Spiral scanner with electronic control

• US 20020143252A1
• Filed: 01/25/2001
• Published: 10/03/2002
• Est. Priority Date: 01/25/2001
• Status: Active Grant

• Current Assignee: Optos Plc (Nikon Corporation)
• Original Assignee: OTI Ophthalmic Technologies Inc.
• Inventors: Charles, Steven, Dunne, Shane Denis
• Granted Patent: US 6,626,834 B2
• Time in Patent Office: Days
• US Class Current: 600/437
• CPC Class Codes: A61B 5/0062 Arrangements for scanning
• CPC Class Codes: A61B 5/0064 Body surface scanning
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 8/4281 characterised by sound-transmitting media or devices for coupling the transducer to the tissue
• CPC Class Codes: A61B 8/4461 Features of the scanning mechanism, e.g. for moving the transducer within the housing of the probe
• CPC Class Codes: A61B 8/483 involving the acquisition of a 3D volume of data
• CPC Class Codes: B06B 1/04 operating with electromagnetism dynamo-electric motors with vibrating magnet, armature or coil system H02K33/00
• CPC Class Codes: G01S 15/8947 using transducers movable by (electro)magnetic means
• CPC Class Codes: G01S 7/521 Constructional features
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 7/1821 for rotating or oscillating mirrors
• CPC Class Codes: G10K 11/004 Mounting transducers, e.g. provided with mechanical moving or orienting device mountings specially adapted to a particular sound-producing device, see the preceding groups G10K1/00 - G10K9/00, e.g. G10K1/26, G10K1/28, G10K9/22; arrangements of sonic watch equipment on submarines B63G8/39; buoys B63B22/00
• CPC Class Codes: G10K 11/355 Arcuate movement

Abstract

A scanning device, typically ultrasonic, can make a volumetric scan of a conical scanning field. A transducer having a permanent magnet at its back end is gimbal mounted in a housing. Behind the permanent magnet is a hemispheric electromagnet coil assembly having at least two wound electromagnet coils. The coils are energized in turn with an alternating current signal, with the signal applied to any coil being out of phase with the signal applied to any other coil by 180°/n, where n is the number of coils in the hemispheric electromagnet coil assembly. Volumetric scanning is possible by periodically modulating the magnitude or frequency of the signals applied to the coils.

Claims

1. A scanning device for scanning a target within a conical scanning field, using a moveable body from which scanning energy may be transmitted linearly outwardly towards a target, and from which signals which are indicative of reflected scanning energy which is reflected from a target in said conical scanning field may be derived for further storage or display, said scanning device comprising:

a housing for said scanning device, said housing having a longitudinal axis;

a moveable body having a generally planar front surface from which scanning energy is transmitted linearly outwardly and towards which reflected scanning energy is directed;

a permanent magnet physically associated with said moveable body so as to be movable therewith;

said moveable body and said permanent magnet being mounted within said housing in such a manner that they are jointly moveable with a tilt motion about a centre of rotation, with at least two degrees of freedom of movement about two axes of rotation which are perpendicularly disposed one to the other, wherein said centre of rotation is located on said longitudinal axis of said housing, and said two perpendicularly disposed axes of rotation intersect at said centre of rotation and are each perpendicular to said longitudinal axis of said housing;

at least two electromagnets having wound electromagnet coils which form a hemispheric electromagnet coil assembly; and

electric drive means for energizing said wound electromagnet coils in cyclic fashion, by applying an alternating current signal to each individual wound electromagnet coil, where the signal applied to each respective wound electromagnet coil has a differing phase than the signal applied to any other wound electromagnet coil;

wherein the alternating current signal applied to each of said wound electromagnet coils is out of phase with the alternating current signal applied to any other wound electromagnet coil; and

wherein the phase relationship among the respective alternating current signals is 180°

/n, where n is the number of wound electromagnet coils in said hemispheric electromagnet coil assembly;

whereby when scanning energy is transmitted linearly away from said moveable body, and said hemispheric electromagnet coil assembly is energized by said elective drive means, a conical scanning field is swept.

2. The scanning device of claim 1, wherein at least one of the magnitude and frequency of the alternating current signal applied to each of said wound electromagnet coils is periodically modulated so as to cause the conical path swept by said transmitted scanning energy to alternately narrow and widen, whereby a target in the conical scanning field of said scanning device is volumetrically scanned.

3. The scanning device of claim 1, wherein said moveable body is an ultrasonic transducer mounted at a first end of a moveable carriage, and said permanent magnet is mounted at an opposed second end thereof.

4. The scanning device of claim 1, wherein said moveable body is a mirror, and a source of scanning energy is directed towards said mirror in a manner so as to be re-transmitted linearly away therefrom.

5. The scanning device of claim 1, wherein said moveable body and said permanent magnet are gimbal mounted within said housing.

6. The scanning device of claim 5, wherein said moveable body and said permanent magnet are mounted on a gimbal having knife-edge bearings.

7. The scanning device of claim 1, wherein said moveable body and said permanent magnet are mounted on an elastomeric membrane which is secured within said housing.

8. The scanning device of claim 1, further comprising an annular permanent magnet mounted in said housing outwardly of said hemispheric electromagnet coil assembly, said annular permanent magnet having a polarity opposite to that of said permanent magnet mounted together with said moveable body so as to repel said permanent magnet away therefrom and towards said longitudinal axis of said housing.

9. The scanning device of claim 1, further comprising a solenoid electromagnet located on said longitudinal axis of said housing at the side of said hemispheric electromagnet coil assembly remote from said permanent magnet and a source of direct current electricity connected to said solenoid electromagnet;

whereby said solenoid electromagnet may be momentarily energized by said source of direct current electricity so as to either attract or repel said permanent magnet.

10. An ultrasonic scanner comprising the scanning device of claim 3 together with signal handling means for processing signals indicative of scanning energy reflected from a target in said conical scanning field so as to derive an image therefrom, and display means for displaying said image.

11. The scanning device of claim 3, wherein an acoustic window encloses a first end of said housing, and closure means encloses an opposed second end of said housing, and all of said ultrasonic transducer, said permanent magnet, and said hemispheric electromagnet coil assembly, are contained within said housing together with an ultrasonic sound conducting fluid.

12. The scanning device of claim 3, wherein said ultrasonic transducer and said permanent magnet are enclosed within a capsule having an acoustic window at a first end thereof remote from said permanent magnet, together with an ultrasonic conducting fluid.

13. The scanning device of claim 3, wherein an acoustic window is located at the end of said housing proximate said ultrasonic transducer, and a pliant and sealed acoustically transparent container of ultrasonic conducting fluid is mounted between said ultrasonic transducer and said acoustic window in acoustically conductive relation therewith.

14. The scanning device of claim 3, wherein a pliant and sealed acoustically transparent container of ultrasonic conducting fluid is mounted in acoustically conductive relation with said ultrasonic transducer.

15. The scanning device of claim 3, wherein an acoustic window is located at the end of said housing proximate said ultrasonic transducer, and a pliant and highly elastic self-contained ball chosen from the group consisting of an acoustically, transparent elastomer, and gelatin, is mounted between said ultrasonic transducer and said acoustic window in acoustically conductive relation therewith.

16. The scanning device of claim 3, wherein a pliant and highly elastic self-contained ball chosen from the group consisting of an acoustically transparent elastomer, and gelatin, is mounted in acoustically conductive relation with said ultrasonic transducer.