An adjustable tube-type laser light source angle expander

Abstract

The present invention discloses an adjustable barrel laser light source angle expander, comprising a barrel with internal threads, wherein a front fixed lens, a zoom lens and a rear fixed lens are sequentially arranged in the barrel, a zoom lens retaining ring is arranged on the zoom lens, and the zoom lens retaining ring is rotated so that the zoom lens retaining ring moves along the barrel internal threads, and an adapter is arranged at one end of the barrel. The advantages of the angle expander are that the beam divergence angle has a large adjustment range, the spot size is continuously adjustable and has good linearity, a compact structure, a small volume, and simple installation and adjustment.

Description

Technical Field

[0001] The invention relates to the field of laser active illumination imaging detection and laser illumination optics, and in particular to a manually adjustable lens barrel type laser light source angle expander. Summary of the invention

[0002] In recent years, underwater distance-gated laser active imaging detection technology has become a research hotspot in the field of computational imaging. The structure and working principle of the underwater distance-gated laser active imaging detection system are basically the same as those of laser radar. By adjusting the divergence angle of the emitted laser beam, the entire target or its key feature parts at a certain distance underwater are illuminated to achieve imaging detection of underwater targets. At present, the optical and mechanical design and manufacturing of laser zoom beam expanders are relatively mature. This technology is suitable for collimated light illumination. In order to change the laser spot size emitted by the imaging detection system to a certain distance, it is necessary to change the laser beam divergence angle. Usually, the purpose of adjusting the laser beam divergence angle can be achieved by adjusting the distance between the beam expander objective and the eyepiece. At present, the beam divergence angle adjustment range of laser zoom beam expanders on the market is generally small, and the system structure is complex, the adjustment process is complex, the adjustment efficiency is low, and the linearity of the spot size change is poor. Summary of the invention

[0004] Based on the above problems, this application provides a manually adjustable barrel-type laser light source expander for the 532nm pulsed laser light source of the laser underwater imaging detection system. The laser beam with a diameter of 10mm incident on the expander can be manually adjusted to change the size of the laser spot at 30m in the air to 300-3000mm. The expander has the advantages of a large adjustment range of the beam divergence angle, continuously adjustable spot size and good linearity, compact structure, small size, and simple installation and adjustment. Its technical solution is as follows:

[0005] An adjustable barrel-type laser light source angle expander comprises a barrel with an internal thread, wherein a front fixed lens, a zoom lens and a rear fixed lens are sequentially arranged in the barrel, a zoom lens retaining ring is provided on the zoom lens, and the zoom lens retaining ring moves along the internal thread of the barrel when the zoom lens retaining ring is rotated, and a converter is provided at one end of the barrel.

[0006] Furthermore, the front fixed lens is a concave lens, the front fixed lens is provided with a front lens retaining ring, the front lens retaining ring is provided with an external thread matching the internal thread of the lens barrel, and the front fixed lens retaining ring is located at the front end of the lens barrel; the rear fixed lens is a convex lens, the rear fixed lens is provided with a rear lens retaining ring, the rear lens retaining ring is provided with an external thread matching the internal thread of the lens barrel, and the rear fixed lens retaining ring is located at the rear end of the lens barrel.

[0007] Furthermore, the zoom lens is a concave lens, and the zoom lens retaining ring is provided with an external thread matching the internal thread of the lens barrel.

[0008] Furthermore, the lens barrel is provided with a groove, and the zoom lens retaining ring is rotated through the groove.

[0009] Furthermore, a scale is provided on the lens barrel.

[0010] Furthermore, a laser beam with a diameter of 10 mm passes through a front fixed lens, a zoom lens and a rear fixed lens in sequence, and the distance between the zoom lens and the front fixed lens is adjusted so that the size variation range of the laser spot diameter at 30 m in the air reaches 300-3000 mm.

[0011] Beneficial Effects

[0012] The angle expander has the advantages of a large adjustment range of the beam divergence angle, continuously adjustable spot size and good linearity, compact structure, small size, and simple installation and adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0014] Figure 1 It is a structural schematic diagram of the present invention.

[0015] Figure 2 It is a cross-sectional schematic diagram of the present invention, wherein 1-front fixed lens; 101-front lens retaining ring; 2-zoom lens; 201-zoom lens retaining ring; 3-rear fixed lens; 4-lens barrel; 5-adapter; 6-groove; 7-ruler; 8-laser beam.

[0016] Figure 3 The figure is a schematic diagram of a 10 mm laser beam after passing through the angle expander lens barrel. The concave surface of the front fixed lens is the first refractive surface, and the other side is the second refractive surface; the concave surface of the zoom lens is the third refractive surface, and the other side is the fourth refractive surface; the convex surface of the rear fixed lens is the fifth refractive surface, and the other side is the sixth refractive surface, where d1 is the distance from the second refractive surface to the third refractive surface in the coaxial optical system; d2 is the distance from the fourth refractive surface to the fifth refractive surface in the coaxial optical system.

[0017] Figure 4 Schematic diagram of an adapter with internal and external threads.

[0018] Figure 5 This is a schematic diagram of the coaxial optical system of the manually adjustable barrel-type laser light source angle expander of the present invention.

[0019] Among them, the symmetry axis of the PP′-coaxial system (i.e., the optical axis), the incident laser beam (aperture ) propagates along the axis of symmetry; after PQ (representing the semi-aperture of the incident light) in the object space passes through the angle expander of the present invention, an image P′Q′ is generated in the image space, where y and y′ represent the object height and image height, respectively, i.e., the semi-aperture size of the incident light beam (y=5mm) and the semi-aperture size of the outgoing light beam reaching the target object (y′=D / 2, the spot diameter at D-30m); l and l′ represent the system object distance and image distance, respectively; O1 and O m Respectively represent the center of the first refractive surface and the mth (m=6 in the present invention) refractive surface; n1 and n′ m Respectively represent the refractive index of the image space medium of the first refractive surface and the refractive index of the image space medium of the mth refractive surface; except for the lens material, the refractive index of the medium mentioned in the present invention is 1; u1 represents the incident angle of the incident light beam, and u1=0 for parallel light incident; -u′ m (in the present invention, m=6) represents the emission angle of the emitted light beam.

[0020] Figure 6 To adjust the distance d1 between the zoom lens and the front fixed lens, the linear fitting of the calculation results of the change of the spot diameter D at 30m in the air. DETAILED DESCRIPTION

[0021] The following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those of ordinary skill in the art to which the present application belongs. It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application.

[0022] like Figure 1 , Figure 2 and Figure 3 As shown, the manually adjustable lens barrel type laser light source angle expander of the present invention comprises a cylindrical lens barrel 4 with internal threads, in which a front fixed lens 1, a zoom lens 2 and a rear fixed lens 3 are installed; the laser beam is incident from the left end of the lens barrel 4 of the angle expander, and passes through the front fixed lens 1, the zoom lens 2 and the rear fixed lens 3 in sequence, wherein the front fixed lens 1 and the zoom lens 2 are both plano-concave lenses, and the rear fixed lens 3 is a plano-convex lens; the front fixed lens 1 is fixed to the left end of the lens barrel 4 by a front lens retaining ring 101, the rear fixed lens 3 is fixed to the right end of the lens barrel 4 by a rear lens retaining ring 301, and the zoom lens 2 is fixed between the front fixed lens 1 and the rear fixed lens 3 by a zoom lens retaining ring 201, and moves along the internal threads of the lens barrel 4; the front lens retaining ring 101, the zoom lens retaining ring 201 and the rear lens retaining ring 301 are all provided with external threads matching the internal threads of the lens barrel 4. A scale 7 is provided on the outer wall of the lens barrel 4.

[0023] Two symmetrical grooves 6 are designed along the axial direction on the lens barrel 4. By using these two symmetrical grooves 6, the zoom lens retaining rings 201 fixed at both ends of the zoom lens can be manually rotated to change the position of the zoom lens 2 to the left and right, change the divergence angle of the emitted light beam, and achieve the purpose of obtaining the desired spot size in the target light field at a certain distance; Figure 5 and Figure 6 As shown, the left end of the angle expander lens barrel is installed with an adapter 5 having internal and external threads through a threaded connection, and the angle expander can be directly installed on the laser light exit window through the adapter 5.

[0024] The optical system principle of the manually adjustable barrel-type laser light source angle expander of the present invention is as follows:

[0025] like Figure 3 As shown, the manually adjustable barrel laser light source angle expander optical system of the present invention adopts a "concave-concave-convex" three-lens structure, which is composed of two plano-concave lenses and one plano-convex lens to form a coaxial optical system with six refractive surfaces (3 spherical surfaces and 3 flat surfaces). The principle of the coaxial optical system is as follows Figure 5 As shown, Figure 5 The first refractive surface (concave spherical surface) and the sixth refractive surface (plane) of the coaxial optical system of the angle expander from left to right are drawn in the figure, and the other refractive surfaces in the middle are omitted; Figure 3 As shown, when the zoom lens 2 is manually adjusted to move left and right, the distance d1 between the second refractive surface and the third refractive surface and the distance d2 between the fourth refractive surface and the fifth refractive surface in the coaxial optical system change accordingly.

[0026] According to the relevant theories of physical optics, under the condition of paraxial approximation, if Figure 5 As shown, the object-image relationship of the coaxial optical system can be expressed as the following set of equations:

[0027] L′ Q′ =T Q′m ST 1Q L Q (1)

[0028] Among them, L Q — the state matrix of the incident ray QM1 passing through the object point Q,

[0029] L′ Q′ —Outgoing ray M passing through object point Q′ m The state matrix of Q′,

[0030] T 1Q —Translation matrix from point Q to point M1,

[0031] T Q′m —From Mm The translation matrix from point to point Q′,

[0032] S—Transfer matrix of the angle-expanding mirror system, S=R m T (m)(m-1) R m-1 ...R3T 32 R2T 21 R1 (m=6 in the present invention). m (m=1…6)—the refraction matrix of the mth refraction surface; T (m)(m-1) (m=1...6)—Translation matrix between the m-1th and mth refractive surfaces.

[0033] Among them, the translation matrix Translation Matrix

[0034] The technical parameters of the optical elements of the manually adjustable barrel-type laser light source angle expander system of the present invention are shown in Table 1. Figure 3 and Figure 5 As shown, in the coaxial optical system of the angle expander, after the distance between the front fixed lens and the rear fixed lens is determined, except when the zoom lens 2 is manually adjusted to move left and right, d1 and d2 are variable quantities (i.e., the translation matrix T 32 and the translation matrix T 54 is a variable), and the other parameters are constants. Based on the above principle, the relationship between the distance d1 between the zoom lens and the front fixed lens and the spot diameter D of the target light field at a certain distance can be solved using formula (1).

[0035] Table 1 Technical parameters of optical system components of manually adjustable tube-type laser light source angle expander

[0036]

[0037] The specific design requirements of a manually adjustable barrel-type laser light source angle expander invented in this invention are as follows:

[0038] Light source characteristics of the angle expander: laser center wavelength: 532nm; laser beam aperture: 10mm; laser beam divergence angle: 1mrad;

[0039] The technical indicators to be achieved by the designed angle expander are: 30m in the air (l ′ =30m) The spot diameter ranges from 300 to 3000mm.

[0040] According to the principle of the manually adjustable barrel laser light source angle expander optical system of the present invention, according to the technical indicators to be achieved by the designed angle expander, the distance from the first refractive surface to the sixth refractive surface of the angle expander coaxial system is set to 71.3 mm, and the distance between the zoom lens 2 and the front fixed lens 1 is adjusted. The calculation results of the change of the spot diameter at 30 m in the air and the linear fitting results are shown in Tables 2 and 3 respectively. Figure 6 shown.

[0041] Table 2 Changes in the spot diameter D at 30m in the air by adjusting the distance d1 between the zoom lens and the front fixed lens

[0042]

[0043] The manually adjustable lens barrel type laser light source angle expander of the present invention is as follows: Figure 2 and Figure 3 As shown in FIG. 1 , by moving the zoom lens 2 left and right along the optical axis, the divergence angle of the outgoing light beam is changed, and the spot size variation range of the target light field at 30m in the air is 300 to 3000mm, and the spot size can be changed from 1 to 3000mm. Figure 6 It can be seen that the change of the spot size has good linearity.

[0044] When the incident laser beam aperture or irradiation distance (i.e., the system object distance l ′ ), the spot size obtained in the target light field changes accordingly; if the incident laser beam aperture or irradiation distance increases, the spot size of the target light field also increases accordingly, otherwise it decreases.

[0045] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An adjustable barrel-type laser light source angle expander, characterized in that: The lens barrel comprises a lens barrel with an internal thread, wherein a front fixed lens, a zoom lens and a rear fixed lens are sequentially arranged in the lens barrel, the zoom lens is provided with a zoom lens retaining ring, and the zoom lens retaining ring moves along the internal thread of the lens barrel when the zoom lens retaining ring is rotated, and an adapter is provided at one end of the lens barrel; the front fixed lens is a concave lens, the front fixed lens is provided with a front lens retaining ring, the front lens retaining ring is provided with an external thread matching the internal thread of the lens barrel, and the front fixed lens retaining ring is located at the front end of the lens barrel; the rear fixed lens is a convex lens, the rear fixed lens is provided with a rear lens retaining ring, the rear lens retaining ring is provided with an external thread matching the internal thread of the lens barrel, and the rear fixed lens retaining ring is located at the rear of the lens barrel; The front fixed lens, zoom lens and rear fixed lens adopt a "concave-concave-convex" three-lens structure, which consists of two plano-concave lenses and one plano-convex lens to form a coaxial optical system with six refractive surfaces; The focal length, curvature radius and rear focal length of the front fixed lens, the rear fixed lens and the zoom lens include:

2. The adjustable barrel-type laser light source angle expander according to claim 1, characterized in that: The zoom lens is a concave lens, and the zoom lens clamping ring is provided with an external thread matching the internal thread of the lens barrel.

3. The adjustable barrel-type laser light source angle expander according to claim 1, characterized in that: The lens barrel is provided with a groove, and the zoom lens clamping ring is rotated through the groove.

4. The adjustable lens barrel type laser light source angle expander according to claim 1, characterized in that: A scale is arranged on the lens barrel.

5. The adjustable barrel-type laser light source angle expander according to claim 1, characterized in that: A laser beam with a diameter of 10 mm passes through the front fixed lens, the zoom lens and the rear fixed lens in sequence. The distance between the zoom lens and the front fixed lens is adjusted so that the size of the laser spot aperture at 30 m in the air can vary from 300 to 3000 mm.

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