CN113741013B

CN113741013B - Telescope lens of visible light imaging spectrometer

Info

Publication number: CN113741013B
Application number: CN202111090302.9A
Authority: CN
Inventors: 陈建军
Original assignee: Qingdao University of Technology
Current assignee: Qingdao University of Technology
Priority date: 2021-09-17
Filing date: 2021-09-17
Publication date: 2022-07-05
Anticipated expiration: 2041-09-17
Also published as: CN113741013A

Abstract

The invention provides a telescope lens of a visible light imaging spectrometer, which comprises 5 optical lenses, wherein the optical lenses are respectively positive, negative, positive and negative focal powers in sequence along the incident direction of light; the focal length of the lens is 11mm, the F number is 1.8, the lens works in a visible light wave band, the wavelength range is 400 nm-700 nm, the field angle is 18 degrees, and the total optical length of the system is 16.8 mm; the visible light lens is designed into an image space telecentric light path structure, can be used as a telescope lens of a visible light imaging spectrometer, and can also be independently used as a visible light imaging lens; the aspheric surface technology is adopted in the design process of the lens, two aspheric lenses are adopted in 5 lenses, all aberrations are corrected in the optimization process, and the lens has the advantages of excellent image quality, large relative aperture, miniaturization, light weight and the like.

Description

Telescope lens of visible light imaging spectrometer

Technical Field

The invention relates to the technical field of optical design, in particular to a telescope lens of a visible light imaging spectrometer.

Background

The visible light imaging spectrometer is widely applied to spectral instruments and has important application in agriculture and forestry, geological survey, hydrological monitoring, disaster investigation and the like. In recent years, rapid development of airborne equipment is promoted along with continuous maturity of unmanned aerial vehicle technology. The volume and the weight are important measurement indexes of the airborne visible light imaging spectrometer, and the airborne visible light imaging spectrometer is required to be miniaturized and lightened for longer-time cruising. The imaging spectrometer mainly comprises a telescopic lens and a light splitting system, wherein the telescopic lens is mainly used for imaging a target, and the light splitting system is mainly used for separating slit images with different wavelengths, so that the visible telescopic system determines the imaging quality of the imaging spectrometer, and the design of the telescopic lens is very important.

In order to ensure good matching between the telescopic system and the light splitting system, the telescopic system is required to have an image-side telecentric light path structure, that is, the chief rays of all the fields of view need to be vertically incident on the slits. Since the telescopic lens determines the imaging quality of the whole imaging spectrometer, the telescopic system needs to be designed as an independent optical system to correct all kinds of aberrations so as to ensure good imaging quality. Meanwhile, in order to meet the use requirements of the unmanned aerial vehicle, the telescopic lens needs to have the characteristics of miniaturization and light weight. Therefore, the design of the telescope lens of the unmanned aerial vehicle-mounted imaging spectrometer has certain technical difficulty.

In order to overcome the defects, a novel telescope lens of the visible light imaging spectrometer is designed.

Disclosure of Invention

In view of this, an embodiment of the present invention provides a telescope lens for a visible light imaging spectrometer, where the telescope lens can be used as a visible light imaging lens alone or as a telescope lens for a visible light imaging spectrometer. The lens is designed into an image space telecentric optical path structure, can be well matched with a light splitting system, meets the technical requirements of a telescopic lens of an imaging spectrometer, adopts an aspheric surface technology to simplify the optical path structure, realizes the miniaturization and the light weight of the lens, simultaneously guarantees the good correction of chromatic aberration through reasonably matching optical materials, and finally has the advantages of excellent image quality, large relative aperture, miniaturization, light weight and the like.

The embodiment of the invention provides a telescope lens of a visible light imaging spectrometer, which comprises a first positive lens, a first negative lens, a second positive lens, a second negative lens and a third positive lens which are coaxially arranged in sequence along the incident direction of light rays, wherein the first positive lens is made of HZBAF16, the clear aperture is smaller than 8mm when the diameter is 7mm, and the thickness is smaller than 3mm when the diameter is 2 mm; the first negative lens is made of HF51, the light transmission aperture is 6mm <7mm, and the thickness is 1mm <2 mm; the second positive lens is made of HLAF3B, 5mm < light-passing aperture <6mm, 2mm < thickness <3 mm; the second negative lens is made of HZF3, the light-passing aperture is 4mm <5mm, and the thickness is 2mm <3 mm; the third positive lens is made of HLAF4, 4mm < light-passing aperture <5mm, and 2mm < thickness <3 mm. The 5 optical materials are selected from Chengdu Guangming glass storehouses, and are all single-price and very cheap optical glass.

Optionally, the clear aperture of the first positive lens is 7.2mm, and the thickness of the first positive lens is 2.80 mm; the clear aperture of the first negative lens is 6.0mm, and the thickness of the first negative lens is 1.04 mm; the light-transmitting aperture of the second positive lens is 5.4mm, and the thickness of the second positive lens is 2.80 mm; the clear aperture of the second negative lens is 4.8mm, and the thickness of the second negative lens is 2.00 mm; the light-transmitting aperture of the third positive lens is 4.6mm, and the thickness of the third positive lens is 2.00 mm.

Optionally, the second positive lens and the second negative lens constitute one cemented lens.

Optionally, the distance between the center of the light exit surface of the third positive lens and the image surface is 1.2 mm.

Optionally, the external dimension of the telescope lens of the visible light imaging spectrometer is 7.2 × 16.8 mm.

Optionally, the focal length of an optical system of the telescope lens of the visible light imaging spectrometer is 11mm, and the F number is 1.8.

Optionally, the spectral range of the telescope lens of the visible light imaging spectrometer is 400 nm-700 nm.

Optionally, the visible light imaging spectrometer has a full field of view of 18 ° of the telephoto lens.

According to the technical scheme, the embodiment of the invention has the following advantages:

1. the working spectral range of the telescopic lens of the visible light imaging spectrometer is 400 nm-700 nm, the telescopic lens has an image space telecentric optical path structure, the technical requirements of the imaging spectrometer on the telescopic lens are matched, the telescopic lens can be perfectly butted with a light splitting system, the focal length of the telescopic lens is 11mm, the F number of the telescopic lens is 1.8, and the lens has super-strong light collecting capacity.

2. The optical path structure of an optical system is simplified by adopting an aspheric surface technology, a final system comprises 5 lenses, wherein 2 lenses are aspheric surfaces, 3 lenses are spherical surfaces, the total length of the system is only 16.8mm, the optical aperture is 7.2mm, and the lens has the advantages of obvious miniaturization and light weight.

Drawings

FIG. 1 is a diagram of an optical path structure of a telescope lens of a visible light imaging spectrometer according to the present invention;

FIG. 2 is a point diagram of a telescope lens of the visible light imaging spectrometer of the present invention;

FIG. 3 is an optical modulation transfer function of a telescope lens of the visible light imaging spectrometer according to the present invention;

reference numerals: 1-a first positive lens; 2-a first negative lens; 3-a second positive lens; 4-a second negative lens; 5-third positive lens.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be described below in a clear and complete manner with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

Referring to fig. 1, which is a diagram of an optical path structure of the present invention, the telescope lens of the visible light imaging spectrometer includes 5 lenses, the 5 lenses are arranged in a positive-negative positive mode, and 2 lenses are aspheric surfaces, which is beneficial to simplifying the optical path structure, ensures the advantages of miniaturization and light weight of the lens, and improves the imaging quality of the lens. The 5 lenses comprise a first positive lens 1, a first negative lens 2, a second positive lens 3, a second negative lens 4 and a third positive lens 5 which are coaxially arranged in sequence along the incident direction of light rays, wherein the first positive lens 1 is made of HZBAF16, the light transmission caliber is 7mm and is less than 8mm, and the thickness is 2mm and is less than 3 mm; the material of the first negative lens 2 is HF51, 6mm < light-passing aperture <7mm, 1mm < thickness <2 mm; the second positive lens 3 is made of HLAF3B, 5mm < light-passing aperture <6mm, 2mm < thickness <3 mm; the material of the second negative lens 4 is HZF3, 4mm < the light-passing aperture <5mm, 2mm < the thickness <3 mm; the third positive lens 5 material is HLAF4, 4mm < clear aperture <5mm, 2mm < thickness <3 mm.

In one embodiment, the clear aperture of the first positive lens 1 is 7.2mm, and the thickness is 2.80 mm; the light transmission aperture of the first negative lens 2 is 6.0mm, and the thickness is 1.04 mm; the light transmission aperture of the second positive lens 3 is 5.4mm, and the thickness is 2.80 mm; the clear aperture of the second negative lens 4 is 4.8mm, and the thickness is 2.00 mm; the light transmission aperture of the third positive lens 5 is 4.6mm, and the thickness is 2.00 mm; therefore, the system focal length of the telescope lens of the visible light imaging spectrometer is 11mm, the F number is 1.8, the full field angle is 18 degrees, the overall dimension is phi 7.2 multiplied by 16.8mm, and the telescope lens has the advantages of excellent image quality, large relative aperture, miniaturization, light weight and the like.

In one embodiment, the second positive lens and the second negative lens form a cemented lens, and the optical material matching of the two lenses ensures that the chromatic aberration of the optical system is well corrected.

In one embodiment, the spectral range of the telescope lens of the visible light imaging spectrometer is 400 nm-700 nm, and 5 optical materials are selected from a Chengdu Guangming glass library and are all optical glass with very low unit price.

The embodiment of the invention is designed into an image space telecentric light path structure, and the chief rays of each field of view of the telescope lens of the visible light imaging spectrometer are vertically incident to the image plane, so that the chief rays are well matched with the light splitting system, and the technical requirements of the telescope lens of the imaging spectrometer are completely met.

Referring to fig. 2, which is a dot-sequence diagram of the telescope lens of the visible light imaging spectrometer of the present invention, it can be seen from the figure that the diffuse speckle RMS corresponding to each field angle is substantially less than 6.5 μm, indicating that the lens has good imaging quality.

Please refer to fig. 3, which shows that the MTF of each field is substantially higher than 0.2 in the spatial frequency range within 200cycles/mm for the optical modulation transfer function MTF of the telephoto lens of the visible light imaging spectrometer of the present invention, which meets the design requirement of the optical lens.

The lens data of the telephoto lens of the visible light imaging spectrometer are shown below. Table 1 shows relevant optical parameters of respective lenses in the optical lens.

TABLE 1

The aspheric surface type adopted in the embodiment of the invention represents a formula:

wherein z is the rise from the aspheric surface vertex when the aspheric surface is at the position with the radius of r along the optical axis direction; c is the paraxial curvature of the aspheric surface, and k is the cone coefficient;A _iis the correction coefficient of the ith order of the aspheric surface.

Table 2 shows the coefficients of the respective aspherical high-order terms in the present embodiment.

TABLE 2

S3

2.29E-03

-2.35E-04

-9.29E-07

2.11E-06

-6.83E-08

-1.50E-08

9.76E-10

S4

7.35E-03

-6.35E-04

1.08E-04

-1.96E-05

1.91E-06

1.88E-07

-3.57E-08

S9

1.08E-03

-6.80E-04

3.55E-04

-3.39E-05

-7.99E-06

1.37E-06

-5.16E-08

S10

-1.84E-02

3.44E-03

9.09E-05

-1.03E-04

-8.38E-07

2.25E-06

-1.60E-07

The telescope lens of the visible light imaging spectrometer has the focal length of 11mm, the F number of 1.8, the working waveband of visible light, the wavelength range of 400-700 nm, the field angle of 18 degrees and the total optical length of 16.8 mm; the lens is designed into an image space telecentric structure, can be used as a telescopic lens of a visible light imaging spectrometer, and can also be used as a visible light lens for independent use; the lens adopts the aspheric surface technology in the design, all kinds of aberrations are corrected, and the lens has the advantages of excellent image quality, large relative aperture, miniaturization, light weight and the like.

The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A telescope lens of visible light imaging spectrometer, its characterized in that: the lens is composed of a first positive lens, a first negative lens, a second positive lens, a second negative lens and a third positive lens which are coaxially arranged in sequence along the incident direction of light;

the material of the first positive lens is HZBAF16, 7mm < the clear aperture <8mm, 2mm < the thickness <3 mm;

the first negative lens is made of HF51, the light transmission aperture is 6mm <7mm, and the thickness is 1mm <2 mm;

the second positive lens is made of HLAF3B, 5mm < light-passing aperture <6mm, 2mm < thickness <3 mm;

the second negative lens is made of HZF3, the light-passing aperture is 4mm <5mm, and the thickness is 2mm <3 mm;

the third positive lens is made of HLAF4, 4mm < light-passing aperture <5mm, and 2mm < thickness <3 mm.

2. The visible light imaging spectrometer telescope lens of claim 1, wherein:

the light-transmitting aperture of the first positive lens is 7.2mm, and the thickness of the first positive lens is 2.80 mm;

the clear aperture of the first negative lens is 6.0mm, and the thickness of the first negative lens is 1.04 mm;

the light-transmitting aperture of the second positive lens is 5.4mm, and the thickness of the second positive lens is 2.80 mm;

the clear aperture of the second negative lens is 4.8mm, and the thickness of the second negative lens is 2.00 mm;

the light-transmitting aperture of the third positive lens is 4.6mm, and the thickness of the third positive lens is 2.00 mm.

3. The visible light imaging spectrometer telescope lens of claim 1, wherein: the second positive lens and the second negative lens constitute a cemented lens.

4. The visible light imaging spectrometer telescope lens of claim 1, wherein: and the distance between the center of the light emergent surface of the third positive lens and the image surface is 1.2 mm.

5. The visible light imaging spectrometer telescope lens of claim 1, wherein: the external dimension of the telescope lens of the visible light imaging spectrometer is phi 7.2 multiplied by 16.8 mm.

6. The visible light imaging spectrometer telescope lens of claim 1, wherein: the focal length of an optical system of the telescope lens of the visible light imaging spectrometer is 11mm, and the F number is 1.8.

7. The visible light imaging spectrometer telescope lens of claim 1, wherein: the spectral range of the telescope lens of the visible light imaging spectrometer is 400 nm-700 nm.

8. The visible light imaging spectrometer telescopic lens of claim 1, wherein: the full field of view of the telescope lens of the visible light imaging spectrometer is 18 degrees.