CONTROL SYSTEM AND APPARATUS FOR USE WITH ULTRA-FAST LASER

• US 20090257464A1
• Filed: 06/23/2009
• Published: 10/15/2009
• Est. Priority Date: 01/30/2001
• Status: Active Grant

• Current Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Dantus, Marcos, Pastirk, Igor, Comstock, Matthew, Lozovoy, Vadim V.
• Granted Patent: US 8,300,669 B2
• Time in Patent Office: Days
• US Class Current: 372/25
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/0073 by tomography, i.e. reconstruction of 3D images from 2D projections A61B5/0066 takes precedence
• CPC Class Codes: G01B 9/02014 by using pulsed light
• CPC Class Codes: G01B 9/02091 Tomographic interferometers, e.g. based on optical coherence
• CPC Class Codes: G01J 11/00 Measuring the characteristics of individual optical pulses or of optical pulse trains
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53
• CPC Class Codes: H01J 49/164 Laser desorption/ionisation, e.g. matrix-assisted laser desorption/ionisation [MALDI] sample holders H01J49/0418
• CPC Class Codes: H01S 3/0057 Temporal shaping, e.g. pulse compression, frequency chirping soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108
• CPC Class Codes: H01S 3/1307 Stabilisation of the phase
• CPC Class Codes: H01S 3/2325 Multi-pass amplifiers, e.g. regenerative amplifiers
• CPC Class Codes: H01S 3/235 Regenerative amplifiers

Abstract

A control system and apparatus for use with an ultra-fast laser is provided. In another aspect of the present invention, the apparatus includes a laser, pulse shaper, detection device and control system. A multiphoton intrapulse interference method is used to characterize the spectral phase of laser pulses and to compensate any distortions in an additional aspect of the present invention. In another aspect of the present invention, a system employs multiphoton intrapulse interference phase scan. Furthermore, another aspect of the present invention locates a pulse shaper and/or MIIPS unit between a laser oscillator and an output of a laser amplifier.

Claims

1. A laser system comprising:

a laser operably emitting a laser beam pulse;

a pulse shaper operably varying a characteristic of the pulse; and

a microscope operably receiving the shaped pulse;

wherein the shaper assists in creating multiphoton intrapulse interference in the pulse to control multiphoton excitation.

2. The system of claim 1, wherein the pulse shaper assists in suppressing three photon or greater transitions induced by the pulse.

3. The system of claim 1, wherein the shaped pulse selectively excites probe molecules.

4. The system of claim 1, wherein the pulse has a duration less than 51 femtoseconds at a focal plane.

5. The system of claim 1, wherein the pulse has a duration less than 10 femtoseconds at a focal plane.

6. The system of claim 1, further comprising:

a detector;

a programmable controller connected to the shaper and detector;

wherein the controller, detector and pulse shaper act to measure phase distortions in the laser pulse and the pulse shaper compensates for the phase distortions at a focal plane.

7. The system of claim 1, further comprising a programmable controller connected to the pulse shaper compensating for phase distortions at the specimen introduced by different microscope objectives, by subtracting a phase distortion associated with each objective, the associated phase distortion being stored in memory of the controller.

8. The system of claim 1, further comprising a controller connected to the pulse shaper, the laser being tunable, and the controller and shaper compensating for phase distortions of the laser beam pulse at a specimen as a laser wavelength is tuned to different frequencies.

9. A laser system comprising:

a coherent light source operably producing laser beam pulses each having a duration less than 51 femtoseconds;

a microscope receiving the pulses;

optics acting upon the pulses;

a pulse shaper shaping and adaptively correcting essentially all orders of spectral phase dispersion introduced by the optics and microscope; and

a detector detecting nonlinear optical signals while ignoring the excitation light source.

10. The system of claim 9, wherein the shaper assists in suppressing three photon or greater transitions in the pulses.

11. The system of claim 9, wherein the shaped pulses selectively excite probe molecules.

12. The system of claim 9, wherein the at least one of the optics is an objective of the microscope.

13. The system of claim 9, wherein at least one of the pulses has a duration less than 10 femtoseconds.

14. The system of claim 9, further comprising:

a programmable controller connected to the shaper and detector;

wherein the controller, detector and pulse shaper act to measure phase distortions output by the laser at a focal plane and the pulse shaper compensates for the phase distortions.

15. The system of claim 9, further comprising a programmable controller connected to the pulse shaper compensating for phase distortions at the specimen introduced by the optics which include different microscope objectives, by subtracting a phase distortion associated with each objective, the associated phase distortion being stored in memory of the controller.

16. The system of claim 9, further comprising a controller connected to the pulse shaper, the laser being tunable, and the controller and shaper compensating for phase distortions of at least one of the laser beam pulses at a specimen as a laser wavelength is tuned to different frequencies.

17. The system of claim 9, further comprising multiphoton intrapulse interference software instructions automatically causing the shaper to compensate for the distortions in the pulses.

18. A laser system comprising:

at least one laser beam pulse;

a pulse shaper shaping and controlling nonlinear optical processes in the pulse;

a microscope acting upon the shaped and controlled pulse; and

a programmable controller including programmed instructions operably controlling the shaper in a calculated manner without use of a learning algorithm.

19. The system of claim 18, wherein the controller comprises a memory database, phase distortions introduced by a microscope objective at a wavelength of excitation are stored in the memory database and are automatically adjusted by at least the shaper.

20. The system of claim 18, wherein the controller automatically causes a characterization measurement and compensation for the pulse.

21. The system of claim 18, wherein the shaper assists in suppressing three photon or greater transitions in the pulse.

22. The system of claim 18, wherein the shaped pulse selectively excites probe molecules.

23. The system of claim 18, wherein the pulse has a duration less than 51 femtoseconds.

24. The system of claim 18, wherein the pulse has a duration less than 10 femtoseconds.

25. The system of claim 18, further comprising:

a detector;

the programmable controller being connected to the shaper and detector;

wherein the controller, detector and pulse shaper act to measure phase distortions output by the laser and the pulse shaper compensates for the phase distortions.

26. The system of claim 18, wherein the programmable controller is connected to the pulse shaper compensating for phase distortions at the specimen introduced by different microscope objectives, by subtracting a phase distortion associated with each objective, the associated phase distortion being stored in memory of the controller.

27. The system of claim 18, wherein the controller is connected to the pulse shaper, the laser is tunable, and the controller and shaper compensate for phase distortions of the laser beam pulse at a specimen as a laser wavelength is tuned to different frequencies.

28. The system of claim 18, further comprising multiphoton intrapulse interference software instructions automatically causing the shaper to compensate for the distortions in the pulse.

29. A laser system comprising:

laser beam pulses, at least one of the pulses having a duration less than 51 femtoseconds;

a microscope including an objective;

a programmable controller, the microscope being connected to and operably communicating with the controller; and

data indicative of phase distortions in at least one of the pulses, introduced by the microscope objective and laser scanning optics, being stored in a memory database in the controller.

30. The system of claim 29, further comprising a shaper connected to the controller, the controller sending a signal to the shaper in response to the detected phase distortions in order to compensate for the distortions in at least one of the pulses.

31. The system of claim 30, wherein the controller moves an optical component associated with the shaper to compensate for the distortions.

32. The system of claim 31, wherein the optical component is a mirror.

33. The system of claim 29, further comprising a detector connected to an output of the objective, the detector including a nonlinear medium to generate a second harmonic associated with the pulses and a spectrometer to obtain a spectrum of the second harmonic, the detector operably sending a signal to the controller which then extracts a phase compensation for correcting and producing transform limited pulses at a microscope sample position.

34. The system of claim 33, further comprising computer software used by the controller to optimize a spectral phase of the pulses to change the photonic excitation of the pulses used for photodynamic therapy on live cells.

35. The system of claim 29, further comprising a shaper assisting in suppressing three photon or greater transitions in the pulses.

36. The system of claim 35, further comprising multiphoton intrapulse interference software instructions automatically causing the shaper to compensate for the distortions in the pulse.

37. The system of claim 29, wherein the pulse has a duration less than 10 femtoseconds.

38. A laser system comprising:

a laser operably emitting a laser beam pulse;

a microscope operably receiving the pulse, the microscope includes different objectives;

a programmable controller; and

optics assisting in measuring phase distortions at a focal plane of the objectives and the controller automatically changing a characteristic of the optics if the objectives are changed.

39. The system of claim 38, wherein the optics are fixed and affect the pulse in a predetermined manner.

40. The system of claim 38, wherein the optics include a shaper operably controlled by the controller to change the shape of the pulse.

41. The system of claim 38, wherein the controller comprises a memory database, phase distortions introduced by the microscope objectives at a wavelength of excitation are stored in the memory database and are automatically adjusted by the optics.

42. A laser system comprising:

an oscillator emitting laser beam pulses;

a microscope performing nonlinear optical microscopy with the pulses; and

a compressor comprising at least one optic which corrects for nonlinear optical dispersion of at least one of the pulses caused by an optical member associated with the microscope.

43. The system of claim 42, further comprising a programmable controller that automatically changes a characteristic of the at least one optic in response to a detected distortion in at least one of the pulses.

44. The system of claim 42, wherein the at least one optic includes a movable prism to correct for linear chirp.

45. The system of claim 42, wherein the at least one optic includes a movable mirror to correct for nonlinear dispersion.

46. The system of claim 42, wherein the at least one optic includes a pulse shaper.

47. The system of claim 42, wherein the at least one optic adjusts intensity of the pulses according to a focal plane depth inside a specimen being acted upon by the pulses.

48. The system of claim 42, wherein the at least one optic corrects for dispersion introduced by a laser-scanning optic.

49. The system of claim 42, wherein the at least one optic includes a spatial light modulator and a curved mirror located downstream of the spatial light modulator.

50. The system of claim 42, wherein the at least one optic eliminates third and higher order dispersion to achieve transform limited pulses at a focal plane of the microscope.

51. The system of claim 42, wherein the oscillator is tunable and distortion compensation is introduced in advance of the dispersion associated with the microscopy based on a pulse characteristic detected during or after the microscopy.

52. A laser system comprising:

a tunable oscillator emitting at least one laser beam pulse;

a detector operably detecting distortion in the at least one pulse;

a compressor;

a programmable controller connected to the oscillator;

at least one optic operably changing a characteristic of the at least one pulse in response to a signal from the controller based at least in part on a real-time signal from the detector, the at least one optic being located in or upstream of the compressor; and

a microscope operably conducting nonlinear optical microscopy with the at least one pulse.

53. The system of claim 52, wherein the at least one optic includes a movable prism to correct for linear chirp.

54. The system of claim 52, wherein the at least one optic includes a movable mirror to correct for nonlinear dispersion.

55. The system of claim 52, wherein the at least one optic includes a pulse shaper.

56. The system of claim 52, wherein the controller comprises a memory database, phase distortions introduced by the microscope objectives at a wavelength of excitation are stored in the memory database and are automatically adjusted by the optics.

57. The system of claim 52, wherein the pulse has a duration less than 51 femtoseconds.

58. The system of claim 52, wherein the programmable controller is connected to the at least one optic compensating for phase distortions at the specimen introduced by different microscope objectives, by subtracting a phase distortion associated with each objective, the associated phase distortion being stored in memory of the controller.

59. The system of claim 52, wherein the controller includes programmed instructions controlling the at least one optic in a calculated manner without using a learning algorithm to compensate for a pulse distortion.

60. A laser system comprising:

a laser emitting pulses;

a pulse shaper;

a microscope; and

a programmable controller selectively causing the shaper to optimize at least one of the emitting source pulses for;

(a) two photon excitation, (b) three photon excitation, (c) second harmonic imaging, (d) third harmonic imaging, and (e) four wave mixing imaging.

61. The system of claim 60, wherein laser source bandwidth is broadened by self phase modulation.

62. The system of claim 60, wherein the controller comprises a memory database, phase distortions introduced by microscope objectives at a wavelength of excitation are stored in the memory database and are automatically adjusted by shaper.

63. The system of claim 60, further comprising multiphoton intrapulse interference software instructions automatically causing the shaper to compensate for the distortions in the pulse.

64. A laser system comprising:

a fiber optic cable;

a laser emitting a laser beam pulse;

a pulse shaper operably shaping the pulse; and

a microscope objective;

the pulse being transmitted by the fiber optic cable from the laser.

65. The system of claim 64, further comprising multiphoton intrapulse interference software instructions automatically causing the shaper to compensate for the distortions in the pulse.

66. The system of claim 64, wherein the pulse shaper assists in suppressing three photon or greater transitions induced by the pulse.

67. The system of claim 64, wherein the pulse has a duration less than 51 femtoseconds at a focal plane.

68. A method of using a laser for nonlinear optical microscopy, the method comprising:

(a) emitting at least one laser beam pulse;

(b) focusing the at least one pulse with a microscope;

(c) detecting undesired distortions in the at least one pulse after or while the microscope is acting upon the at least one pulse; and

(d) calculating a correction to compensate for the pulse distortions within 15 seconds or less.

69. The method of claim 68, further comprising a computer including software which calculates the desired correction without an evolutionary learning algorithm.

70. The method of claim 68, further comprising automatically using a computer to vary the shape of the pulses in response to the detecting and calculating steps.

71. The method of claim 68, further comprising:

(a) introducing a reference phase into a train of the pulses;

(b) measuring a characteristic of the output pulses;

(c) calculating a spectral phase from the measured characteristics;

(d) introducing a compensation phase approaching a desired pulse; and

(e) repeating the introducing step (a) through introducing step (d) multiple times to reduce a time-bandwidth product of the output pulse.

72. The method of claim 68, further comprising using programmable instructions to implement multiphoton intrapulse interference phase scan characterization and compensation on the at least one pulse.