Transmission type sample amplitude and phase imaging device and method

Abstract

The invention discloses a transmission type sample amplitude and phase imaging device and a transmission type sample amplitude and phase imaging method. A small-aperture diaphragm is moved for scanning, diffraction spots of the small-aperture diaphragm at certain distances are used as light for illuminating a sample, the diffraction spots of the small-aperture diaphragm at different positions are recorded by using a detector in an image plane of the small-aperture diaphragm in an imaging system, and a complex amplitude transmittance function of the sample is obtained through a computer in an iterative operation way, so that amplitude information can be obtained, and phase imaging can be realized. In addition, by each diffraction pattern, the light intensity distribution of the diffraction spots can be recorded, and the actual position, which corresponds to the light intensity distribution, of the small-aperture diaphragm can be obtained through relevancy operation to realize translation stage accuracy-independent reproductive image reconstruction, so that errors caused by the low accuracy of a translation stage are eliminated.

Description

technical field [0001] The invention relates to imaging and phase measurement of a transmission sample, in particular to a device and method for imaging the amplitude and phase of a transmission sample independent of the precision of a translation stage. Background technique [0002] Coherent Diffraction Imaging (CDI) algorithm is a method to directly obtain the phase information of the sample from the intensity of the scattered spots in the light field. The method was proposed by Hoppe et al. around 1970, and gradually developed after being perfected by Fienup et al. (see J.R. Fienup. Phase retrieval algorithms: a comparison [J], Appl. ). The method is to place a light-shielding screen with holes with known spatial distribution on the back surface of the sample, illuminate the object with a coherent light source and make only a small part of the light of the object pass through the CCD at a certain distance from the concept hole. Record. The CDI algorithm is as follows: ...

AI Technical Summary

Problems solved by technology

[0009] The CDI algorithm has a simple structure and can theoretically reach the resolution of the diffraction limit, but this imaging method requires the sample to be an isolated object, and theoretically it cannot distinguish the object itself from its conjugate and the convolution of itself and other functions combination, it is often difficult to obtain an ideal reconstructed image for slightly complex objects, which greatly limits its application range

[0010] The PIE (ptychographical iterative engine) algorithm is an iterative algorithm based on the CDI algorithm. It performs amplitude and phase reconstruction by scanning the diffraction spots of different parts of the sample (adjacent scanning positions overlap), which overcomes the shortcomings of CDI. The algorithm theoretically The limit resolution determined by the wavelength can be obtained. This method needs to record the diffraction spots at different scanning positions. In actual operation, at least 100 diffraction spots are required. However, this algorithm requires high movement accuracy of the scanning device, and the current It is difficult for the translation stage to meet the accuracy requirements, and the error of the translation stage becomes a main source of the error of the algorithm, which also limits the application range of the algorithm

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