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In the late 1980s, the first high-throughput screening equipment emerged. High-throughput screening is based on experimental methods at the molecular and cellular levels, using microplate formats as experimental tool carriers, and executing experimental processes through automated operating systems. This technology collects experimental result data through sensitive and fast detection instruments and uses computers for analysis and processing, enabling the detection of tens of millions of samples at the same time.

In 1997, the first fully integrated high-content imaging platform was launched. High-content screening is a high-throughput screening method that detects the effects of screened samples on various attributes and physiological states of cells (such as cell morphology, growth and differentiation status, migration and apoptosis, cell metabolic pathways, and various links of signal pathways) while maintaining the integrity of cell structure and function.

Bright-field imaging presented the microscopic world to people, making life sciences visible. However, for transparent or semi-transparent samples, the contrast provided by bright-field imaging is low, making it difficult to distinguish sample details.

Bright-field staining can significantly improve the contrast of samples under a bright-field microscope by using specific dyes to react specifically with different components in cells, allowing direct observation of cell morphology and structure under different colors. But the staining process may cause cell damage or even death.

Phase-contrast imaging converts the optical path difference of light passing through the sample into amplitude difference, solving the problem of low contrast of transparent samples under ordinary bright-field microscopes without staining. However, for highly transparent samples or samples with small phase changes, the contrast is still limited, and quantitative analysis cannot be performed.

Fluorescence imaging uses fluorescent dyes or fluorescent probes to label samples, which can provide high-contrast images. Compared with bright-field staining, it causes less damage to samples and can quantify target molecules through fluorescence intensity. However, it has the disadvantages of phototoxicity and photobleaching.

Differential interference contrast imaging uses polarized light and differences in sample thickness or optical density to enhance contrast, which can highlight details of the sample surface and internal structure. But it is mainly used for qualitative analysis and still difficult to perform accurate quantitative measurement.

Confocal fluorescence imaging achieves near-diffraction-limit resolution imaging by restricting out-of-focus stray light through a pinhole conjugate to the sample plane. However, it also has the problems of phototoxicity and photobleaching, and its point-by-point scanning method results in relatively slow imaging speed.

Digital holographic imaging uses photoelectric sensors to record holograms and realizes holographic reconstruction and processing of samples by simulating optical diffraction processes with computers. It can provide phase information to quantify physical parameters such as the optical thickness and refractive index of samples, but complex digital processing algorithms are required to reconstruct images.

Super-resolution fluorescence imaging can break through the optical diffraction limit, but it has slow imaging speed and complex data processing, and still cannot avoid the impact of labeling on cell viability.

Quantitative phase imaging technology does not require cell labeling or fluorescent probes. It realizes high-contrast quantitative imaging by reconstructing the phase information of the light field. While maintaining cell viability, it can in-depth analyze cell structure, dynamic behavior, and extract key biological information such as cell dry mass and mechanical properties. It is a technology that combines the advantages of label-free imaging and high-content analysis, providing a non-invasive long-term monitoring method for live cell research.

It recovers phase information by analyzing the light intensity distribution, but generally, it is not as good as the interferometric method in terms of absolute accuracy.

It recovers phase information by allowing an object light wave passing through the sample to interfere with a reference light wave, generating an interference pattern, and analyzing these interference fringes.