1. Oelze - ECE 571 Lecture 2 Biological Measurement 1 BIOE 571

2. Oelze - ECE 571 Lecture 2 I. Topics Covered Today Generation of ultrasoundGeneration of ultrasound Types of sourcesTypes of sources Importance of bandwidth to ultrasonic imagingImportance of bandwidth to ultrasonic imaging Importance of field characteristics of sources to ultrasonic imagingImportance of field characteristics of sources to ultrasonic imaging Modeling of fieldsModeling of fields

3. Oelze - ECE 571 Lecture 2 Single-element Transducer Wire Damping Material Crystal Acoustic Matching Layer Insulating Layer

4. Oelze - ECE 571 Lecture 2 Importance of Bandwidth h(t) v(t) v(t)*h(t)

5. Oelze - ECE 571 Lecture 2 Range Resolution T1T1T1T1 T2T2T2T2 A-mode

6. Oelze - ECE 571 Lecture 2 Beam Patterns

7. Oelze - ECE 571 Lecture 2 Imaging with a Flat Piston

8. Oelze - ECE 571 Lecture 2 Imaging with a Flat Piston

9. Oelze - ECE 571 Lecture 2 Imaging with a Flat Piston

10. Oelze - ECE 571 Lecture 2 Imaging with a Flat Piston

11. Oelze - ECE 571 Lecture 2 Imaging with a Flat Piston

12. Oelze - ECE 571 Lecture 2 Imaging with a Flat Piston

13. Oelze - ECE 571 Lecture 2 Imaging with a Flat Piston

14. Oelze - ECE 571 Lecture 2 B-Mode Imaging

15. Oelze - ECE 571 Lecture 2 B-Mode Imaging

16. Oelze - ECE 571 Lecture 2 B-Mode Imaging

17. Oelze - ECE 571 Lecture 2 B-Mode Imaging

18. Oelze - ECE 571 Lecture 2 B-Mode Imaging

19. Oelze - ECE 571 Lecture 2 B-Mode Imaging

20. Oelze - ECE 571 Lecture 2 B-Mode Imaging

21. Oelze - ECE 571 Lecture 2 B-Mode Imaging

22. Oelze - ECE 571 Lecture 2 B-Mode Imaging

23. Oelze - ECE 571 Lecture 2 B-Mode Imaging

24. Oelze - ECE 571 Lecture 2 B-Mode Imaging

25. Oelze - ECE 571 Lecture 2 B-Mode Imaging

26. Oelze - ECE 571 Lecture 2 B-Mode Imaging

27. Oelze - ECE 571 Lecture 2 B-Mode Imaging

28. Oelze - ECE 571 Lecture 2 Array Transducers

29. Oelze - ECE 571 Lecture 2 Linear Array 1.Can steer beam in azimuth plane only (along y) 2.Non-symmetric beam (tighter in y than x) 3.Can focus to different depths x y

30. Oelze - ECE 571 Lecture 2 Annular Array 1.Can change focal length 2.Symmetric beam x y

31. Oelze - ECE 571 Lecture 2 1.5D Array 1.Can steer beam in azimuth plane (y) 2.Non-symmetric beam (tighter in y than x) 3.The transverse plane (x) is used for elevational focusing x y

32. Oelze - ECE 571 Lecture 2 2D Array 1.Can steer beam in both directions (x and y) 2.Elevational focusing 3.Many channels needed to operate x y

33. Oelze - ECE 571 Lecture 2 Array Imaging: Steering, Low F-Number

34. Oelze - ECE 571 Lecture 2 Array Imaging: Steering, Low F-Number

35. Oelze - ECE 571 Lecture 2 Array Imaging: Steering, Low F-Number

36. Oelze - ECE 571 Lecture 2 Array Imaging: Steering, Low F-Number

37. Oelze - ECE 571 Lecture 2 Array Imaging: Steering, Low F-Number

38. Oelze - ECE 571 Lecture 2 Array Imaging: Steering, Low F-Number

39. Oelze - ECE 571 Lecture 2 Array Imaging: Steering, High F-Number Same Trade-offs as with single elements except, no need to translate source (electronic steering) and no need to use multiple transducers with different f-numbers (electronic focusing)…

40. Oelze - ECE 571 Lecture 2 Simple Linear Array: Mainlobes kd = 8.16 N = 10 Multiple main lobes can occur, which causes image degradation in a ultrasonic imaging system.

41. Oelze - ECE 571 Lecture 2 Simple Linear Array: Mainlobes kd = 5.6549 N = 10 Only one mainlobe and no grating lobes

42. Oelze - ECE 571 Lecture 2 Simple Linear Array: Steering kd = 5.6549 N = 10

43. Oelze - ECE 571 Lecture 2 Simple Linear Array: Steering kd = 5.6549 N = 10 With same settings and steering the beam to 45 degrees, we can see the mainlobe at -23 degrees (but still 10 lobes away).

44. Oelze - ECE 571 Lecture 2 Simple Linear Array: Steering kd = 2.8724 N = 10 One mainlobe, but fundamental engineering trade-off is that the mainlobe is wider.

45. Oelze - ECE 571 Lecture 2 Linear Array Element has width 2a and height 2b x y

46. Oelze - ECE 571 Lecture 2 Simple Linear Array: Element Factor - H e - H e -- H H TOT H TOT kd = 5.6549 N = 10.

47. Oelze - ECE 571 Lecture 2 Simple Linear Array: Element Factor - H e - H e -- H H TOT H TOT kd = 8.482 N = 10.

48. Oelze - ECE 571 Lecture 2 Simple Linear Array: Element factor - H e - H e -- H H TOT H TOT kd = 5.6549 N = 10.

49. Oelze - ECE 571 Lecture 2 Simple Linear Array: Steering - H e - H e -- H H TOT H TOT kd = 5.6549 N = 10.

50. Oelze - ECE 571 Lecture 2 Simple Linear Array: Steering - H e - H e -- H H TOT H TOT kd = 2.8274 N = 10.

51. Oelze - ECE 571 Lecture 2 Simple Linear Array: Apodization -- H - apodization H - no apodization H - no apodization kd = 2.8274 N = 10

52. Oelze - ECE 571 Lecture 2 Simple Linear Array: Apodization kd = 5.1408 N = 10 -- H - apodization H - no apodization H - no apodization 0° steering 0° steering

53. Oelze - ECE 571 Lecture 2 Simple Linear Array: Apodization kd = 5.1408 N = 10 -- H - apodization H - no apodization H - no apodization 45° steering 45° steering