Apparatus and methods for full spatio-temporal characterization of ultrashort light pulses
Apparatus and methods of full spatio-temporal characterization of ultrashort pulses from an input pulse-beam source. An interferometer system generates a first, second, third, and fourth replica of the input pulse-beam such that the second replica has a varying delay with respect to the first replica and the fourth replica has a varying delay with respect to the third replica. A reference plane is imaged onto a nonlinear spectral measurement device based upon the first and second replicas, and the reference plane is also imaged onto a wavefront sensitive (WFS) imaging element based on the third and fourth replicas. The signals from the WFS imaging element and the spectral signal are used to compute a pulse temporal spectral profile of the input pulse-beam.
1. Apparatus for full spatio-temporal characterization of ultrashort pulses comprising:
an input pulse-beam source of ultrashort pulses;
an interferometer system configured to generate a first, second, third, and fourth replica of the input pulse-beam such that the second replica has a varying delay with respect to the first replica and the fourth replica has a varying delay with respect to the third replica;
a spectral measurement path including a spectral-measurement-path imaging element and a nonlinear spectral measurement device;
a wavefront sensitive (WFS) path including a WFS imaging element and a WFS measurement device; and
a processor;
wherein the apparatus is configured such that the spectral-measurement-path imaging element images a reference plane at the nonlinear spectral measurement device based upon the first and second replicas;
wherein the WFS imaging element images the reference plane at the WFS measurement device based upon the third and fourth replicas;
wherein the WFS measurement device generates a WFS signal based upon the imaged reference plane at the WFS measurement device;
wherein the nonlinear spectral measurement device generates a spectral signal based upon the imaged reference plane at the nonlinear spectral measurement device; and
wherein the processor is configured to receive the WFS signal and the spectral signal and to compute a pulse temporal spectral profile of the input pulse-beam.
2. The apparatus of claim 1 wherein the WFS measurement device is a Shack-Hartman wavefront sensor.
3. The apparatus of claim 1 wherein the WFS measurement device is a lateral shearing interferometer.
4. The apparatus of claim 1 wherein the interferometer system includes a single interferometer configured to generate all of the replicas and vary the delay among them.
5. The apparatus of claim 4 wherein the interferometer is a Mach-Zehnder interferometer.
6. The apparatus of claim 1 further comprising a calibration mechanism configured to block either the spectral measurement path or the wavefront sensitive path with either a diffraction limited aperture or a mask and to record WFS and spectral data of a fiducial image at the reference plane.
7. The apparatus of claim 1 wherein the nonlinear spectral measurement device comprises a nonlinear crystal and a spectrometer, the spectrometer configured to sample the spectral measurement path.
8. A method of fully spatio-temporally characterizing ultrashort pulses comprising the steps of:
providing an input pulse-beam of ultrashort pulses;
generating a first, second, third, and fourth replica of the input pulse-beam such that the second replica has a varying delay with respect to the first replica and the fourth replica has a varying delay with respect to the third replica;
providing a nonlinear spectral measurement device;
imaging a reference plane at the nonlinear spectral measurement device based upon the first and second replicas;
generating a spectral signal with the nonlinear spectral measurement device based upon the imaged reference plane at the nonlinear spectral measurement device providing a wavefront sensitive (WFS) imaging element;
imaging the reference plane at a WFS measurement device based upon the third and fourth replicas;
generating a WFS signal with the WFS measurement device based upon the imaged reference plane at the WFS measurement device; and
receiving the WFS signal and the spectral signal and computing a pulse temporal spectral profile of the input pulse-beam.
9. The method of claim 8 wherein the WFS measurement device is a Shack-Hartman wavefront sensor.
10. The method of claim 8 wherein the WFS measurement device is a lateral shearing interferometer.
11. The method of claim 8 wherein the step of generating a first, second, third, and fourth replica utilizes a single interferometer to generate all of the replicas and vary the delay among them.
12. The method of claim 11 wherein the interferometer is a Mach-Zehnder interferometer.
13. The method of claim 8 further comprising a calibration process including the steps of blocking either the first and second replicas or the third and fourth replicas and recording WFS and spectral data of a fiducial image at the reference plane.
14. The method of claim 13 further comprising the steps of unblocking the replicas blocked in claim 13 , blocking the remaining replicas, and recording WFS and spectral data of a fiducial image at the reference plane.