Pistol type three-wavelength laser water quality detection optical instrument based on DMD (Digital Micromirror Device)

Abstract

The invention discloses a DMD-based pistol-type three-wavelength laser water quality detection optical instrument which is characterized in that an X prism is arranged on an integrated module at the front end of a water quality detection optical instrument body, and a 420 blue-violet laser, a 280 ultraviolet laser, a 680 red laser and a bonding lens shaping module are respectively arranged on the periphery of the X prism in the horizontal direction; a micro sample pool and a TIR steering prism are arranged on one side of the balsaming lens shaping module, a focusing coupling module, a receiver, an embedded control module and a power supply module are arranged under the TIR steering prism, the water quality detection optical instrument body can detect various water quality parameters such as COD, turbidity and nitrate at the same time, the field operation convenience is greatly improved, and the water quality detection optical instrument can be applied to water quality detection. The device adapts to the rapid detection requirement of emergency monitoring, is combined with a temperature compensation algorithm, ensures that the detection precision meets the field detection requirement, solves the problems of low divergent beam combination efficiency and poor coaxiality in a traditional optical instrument, effectively improves the utilization rate of weak attenuation optical signals, and improves the modulation efficiency and the detection precision.

Description

Technical Field

[0001] This invention relates to the field of optical instrument technology, specifically to a pistol-type three-wavelength laser water quality detection optical instrument based on DMD. Background Technology

[0002] Water quality testing is an important part of environmental protection and water resource management. Traditional water quality testing methods mostly rely on large laboratory instruments, such as ultraviolet-visible spectrophotometers and high-performance liquid chromatographs. Although these instruments have high detection accuracy, they are bulky, complex to operate, and have long testing cycles, which cannot meet the needs of rapid on-site testing and emergency monitoring.

[0003] In recent years, handheld optical instruments for water quality testing have developed rapidly, but existing technologies still have the following shortcomings: First, most use single-wavelength or dual-wavelength light sources, resulting in limited detection parameters and an inability to simultaneously detect multiple water quality indicators; second, the optical system design is unreasonable, with lasers and detectors scattered, leading to large instrument size and poor portability; third, the light source is a divergent beam, resulting in poor compatibility with beam combining components, low beam combining efficiency, and poor coaxiality, affecting detection accuracy; fourth, the optical path transmission path design is unreasonable, resulting in high optical loss and low detector receiving efficiency; and fifth, there is a lack of ergonomic handheld structure design, leading to poor on-site operation convenience, especially in emergency monitoring scenarios, making it difficult to achieve rapid and accurate water sample testing.

[0004] Digital micromirror devices (DMDs), as high-speed spatial light modulators, are characterized by fast modulation speed, high precision, and strong stability, and have been widely used in fields such as spectral analysis and optical communication. Combining DMDs with multi-wavelength lasers can achieve rapid wavelength gating and signal modulation, improving detection speed and signal-to-noise ratio. However, there is currently no handheld water quality testing optical instrument with a pistol-like structure that integrates three wavelength lasers (280nm / 420nm / 680nm) at the detection front end, places the detector at the grip end, and adopts a "rear-incident laser - 90° folded optical path - DMD modulation - rear-mounted detector" configuration.

[0005] Therefore, there is an urgent need for a handheld optical instrument for water quality testing that is compact, fast, accurate, and easy to operate to solve this problem in the existing technology. Summary of the Invention

[0006] The purpose of this invention is to provide a pistol-type three-wavelength laser water quality detection optical instrument with DMD that solves the problem of limited detection parameters in existing handheld optical instruments. It employs a 90° folded optical path design to form an ergonomic pistol-like structure, significantly improving on-site operation convenience and adapting to the rapid detection needs of emergency monitoring. Combined with a temperature compensation algorithm, it ensures that the detection accuracy meets on-site detection requirements. This invention also solves the problems of low beam combining efficiency and poor coaxiality in traditional optical instruments, effectively improving the utilization rate of weak attenuated light signals and enhancing modulation efficiency and detection accuracy.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a pistol-type three-wavelength laser water quality detection optical instrument based on DMD, comprising a water quality detection optical instrument body and a front-end integrated module, characterized in that: the water quality detection optical instrument body is provided with a front-end integrated module, the front-end integrated module is provided with an X-prism, and a 420 blue-violet laser, a 280 ultraviolet laser, a 680 red laser, and a cemented lens shaping module are respectively provided around the X-prism in the horizontal direction, wherein the 280 ultraviolet laser, the X-prism, and the cemented lens shaping module are arranged on the same straight line; The cemented lens shaping module has a miniature sample cell and a TIR steering prism on one side. The miniature sample cell is located on the detection surface at the middle of the gun body. The focusing coupling module, receiver, embedded control module and power supply module are located directly below the TIR steering prism.

[0008] Preferably, an LCD screen is provided above the front-end integrated module, and the three laser beams of the 420 blue-violet laser, 280 ultraviolet laser and 680 red laser on the front-end integrated module are combined and incident rearward along the axis of the gun body.

[0009] Preferably, the cemented lens shaping module is an achromatic cemented doublet lens.

[0010] Preferably, the X-prism is a four-way beam-combining optical prism.

[0011] Preferably, a DMD modulation module is provided above the TIR steering prism, and the DMD modulation module includes a 0.2-inch WVGA digital micromirror device and a DLPC150 driver chip.

[0012] Preferably, the focusing coupling module is an aspherical focusing lens.

[0013] Preferably, the embedded control module and power supply module include an FPGA+ARM core board, an OLED display screen and physical buttons, and the power supply module is an 18650 dual-cell lithium battery pack.

[0014] Compared with the prior art, the beneficial effects of the present invention are: (1) The optical path fine-tuning calibration module is a miniature threaded adjustment mechanism, which is set between the laser collimation preprocessing module and the X-prism beam combining module. It is used to calibrate the laser incident angle and calibrate the incident deviation of the three parallel lasers to ≤0.01°, so as to ensure that the light spot falls accurately on the coating area of ​​the X-prism, avoid energy loss caused by beam overflow, and at the same time ensure that the incident angle of the three lasers matches the design optical path of the X-prism, thereby improving the beam combining efficiency and coaxiality. (2) The miniature sample cell is embedded in the detection surface at the middle of the gun body. The composite laser irradiates the water sample vertically. The pollutants in the water sample selectively absorb the laser of a specific wavelength, forming an attenuated light signal related to the concentration of pollutants. The attenuated light signal enters the DMD modulation module after secondary reflection by the TIR turning prism, realizing the closed-loop utilization of the optical path and further reducing the size of the optical instrument. (3) The focusing coupling module is an aspherical focusing lens that converges the modulated optical signal into a light spot with a diameter of 0.1-0.15 mm, which is incident and coupled to the photosensitive surface of the photodetector module with a coupling efficiency of ≥95%; (4) The water quality testing optical instrument can simultaneously detect multiple water quality parameters such as COD, turbidity, and nitrate, solving the problem of single detection parameters in existing handheld optical instruments. It adopts a 90° folded optical path design to form an ergonomic pistol-like structure, which greatly improves the convenience of on-site operation and meets the rapid detection needs of emergency monitoring. Combined with the temperature compensation algorithm, it ensures that the detection accuracy meets the on-site detection requirements. It solves the problems of low beam combining efficiency and poor coaxiality in traditional optical instruments, effectively improving the utilization rate of weak attenuated light signals and improving modulation efficiency and detection accuracy. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the main structure of the optical instrument for water quality testing according to the present invention.

[0016] In the diagram: 1. Main body of the water quality testing optical instrument; 2. LCD screen; 3. 420 blue-violet laser; 4. 280 ultraviolet laser; 5. 680 red laser; 6. X-ray prism; 7. Front-end integrated module; 8. Cemented lens shaping module; 9. Miniature sample cell; 10. DMD modulation module; 11. TIR steering prism; 12. Focusing coupling module; 13. Receiver; 14. Embedded control module and power supply module. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figure 1 This invention provides a technical solution: a pistol-type three-wavelength laser water quality detection optical instrument based on DMD, comprising a water quality detection optical instrument body 1 and a front-end integrated module 7. The water quality detection optical instrument body 1 is provided with the front-end integrated module 7, and an LCD screen 2 is provided above the front-end integrated module 7. An X-prism 6 is provided on the front-end integrated module 7. A 420 blue-violet laser 3, a 280 ultraviolet laser 4, a 680 red laser 5, and a cemented lens shaping module 8 are respectively provided around the X-prism 6 in the horizontal direction. The 280 ultraviolet laser 4, the X-prism 6, and the cemented lens shaping module 8 are arranged on the same straight line.

[0019] A micro sample cell 9 and a TIR steering prism 11 are provided on one side of the cemented lens shaping module 8. The micro sample cell 9 is located on the detection surface at the middle of the gun body. A focusing coupling module 12, a receiver 13, an embedded control module and a power supply module 14 are provided directly below the TIR steering prism 11.

[0020] The main body 1 of the water quality testing optical instrument is equipped with a laser collimation preprocessing module, which includes three miniature collimating lenses, each corresponding to one of the three lasers, used to convert divergent laser light into parallel light.

[0021] The optical path fine-tuning calibration module is a miniature threaded adjustment mechanism used to calibrate the laser incident angle, ensuring that the parallel light is accurately incident on the X-prism 6. The X-prism 6 is used to combine three parallel laser beams of different wavelengths into a single composite laser beam. The adjustment accuracy of the optical path fine-tuning calibration module is ±0.005°, used to calibrate the incident deviation of the three parallel laser beams to ≤0.01°, ensuring that the light spot falls accurately on the coated area of ​​the X-prism and avoiding beam overflow.

[0022] The optical path fine-tuning calibration module is a miniature threaded adjustment mechanism located between the laser collimation preprocessing module and the X-prism beam combining module. It is used to calibrate the laser incident angle, calibrating the incident deviation of the three parallel laser beams to ≤0.01°, ensuring that the light spot accurately falls on the coating area of ​​the X-prism, avoiding energy loss caused by beam overflow, and ensuring that the incident angle of the three laser beams matches the designed optical path of the X-prism, thereby improving beam combining efficiency and coaxiality.

[0023] X-prism 6 is a four-way beam combining optical prism that combines three parallel laser beams of different wavelengths into a single composite laser beam. The X-prism is made of fused silica and measures 12 mm × 12 mm × 12 mm. Its X-face is coated with a 280 nm anti-reflection coating, a 420 nm high-reflection coating, a 680 nm high-reflection coating, and a full-band anti-reflection coating, respectively. 280 nm ultraviolet light passes through the prism along the central axis, while 420 nm blue-violet light and 680 nm red light are reflected by their respective high-reflection coatings and become coaxial with the ultraviolet light. The beam combining efficiency is ≥95%, and the coaxiality deviation of the combined laser beam is ≤0.01°.

[0024] The front-end integrated module 7 contains three laser beams: a 420 blue-violet laser 3, a 280 ultraviolet laser 4, and a 680 red laser 5. After the three laser beams are combined, they are incident rearward along the axis of the gun body.

[0025] Cemented lens shaping module 8 is an achromatic double cemented lens used for collimation optimization, spot shaping and chromatic aberration elimination of composite lasers.

[0026] The cemented lens shaping module is a double cemented achromatic lens of fused silica and optical glass, with a diameter of 10mm and a 280-700nm broadband anti-reflection coating on the surface. It has a transmittance of ≥95% for lasers across the entire wavelength range and shapes the composite laser into a 4×4mm square parallel spot, which is precisely matched with the effective working area of ​​the DMD, while eliminating the chromatic aberration of lasers of different wavelengths.

[0027] A DMD modulation module 10 is located above the TIR steering prism 11. The DMD modulation module 10 includes a 0.2-inch WVGA digital micromirror device and a DLPC150 driver chip, which is used to quickly gate and Walsh-Hadamard code the three-wavelength attenuated light signal passing through the sample cell.

[0028] The steering prism is a TIR prism made of fused silica, measuring 15 mm × 15 mm. The inclined surface is coated with a 280-700 nm high-reflection film (reflectivity ≥ 99%), and the outer optical surface of the TIR prism is coated with a broadband anti-reflection film. The parallel light output from the cemented lens is incident perpendicularly on the inclined surface of the prism, and after being reflected by the inclined surface, it is projected onto the DMD, forming a pistol-style folded optical path. This achieves both a compact optical path design and an ergonomic handheld structure.

[0029] The digital micromirror device of the DMD modulation module supports a wavelength range of 280-700nm, a micromirror flip time ≤2μs, a wavelength gating switching time ≤10ms, and a Walsh-Hadamard coding modulation frequency ≥1kHz. The attenuated optical signal is incident parallel to the DMD surface, modulated and reflected by the micromirror, and then transmitted along the folded optical path to the focusing coupling module below the gun handle, forming a pistol-style folded optical path.

[0030] The miniature sample cell 9 is located on the detection surface at the middle of the gun body to hold the water sample to be tested. After the composite laser irradiates the water sample, it undergoes absorption, forming an attenuated light signal related to the concentration of pollutants. The miniature sample cell 9 is made of quartz, with an optical path of 10mm and a volume of ≤500μL. It is embedded in the middle of the gun head. The composite laser irradiates the water sample vertically, and the attenuated light signal passing through the sample cell travels backward along the optical path. After secondary reflection by the TIR steering prism, it enters the DMD modulation module.

[0031] The focusing coupling module 12 is an aspherical focusing lens used to converge the modulated optical signal into a precise light spot.

[0032] The embedded control module and power supply module 14 include an FPGA+ARM core board, an OLED display screen and physical buttons. The power supply module is an 18650 dual-cell lithium battery pack, which is used to control the collaborative work of each module, process detection data and output detection results.

[0033] The photoelectric detection module on the main body 1 of the water quality testing optical instrument is located at the rear end of the optical instrument (below the handle) and is used to receive the focused modulated light signal and convert it into an electrical signal.

[0034] The 280nm UV laser is a miniature deep ultraviolet semiconductor laser in a TO-56 package, with a wavelength of 280±5nm, output power ≥10mW, beam quality M²≤1.5, and initial divergence angle ≤10°. Both the 420nm blue-violet laser and the 680nm red laser are miniature VCSEL lasers. The 420nm laser has an output power of ≥50mW, a wavelength of 420±5nm, and an initial divergence angle of ≤15°. The 680nm laser has an output power of ≥100mW, a wavelength of 680±3nm, and an initial divergence angle of ≤15°. The beam quality of both lasers is M≤1.3. The three lasers emit lasers backward along the axis of the gun body, forming a coaxial incident optical path.

[0035] A 280nm ultraviolet laser, paired with a dedicated quartz collimating lens for the ultraviolet band, with a numerical aperture NA=0.15, converts divergent laser light into parallel light with a parallelism deviation ≤0.02°.

[0036] A 420nm blue-violet laser and a 680nm red laser are paired with a visible light band glass collimating lens with a numerical aperture NA=0.2 to convert divergent laser light into parallel light with a parallelism deviation ≤0.01°. The collimating lens and laser are integrated into a single package with a volume ≤φ6×8mm.

[0037] The water quality testing optical instrument adopts a 90° folded optical path design, which folds the entire optical path of collimation preprocessing, optical path calibration, beam combining, shaping, sample cell, DMD modulation, focusing coupling and detection into a length of ≤100mm. The overall size of the instrument is ≤160×80×40mm and the weight is ≤500g, forming a pistol-style handheld structure that is suitable for on-site operation needs.

[0038] The focusing coupling module 12 is an aspherical focusing lens with a focal length of 10mm, a numerical aperture NA=0.25, and a light transmission diameter of 8mm. It focuses the modulated light signal into a light spot with a diameter of 0.1-0.15mm, which is incident and coupled to the photosensitive surface of the photodetector module with a coupling efficiency of ≥95%.

[0039] The main body of this water quality testing optical instrument 1 can simultaneously detect multiple water quality parameters such as COD, turbidity, and nitrate, solving the problem of single-parameter detection in existing handheld optical instruments. It innovatively adopts a 90° folded optical path design to form an ergonomic pistol-like structure, which greatly improves the convenience of on-site operation and adapts to the rapid detection needs of emergency monitoring. Combined with a temperature compensation algorithm, it ensures that the detection accuracy meets the requirements of on-site detection. It solves the problems of low beam combining efficiency and poor coaxiality in traditional optical instruments, effectively improving the utilization rate of weak attenuated light signals and improving modulation efficiency and detection accuracy.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pistol-type three-wavelength laser water quality detection optical instrument based on DMD, comprising a water quality detection optical instrument body (1) and a front-end integrated module (7), characterized in that: The water quality testing optical instrument body (1) is provided with a front-end integrated module (7), and an X-prism (6) is provided on the front-end integrated module (7). A 420 blue-violet laser (3), a 280 ultraviolet laser (4), a 680 red laser (5), and a cemented lens shaping module (8) are respectively provided around the X-prism (6) in the horizontal direction. The 280 ultraviolet laser (4), the X-prism (6), and the cemented lens shaping module (8) are arranged on the same straight line. The cemented lens shaping module (8) has a miniature sample cell (9) and a TIR steering prism (11) on one side. The miniature sample cell (9) is located on the detection surface at the middle of the gun body. The TIR steering prism (11) is located directly below a focusing coupling module (12), a receiver (13), an embedded control module, and a power supply module (14).

2. The pistol-type three-wavelength laser water quality detection optical instrument based on DMD according to claim 1, characterized in that: The front-end integrated module (7) is equipped with an LCD screen (2) on top. The three laser beams of the front-end integrated module (7), namely the 420 blue-violet laser (3), the 280 ultraviolet laser (4), and the 680 red laser (5), are combined and then incident on the rear along the axis of the gun body.

3. The pistol-type three-wavelength laser water quality detection optical instrument based on DMD according to claim 1, characterized in that: The cemented lens shaping module (8) is an achromatic cemented doublet lens.

4. The pistol-type three-wavelength laser water quality detection optical instrument based on DMD according to claim 1, characterized in that: The X-prism (6) is a four-way beam-combining optical prism.

5. The pistol-type three-wavelength laser water quality detection optical instrument based on DMD according to claim 1, characterized in that: The TIR steering prism (11) is provided with a DMD modulation module (10) above it. The DMD modulation module (10) includes a 0.2-inch WVGA digital micromirror device and a DLPC150 driver chip.

6. The pistol-type three-wavelength laser water quality detection optical instrument based on DMD according to claim 1, characterized in that: The focusing coupling module (12) is an aspherical focusing lens.

7. The pistol-type three-wavelength laser water quality detection optical instrument based on DMD according to claim 1, characterized in that: The embedded control module and power supply module (14) include an FPGA+ARM core board, an OLED display screen and physical buttons, and the power supply module is an 18650 dual-cell lithium battery pack.

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