Device for automatically positioning and centering a microscope optical head

• US 6,175,642 B1
• Filed: 04/29/1996
• Issued: 01/16/2001
• Est. Priority Date: 04/28/1995
• Status: Expired due to Fees

• Current Assignee: Ospedale San Raffaele Srl (Policlinico San Donato S.p.A.)
• Original Assignee: Fondazione Centro S. Raffaele Del Monte Tabor
• Inventors: Azzolini, Claudio, Fortini, Alberto, Carena, Marco, Brancato, Rosario, Gobbi, Pier Giorgio
• Primary Examiner(s): Chang, Jon
• Assistant Examiner(s): Patel, Jayanti K.
• Application Number:
  US08/639,751
• Time in Patent Office: 1,723 Days
• Field of Search: 382/128, 382/133, 382/134, 382/103, 382/107, 359/363, 359/368, 359/369, 359/371, 359/385, 359/386, 359/391, 359/362, 359/372, 359/374, 359/375, 359/376, 359/377, 359/397, 359/656, 359/696-698, 606/4, 606/1, 606/2, 128/897, 128/898, 348/61, 348/77-79, 348/169-172, 351/206, 351/208, 351/210, 351/221, 396/14, 396/18
• US Class Current: 382/128
• CPC Class Codes: A61B 90/20 Surgical microscopes characterised by non-optical aspects
• CPC Class Codes: G02B 21/0012 Surgical microscopes counterbalanced structures for surgical microscopes G02B7/001
• CPC Class Codes: G02B 21/24 Base structure

Abstract

A device for automatically positioning and centering the optical head of a microscope, for example for surgical use, the optical head being connected to a drive unit. This device analyzes the image framed by the microscope objective by use of an automatic system for analyzing the image light distribution, for example a video camera connected to a processing circuit and possibly to a microprocessor, then processes the image until a reference point of the light distribution is identified by dividing the image into N subzones. Then, on the basis of information regarding the position of the reference point, the device controls the drive unit of the microscope optical head to return the reference point to within a predetermined tolerance zone, if possible.

Claims

1. A device for automatically positioning and centering an optical head of a medical microscope having an objective arranged for framing a movable image, comprising:

a drive unit arranged for laterally moving said objective so as to vary framing of the movable image; and

an automatic image analysis system including a microprocessor arranged for identifying the position of a single reference point, said automatic image analysis system arranged for analyzing for light distribution of the movable image framed by said objective, for processing said light distribution to obtain the single reference point of light distribution, and for controlling said drive unit as a function of said reference point for achieving and maintaining a centered relationship of said reference point relative to said optical head.

2. The device of claim 1, wherein:

said automatic image analysis system includes a video camera operatively connected to an electronic image-processing circuit for providing a video signal from said video camera thereto.

3. The device of claim 2, wherein:

said automatic image analysis system further includes, operatively connected switch said video camera, a microprocessor, a system memory, a system bus, switching devices, and an image acquisition card arranged for sampling said video signal and to obtain a sample, and for storing said sample in said memory as an image matrix.

4. The device of claim 2, wherein:

said drive unit includes a plurality of electric motors operatively connected by reduction gearing to said optical head and arranged for receiving commands from said electronic circuit.

5. The device of claim 1, wherein:

said automatic image analysis system includes a photosensitive matrix operatively connected to a microprocessor.

6. The device of claim 5, wherein:

said microprocessor is arranged to identify the position of said single reference point of light distribution by recognizing at least one of a specific shape and an orientation of localized difference in light distribution within said image.

7. The device of claim 1, wherein said image has a luminous baricenter, and:

said automatic image analysis system is arranged to obtain as said single reference point, said luminous baricenter of said image.

8. The device of claim 7, wherein:

said automatic image analysis system includes a microprocessor arranged for identifying the position of said single reference point, by dividing the image into a given number of zones, measuring light level in each of said zones, and for calculating said luminous barycenter by assigning to each said zone a weight which depends on the respective light level in each zone.

9. The device of claim 8, wherein:

said microprocessor of said automatic image analysis system is arranged for subtracting from said light levels in each of said zones as measured, the mean light level of all of said zones before performing and calculating.

10. The device of claim 1, wherein said image has a brightest point, and:

said automatic image analysis system is arranged to obtain as said single reference point said brightest point of said image.

11. The device of claim 10, wherein:

said automatic image analysis system includes a microprocessor arranged for identifying the position of said single reference point, by dividing the image into a given number of zones, measuring light level in each of said zones, and for calculating said brightest point by assigning to each said zone a weight which depends on the respective light level in each zone.

12. The device of claim 1, wherein:

said automatic image analysis system includes a microprocessor arranged for identifying the position of said single reference point, by dividing the image into a given number of zones, measuring light level in each of said zones, and for calculating one of a luminous baricenter and a brightest point of said image by assigning to each said zone a weight which depends on the respective light level in each zone; and

said zones are arranged in a square array having an equal number of zones per side.

13. The device of claim 1, wherein:

said automatic image analysis system is arranged for analyzing for light distribution the image formed by said objective, within a specific spatial band, by imposing wavelength-sensitive optical filtration on said image.

14. The device of claim 1, wherein:

said automatic image analysis system is arranged for analyzing light distribution the image formed by said objective, within the visible region of optical radiation, by imposing wavelength-sensitive optical filtration on said image.

15. The device of claim 1, wherein:

said automatic image analysis system is arranged for analyzing light distribution the image formed by said objective, within the visible infrared region of optical radiation, by imposing wavelength-sensitive optical filtration on said image.

16. The device of claim 1, wherein:

said automatic image analysis system is arranged for analyzing light distribution the image formed by said objective, within the visible ultraviolet region of optical radiation, by imposing wavelength-sensitive optical filtration on said image.

17. The device of claim 1, wherein:

said automatic image analysis system includes a microprocessor arranged for identifying the position of said single reference point, by dividing the image into a given number of zones, measuring light level in each of said zones, and for calculating one of a luminous baricenter and a bright point of said image by assigning to each said zone a weight which depends on the respective light level in each zone;

said automatic image analysis system being arranged to provide said controlling by being arranged to perform a check to determine whether said single reference point of light distribution lies within a predetermined tolerance zone, and, if not, for calculating a movement vector and operating said drive unit for causing said optical head to move along said movement vector so as to cause said single reference point of light distribution to lie within said predetermined zone.

18. The device of claim 17, wherein:

said automatic image analysis system is arranged to calculate said movement vector by making successive determinations of location of said single reference point of light distribution.

19. The device of claim 17, wherein said tolerance zone has a center, and:

said automatic image analysis system is arranged to calculate as said movement vector a vector joining said center of said tolerance zone and the location of said single reference point of light distribution.

20. The device of claim 1, wherein:

said automatic image analysis system is arranged to acquire information as to the light distribution of the image formed by said objective by including a photosensitive element having a center and arranged to generate signals proportional to the extend of off-centering of said light distribution along two mutually perpendicular axes, from said center of said photosensitive element.

21. The device of claim 20, wherein:

said photosensitive element is a position-sensitive semiconductor diode.

22. The device of claim 20, wherein:

said photosensitive element is one of a quadrant optoelectronic sensor and a segmented optoelectronic sensor.

23. The device of claim 20, wherein:

said photosensitive element is an optoelectronic image dissector tube.

24. The device of claim 20, wherein:

said drive unit includes a plurality of electric motors operatively connected by reduction gearing to said optical head and arranged for receiving commands from said microprocessor.

25. The device of claim 1, further comprising:

means applicable to the image for increasing at least one of diffusivity and/or reflectivity of the image to optical radiation.

26. The device of claim 25, wherein:

said means applicable to the image comprise at least one diffusive or reflective marker arranged to be positioned within the image framed by said objective.

27. The device of claim 25, wherein:

said means applicable to the image comprise a surgical instrument.

28. The device of claim 27, wherein:

said instrument is an instrument configured for use in performing opthalmic surgery.

29. The device of claim 27, wherein:

said instrument is an instrument configures for use performing vitreo-retinal surgery.

30. The device of claim 27, wherein:

said instrument is an instrument configured for use in performing neurosurgery.

31. The device of claim 27, wherein:

said instrument is an instrument configured for use in plastic surgery.