Parallel light source with adjustable light spot diameter

Abstract

The utility model discloses a parallel light source with an adjustable light spot diameter. The parallel light source comprises a mechanical aperture assembly and a doublet lens, the mechanical aperture assembly comprises a first circular plate, a second circular plate and a plurality of fanning strips, a first through hole is formed in the center of the first circular plate, a second through hole is formed in the center of the second circular plate, the first through hole and the second through hole form an aperture, and the fanning strips are all located between the first circular plate and the second circular plate. The plurality of fanning strips are uniformly arranged along the radial outer edge of the aperture, the fanning strips are provided with knobs, and the first circular plate is provided with a sliding groove for sliding of the knobs; the doublet lens comprises a first lens and a second lens. According to the parallel light source with the adjustable and controllable light spot diameter, the production cost and the assembly tolerance are reduced, and the adjustable and controllable light spot diameter of the parallel light source is achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a parallel light source with adjustable light spot diameter belongs to light source technical field. BACKGROUND

[0002] At present, parallel light source is widely used in laser scanning machine, image measuring instrument, medical equipment, automation equipment, machine vision, microscopic technique and other fields, it can make the image magnification not change with the change of object distance in a certain object distance range. The parallel half angle of parallel light source can be less than 0.1 degree, and can reach high uniformity, and the uniformity can be greater than 90%. The light emitted by the parallel light source is parallel through the measured material, and the light direction does not change, and there is almost no attenuation.

[0003] Compared with ordinary backlight, the telecentric parallel light source can eliminate the edge blur caused by light source diffusion and other phenomena, obtain clear and sharp image, and greatly improve the measurement precision. The telecentric lens is particularly suitable for shooting cylindrical and circular objects. When detecting three-dimensional objects or when image size and shape accuracy is very important, according to the principle characteristics and unique advantages of telecentric lens, the telecentric lens detection scheme is very effective, and the parallel light source as its best partner is also indispensable. It can be said that with the help of parallel light source, the technical advantages of high-precision detection can be better highlighted. Parallel light source can provide light source for various measuring equipment, so that the detection precision is higher, and the measurement is more accurate.

[0004] According to the principle of geometric optics, the object at infinity will be imaged on the focal plane after passing through the lens; on the contrary, the light emitted from the focal plane of the lens will become a parallel light after passing through the lens. If an object is placed on the focal plane of the lens, it will be imaged at infinity.

[0005] For the design of parallel light source, the three-piece combined lens is mainly used on the market, two of which are double-cemented lenses, and one is a single spherical lens. Generally, glass lenses are used, which are high in price and complex in process. More lenses will result in higher cost, so using the least lenses to achieve good results can greatly save cost. In addition, the design has high requirements for mechanical assembly, because the concentricity of the lens must be ensured, and if the installation angle or position is not correct, it will affect the shape of the light spot. In addition, the biggest restriction on the universality of the lens is that the parallel light source on the market can only produce one size of light spot, but the illuminated object is large or small, which limits the application scene of the light source.

[0006] For example, the patent with application number CN201821337781.3 "A high-telecentricity parallel light source with an exit pupil diameter of 70mm" discloses a parallel light source with a light spot diameter of 70mm. In this patent, three lenses are used, two of which are double-cemented lenses cemented together, and the other is a single spherical mirror. The first lens G1 and the second lens G2 in this patent form a cemented lens B for condensing light and controlling the chief ray to be perpendicular to the optical axis at the exit wave surface of the cemented lens B. The third lens G3 receives the exit light of the cemented lens B and controls the chief ray to be perpendicular to the optical axis at the exit wave surface of the third lens G3 (i.e., makes the chief ray parallel to the optical axis), thereby making the parallelism of the optical system less than 0.05. This design method requires three lenses, so the cost is relatively high. Moreover, the double-cemented lens B composed of G1 and G2 and the lens G3 have poor concentricity during assembly, so high processing precision is required, resulting in high cost. The installation precision of the lenses during installation is also high, and if the installation angle or position is not correct, it will affect the shape of the light spot. SUMMARY

[0007] The technical problem to be solved by the utility model is to overcome the shortcomings of the prior art, provide a parallel light source with adjustable light spot diameter, reduce production cost and assembly tolerance, and realize adjustable light spot diameter of the parallel light source.

[0008] To solve the above technical problems, the technical scheme of the utility model is:

[0009] A parallel light source with adjustable light spot diameter, comprising a mechanical aperture assembly and a double-cemented lens.

[0010] The mechanical aperture assembly comprises a first circular plate, a second circular plate and a plurality of sector-shaped pieces. A first through hole is formed in the center of the first circular plate, and a second through hole is formed in the center of the second circular plate. The first through hole and the second through hole constitute an aperture. The plurality of sector-shaped pieces are located between the first circular plate and the second circular plate, and are evenly arranged along the radial outer edge of the aperture. A knob is arranged on each sector-shaped piece. A sliding groove is arranged on the first circular plate for the sliding of the knob.

[0011] The double-cemented lens comprises a first lens and a second lens. The first lens is located at the first through hole of the first circular plate, and the second lens is cemented to the first lens. The first lens is a convex-concave lens with negative focal power, and the second lens is a double-convex lens with positive focal power.

[0012] Further, the refractive index of the first lens is n1, and the Abbe number of the first lens is v1. n1 and v1 satisfy the relationship:

[0013] 1.70 < n1 < 1.80;

[0014] 20 < v1 < 30.

[0015] Further, the refractive index of the second lens is n2, and the Abbe number of the second lens is v2, and n2 and v2 satisfy the relationship:

[0016] 1.55 < n2 < 1.70;

[0017] 50 < v2 < 60.

[0018] Further, the first lens is provided with a first lens first curved surface and a first lens second curved surface, the radius of curvature of the first lens first curved surface is 321.0135mm, the radius of curvature of the first lens second curved surface is 67.6650mm, and the first lens second curved surface is a cemented surface.

[0019] Further, the second lens is provided with a second lens first curved surface and a second lens second curved surface, the second lens first curved surface is cemented with the first lens second curved surface, and the radius of curvature of the second lens second curved surface is -81.7058mm.

[0020] Further, the center distance of the first lens first curved surface and the first lens second curved surface is 6mm, and the center distance of the first lens second curved surface and the second lens second curved surface is 20mm.

[0021] Further, the focal length of the double cemented lens is 120mm.

[0022] By adopting the above technical scheme, the utility model has the following beneficial effects:

[0023] 1. The utility model only uses a piece of double cemented lens to realize the effect of parallel light source, reduces production cost and assembly tolerance.

[0024] 2. The utility model adds a mechanical aperture, can realize the partial shielding of lens aperture, can obtain 35-70mm uniform light spot, and can make the use scene of light source more extensive. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is the front view of the parallel light source with adjustable light spot diameter of the utility model;

[0026] Figure 2 It is the side view of Figure 1 ;

[0027] Figure 3 It is the structure schematic view of the mechanical aperture assembly of the utility model;

[0028] Figure 4The second circular plate and the fan-shaped piece structure schematic view of the utility model;

[0029] Figure 5 The double cemented lens structure schematic view of the utility model;

[0030] Figure 6 The light path schematic view of the double cemented lens of the utility model;

[0031] Figure 7 The light spot size schematic view when the aperture of the utility model is the smallest;

[0032] Figure 8 The light spot size schematic view when the aperture of the utility model is the largest. DETAILED DESCRIPTION

[0033] In order to make the content of the utility model more easily be clearly understood, the following according to specific embodiment and combining with the drawings, the utility model is further explained in detail.

[0034] As Figure 1 shown, the embodiment provides a parallel light source with adjustable light spot diameter, which comprises a mechanical aperture assembly and a double cemented lens C. By adding the mechanical aperture assembly, the aperture of the double cemented lens C can be partially blocked, and thus a uniform light spot of 35-70mm can be obtained. The embodiment is based on the imaging optical theory, and uses the double cemented lens C composed of two lenses to meet the design requirements, so that a circular light spot with uniform irradiance distribution is obtained. The light source used in the embodiment is an LED light source conforming to Lambert distribution, and the surface of the lens adopts a spherical surface which is easy to process.

[0035] As Figures 1 to 4 shown, the mechanical aperture assembly of the embodiment comprises a first circular plate 1, a second circular plate 2 and a plurality of fan-shaped pieces 3. A first through hole is formed in the center of the first circular plate 1, and a second through hole is formed in the center of the second circular plate 2, and the first through hole and the second through hole constitute an aperture 6. The maximum light spot size supported by the embodiment is 70mm, so the entrance pupil diameter is set to 70mm. The six fan-shaped pieces 3 are located between the first circular plate 1 and the second circular plate 2, and the six fan-shaped pieces 3 are uniformly arranged along the radial outer edge of the aperture. A knob 4 is arranged on the fan-shaped piece 3, and a sliding groove 5 for the sliding of the knob 4 is arranged on the first circular plate 1. By rotating the knob 4, the relative position of the fan-shaped piece 3 can be changed. When the knob 4 is at the outermost end, the diameter of the light passing hole surrounded by the fan-shaped piece 3 is larger, as Figure 7 shown, the largest light spot can be obtained. When the knob 4 fluctuates inward, the area of the light passing hole surrounded by the fan-shaped piece 3 decreases, and the light spot size also decreases accordingly. When the knob 4 is rotated to the innermost side, the area of the light passing hole surrounded by the fan-shaped piece 3 at this time is the smallest, as Figure 8 shown, which is also the smallest light spot size that the system can obtain.

[0036] As Figure 1 , 2 , 5, the double cemented lens C of the embodiment comprises a first lens G1 and a second lens G2, the first lens G1 is located at the first through hole of the first circular plate 1, the second lens G2 is cemented with the first lens G1, the first lens G1 is a convex-concave lens with negative focal power, and the second lens G2 is a double convex lens with positive focal power.

[0037] The material with high refractive index and low dispersion coefficient is selected for the first lens G1, the refractive index of the first lens G1 is n1, the Abbe number of the first lens G1 is v1, and n1 and v1 satisfy the relationship:

[0038] 1.70 < n1 < 1.80;

[0039] 20 < v1 < 30.

[0040] The material with high refractive index and low dispersion coefficient is selected for the second lens G2, the refractive index of the second lens G2 is n2, the Abbe number of the second lens G2 is v2, and n2 and v2 satisfy the relationship:

[0041] 1.55 < n2 < 1.70;

[0042] 50 < v2 < 60.

[0043] The combination of low dispersion and high dispersion materials can achieve achromatic effect.

[0044] As Figure 5 shown, the curvature radius of the first surface S1 of the first lens G1 of the embodiment is 321.0135mm, the curvature radius of the second surface S2 of the first lens G1 is 67.6650mm, and the second surface S2 of the first lens G1 is the cemented surface; the curvature radius of the second surface S3 of the second lens G2 is -81.7058mm; the center distance of the surface S1 and the surface S2 is 6mm, the center distance of the surface S2 and the surface S3 is 20mm; and the focal length of the double cemented lens C is 120mm. The light source used in the embodiment is an LED white light source, and the wavelength range is 380nm-760nm, as Figure 5 shown, the center distance L1 between the position of the light source and the surface S1 of the first lens G1 is 104.7479mm, and the optical path of the double cemented lens C is as Figure 6 shown.

[0045] The above-described specific embodiments further specifically describe the technical problems, technical solutions and beneficial effects solved by the present application, and it should be understood that the above-described specific embodiments are merely specific embodiments of the present application and are not used to limit the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A collimated light source with adjustable spot diameter, characterized in that: It includes a mechanical aperture assembly and a double cemented lens (C); The mechanical aperture assembly includes a first circular plate (1), a second circular plate (2) and a plurality of sector pieces (3), a first through hole is formed in the center of the first circular plate (1), a second through hole is formed in the center of the second circular plate (2), the first through hole and the second through hole constitute an aperture (6), the plurality of sector pieces (3) are located between the first circular plate (1) and the second circular plate (2), the plurality of sector pieces (3) are evenly arranged along the radial outer edge of the aperture, the sector piece (3) is provided with a knob (4), and the first circular plate (1) is provided with a sliding groove (5) for sliding of the knob (4); The double cemented lens (C) includes a first lens (G1) and a second lens (G2), the first lens (G1) is located at the first through hole of the first circular plate (1), the second lens (G2) and the first lens (G1) are cemented and connected, the first lens (G1) is a convex-concave lens with negative focal power, and the second lens (G2) is a double convex lens with positive focal power.

2. The parallel light source with adjustable spot diameter according to claim 1, characterized in that: The refractive index of the first lens (G1) is n1, the Abbe number of the first lens (G1) is v1, n1 and v1 satisfy the relationship: 1.70<n1<1.80； 20<v1<30。 3. The parallel light source with adjustable spot diameter according to claim 1, characterized in that: The refractive index of the second lens (G2) is n2, the Abbe number of the second lens (G2) is v2, n2 and v2 satisfy the relationship: 1.55<n2<1.70； 50<v2<60。 4. The parallel light source with adjustable spot diameter according to claim 1, characterized in that: The first lens (G1) is provided with a first lens first curved surface (S1) and a first lens second curved surface (S2), the curvature radius of the first lens first curved surface (S1) is 321.0135mm, the curvature radius of the first lens second curved surface (S2) is 67.6650mm, and the first lens second curved surface (S2) is a cemented surface.

5. The parallel light source with adjustable spot diameter according to claim 4, characterized in that: The second lens (G2) is provided with a second lens first curved surface and a second lens second curved surface (S3), the second lens first curved surface is cemented with the first lens second curved surface (S2), and the curvature radius of the second lens second curved surface (S3) is-81.7058mm.

6. The parallel light source with adjustable spot diameter according to claim 5, characterized in that: The center distance of the first lens first curved surface (S1) and the first lens second curved surface (S2) is 6mm, and the center distance of the first lens second curved surface (S2) and the second lens second curved surface (S3) is 20mm.

7. The parallel light source with adjustable spot diameter according to claim 6, characterized in that: The focal length of the double cemented lens (C) is 120mm.

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