Abstract
The image reconstruction process in super-resolution structured illumination microscopy (SIM) is investigated. The structured pattern is generated by the interference of two Gaussian beams to encode undetectable spectra into detectable region of microscope. After parameters estimation of the structured pattern, the encoded spectra are computationally decoded and recombined in Fourier domain to equivalently increase the cut-off frequency of microscope, resulting in the extension of detectable spectra and a reconstructed image with about two-fold enhanced resolution. Three different methods to estimate the initial phase of structured pattern are compared, verifying the auto-correlation algorithm affords the fast, most precise and robust measurement. The artifacts sources and detailed reconstruction flowchart for both linear and nonlinear SIM are also presented.
Highlights
Due to thenite aperture size in a lens imaging system, the information with high spatial frequencies will be lost by the di®raction of light wavefront, imposing an ultimate barrier in optical resolution to conventional optical microscopy
Since theoretical model allows the numerical calculation of point spread function (PSF) in various systems and conditions, in this work we modeled the PSF of a conventional microscope by using the scalar di®raction approach.[11,12,13]
The overlapped sample spectra are shifted to their correct spectral positions to extend the e®ective support region of optical transfer function (OTF) in Fourier domain, ̄nally resulting in a reconstructed image with about two-fold enhanced spatial resolution
Summary
Due to thenite aperture size in a lens imaging system, the information with high spatial frequencies will be lost by the di®raction of light wavefront, imposing an ultimate barrier in optical resolution to conventional optical microscopy. The achievable highest optical resolution, or the minimum resolvable distance between two objects in a conventional light microscope, is about 200 nm.[1] To circumvent the di®raction limitation and achieve super-resolution image, in the past two decades a number of optical methods have been developed and got tremendous success by combining themselves with °uorescent probe techniques. Among those methods, stimulated emission depletion (STED) is based on depleting °uorescence emission in the peripheral area of a light focus, while stochastic optical reconstruction microscopy (STORM) and. Since the initial phase of pattern acts as a crucial factor in image reconstruction, a comparison between di®erent methods of pattern phase measurement is carried out, revealing that the auto-correlation method achieves highest performance under a realistic signal-to-noise ratio (SNR)
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