Single grating laser pulse stretcher and compressor

• US 5,329,398 A
• Filed: 11/05/1992
• Issued: 07/12/1994
• Est. Priority Date: 11/05/1992
• Status: Expired due to Fees

• Current Assignee: Novatec Laser Systems Incorporated
• Original Assignee: Novatec Laser Systems Incorporated
• Inventors: Lai, Ming, Lai, Shui T.
• Primary Examiner(s): Ben, Loha
• Assistant Examiner(s): Juba, Jr., John
• Application Number:
  US07/972,169
• Time in Patent Office: 614 Days
• Field of Search: 359/347, 359/348, 359/349, 359/130, 359/566, 359/572, 359/615, 359/558, 372/23, 372/25, 372/102
• US Class Current: 359/566
• CPC Class Codes: G02B 27/0911 Anamorphotic systems
• CPC Class Codes: G02B 27/4233 having a diffractive element [DOE] contributing to a non-imaging application diffusers having a diffractive element G02B5/0252; filters having a diffractive element G02B5/203; systems for controlling the direction of light having diffractive elements G02B26/0808; scanning systems having diffractive elements G02B26/106; beam shaping systems using diffractive optical elements G02B27/0944; beam splitting or combining systems operating by diffraction G02B27/1086
• 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

Abstract

A single-grating method and apparatus is described for a laser pulse stretcher and compressor. The method and apparatus exploits a two-layer vertical structure. One layer for the stretcher, and the other, for the compressor. Such a stretch-compressor is particularly suitable for using in a chirped-pulse or regenerative laser amplifier where laser wavelength tuning is desirable. When a change in the wavelength is applied, only one rotational adjustment is required to resume the alignment of the whole stretcher and compressor. This apparatus shows significant simplification in structure and alignment over the existing stretcher and compressor systems.

Claims

1. A stretcher for a pulsed laser beam, said pulsed laser beam having a predetermined frequency, comprising:

a single laser beam diffracting grating element, said grating element having a vertical and horizontal dimension;

a focusing element;

a reflector; and

a retro-reflective element;

means for directing said pulsed laser beam,

wherein said pulsed laser beam is directed firstly to said grating element, secondly from said grating element back through said focusing element to said reflector, thirdly reflected back from said reflector through said focusing element to said grating element, fourthly diffracted from said grating element to said retro-reflective element where said beam is reflected along a substantially parallel path and fifthly said pulsed laser beam is re-directed to said grating element, and sixthly diffracted from said grating element through said focusing element onto said reflector and seventhly from said reflector through said focusing element to said grating element and eighthly from said grating element out of said pulsed laser beam stretcher for further processing, laser beam is horizontally offset from said fourthly directed pulsed laser beam and said fifthly directed pulsed laser beam is horizontally offset from said sixthly directed pulsed laser beam said firstly directed pulsed laser beam is vertically offset from said eighthly directed pulsed laser beam.

2. The invention as defined in claim 1 wherein the predetermined frequency of said pulsed laser beam can be changed to a second predetermined frequency and said stretcher can be adapted to said second predetermined frequency by repositioning only said grating element.

3. The invention as defined in claim 1 wherein said focusing element is a focusing lens.

4. The invention as defined in claim 1 wherein said retro-reflecting element is a roof mirror.

5. A compressor for a pulsed laser beam, said pulsed laser beam having a predetermined frequency comprising:

a first retro-reflector;

a diffracting grating element;

a second retro-reflector; and

a means for directing said laser beam;

wherein said pulsed laser beam is firstly directed to said grating element and secondly diffracted from said grating element to said first retro-reflector, thirdly reflected from said first retro-reflector to said grating element, fourthly the pulsed laser beam is directed to said second retro-reflector where the beam elevation is changed, fifthly said pulsed laser beam is directed back to said grating element, sixthly directed to said first retro-reflector, seventhly reflected back to said grating element and eightly out of said compressor, said secondly directed pulsed laser beam is horizontally off set from said thirdly directed pulsed laser beam and said firstly directed pulsed laser beam is off set vertically from said eighthly directed pulsed laser beam.

6. The invention as defined in claim 5 wherein the predetermined frequency of said pulsed laser beam can be changed to a second predetermined frequency and said compressor can be adapted to said second predetermined frequency by repositioning only said grating element.

7. The invention as defined in claim 5 wherein said retro-reflecting elements are roof mirror.

8. A combined stretcher and compressor for a pulsed laser beam, said pulsed laser beam having a predetermined frequency, comprising:

a single laser beam diffracting grating element, said single grating element having a vertical and horizontal dimension;

a focusing element;

a first reflector;

a first retro-reflector;

a second retro-reflector;

a third retro-reflector;

a pulsed laser amplifying means for amplifying said pulsed laser beam, having an input and an output; and

a means for directing said laser beam;

wherein said pulsed laser beam is directed firstly to said grating element, secondly from said grating element through said focusing element to said first reflector, thirdly reflected back from said first reflector through said focusing element to said grating element, fourthly diffracted from said grating element and directed to said first retro-reflector where said beam is reflected along a substantially parallel path and fifthly said pulsed laser beam is re-directed back to said grating element, and sixthly diffracted from said grating element through said focusing element onto said first reflector and seventhly from said first reflector through said focusing element to said grating element and eightly from said grating element out of said pulsed laser beam stretcher for further processing, and said firstly directed pulsed laser beam is vertically offset from said eighthly directed pulsed laser beam and the output beam from said stretcher is directed to the input of said pulsed laser amplifying means, the amplified output from said pulsed laser amplifying means is firstly directed to said grating element and secondly diffracted from said grating element to said second retro-reflector, thirdly directly from said second retro-reflector to said grating element, fourthly said pulsed laser beam directed to said third retro-reflector where its beam elevation is changed, fifthly said pulsed laser beam is directed back to said grating means, sixthly directed to said second retro-reflector, seventhly reflected back to said grating element and eighthly directed out of said compressor, said secondly directed pulsed laser beam from said amplifier is horizontally off set from said thirdly directed pulsed laser beam from said laser amplifier and said firstly directed pulsed laser beam from said amplifier is off set vertically from said eighthly directed pulsed laser beam exiting from the output of said compressor.

9. The invention as defined in claim 8 wherein the predetermined frequency of said pulsed laser beam can be changed to a second predetermined frequency and said stretcher and compressor can be adapted to said second predetermined frequency by repositioning only said grating element.

10. The invention as defined in claim 8 wherein said focusing element is a focusing lens.

11. The invention as defined in claim 8 wherein at least said first and second retro-reflecting elements are roof mirrors.

12. The invention as defined in claim 8 wherein the predetermined spectral frequency of said pulsed laser beam can be changed to a second predetermined spectral frequency and said stretcher and compressor can be adapted to said second predetermined frequency by repositioning said grating element.

13. A combined laser pulse stretcher and compressor device comprising:

a laser source generating a pulsed laser beam with predetermined spectral content and predetermined temporal pulse width;

a single optical diffraction grating element;

a laser pulse stretcher means for temporally stretching pulses of said pulsed laser beam; and

a laser pulse compressor means for temporally compressing pulses of said pulsed laser beam,

such that said single optical diffraction grating element is used in both the laser pulse stretcher means and the laser pulse compressor means to control the temporal stretching and compressing of the pulses of said pulsed laser beam;

wherein a predetermined spectral frequency of said pulsed laser beam can be changed to a second predetermined spectral frequency and said laser pulse stretcher means and said laser pulse compressor means can be adapted to said second predetermined spectral frequency by repositioning said single optical diffraction grating element.

14. The invention as defined in claim 13 wherein said laser pulse stretcher means, comprises:

means for directing said pulsed laser beam;

a grating element, said grating element having a vertical and horizontal dimension;

a focusing element;

a mirror reflector;

a roof mirror retro-reflective element;

said pulsed laser beam is directed firstly to said grating element, secondly diffracted from said grating element through said focusing element to said reflector, thirdly reflected back from said reflector through said focusing element to said grating element, fourthly diffracted from said grating element to said retro-reflective element where said beam is reflected along a substantially parallel path, and fifthly said pulsed laser beam is re-directed to said grating element, and sixthly diffracted from said grating element through said focusing element onto said reflector, seventhly reflected from said reflector through said focusing element back to said grating element, and eighthly diffracted from said grating element out of said laser pulse stretcher for further processing.

15. The invention as defined in claim 13 wherein said laser pulse compressor means comprises:

means for directing said laser source;

a grating element, said grating element having a vertical and horizontal dimension;

a first roof mirror retro-reflector;

a second roof mirror retro-reflector;

said pulsed laser beam is firstly directed to said grating element and secondly diffracted from said grating element to said first retro-reflector, thirdly reflected from said first retro-reflector to said grating element, fourthly the pulsed laser beam is diffracted to said second retro-reflector where the beam elevation is changed, fifthly said pulsed laser beam is directed back to said grating means, sixthly directed to said first retro-reflector, seventhly reflected back to said grating element and eighthly diffracted out of said compressor, said secondly directed pulsed laser beam is horizontally offset from said thirdly directed pulsed laser beam, and said fifthly directed pulsed laser beam is offset vertically from said fourthly directed pulsed laser beam.

16. The invention as defined in claim 13 wherein said grating element comprises at least two sections.