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EP-4740053-A1 - MEDICAL SURGICAL MICROSCOPE WITH TARGET AUTOFOCUS AND METHOD FOR ADJUSTING THE FOCUS OF A MEDICAL SURGICAL MICROSCOPE

EP4740053A1EP 4740053 A1EP4740053 A1EP 4740053A1EP-4740053-A1

Abstract

The present disclosure relates to a medical surgical microscope (1) for a surgical procedure on a patient (P), comprising: a moveable microscope head (2) with an optical system (4) with a focus system (6) for focus adjustment to a focal point (8), the microscope (1) being adapted to provide an optical magnification of a target surgical area and to generate a digital microscope image, a movable robotic microscope arm (16) that is connected to a microscope base (18) to which the movable microscope head (2) is connected that is adapted to adjust a position and/ or an orientation of the microscope head (2), and a control unit (22) that is at least adapted to control the focus system (6) and the movable robotic microscope arm (16). The control unit (22) is adapted to: detect a first focal point (8) of the focus system (6) in a first position and orientation of the microscope head (2), wherein the first focal point (8) is located in a first focal plane (36) that is perpendicular to the optical axis (10) of the microscope head (2) in the first position and/or orientation, move the microscope head (2) into a second position and/or orientation, compute a second focal point (8') by determining a second focal plane (36') that crosses the first focal point (8) and is perpendicular to the optical axis (10') of the microscope head (2') in the second position and/or orientation in which the second focal point (8') is located, and to adjust the focus of the focusing system (6) to the second focal point (8') and for every point in time, the first focal point (8) is projected on the point where the second focal plane (36') and the optical axis (10') cross.

Inventors

  • Beyl, Tim
  • STAWIASKI, Jean

Assignees

  • B. Braun New Ventures GmbH

Dates

Publication Date
20260513
Application Date
20240703

Claims (15)

  1. 1 . A medical surgical microscope (1 ) for a surgical procedure on a patient (P), comprising: a moveable microscope head (2) with an optical system (4) with a focus system (6) for focus adjustment to a focal point (8), the microscope (1 ) being adapted to provide an optical magnification of a target surgical area, in particular in the direction of a first optical axis (10), and to generate a digital microscope image, preferably by means of a microscope sensing unit, a movable robotic microscope arm (16) that is connected to a microscope base (18) to which the movable microscope head (2) is connected that is adapted to actively adjust a position and/or an orientation of the microscope head (2), and a control unit (22) that is at least adapted to control the focus system (6) and the movable robotic microscope arm (16), characterized in that the control unit (22) is further adapted to: detect a first focal point (8) of the focus system (6) in a first position and orientation of the microscope head (2), wherein the first focal point (8) is located in a first focal plane (36) that is perpendicular to the optical axis (10) of the microscope head (2) in the first position and/or orientation, move the microscope head (2) into a second position and/or orientation, compute a second focal point (8’) by determining a second focal plane (36’) that intersects the first focal point (8) and is perpendicular to the optical axis (1 O’) of the microscope head (2’) in the second position and/or orientation in which the second focal point (8’) is located, and adjust the focus of the focusing system (6) to the second focal point (8’), wherein for every point in time, the first focal point (8) is projected on the point where the second focal plane (36’) and the optical axis (10’) cross.
  2. 2. The medical surgical microscope (1 ) according to claim 1 , characterized in that the control unit (22) is further adapted to transform the position of the first focal point (8) of a local coordinate system of the microscope head (2) into a local coordinate system of the microscope base (18), in order to continuously calculate the position of the first focal point (8) relative to the microscope base (18).
  3. 3. The medical surgical microscope (1) according to claim 2, characterized in that the control unit (22) is adapted to calculate the transformation of the first focal point (8) of the local coordinate system of the microscope head (2) into the local coordinate system of the microscope base (18) by calculating a first transformation (28) from the local coordinate system of the microscope head (2) to a local coordinate system of a microscope flange (31 ), and calculate a second transformation (30) from the microscope flange (31 ) to the microscope base (18), in order to enhance a calculation process.
  4. 4. The medical surgical microscope (1 ) according to claim 1 , characterized in that the control unit (22) is adapted to calculate a focal length (38; 38’) by calculating a distance between the optical system (4) of the microscope head (2) and the focal plane (36; 36’) in which the current focal point (8; 8’) is located.
  5. 5. The medical surgical microscope (1 ) according to claim 4, characterized in that the focus system (6) is adapted to adjust the focus by explicitly setting the focus to the focal length (38’) of the second focal point (8’) calculated by the control unit (22).
  6. 6. The medical surgical microscope (1 ) according to claim 4 or 5, characterized in that the control unit (22) is adapted to perform a contrast focusing within a predetermined focal length range around the focal length (38’) of the second focal point (8’), in order to fine-tune the focus of the focusing system (6).
  7. 7. The medical surgical microscope (1 ) according to any one of the preceding claims, characterized in that the control unit (22) is adapted to set, based on a calculated focal length (38’) of the second position and/or orientation of the microscope head (2’), a minimum focal length and/or a maximum focal length as focus limiters, and the control unit (22) is adapted to perform a contrast focusing within the focus limiters.
  8. 8. The medical surgical microscope (1) according to claim 7, characterized in that a minimum focal length and a maximum focal length is set, wherein the minimum focal length and the maximum focal length are equidistant to the focal length (38’) calculated by the control unit (22), or a difference between the maximum focal length and the focal length (38’) is smaller than a difference between the focal length (38’) and the minimum focal length, or a difference between the maximum focal length and the focal length (38’) is larger than a difference between the focal length (38’) and the minimum focal length.
  9. 9. The medical surgical microscope (1 ) according to any one of the preceding claims, characterized in that the focus system (6) is adapted to adjust the focus based on a velocity information of the robotic microscope head (2) calculated by the control unit (22), preferably by using the first position and orientation of the microscope head (2) and by integrating an velocity vector as well as a rotation velocity.
  10. 10. The medical surgical microscope (1 ) according to any one of the preceding claims, characterized in that the control unit (22) is adapted to calculate the current focal length (38’) of a moving microscope head (2’) in real time and to continuously adjust the focal length (38’) of the focus system (6) accordingly.
  11. 11 . The medical surgical microscope (1 ) according to any one of the preceding claims, characterized in that the control unit (22) is adapted to control a focus motor of the focus system (6) via a velocity control or via a current control in order to adjust the focus of the focusing system (6).
  12. 12. Method for adjusting the focus on a target surgical area, in particular for a medical surgical microscope (1 ) according to any one of the preceding claims, characterized by the steps: - Detecting (S1 ) a first focal point (8) of a focus system (6) of an optical system (4) in a first position and orientation of a movable microscope head (2) by a control unit (22); - Determining (S2), by the control unit (22), of a first focal plane (36) that intersects the first focal point (8) and is perpendicular to an optical axis (10) of the microscope head (2) in the first position and/or orientation; - Focusing (S3), by a focusing system (6), on the first focal point (8); - Moving (S4), preferably by a movable robotic microscope arm (16), the microscope head (2) from the first position and/or orientation to a second position and/or orientation; - Computing (S5) a second focal point (8’) by determining a second focal plane (36’) that intersects the first focal point (8) and is perpendicular to an optical axis (10’) of the microscope head (2’) in the second position and/or orientation in which the second focal point (8’) is located; and - Adjusting (S6) the focus of the focusing system (6) to the second focal point (8’).
  13. 13. Method for adjusting the focus according to claim 12, characterized by the additional steps of: - Calculating a focal length (38; 38’) by calculating a distance between the optical system (4) of the microscope head (2; 2’) and the focal plane (36; 36’) in which the first or second focal point (8; 8’) is located - Adjusting the focus by explicitly setting the focus to the focal length (38; 38’) of the first or second focal point (8, 8’).
  14. 14. A computer readable storage medium comprising instructions which, when executed by a computer, causes the computer to perform the method steps according to claim 12 or 13.
  15. 15. A computer program comprising instructions which, when executed by a computer, causes the computer to perform the method steps according to claim 12 or

Description

Medical surgical microscope with target autofocus and method for adjusting the focus of a medical surgical microscope Description Technical field The present disclosure relates to a medical surgical microscope for a surgical procedure on a patient, comprising a movable microscope head with an optical system with an actuable or controllable focus system for focus adjustment to a focal point in particular in the direction of a first optical axis, and to generate a digital microscope image, preferably by means of a microscope sensing unit. The surgical microscope further comprises a movable robotic microscope arm that is connected to a microscope base to which the movable microscope head is connected, in particular articulated or mounted, that is adapted to adjust a position and/or an orientation of the microscope head and a control unit that is at least adapted to control the focus system and the movable robotic microscope arm. The optical system is preferably adjustable relative to the microscope base. In addition, the disclosure relates to a focusing method and a computer-readable storage medium and computer program according to the preamble of the independent claims of the disclosure. Background of the disclosure Surgical microscopes are standard devices used in surgical procedures, particularly in neurosurgery, spinal surgery and microsurgery. These surgical microscopes usually comprise an optical system with a focus system. Usually multiple lenses in serial configuration with at least one lens being translational movable within the lens system are used for a focus operation and serve as the focus system. After the “last” lens of the optical system (averted to the front lens) a sensing unit, such as a CMOS sensor, is used to detect the final image of the microscope and digitally provide the image. An operator/ surgeon can have the microscopic image/ the microscopic image magnified for visual display of the (digitally) recorded microscope image via a display device such as an OP-monitor. In case the surgical microscopes have a movable microscope head that is controlled by a surgeon or medical professional, the microscope head is moved either manually or actively by a robotic microscope arm and with every movement, the focus must always be adjusted as a distance and orientation to a target surgical area or target point of interest and thus, the focus that needs to be adjusted changes. This focusing step is usually performed using a current captured optical microscope image while performing contrast or phase optimisation to adjust the focus/ focal length in order to obtain a sharp image of the target surgical area. This type of focusing is an iterative process and actuators are usually used to perform the automatic focusing (autofocusing). The disadvantage of this type of focusing is that the focusing process usually takes 0.2 to 2 seconds and is accompanied by an unstable microscope image during focus adjustment and noise generated by the actuators. This complex and lengthy focusing step leads to an interruption of the operation and, if repeated several times, to a loss of concentration of the surgeon. Another problem arises when the direct view of the surgical target area is temporarily blocked by either by instruments or by fluid. Among other things, this results in an unintentional activation of the autofocus. Although a single one-time, (initial) focus adjustment or focusing step is relatively short (a few seconds) and does not take much time, the surgical microscope is continuously in motion during surgical procedures, therefore, constantly recurring temporary loss of image sharpness/ focus as well as the time needed for constant focus adjustment steps are very annoying and can lead to a significant impairment of the surgeon. For this reason, surgeons often even deactivate the autofocus or adjust the focus manually themselves, which in turn requires the additional (manual) operation by the surgeon and can delay a procedure. Constant focus adjustment when using a surgical microscope is therefore currently still associated with many complications and with an impairment of patient safety. Brief description of the disclosure Therefore, the tasks and objectives of the present disclosure are to avoid or at least to reduce the disadvantages of the prior art and, in particular, to provide a medical surgical microscope, a focusing method as well as a computer-readable storage medium and computer program, which enable better, simpler, safer and more reliable focusing during a surgical procedure. Another task is to further increase a focus adjustment speed and to shorten the time of the surgical procedure for a surgeon as well as providing an even more interference-free autofocus of a surgical microscope. The object of the present disclosure are achieved according to the present invention with regard to a medical surgical microscope with the features according to claim 1 and according to the present inventi