Laser illumination systems and methods for dual-excitation wavelength non-linear optical microscopy and micro-spectroscopy systems

• US 9,634,454 B1
• Filed: 07/07/2015
• Issued: 04/25/2017
• Est. Priority Date: 01/17/2012
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation), Arizona Board of Regents (University of Arizona)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation), Arizona Board of Regents (University of Arizona)
• Inventors: Kieu, Khanh, Peyghambarian, Nasser, Xie, Xiaoliang Sunney, Freudiger, Christian W., Fu, Dan
• Primary Examiner(s): Petkovsek, Daniel
• Application Number:
  US14/793,099
• Time in Patent Office: 658 Days
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 2021/653 Coherent methods [CARS]
• CPC Class Codes: G01N 2021/655 Stimulated Raman
• CPC Class Codes: G02B 21/002 Scanning microscopes scanning near field optical microscopes G01Q60/18
• CPC Class Codes: G02B 21/0032 Optical details of illumination, e.g. light-sources, pinholes, beam splitters, slits, fibers G02B21/0036 - G02B21/008; means for illumination of specimens in general G02B21/06
• CPC Class Codes: G02B 21/0064 multi-spectral or wavelength-selective arrangements, e.g. wavelength fan-out, chromatic profiling G02B21/0076 takes precedence
• CPC Class Codes: G02B 21/008 Details of detection or image processing, including general computer control
• CPC Class Codes: G02B 21/06 Means for illuminating specimens
• CPC Class Codes: G02B 21/16 adapted for ultraviolet illumination ; Fluorescence microscopes G02B21/0076 takes precedence
• CPC Class Codes: G02B 2207/114 Two photon or multiphoton effect
• CPC Class Codes: G02B 27/1006 for splitting or combining different wavelengths G02B27/1086, G02B27/141 take precedence
• CPC Class Codes: G02F 1/353 Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
• CPC Class Codes: G02F 1/354 Third or higher harmonic generation
• CPC Class Codes: G02F 1/3551 Crystals
• CPC Class Codes: G02F 1/383 of the optical fibre type
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B
• 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 3/0092 Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/06754 : Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/06791 : Fibre ring lasers fibre laser gyrometers G01C19/72
• CPC Class Codes: H01S 3/1118 : Semiconductor saturable absorbers, e.g. semiconductor saturable absorber mirrors [SESAMs]; Solid-state saturable absorbers, e.g. carbon nanotube [CNT] based
• CPC Class Codes: H01S 3/1608 : erbium
• CPC Class Codes: H01S 3/1616 : thulium
• CPC Class Codes: H01S 3/1618 : ytterbium
• CPC Class Codes: H01S 3/2308 : Amplifier arrangements, e.g. MOPA
• CPC Class Codes: H01S 3/2383 : Parallel arrangements
• CPC Class Codes: H01S 3/2391 : emitting at different wavelengths

Abstract

An illumination system is disclosed for providing dual excitation wavelength illumination for non-linear optical microscopy and micro-spectroscopy. The illumination system includes a laser system for providing a first train of pulses at a center optical frequency ω₁, a frequency converting system for providing at least a second train of pulses at a center optical frequency ω₂ and a third train of pulses at a center optical frequency ω₃, where ω₂ is different from ω₁ and ω₃ responsive to the first train of pulses, an amplifier system for amplifying the second train of pulses to provide an amplified second train of pulses, and an adjustment means for adjusting a time delay between the amplified second train of pulses and the third train of pulses for the dual-excitation wavelength illumination.

Claims

1. An illumination system for providing dual excitation wavelength illumination for non-linear optical microscopy and micro-spectroscopy, said illumination system comprising:

a laser system for providing a first train of pulses at a center optical frequency ω

₁;

a frequency converting system for providing at least a second train of pulses at a center optical frequency ω

₂ and a third train of pulses at a center optical frequency ω

₃, where ω

₂ is different from ω

₁ and ω

₃ responsive to the first train of pulses;

an amplifier system for amplifying the second train of pulses to provide an amplified second train of pulses; and

an adjustment means for adjusting a time delay between the amplified second train of pulses and the third train of pulses for the dual-excitation wavelength illumination.

2. The illumination system as claimed in claim 1, wherein the amplifier systems is a picosecond amplifier system and the amplified second train of pulses has a pulse duration of at least 0.5 picoseconds.

3. The illumination system as claimed in claim 1, that further includes an optical splitting means for splitting the second train of pulses and the third train of pulses;

and a combining means for combining the amplified second train of pulses with the third train of pulses to provide the amplified second train of pulses and the third train of pulses as a collinear train of laser pulses for the dual-excitation wavelength illumination.

4. The illumination system as claimed in claim 3, wherein the adjustment means for adjusting a time delay between the amplified second train of pulses and the third train of pulses includes a manual or motorized optical delay line.

5. The illumination system as claimed in claim 3, wherein the third split train of pulses is frequency doubled (SHG) or tripled (THG).

6. The illumination system as claimed in claim 3, wherein the third split train of pulses is frequency doubled (SHG) or tripled (THG).

7. The illumination as claimed in claim 1, wherein said illumination system further includes a second laser amplifier for amplifying the third train of pulses.

8. The illumination system as claimed in claim 7, wherein said second laser amplifier includes a tunable narrowband filter.

9. The illumination system as claimed in claim 1, wherein ω

₁=ω

₃.

10. The illumination system as claimed in claim 1, wherein the adjustment means for adjusting a time delay between the amplified second train of pulses and the third train of pulses includes a fiber of controlled length and controlled dispersion.

11. The illumination system as claimed in claim 1, wherein said laser system is an Ytterbium fiber laser.

12. The illumination system as claimed in claim 11, wherein said amplifier system is an Erbium fiber amplifier.

13. The illumination system as claimed in claim 11, wherein said amplifier system is an Thulium fiber amplifier.

14. The illumination system as claimed in claim 1, wherein said laser system is an Erbium fiber laser.

15. The illumination system as claimed in claim 14, wherein said amplifier system is a Ytterbium fiber amplifier.

16. The illumination system as claimed in claim 14, wherein said amplifier system is a Thulium fiber amplifier.

17. The illumination system as claimed in claim 14, wherein said amplifier system is a Holmium fiber amplifier.

18. The illumination system as claimed in claim 1, wherein said laser system is a Titanium Sapphire laser.

19. The illumination system as claimed in claim 1, wherein the amplified second train is frequency doubled (SHG) or tripled (THG).

20. The illumination system as claimed in claim 1, wherein said laser system includes a laser oscillator.

21. The illumination system as claimed in claim 1, wherein said frequency shifting system includes a highly non-linear fiber.

22. The illumination system as claimed in claim 1, wherein said frequency shifting system includes a photonic crystal fiber.

23. The illumination system as claimed in claim 1, wherein said amplifier system includes a tunable narrowband filter.

24. A dual-excitation wavelength non-linear optical microscopy and micro-spectroscopy system comprising:

a laser system for providing a first train of pulses at a center optical frequency ω

₁;

a frequency converting system for providing at least a second train of pulses at a center optical frequency ω

₂ and a third train of pulses at a center optical frequency ω

₃, where ω

₂ is different from ω

₁ and ω

₃ responsive to the first train of pulses;

an amplifier system for amplifying the second train of pulses to provide an amplified second train of pulses;

an adjustment means for adjusting a time delay between the amplified second train of pulses and the third train of pulses;

a focusing means for focusing the amplified second train of pulsed and the third train of pulses into a common focal volume; and

a detection means for detection means for detecting a dual-wavelength non-linear optical signal.

25. The microscopy and micro-spectroscopy system as claimed in claim 24, wherein the system further includes a scanning means for scanning the center of the common focal volume in at least two dimensions.