RU-2861691-C1 - PHASE MICROSCOPE AND METHOD FOR OBTAINING IMAGE

Abstract

FIELD: optics; microscopy. SUBSTANCE: method for obtaining an image using a phase microscope includes directing radiation from a radiation source to a scanning mirror, scanning a sample in the plane of the object stage, obtaining a shear interferogram and restoring the phase profile of the sample using the phase step method. A laser is used as the radiation source, and during scanning, an alternating signal is additionally supplied to the scanning mirror, the amplitude and frequency of which enable suppression of the laser speckle noise. EFFECT: increasing the clarity and information content of the image obtained on the microscope. 2 cl, 6 dwg

Inventors

• Samojlenko Aleksej Andreevich

Dates

Publication Date

20260507

Application Date

20250722

Claims (2)

1. 1. A method for obtaining an image using a phase microscope, which includes directing radiation from a radiation source to a scanning mirror, scanning a sample in the plane of the stage, obtaining a shear interferogram and reconstructing the phase profile of the sample using the phase step method, characterized in that a laser is used as a radiation source, and during scanning, an alternating signal is additionally supplied to the scanning mirror, the amplitude and frequency of which ensure the possibility of suppressing laser speckle noise.
2. 2. A phase microscope containing a radiation source, a scanning mirror with a control unit, a lens system, a sample stage located between two objectives, an interferometer with a movable and fixed mirror, and a receiving light-sensitive matrix, characterized in that the radiation source is in the form of a laser, and the control unit for the scanning mirror is equipped with an alternating signal generator, the amplitude and frequency of which provide the ability to suppress laser speckle noise.

Description

The invention relates to the field of optics, namely to phase microscopes and methods for their operation, and can be used to obtain a three-dimensional structure of transparent objects that have a weak contrast in transmitted light, for example, biological cells. A tomographic phase microscope with differential interference contrast is known from the prior art, comprising a radiation source, a scanning mirror with a control unit, a lens system, a stage for a sample located between two objectives, an interferometer with a movable and fixed mirror, and a receiving light-sensitive matrix (see G. Vishnyakov, G. Levin, V. Minaev, M. Latushko, N. Nekrasov, and V. Pickalov, "Differential interference contrast tomography," Opt. Lett. 41, 3037-3040, 2016; https://doi.org/10.1364/OL.41.003037). A method of operating such a microscope is also known from the same source, including directing radiation from the radiation source to the scanning mirror, scanning the sample in the plane of the stage, obtaining a shear interferogram, and reconstructing the phase profile of the sample using the phase step method. To measure a sample's three-dimensional structure, it is necessary to obtain a set of images (projections) of the sample from different angles. This allows tomography algorithms to reconstruct the sample's internal structure from the set of projections. To obtain phase profiles, two images of the sample, obtained on the moving and fixed mirrors, must interfere on the receiving photosensitive matrix. Interference is possible if the coherence length of the source is sufficiently large compared to the shift between the images. To describe this phenomenon, consider pairs of photons arriving at the same time and at the same point in the matrix along different paths—one photon passing through a fixed mirror, the other through a moving mirror. Because these photons traveled different paths, they exited the source at different times. If the radiation source is sufficiently coherent, an interference pattern will appear on the matrix. However, if the phase of the photons in the pair changes chaotically between generations, the phase on the matrix will also be chaotically formed, and the interference pattern will not be visible. A well-known phase microscope uses a point LED as a radiation source. It has a short coherence length, so an interference pattern is formed only with a small shift, on the order of a few pixels. As a result, the phase profile is a derivative of the sample's phase profile along the shift direction. This image is called a DIC (Differential Interference Contrast) image and, by itself, is uninformative. Obtaining the true phase profile of the sample requires additional complex numerical processing. Thus, the disadvantages of known technical solutions are the complexity of data processing and insufficient clarity of the resulting image. The technical challenge is to eliminate these shortcomings and ensure the possibility of relatively simple modernization of existing equipment. The technical result consists of increasing the clarity and information content of images obtained with a microscope. The stated problem is solved, and the technical result is achieved, by using a laser as the radiation source, according to the operating method of a phase microscope, which includes directing radiation from a radiation source to a scanning mirror, scanning a sample in the plane of the stage, obtaining a shear interferogram, and reconstructing the phase profile of the sample using the phase step method. During scanning, an alternating signal is additionally supplied to the scanning mirror, the amplitude and frequency of which ensure the possibility of suppressing laser speckle noise. In this phase microscope, which comprises a radiation source, a scanning mirror with a control unit, a lens system, a sample stage located between the two objectives, an interferometer with a movable and fixed mirror, and a receiving photosensitive matrix, the radiation source is implemented as a laser, and the scanning mirror control unit is equipped with an alternating signal generator, the amplitude and frequency of which ensure the possibility of suppressing laser speckle noise. Fig. 1 shows a diagram of the proposed phase microscope; Fig. 2 - visualization of the beam tilt during scanning; Fig. 3 - interferogram of an erythrocyte with a large shift, obtained in the light of a highly coherent laser; Fig. 4 shows an interferogram of an erythrocyte with destruction of coherence and a large shift, obtained using the proposed method; Fig. 5 shows a phase profile of an erythrocyte with coherence destruction and a large shift, obtained using the proposed method; Fig. 6 shows the phase profile of an erythrocyte obtained in the light of a low-coherence source using the prototype solution. The proposed phase microscope contains a radiation source in the form of a laser 1, a scanning mirror 2 with a control unit 3, a lens system (containing a fo