Method and Apparatus for Ultrafast Time-Resolved Digital Holography

Patent metadata

Field	Value
Publication number	US-2018329191-A1
Application number	US-201715670683-A
Country	US
Kind code	A1
Filing date	Aug 7, 2017
Priority date	May 11, 2017
Publication date	Nov 15, 2018
Grant date	—

Abstract

A method for ultrafast time-resolved digital holography comprises (a) providing tunable timescale at least two tick-tock pulses arriving on a sample to be measured at various timescales, (b) spatial encoding for wavefronts of the sample by utilizing at least one optical encoder, (c) utilizing a digital holographic access unit to record a composite hologram of the spatial encoded wavefronts by the same single pulse source, (d) utilizing an encoder for obtaining at least two holograms, and (e) utilizing a compressive sensing approach or a non-linear image restoration approach and a wavefront reconstruction approach to obtain the reconstructed wavefronts information of the sample.

First claim

What is claimed is:

1 . A method for time-resolved digital holography, comprising:
providing at least two beam pulses with adjustable elapsed time which arrive on a sample under measuring at different time points; spatially encoding for a wavefront of said at least two beam pulses by an optical encoder; recording a one-shot composite digital hologram of said encoded spatial wavefront by a digital holographic access unit in a single exposing process; decoding said composite digital hologram to obtain at least two different digital holograms by at least one decoder; utilizing an image processing approach for processing said at least two different digital holograms to recover hologram data of said sample; and utilizing a wavefront reconstructing approach to reconstruct said hologram data to obtain a reconstructed wavefront of said sample.

2 . The method of claim 1 , wherein said optical encoder includes a spatial light modulator.

3 . The method of claim 1 , wherein said optical encoder includes a micro display.

4 . The method of claim 1 , wherein said digital holographic access unit includes a photodetector array.

5 . The method of claim 1 , wherein said digital holographic access unit includes an image sensor.

6 . The method of claim 1 , wherein said wavefront reconstructing approach includes Fourier transform approach.

7 . The method of claim 1 , wherein said wavefront reconstructing approach includes convolution approach.

8 . The method of claim 1 , wherein said wavefront reconstructing approach includes angular spectrum approach.

9 . The method of claim 1 , wherein said wavefront reconstructing approach includes Fresnel diffraction approximation approach.

10 . The method of claim 1 , wherein said image processing approach includes a compressive sensing approach.

11 . The method of claim 1 , wherein said image processing approach includes a non-linear image recovery approach.

12 . An apparatus for time-resolved digital holography, comprising:
a pulsed laser for creating at least two beam pulses which arrive on a sample under measuring at different time points; an optical encoder for spatially encoding a wavefront of said at least two beam pulses; a digital holographic access unit for recording said encoded spatial wavefront of said at least two beam pulses; and a wavefront reconstruction unit to reconstruct said wavefront of said at least two beam pulses.

13 . The apparatus of claim 12 , wherein said optical encoder includes a spatial light modulator.

14 . The apparatus of claim 12 , wherein said optical encoder includes a micro display.

15 . The apparatus of claim 12 , wherein said digital holographic access unit includes a photodetector array.

16 . The apparatus of claim 12 , wherein said digital holographic access unit includes an image sensor.

17 . The apparatus of claim 12 , wherein said wavefront reconstruction unit includes at least one computer, used for decoding, separating wavefront of said at least two beam pulses.

18 . The apparatus of claim 12 , further comprising a beam splitting element configured in front of said pulsed laser.

19 . The apparatus of claim 12 , wherein said pulsed laser includes a Ti-sapphire laser.

20 . The apparatus of claim 12 , further comprising at least one fiber grating to split said at least two beam pulses.

Assignees

• Univ Nat Taiwan Normal

Inventors

• Cheng Chau-Jern
• Lin Yu-Chih

Classifications

• G02B21/365

  Control or image processing arrangements for digital or video microscopes (G02B21/361, G02B21/362 take precedence) · CPC title

• G02B21/06 Primary

  Means for illuminating specimens · CPC title

• G02F1/39 Primary

  for parametric generation or amplification of light, infrared or ultraviolet waves · CPC title

• G01R31/311

  of integrated circuits {(G01R31/31728 takes precedence)} · CPC title