A surgical microscope dual laser point auto-focusing device and method

Abstract

This invention discloses a dual-laser-point autofocus device and method for surgical microscopes, relating to the field of surgical microscope technology. The invention employs a two-dimensional PSD chip as the core for laser point position detection, avoids optical path interference through time-division control of two laser points, and uses a servo motor or stepper motor to drive the displacement of a large objective lens. Focusing is determined based on laser point overlap, and a closed-loop adjustment algorithm achieves high-precision, high-response-speed autofocus, suitable for high-precision surgical scenarios such as neurosurgery and ophthalmology, solving the problems of insufficient focusing accuracy, slow response, and susceptibility to interference in traditional surgical microscopes.

Description

Technical Field

[0001] This invention relates to the field of surgical microscope technology, specifically to a dual-laser-point autofocus device and method for surgical microscopes. Background Technology

[0002] Surgical microscopes are core equipment for precision surgeries such as neurosurgery and ophthalmology. The focusing accuracy directly affects the clarity of the surgical field and the safety of the surgery.

[0003] Traditional surgical microscopes in the prior art mostly rely on manual adjustment or single-laser focusing, which suffers from insufficient focusing accuracy, slow response speed, and susceptibility to interference from reflections from the target surface. Some autofocus technologies use multiple lasers emitted simultaneously, which can easily lead to superimposed interference in the optical paths, resulting in large errors in focus determination and failing to meet the requirements of high-precision surgery. Therefore, this invention provides a dual-laser-point autofocus device and method for surgical microscopes. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a dual-laser-point autofocus device and method for surgical microscopes, thereby solving the aforementioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a dual-laser-point autofocus device for a surgical microscope, comprising: The laser emitting module includes two lasers of the same wavelength, which output two coaxial laser beams. The time-division control module has a built-in timing controller and laser drive circuit. It outputs timing level signals to control the two lasers to conduct in a time-division manner, and is used to control the two lasers to emit in a time-division manner. The two-dimensional PSD detection module is a planar array two-dimensional PSD chip, equipped with signal amplification circuit and filtering circuit, used to acquire the position signal of reflected laser points; The objective lens drive module, equipped with a large objective lens, is driven by a motor to complete the displacement adjustment; The control core module is connected to the two-dimensional PSD detection module. It is used to receive the reflected laser point position signal collected by the two-dimensional PSD detection module, determine the focal state based on the laser point coincidence, and output driving commands to the objective lens driving module through an algorithm.

[0006] Preferably, the laser wavelength of the laser emitting module is selected from the 650nm visible light band, and the laser power is 0.5~1mW, with the coaxiality error between the two lasers ≤0.02°.

[0007] Preferably, the emission time of both lasers is 200ms, and the switching delay between the two lasers is ≤300ms.

[0008] Preferably, the position resolution of the two-dimensional PSD chip is ≤0.5μm, the X and Y axis coordinates of the reflected laser point are collected, the collection frequency is 50Hz, and the peak sensitivity wavelength is matched with the wavelengths of the two lasers. The detection error is eliminated by linear fitting calibration to ensure the accuracy of laser point position detection.

[0009] Preferably, the motor is either a servo motor or a stepper motor. The servo motor is a closed-loop drive and is suitable for micron-level high-precision focusing scenarios, while the stepper motor is an open-loop drive and is suitable for low-cost conventional focusing scenarios. Both the servo motor and the stepper motor are equipped with a precision guide rail transmission structure.

[0010] Preferably, the control core module uses a 32-bit MCU or DSP chip as its core, with built-in focusing algorithm and motor driver program, receives the coordinate signal from the two-dimensional PSD chip, performs real-time calculations, and outputs drive commands.

[0011] Preferably, the control core module is also equipped with a communication interface, which supports linkage with the main control system of the surgical microscope, feedback of focusing status, and realization of integrated control.

[0012] A method for automatic focusing of a surgical microscope using dual laser points includes the following steps: Step 1, Preoperative preparation: Select the drive motor according to the type of surgery (servo motor for neurosurgery / ophthalmology, stepper motor for routine surgery), preset the overlap threshold (default 1μm) and laser timing parameters in the control core, start the surgical microscope, complete the self-test of each module, and ensure that there are no faults; Step 2, Initial laser projection: The control core triggers the time-sharing control module, which controls the two lasers to be projected onto the surgical target surface in a time-sharing manner according to the timing sequence. After being reflected by the target surface, the laser is transmitted to the two-dimensional PSD detection module. Step 3, Position Acquisition and Calibration: The 2D PSD chip acquires the original coordinates of the two laser points, and after filtering and calibration, the standard coordinates are transmitted to the control core module; Step 4, Focus Judgment and Adjustment: The control core uses an algorithm to determine the overlap. If the focus is correct, the drive stops. If the focus is not correct, the defocus direction and distance are calculated. After the displacement is completed, the "projection-acquisition-judgment" process is repeated to form a closed-loop adjustment. Step 5, Focusing Complete and Locking: When the two laser points coincide, the control core outputs a focusing complete signal to lock the objective lens position, preventing accidental displacement during the procedure. At the same time, the focusing status is fed back to the microscope's main control system, indicating that the field of view is clear. Step 6, Real-time Focusing During Surgery: If the target surface shifts during the surgery, causing defocusing, the 2D PSD chip collects the coordinates in real time and triggers the algorithm to automatically repeat the above focusing process, achieving seamless real-time focusing without manual intervention.

[0013] Preferably, the coordinate calibration in step 3 specifically includes: The 2D PSD chip acquires the original coordinates (X1 original, Y1 original) and (X2 original, Y2 original). First, it eliminates environmental interference noise through a filtering algorithm, and then substitutes them into the preset calibration formula: X standard = Kx × X original + Bx, Y standard = Ky × Y original + By (Kx and Ky are linear calibration coefficients, and Bx and By are offset compensation values). The calibrated standard coordinates (X1, Y1) and (X2, Y2) are output to eliminate system errors.

[0014] Preferably, the overlap determination in step 4 specifically includes: setting a preset overlap threshold T≤1μm, calculating the coordinate difference between the two laser points ΔX=|X1-X2| and ΔY=|Y1-Y2|; if ΔX≤T and ΔY≤T, it is determined that the laser points overlap, the focus is correct, and a stop driving command is output; if ΔX>T or ΔY>T, it is determined that the focus is off, and the next step of defocus calculation is performed. The defocus calculation specifically includes: first, determining the defocus direction; if X1 > X2, the objective lens needs to be moved backward; if X1 < X2, it needs to be moved forward. The logic for determining the Y-axis direction is the same. Then, calculate the defocus distance D = √(ΔX). 2 +ΔY 2 By using a preset scaling factor K (K=1.2, to adapt to the relationship between objective lens displacement and laser point offset), the objective lens target displacement is converted into S=K×D, ensuring that the displacement accurately matches the defocusing requirements; The drive adjustment specifically includes: outputting drive commands based on the defocus direction and target displacement; the servo motor adopts a PID control algorithm (proportional coefficient P=0.6, integral coefficient I=0.1, derivative coefficient D=0.05) to quickly eliminate displacement deviation and avoid overshoot; the stepper motor directly outputs the corresponding number of pulses to drive the objective lens to the target position; after the displacement is completed, the laser projection and coordinate acquisition are retried and the calculation is repeated until the laser points coincide.

[0015] Beneficial effects Compared with the prior art, the present invention has the following advantages: High focusing accuracy: Using laser point coincidence as the core judgment standard, combined with a two-dimensional PSD chip and servo motor solution, the focusing accuracy reaches ±0.1μm, and the stepper motor solution reaches ±1μm, fully meeting the high precision requirements of different surgical scenarios.

[0016] Strong anti-interference capability: The dual-laser time-division emission design completely avoids the superposition interference of the two optical paths, adapts to surgical target surfaces with different reflective properties (such as tissues and instruments), and at the same time, the filtering algorithm eliminates environmental noise, resulting in stable judgment results.

[0017] Wide adaptability: Dual motor drive options are available, balancing high precision and low cost requirements, making it suitable for various surgical scenarios such as neurosurgery, ophthalmology, general surgery, and orthopedics, and highly practical.

[0018] Fast response speed: laser switching delay ≤300ms, algorithm calculation time ≤10ms, single focusing completion time ≤1.5s, no perceptible focus replenishment during surgery, and does not affect the continuity of the surgical procedure.

[0019] High safety: Laser power is controlled within a safe range to avoid damage to surgical tissue. Attached Figure Description

[0020] Figure 1 This is an overall structural block diagram of the present invention; Figure 2 This is a flowchart of the focusing method of the present invention; Figure 3 This is the timing diagram of the dual-laser time-division control of the present invention; Figure 4 This is a schematic diagram of the laser point overlap / defocus state of the present invention. Detailed Implementation

[0021] 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.

[0022] Please see Figure 1 A dual-laser-point autofocusing device for a surgical microscope, comprising: The laser emitting module includes two lasers of the same wavelength, which output two coaxial laser beams. The dual-laser time-division emission design completely avoids interference from the superposition of the two optical paths, adapts to surgical target surfaces with different reflective properties (such as tissues and instruments), and at the same time, the filtering algorithm eliminates environmental noise, resulting in stable judgment results and strong anti-interference ability.

[0023] The time-division control module is rigidly connected to the laser emission module via wires. It has a built-in timing controller and laser drive circuit, and outputs timing level signals to control the two lasers to conduct in a time-division manner, which is used to control the two lasers to emit in a time-division manner. The two-dimensional PSD detection module is embedded in the microscope optical path receiver. It is a planar array two-dimensional PSD chip, equipped with signal amplification circuit and filtering circuit, used to acquire the position signal of reflected laser points; The objective lens drive module, equipped with a large objective lens, is driven by a motor to complete the displacement adjustment; The control core module is connected to the two-dimensional PSD detection module via a data cable and to the objective lens drive module via a motor drive cable. It is used to receive the reflected laser point position signal collected by the two-dimensional PSD detection module, determine the focal state based on the laser point coincidence, and output drive commands to the objective lens drive module through an algorithm.

[0024] Using laser point overlap as the core judgment criterion, combined with a two-dimensional PSD chip and servo motor solution, the focusing accuracy reaches ±0.1μm, and the stepper motor solution reaches ±1μm, fully meeting the high precision requirements of different surgical scenarios, with high focusing accuracy.

[0025] Specifically, the laser wavelength of the laser emission module is selected from the 650nm visible light band, which is precisely matched with the peak sensitivity wavelength of the two-dimensional PSD chip, and the laser power is 0.5~1mW to avoid damaging surgical tissue while ensuring the intensity of the reflected signal; the coaxiality error of the two lasers is ≤0.02° to ensure the consistency of the projection path.

[0026] Specifically, the emission time of both lasers is 200ms, and the switching delay between the two channels is ≤300ms, which avoids optical path superposition interference, ensures the overall focusing response speed, and supports custom adjustment of timing parameters.

[0027] Specifically, the position resolution of the two-dimensional PSD chip is ≤0.5μm, the X and Y axis coordinates of the reflected laser point are collected, the acquisition frequency is 50Hz, and the peak sensitivity wavelength is matched with the wavelengths of the two lasers. The detection error is eliminated by linear fitting calibration to ensure the accuracy of laser point position detection.

[0028] Specifically, the motor should be either a servo motor or a stepper motor.

[0029] Servo motor drive (high-precision scenarios, suitable for neurosurgery / ophthalmology) core configuration: a permanent magnet synchronous servo motor with a rated speed of 3000 r / min is selected, and a 1024-line incremental encoder is used to form a closed-loop control; the motor is connected to the precision guide rail through a precision planetary reducer (reduction ratio 1:50), which amplifies the torque and improves the displacement accuracy.

[0030] Drive logic: The control core outputs a PWM drive signal, the motor drives the guide rail to drive the large objective lens to move, the encoder collects the motor rotation angle signal in real time, converts it into the actual displacement of the objective lens, and feeds it back to the control core; the core compares the target displacement (calculated from the defocus distance) with the actual displacement, and dynamically adjusts the PWM duty cycle to achieve displacement closed-loop correction.

[0031] Key advantages: Positioning accuracy ±0.1μm, response time ≤0.5s, strong anti-interference ability, overload capacity up to 1.5 times the rated load, smooth operation without shaking, suitable for neurosurgery and ophthalmology surgery with extremely high focusing accuracy requirements.

[0032] Stepper motor drive method (low-cost scenario, suitable for routine surgical procedures) core configuration: a two-phase hybrid stepper motor is selected, with a step angle of 1.8°, a microstepping accuracy of 32 microsteps, no encoder feedback, and open-loop control; the motor is connected to the guide rail via a synchronous belt, which is simple in structure and low in cost.

[0033] Drive logic: The control core outputs pulse signals and direction signals, and the motor rotates at a fixed step angle. One pulse corresponds to a lens displacement of 0.5μm. The displacement distance is controlled by the number of pulses, and the direction signal controls the displacement direction (forward / backward).

[0034] Core advantages: Simple control logic, cost is only 1 / 3 of that of servo motor solutions, high low-speed torque, stable operation, focusing accuracy ±1μm, suitable for routine surgical scenarios such as general surgery and orthopedics, meeting basic high-precision focusing requirements.

[0035] The dual-motor drive scheme balances the needs of high precision and low cost, and is suitable for various surgical scenarios such as neurosurgery, ophthalmology, general surgery, and orthopedics. It is highly practical and widely adaptable.

[0036] Specifically, the control core module uses a 32-bit MCU or DSP chip as its core, with built-in focusing algorithm and motor driver program. It receives the coordinate signal from the two-dimensional PSD chip, performs real-time calculations, and outputs drive commands.

[0037] Specifically, the control core module is also equipped with a communication interface, which supports linkage with the main control system of the surgical microscope, provides feedback on the focusing status, and achieves integrated control.

[0038] Please see Figure 2-4 A method for automatic focusing of a surgical microscope using dual laser points, comprising the following steps: Step 1, Preoperative preparation: Select the drive motor according to the type of surgery (servo motor for neurosurgery / ophthalmology, stepper motor for routine surgery), preset the overlap threshold (default 1μm) and laser timing parameters in the control core, start the surgical microscope, complete the self-test of each module, and ensure that there are no faults; Step 2, Initial laser projection: The control core triggers the time-sharing control module, which controls the two lasers to be projected onto the surgical target surface in a time-sharing manner according to the timing sequence. After being reflected by the target surface, the laser is transmitted to the two-dimensional PSD detection module. Step 3, Position Acquisition and Calibration: The 2D PSD chip acquires the original coordinates of the two laser points, and after filtering and calibration, the standard coordinates are transmitted to the control core module; Step 4, Focus Judgment and Adjustment: The control core uses an algorithm to determine the overlap. If the focus is correct, the drive stops. If the focus is not correct, the defocus direction and distance are calculated. After the displacement is completed, the "projection-acquisition-judgment" process is repeated to form a closed-loop adjustment. Step 5, Focusing Complete and Locking: When the two laser points coincide, the control core outputs a focusing complete signal to lock the objective lens position, preventing accidental displacement during the procedure. At the same time, the focusing status is fed back to the microscope's main control system, indicating that the field of view is clear. Step 6, Real-time Focusing During Surgery: If the target surface shifts during the surgery, causing defocusing, the 2D PSD chip collects the coordinates in real time and triggers the algorithm to automatically repeat the above focusing process, achieving seamless real-time focusing without manual intervention.

[0039] Specifically, the coordinate calibration in step 3 includes: The 2D PSD chip acquires the original coordinates (X1 original, Y1 original) and (X2 original, Y2 original). First, it eliminates environmental interference noise through a filtering algorithm, and then substitutes them into the preset calibration formula: X standard = Kx × X original + Bx, Y standard = Ky × Y original + By (Kx and Ky are linear calibration coefficients, and Bx and By are offset compensation values). The calibrated standard coordinates (X1, Y1) and (X2, Y2) are output to eliminate system errors.

[0040] Specifically, the overlap determination in step 4 includes: setting a preset overlap threshold T≤1μm, calculating the coordinate difference between the two laser points ΔX=|X1-X2| and ΔY=|Y1-Y2|; if ΔX≤T and ΔY≤T, it is determined that the laser points are overlapped, the focus is correct, and a stop drive command is output; if ΔX>T or ΔY>T, it is determined that the focus is off, and the next step of defocus calculation is performed. The defocus calculation specifically includes: first, determining the defocus direction; if X1 > X2, the objective lens needs to be moved backward; if X1 < X2, it needs to be moved forward. The logic for determining the Y-axis direction is the same. Then, calculate the defocus distance D = √(ΔX). 2 +ΔY 2 By using a preset scaling factor K (K=1.2, to adapt to the relationship between objective lens displacement and laser point offset), the objective lens target displacement is converted into S=K×D, ensuring that the displacement accurately matches the defocusing requirements; The drive adjustment specifically includes: outputting drive commands based on the defocus direction and target displacement; the servo motor adopts a PID control algorithm (proportional coefficient P=0.6, integral coefficient I=0.1, derivative coefficient D=0.05) to quickly eliminate displacement deviation and avoid overshoot; the stepper motor directly outputs the corresponding number of pulses to drive the objective lens to the target position; after the displacement is completed, the laser projection and coordinate acquisition are retried and the calculation is repeated until the laser points coincide.

[0041] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0042] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0043] 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 dual-laser-point autofocus device for a surgical microscope, characterized in that, include: The laser emitting module includes two lasers of the same wavelength, which output two coaxial laser beams. The time-division control module is rigidly connected to the laser emission module via wires. It has a built-in timing controller and laser drive circuit, and outputs timing level signals to control the two lasers to conduct in a time-division manner, which is used to control the two lasers to emit in a time-division manner. The two-dimensional PSD detection module is embedded in the microscope optical path receiver. It is a planar array two-dimensional PSD chip, equipped with signal amplification circuit and filtering circuit, used to acquire the position signal of reflected laser points; The objective lens drive module, equipped with a large objective lens, is driven by a motor to complete the displacement adjustment; The control core module is connected to the two-dimensional PSD detection module via a data cable and to the objective lens drive module via a motor drive cable. It is used to receive the reflected laser point position signal collected by the two-dimensional PSD detection module, determine the focal state based on the laser point coincidence, and output drive commands to the objective lens drive module through an algorithm.

2. The surgical microscope dual-laser-point autofocus device according to claim 1, characterized in that, The laser emission module uses a 650nm visible light wavelength and has a laser power of 0.5 to 1mW. The coaxiality error between the two laser beams is ≤0.02°.

3. The surgical microscope dual-laser-point autofocus device according to claim 1, characterized in that, The emission time of both lasers is 200ms, and the switching delay between the two channels is ≤300ms.

4. The surgical microscope dual-laser-point autofocus device according to claim 1, characterized in that, The two-dimensional PSD chip has a position resolution of ≤0.5μm, acquires the X and Y axis coordinates of the reflected laser point, acquires the frequency of 50Hz, and the peak sensitivity wavelength matches the wavelengths of the two lasers. The detection error is eliminated through linear fitting calibration to ensure the accuracy of laser point position detection.

5. The surgical microscope dual-laser-point autofocus device according to claim 1, characterized in that, The motor is selected from either a servo motor or a stepper motor. The servo motor is a closed-loop drive and is suitable for micron-level high-precision focusing scenarios. The stepper motor is an open-loop drive and is suitable for low-cost conventional focusing scenarios. Both the servo motor and the stepper motor are equipped with a precision guide rail transmission structure.

6. The surgical microscope dual-laser-point autofocus device according to claim 1, characterized in that, The control core module uses a 32-bit MCU or DSP chip as its core, with built-in focusing algorithm and motor driver program. It receives the coordinate signal from the two-dimensional PSD chip, performs real-time calculations, and outputs drive commands.

7. The surgical microscope dual-laser-point autofocus device according to claim 1, characterized in that, The control core module is also equipped with a communication interface, which supports linkage with the main control system of the surgical microscope, feedback on the focusing status, and realization of integrated control.

8. A method for automatic focusing of a surgical microscope using dual laser points, characterized in that, Includes the following steps: Step 1, Preoperative preparation: Select the drive motor according to the type of surgery (servo motor for neurosurgery / ophthalmology, stepper motor for routine surgery), preset the overlap threshold (default 1μm) and laser timing parameters in the control core, start the surgical microscope, complete the self-test of each module, and ensure that there are no faults; Step 2, Initial laser projection: The control core triggers the time-sharing control module, which controls the two lasers to be projected onto the surgical target surface in a time-sharing manner according to the timing sequence. After being reflected by the target surface, the laser is transmitted to the two-dimensional PSD detection module. Step 3, Position Acquisition and Calibration: The 2D PSD chip acquires the original coordinates of the two laser points, and after filtering and calibration, the standard coordinates are transmitted to the control core module; Step 4, Focus Judgment and Adjustment: The control core uses an algorithm to determine the overlap. If the focus is correct, the drive stops. If the focus is not correct, the defocus direction and distance are calculated. After the displacement is completed, the "projection-acquisition-judgment" process is repeated to form a closed-loop adjustment. Step 5, Focusing Complete and Locking: When the two laser points coincide, the control core outputs a focusing complete signal to lock the objective lens position, preventing accidental displacement during the procedure. At the same time, the focusing status is fed back to the microscope's main control system, indicating that the field of view is clear. Step 6, Real-time Focusing During Surgery: If the target surface shifts during the surgery, causing defocusing, the 2D PSD chip collects the coordinates in real time and triggers the algorithm to automatically repeat the above focusing process, achieving seamless real-time focusing without manual intervention.

9. The method for automatic focusing of a surgical microscope using dual laser points according to claim 8, characterized in that, Step 3, coordinate calibration, specifically includes: The 2D PSD chip acquires the original coordinates (X1 original, Y1 original) and (X2 original, Y2 original). First, it eliminates environmental interference noise through a filtering algorithm, and then substitutes them into the preset calibration formula: X standard = Kx × X original + Bx, Y standard = Ky × Y original + By (Kx and Ky are linear calibration coefficients, and Bx and By are offset compensation values). The calibrated standard coordinates (X1, Y1) and (X2, Y2) are output to eliminate system errors.

10. The method for automatic focusing of a surgical microscope using dual laser points according to claim 8, characterized in that, Step 4, the overlap determination, specifically includes: setting a preset overlap threshold T≤1μm, calculating the coordinate difference between the two laser points ΔX=|X1-X2| and ΔY=|Y1-Y2|; if ΔX≤T and ΔY≤T, it is determined that the laser points overlap, the focus is correct, and a stop drive command is output; if ΔX>T or ΔY>T, it is determined that the focus is off, and the next step of the defocus calculation is performed. The defocus calculation specifically includes: firstly determining the defocus direction, if X1>X2, the objective lens needs to be displaced backward, if X1X2, the objective lens needs to be displaced forward, and the determination logic in the Y-axis direction is consistent; secondly, calculating the defocus distance D=√(ΔX 2 +ΔY 2 ), and through a preset proportional coefficient K (K=1.2, which is suitable for the correlation between the displacement of the objective lens and the offset of the laser point), the objective lens target displacement amount S=K×D is converted, so as to ensure that the displacement accurately matches the defocus requirement; The drive adjustment specifically includes: outputting drive commands based on the defocus direction and target displacement; the servo motor adopts a PID control algorithm (proportional coefficient P=0.6, integral coefficient I=0.1, derivative coefficient D=0.05) to quickly eliminate displacement deviation and avoid overshoot; the stepper motor directly outputs the corresponding number of pulses to drive the objective lens to the target position; after the displacement is completed, the laser projection and coordinate acquisition are retried and the calculation is repeated until the laser points coincide.

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