ACOUSTIC MICRO IMAGING DEVICE HAVING AT LEAST ONE BALANCED LINEAR MOTOR ASSEMBLY

Abstract

A scanning acoustic microscope including an ultrasonic transducer and a balanced linear motor assembly is disclosed. The balanced linear motor assembly includes a counterweight that is mounted for movement along a linear path that is parallel to the first linear path on which the transducer travels. The counterweight has a mass that is generally equal to the mass of the rotor and the transducer. The counterweight is being adapted to be moved, when the scanning acoustic microscope is used to interrogate a sample, along the second linear path at the same time that the rotor and transducer are being moved along the first linear path to allow the transducer to accelerate and decelerate without creating vibration.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Various examples objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

FIG. 1 is a schematic drawing which shows a scanning acoustic microscope that incorporates aspects of the present invention;

FIG. 2A-2C are general, schematic diagrams which illustrate a first embodiment of the present invention that includes three separate balanced linear motor assemblies that are used to drive an ultrasonic transducer in the X, Y and Z directions;

FIG. 2D is a drawing which illustrates the space in which the ultrasonic transducer shown in FIGS. 2A-2C can be moved from an initial position to an outer limit in each of the X, Y and Z directions;

FIGS. 3 and 3A-3B are perspective views of a balanced linear motor assembly that is used to move an ultrasonic transducer along the X axis;

FIGS. 3C and 3D are close-up views of a portion of the balanced linear motor assembly that is shown in FIGS. 3-3B;

FIGS. 4A-4C illustrate a second embodiment of the present invention, in which separate balanced linear motor assemblies are used to control the movement of an ultrasonic transducer in the X and Y directions, with a conventional stepper motor assembly being used to control transducer movement in the Z direction;

FIG. 5 is a general, schematic diagram of an embodiment of the present invention, in which two ultrasonic transducers are mounted on the stator of a linear motor for movement in opposite directions along the X axis defined by the linear motor stator; and

FIG. 6 is a general flowchart that illustrates how a graphical interface can be used to define the path of movement of an ultrasonic transducer to allow the scan of a sample to take place.

Claims

1. A scanning acoustic microscope, comprising: an ultrasonic transducer:a balanced linear motor assembly including a rotor on which the transducer is mounted,a stator on which the rotor and transducer are mounted for movement along a first linear path defined by the stator, anda counterweight that is mounted for movement along a second linear path that is parallel to the first linear path, the counterweight having a mass that is generally equal to the mass of the rotor and the transducer;a controller that is electrically connected to the transducer and the balanced linear motor assembly, the controller being adapted to cause the rotor and transducer to be moved along the first linear path in a predetermined sequence of movements to at least partially interrogate a sample; andthe counterweight being adapted to be moved, when the sample is being interrogated, along the second linear path at the same time that the rotor and transducer are being moved along the first linear path.

2. The scanning acoustic microscope of claim 1, wherein the transducer follows one or more non-linear traces when the sample is being interrogated.

3. The scanning acoustic microscope of claim 1, wherein the transducer is operatively coupled to the sample via a coupling medium when the sample is being interrogated, the controller being adapted to cause the ultrasonic transducer to emit a pulse of acoustic energy toward each one of a plurality of three-dimensionally varied points located within a given volume defined inside of the sample, the transducer having, for each one of the pulses, a focal point that is disposed at the same location within the given volume of the sample as the corresponding one of the three dimensionally varied points.

4. The scanning acoustic microscope of claim 1, wherein the transducer is operatively coupled to the sample via a coupling medium when the sample is being interrogated, the controller being adapted to cause the ultrasonic transducer to emit a pulse of acoustic energy toward each one of a plurality of three-dimensionally varied points located within a given volume defined inside of the sample, the transducer having, for each one of the pulses, a focal point that is disposed at the same location within the given volume of the sample as the corresponding one of the three dimensionally varied points, the controller being further adapted to cause the transducer to receive a reflection signal corresponding to each one of the pulses, each one of the reflection signals comprising an A-Scan of the sample that is in-focus at the point within the given volume of the sample corresponding thereto, all of the reflection signals representing acoustic impedance features present within the given volume defined inside of the sample.

5. The scanning acoustic microscope of claim 1, further comprising a second linear motor assembly for moving at least the transducer in a direction that is perpendicular to the first linear path.

6. The scanning acoustic microscope of claim 1, further comprising a second balanced motor assembly for moving at least the transducer in a direction that is perpendicular to the first linear path.

7. The scanning acoustic microscope of claim 1, wherein the first linear path is co-linear with the second linear path.

8. The scanning acoustic microscope of claim 1, wherein the counterweight comprises a second ultrasonic transducer.

9. The scanning acoustic microscope of claim 1, wherein the transducer can be returned to a selected speed of the balanced linear motor assembly when changing directions without inducing vibration.

10. The scanning acoustic microscope of claim 1, wherein the sample comprises a microelectronic sample.

11. The scanning acoustic microscope of claim 1, further comprising a belt and pulley assembly that connects the counterweight to the transducer and rotor.

12. The scanning acoustic microscope of claim 1, wherein controller is adapted to cause the transducer to be moved in an X-Y raster scan with respect to the sample.

13. The scanning acoustic microscope of claim 1, wherein the first and second linear paths are spaced apart from each other, the center of the mass of the counterweight being located to reduce at least some of the rotational forces that are generated when the transducer is slowed down and changes direction.

14. The scanning acoustic microscope of claim 1, wherein the sample comprises a sealed package.

15. The scanning acoustic microscope of claim 1, wherein the sample comprises a biological material.