In the realm of optical imaging, resolution plays a crucial role in determining how much information can be captured by an imaging system. Traditional optical systems face limitations imposed by the Abbe diffraction limit, which causes an ideal point object to appear as a blurred spot, making it challenging to distinguish between closely spaced points.
A research team from Zhejiang University has undertaken a significant study titled “Numerical Investigation of Resolution in Single Emitter Localization-Based Imaging Systems.” This research aims to address the limitations of previous studies on Single-Molecule Localization Microscopy (SMLM) by comprehensively analyzing the various factors that affect localization precision and resolution.
Previous investigations into SMLM have often considered a restricted set of parameters. In contrast, this study employs a numerical analysis methodology that systematically examines key factors influencing these imaging characteristics. It includes a broader range of parameters, such as the effects of additive noise, like thermal noise, and multiplicative noise, such as that generated by amplifier circuits, on localization precision.
The researchers also evaluated the impact of sampling frequency, determining the optimal frequency needed to meet different resolution requirements. By deriving a series of essential equations, they quantified how variables such as noise levels, photon counts, Point Spread Function (PSF) width, pixel size, quantum efficiency, and pixel filling factor affect system performance.
Among their findings, the study establishes mathematical relationships linking resolution limits with localization precision, revealing that resolution width correlates positively with noise factors while negatively with photon counts and quantum efficiency. Additionally, the impacts of PSF width and pixel size on resolution are shown to be non-linear.
Extensive numerical simulations and quantitative analyses validate the study”s conclusions. For instance, when multiplicative noise constitutes over half of the total system noise, an increase in photon count exacerbates the effects of this noise. Conversely, in systems dominated by additive noise, increasing pixel size or decreasing PSF width generally enhances localization precision.
The research offers crucial guidelines for optimizing imaging systems. It calculates the ideal matching ratio between PSF width and pixel size for various scenarios and clarifies the minimum Signal-to-Noise Ratio (SNR) necessary to achieve super-resolution. Specifically, an SNR greater than 4.93 dB is required when the photon count is 1,000 to surpass the Rayleigh criterion in one-dimensional cases.
By emphasizing the importance of maximizing both quantum efficiency and the pixel filling factor of detectors, this study provides essential insights that can aid in designing and optimizing advanced optical imaging systems, including fluorescence microscopy. The authors of this paper include Yueying Wang, Yiwen Hu, Yuehan Zhao, Cuifang Kuang, and Xiang Hao.
The full text of the open-access paper can be found at this link.
