A telescopic conical extinction focusing sleeve for low frequency low noise detection systems

Abstract

The utility model belongs to photoelectric detection and precise optical technology field, concretely relates to a telescopic taper extinction focusing sleeve for low frequency low noise detection system, including the sleeve, the sleeve is cylindrical structure, the sleeve closed one end surface middle position is equipped with through -hole, the sleeve inside slide connection has extinction taper barrel, extinction taper barrel one end is provided with plane lens, is equipped with guide hole on the lateral wall of sleeve, the guide hole is slidably connected with locking part, locking part passes through sleeve and extinction taper barrel screw fixed, the distance of light focusing is adjusted through the reciprocating sliding of locking part in guide hole, the application of the utility model can effectively block unnecessary residual stray laser in the light path and the light source in the environment, so that the noise of the detector introduced by stray light is reduced synchronously, thereby the signal quality is improved significantly, especially for the measurement of HZ and Hz below low frequency band and low signal-to-noise ratio signal has remarkable effect.

Description

Technical Field

[0001] This utility model belongs to the field of photoelectric detection and precision optics technology, specifically relating to a telescopic conical extinction focusing sleeve for a low-frequency, low-noise detection system. Background Technology

[0002] In high-precision optical measurements such as low-frequency, low-noise detection, the key to ensuring signal-to-noise ratio and long-term measurement stability lies in how to stably and efficiently focus the signal light onto the detector while maximally shielding it from ambient stray light. It is important to emphasize that stray light not only creates optical background noise but also converts into electrical noise for the detector via photoelectric conversion. The unwanted light power entering the detector increases the DC component of the photocurrent and shot noise levels. Furthermore, through amplification links and coupling with power supply / ground lines, this further amplifies low-frequency 1 / f noise in the Hz and below frequency bands, resulting in strong low-frequency noise and thus reducing the system's signal-to-noise ratio.

[0003] Currently, the closest existing technology to achieve this function is the commercially available general-purpose adjustable lens barrel. These products typically employ a combination of a straight inner wall + matte threads / coating + threaded or slider focusing. While they achieve basic focusing functionality, they suffer from the following main shortcomings in high-precision applications: 1. Poor stray light isolation: The segmented telescopic structure is prone to gaps at the joints, allowing ambient stray light to leak in from the sides. At the same time, the inner wall of the straight cylinder is prone to forming grazing incidence and multiple reflection paths. Light may repeatedly bounce inside the tube before reaching the detector, forming optical background noise, which is further converted into electrical noise.

[0004] 2. Poor focusing accuracy and repeatability: Focusing of general-purpose telescopes largely relies on the operator's experience, lacking a clear "effective working range" based on performance indicators. This leads to inconsistent results for each adjustment and makes the telescope prone to displacement under vibration or temperature changes, affecting the long-term stability of measurements and low-frequency noise levels.

[0005] 3. Risk of electrical noise amplification: Due to light leakage from the slit and multiple reflections within the cavity, the useless light power reaching the detector increases, and the equivalent noise current and low-frequency drift of the detection link are amplified, resulting in a decrease in SNR, which is particularly detrimental to signals with low signal-to-noise ratio.

[0006] Therefore, there is an urgent need for a dedicated focusing device that is simple in structure, has good sealing performance, and has a parametrically designed focusing range, and can simultaneously isolate stray light and the electrical noise caused by stray light. Utility Model Content

[0007] This invention addresses the problem that existing technologies cannot suppress stray light and the electrical noise caused by stray light by providing a telescopic conical extinction focusing sleeve for low-frequency, low-noise detection systems.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A telescopic conical extinction focusing sleeve for a low-frequency, low-noise detection system includes an outer sleeve, which is cylindrical in shape. One end of the outer sleeve is open, and the other end is closed. A through hole is provided in the middle of the closed end face of the outer sleeve. An extinction cone is slidably connected inside the outer sleeve. A plane lens is provided at one end of the extinction cone. The plane lens is threadedly connected to the extinction cone through a lens retainer. A guide hole is provided on the side wall of the outer sleeve. A locking component is slidably connected in the guide hole. The locking component passes through the outer sleeve and is threadedly fixed to the extinction cone. The focusing distance is adjusted by the reciprocating sliding of the locking component in the guide hole.

[0009] Furthermore, the matte cone is configured as a cylindrical structure, with a conical through hole inside. One end of the matte cone is configured as a small hole, which corresponds to the through hole. The other end of the matte cone is configured as a large hole, with a lens pressure ring threaded to one end of the large hole. A fixing groove is provided on the side wall of the matte cone, which corresponds to the locking component.

[0010] Furthermore, the locking component includes a bolt, which is threaded into the fixing groove and connected to the side wall of the matte cone barrel. A nut is threaded onto the bolt, and the bolt is locked by the nut.

[0011] Furthermore, the length of the guide hole is greater than the bolt diameter.

[0012] Furthermore, the inner wall of the extinction cone is set to be arc-shaped. The arc shape is designed based on the focusing characteristics of Gaussian beams and the integration requirements of multi-Gaussian beam shapes, taking into account the precision redundancy characteristics of planar lens processing and machining. By adapting to the transmission path of Gaussian beams, the signal light path is accurately guided, avoiding stray light from continuously reflecting on the inner wall of the extinction cone. At the same time, it is compatible with component processing error redundancy, ensuring the structural consistency of mass production.

[0013] Compared with the prior art, the present invention has the following advantages: Compared to the general-purpose adjustable lens tubes used in existing telescopes, this invention features an extinction lens tube specifically designed for photoelectric detection: 1. Strong stray light isolation effect: Existing telescopes with general-purpose adjustable focusing tubes adopt a straight tube structure without dedicated sealing and optical path adaptation design. Stray light can easily invade the inside of the tube, resulting in high background noise and electronic noise of the detector. The application of this utility model can effectively isolate stray light through the sealing design of the outer tube and the arc-shaped light transmission path designed for focusing parameters and range. This reduces the background noise of the detector and the electrical noise introduced by stray light simultaneously, thereby directly improving the signal-to-noise ratio of low-frequency measurements and significantly improving signal quality.

[0014] 2. High focusing accuracy and repeatability: Existing general-purpose lens barrel connection structures have weak stability and are prone to positional shifts when subjected to vibration or temperature changes, resulting in poor focusing accuracy and repeatability. This utility model ensures the stability of the matting cone barrel inside the outer sleeve through the threaded connection of the fixing groove and bolt, and can maintain its stability even under vibration or temperature changes.

[0015] 3. Improved optical path sealing and adjustment continuity: Existing general-purpose lens barrels lack targeted optical path parameterization design, making light leakage easy to occur during focusing and resulting in insufficient adjustment continuity. This utility model has a guide hole on the outer tube, and the entire optical path is parameterized according to standard Gaussian beam theory, clarifying the effective working window to guide mechanical design. Furthermore, it adopts a sliding design of the matting cone barrel to ensure that the solid tube wall of the matting cone barrel can completely block the guide hole from the inside at any position, effectively eliminating the risk of light leakage and achieving "seamless" adjustment.

[0016] 4. Reduced electrical noise amplification, enabling effective detection of low-frequency, low signal-to-noise ratio signals; The internal light-transmitting surface of the extinction cone of this invention is designed as an arc-shaped cone structure that adapts to focal length variations within a certain range. Compared to the straight cylinder structure in the prior art, the slope of the front half of this arc is greater than 45°, which can form a high proportion of reverse reflection of incident stray light, reducing the retention and multiple reflections of stray light inside the cone; at the same time, the arc structure can more accurately guide the signal light path and weaken the diffuse reflection of stray light—under the dual effect, the stray light suppression capability is significantly improved, greatly reducing the problem of electrical noise amplification, and realizing the effective detection of low-frequency, low signal-to-noise ratio signals.

[0017] 5. This utility model has a simple structure, low cost, and is easy to disassemble and maintain. It can be adapted to products with various focal lengths and detector sizes according to different environments, and has a wide range of applications.

[0018] 6. The locking component of this utility model is easy to operate and can shorten the assembly and adjustment time of a single product by 30-60%, greatly improving the consistency and efficiency of mass production and the ability requirements of practitioners. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a cross-sectional view of the present invention; Figure 3 This is a three-dimensional sectional view of the present invention; In the diagram, 1 is the outer sleeve, 2 is the through hole, 3 is the matting cone, 4 is the plane lens, 5 is the lens retaining ring, 6 is the guide hole, 7 is the locking component, 8 is the small hole, 9 is the large hole, 10 is the fixing groove, 11 is the bolt, and 12 is the nut. Detailed Implementation

[0020] To further illustrate the technical solution of this utility model, the following embodiments will be used to further explain this utility model.

[0021] like Figures 1-3As shown, a telescopic conical extinction focusing sleeve for a low-frequency, low-noise detection system includes an outer sleeve 1, which is cylindrical in shape. One end of the outer sleeve 1 is open, and the other end is closed. A through hole 2 is provided in the middle of the closed end face of the outer sleeve 1. An extinction cone 3 is slidably connected inside the outer sleeve 1. A plane lens 4 is provided at one end of the extinction cone 3. The distance from the plane lens 4 to the detector's working surface is set to 43.9 mm to 49.1 mm. The plane lens 4 is threadedly connected to the extinction cone 3 through a lens retainer 5. A guide hole 6 is provided on the side wall of the sleeve 1. A locking component 7 is slidably connected in the guide hole 6. By manually moving the locking component 7, the matte cone 3 can be moved along the guide hole 6. The length of the guide hole 6 can limit the maximum movable range of the matte cone 3. The locking component 7 passes through the outer sleeve 1 and is threadedly fixed to the matte cone 3. The guide hole 6 is opened on the outer sleeve 1, and the tube wall of the matte cone 3 is complete and opaque. Therefore, in any telescopic position, the solid tube wall of the matte cone 3 will completely block the guide hole 6 from the inside, thus naturally preventing any stray light from leaking in from the guide hole 6 and ensuring the overall light transmission. To ensure the airtightness of the optical path, the extinction cone 3 is configured as a cylindrical structure with a conical through-hole 2 inside. The inner wall of the extinction cone 3 is arc-shaped. This arc-shaped structure is designed based on Gaussian beam focusing theory and the requirement for redundant processing accuracy: on the one hand, it adapts to the Gaussian beam transmission path to ensure signal light focusing efficiency; on the other hand, it is compatible with the processing error redundancy of lenses and mechanical components to avoid optical path deviation; at the same time, it is combined with the slope design of the first half >45° to adapt to the stray light back reflection characteristics from a structural perspective. One end of the extinction cone 3 is configured as a small hole 8, which corresponds to the through-hole 2. The other end of the matte cone 3 is provided with a large hole 9. A lens retaining ring 5 is threaded to one end of the large hole 9. A fixing groove 10 is provided on the side wall of the matte cone 3. The fixing groove 10 corresponds to the locking component 7. The locking component 7 includes a bolt 11. The bolt 11 enters the fixing groove 10 and is threadedly connected to the side wall of the matte cone 3. A nut 12 is threaded onto the bolt 11, and the bolt 11 is locked by the nut 12. The length of the guide hole 6 is greater than the diameter of the bolt 11. By manually pushing and pulling the bolt, the matte cone 3 can be moved back and forth within the range of the guide hole 6 to achieve focus position adjustment. After adjusting to the optimal position, tighten the nut 12 on the outside of the bolt 11 to fix the matte cone 3 and the outer sleeve 1.

[0022] This utility model design is derived from the following formula: Minimum spot radius behind the lens

[0023] Coupling efficiency η:

[0024] Defocused light spot radius w Δz :

[0025] Where λ is the operating wavelength. The focal length of the plane lens. Let ω be the incident beam radius of the plane lens, ω be the spot radius, and α be the effective radius of the photodiode. The minimum spot radius after the plane lens. This refers to the axial defocusing amount. is the Rayleigh length of the Gaussian beam.

[0026] The foregoing has shown and described the main features and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model.

[0027] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A telescopic conical extinction focusing sleeve for a low-frequency, low-noise detection system, characterized in that: The device includes an outer sleeve (1), which has a cylindrical structure. One end of the outer sleeve (1) is open, and the other end is closed. A through hole (2) is provided in the middle of the closed end face of the outer sleeve (1). An anti-glare cone (3) is slidably connected inside the outer sleeve (1). A plane lens (4) is provided at one end of the anti-glare cone (3). The plane lens (4) is threadedly connected to the anti-glare cone (3) through a lens retainer (5). A guide hole (6) is provided on the side wall of the outer sleeve (1). A locking component (7) is slidably connected in the guide hole (6). The locking component (7) passes through the outer sleeve (1) and is threadedly fixed to the anti-glare cone (3). The distance of light focusing is adjusted by the reciprocating sliding of the locking component (7) in the guide hole (6).

2. The telescopic conical extinction focusing sleeve for a low-frequency, low-noise detection system according to claim 1, characterized in that: The matte cone barrel (3) is configured as a cylindrical structure. A conical through hole is provided inside the matte cone barrel (3). One end of the matte cone barrel (3) is configured as a small hole (8), which corresponds to the through hole (2). The other end of the matte cone barrel (3) is configured as a large hole (9). A lens pressure ring (5) is threaded to one end of the large hole (9). A fixing groove (10) is provided on the side wall of the matte cone barrel (3), which corresponds to the locking component (7).

3. A telescopic conical extinction focusing sleeve for a low-frequency, low-noise detection system according to claim 1, characterized in that: The locking component (7) includes a bolt (11), which is threaded into the fixing groove (10) and the side wall of the matte cone barrel (3). A nut (12) is threaded onto the bolt (11), and the bolt (11) is locked by the nut (12).

4. A telescopic conical extinction focusing sleeve for a low-frequency, low-noise detection system according to claim 1, characterized in that: The length of the guide hole (6) is greater than the diameter of the bolt (11).

5. A telescopic conical extinction focusing sleeve for a low-frequency, low-noise detection system according to claim 2, characterized in that: The inner wall of the matting cone (3) is set to be arc-shaped.

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