The chief ray in the image space is parallel to the optical axis and perpendicularly incident on the image plane; along the light incident direction, the focal lengths of the respective lenses correspond to f1, f2, f3, f4, f6, f7, f8, f9, f 10 Their normalized values relative to the telescope focal length f are respectively f’1 = 0, -2.5 ≤ f’2 ≤ -1.5, 7 ≤ f’3 ≤ 8, 7 ≤ f’4 ≤ 8, 0.5 ≤ f’6 ≤ 1.5, -4.0 ≤ f’7 ≤ -3.0, 0.4 ≤ f’8 ≤ 1, -0.8 ≤ f’9 ≤ -0.2, 0.3 ≤ f’ 10 ≤ 1. The refractive indices of the respective lenses correspond to n1, n2, n3, n4, n6, n7, n8, n9, n 10 The corresponding value ranges are respectively 1.5 ≤ n1 ≤ 2.0, 2.0 ≤ n2 ≤ 3.0, 2.0 ≤ n3 ≤ 3.0, 2.0 ≤ n4 ≤ 3.0, 1.2 ≤ n6 ≤ 1.7, 1.2 ≤ n7 ≤ 1.7, 2.0 ≤ n8 ≤ 3.0, 2.0 ≤ n9 ≤ 3.0, 2.0 ≤ n 10 ≤ 3.0.

[0035] Preferably, the maximum aperture of the lens is less than 14.50 mm, the maximum aperture of the first planar window sheet 1 is less than 19 mm, and the maximum focal length of the lens is 15 mm. More preferably, the lens material of the telescope includes any three of chalcogenide glass, quartz series, and fluorides.

[0036] Using the theory of thermal aberration correction and chromatic aberration correction, infrared optical glass materials with higher transmittance are selected, so that the imaging quality is close to the optical diffraction limit within a certain temperature range.

[0037] The telescope is small in size, and the total system length is 62 mm; the maximum aperture of the lens in the telescope is less than 14.50 mm, and the maximum aperture of the first planar window sheet 1 is less than 19 mm.

[0038] The diaphragm is placed on the front focal plane of the rear group of lenses, so that the telescope has the characteristic of image space telecentricity, that is, the image space rays are perpendicular to the image plane, which can ensure uniform illuminance on the image plane. At the same time, the image space telecentric optical path is relatively easy to be spliced with the spectroscopic system to form a new spectrometer system.

[0039] The first piece of the telescope is the window protection glass, which is selected according to the actual situation. There is enough space between the rear surface of the last lens of the telescope and the image plane for placing the detector. All the lenses adopt spherical surfaces, and the system is concentric and coaxial, which reduces the processing and manufacturing costs and the detection difficulty, and is easy to assemble and adjust.

[0040] For each lens of the short-wave infrared telescope for short-distance detection, this embodiment provides a preferred solution. The specific data and the materials used are shown in Table 1.

[0041] Table 1 Optical structure parameters of the lens

[0042]

[0043]

[0044] See Appendix Figures 2 - 7 , for the optical system of this embodiment at -10 °C, 20 °C, and 40 °C, the modulation transfer function (MTF) curve, the detector pixel size is 30 μm × 30 μm, and at the Nyquist frequency of 16.7 lp / mm, the MTF of the system remains stable at different temperatures and is greater than 0.85, and the imaging quality is close to the optical diffraction limit.

[0045] See Appendix Figures 8 - 13 , for the optical system of this embodiment at -10 °C, 20 °C, and 40 °C, the spot diagram on the image plane is obtained by ray tracing. The circles in the figure represent the system diffraction Airy disk. The energy of the spot diagram at each field of view is concentrated within the Airy disk range, and it has good imaging quality.

[0046] See Appendix Figure 14, the field curvature distortion diagram of the optical system in this embodiment, the distortion is less than 1.32%, and the image will not be distorted.

[0047] See the appendix Figure 15 , the relative illuminance curve diagram of the optical system in this embodiment. It can be seen that the relative illuminance on the image plane is uniform, and the relative illuminance value in the edge field of view is close to 1.

[0048] As can be seen from the above, the short-distance detection short-wave infrared telescope provided by the present invention has good imaging quality within the detection distance range of 1050 mm to 1500 mm at -10°C to 40°C; at the same time, it is small in size and convenient for application. Coupled with the image-side telecentric characteristic, it is easy to be spliced with other systems to form a new system.

[0049] Finally, it should be noted that: the above embodiments are only used to illustrate the present invention patent and do not limit the technical solutions described in the present invention patent. Therefore, although this specification has described the present invention in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified; and all technical solutions and their improvements that do not depart from the scope of the present invention should be covered by the scope of the claims of the present invention.

Claims

1. A short-distance detection short-wave infrared telescope, characterized in that: The telescope is a transmissive optical system; the structure of the optical system is a coaxial structure; all the lenses of the telescope are spherical surfaces; along the light incident direction, there are successively a first planar window plate (1), a second negative meniscus lens (2), a third positive meniscus lens (3), a fourth positive meniscus lens (4), an aperture stop (5), a fifth positive biconvex lens (6), a sixth negative meniscus lens (7), a seventh positive biconvex lens (8), an eighth negative biconvex lens (9), and a ninth positive biconvex lens (10); the chief ray in the image space is parallel to the optical axis and perpendicularly incident on the image plane; along the light incident direction, the focal lengths of the respective lenses correspond to f1, f2, f3, f4, f6, f7, f8, f9, f 10 , and their normalized values relative to the telescope focal length f correspond to f’1 = 0, -2.5 ≤ f’2 ≤ -1.5, 7 ≤ f’3 ≤ 8, 7 ≤ f’4 ≤ 8, 0.5 ≤ f’6 ≤ 1.5, -4.0 ≤ f’7 ≤ -3.0, 0.4 ≤ f’8 ≤ 1, -0.8 ≤ f’9 ≤ -0.2, 0.3 ≤ f’ 10 ≤ 1; the first planar window plate (1) is made of sapphire, the second negative meniscus lens (2), the third positive meniscus lens (3), the fourth positive meniscus lens (4), the seventh positive biconvex lens (8), the eighth negative biconvex lens (9), and the ninth positive biconvex lens (10) are made of chalcogenide glass, the fifth positive biconvex lens (6) is made of fluoride, and the sixth negative meniscus lens (7) is made of quartz; along the light incident direction, the refractive indices of the respective lenses correspond to n1, n2, n3, n4, n6, n7, n8, n9, n 10 , and the corresponding value ranges are respectively 1.5 ≤ n1 ≤ 2.0, 2.0 ≤ n2 ≤ 3.0, 2.0 ≤ n3 ≤ 3.0, 2.0 ≤ n4 ≤ 3.0, 1.2 ≤ n6 ≤ 1.7, 1.2 ≤ n7 ≤ 1.7, 2.0 ≤ n8 ≤ 3.0, 2.0 ≤ n9 ≤ 3.0, 2.0 ≤ n 10 ≤ 3.

0.

2. The short-distance detection short-wave infrared telescope according to claim 1, wherein: The working wavelength band of the telescope is 1000nm to 2500nm, the working temperature range is -10°C to 40°C, and the applicable detection distance range is 1050mm to 1500mm.

3. The short-range detection short-wave infrared telescope according to claim 1, characterized in that: The maximum field of view angle of the telescope is 35.6°.

4. A short-distance detection short-wave infrared telescope according to claim 1, characterized in that: The maximum relative aperture of the telescope is F / 3.

0.

5. A short-distance detection short-wave infrared telescope according to claim 1, characterized in that: The maximum focal length of the lens in the telescope is 15mm.

6. The short-range detection short-wave infrared telescope according to claim 1, characterized in that: The telescope is applicable to a detector resolution of 640×512 and a pixel size of 30μm×30μm.

7. The short-distance detection short-wave infrared telescope according to claim 1, wherein: The total length of the telescope system is 62mm; the maximum aperture of the lens in the telescope is less than 14.50mm, and the maximum aperture of the first planar window sheet (1) is less than 19mm.

8. The short-distance detection short-wave infrared telescope according to claim 1, characterized in that: The telescope has the property of image-space telecentricity.

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