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A new scheme of super-resolution optical fluctuation imaging (SOFI) is proposed to broaden its application in the high-order case by separating the elimination of shot noise from the computation of cumulant, applying the low-pass denoising (LPD) operator to SOFI. The high-order cumulants are derived from a basic recursion of moments with the suppression of shot noise by the LPD on raw data. SOFI based on LPD (LPD-SOFI) demonstrates a 10.6-fold lateral resolution enhancement with the cumulant order of the 16th and a seven-fold three-dimensional resolution enhancement with the cumulant order of the 10th in experiments performed on a sparse sample of quantum dots.

In order to further improve the lateral resolution required for ultraprecision measurement of discontinuous surface contours, a new laser heterodyne confocal probe (LHCP) has been proposed for use in making ultraprecision bipolar absolute measurements. The new probe follows the principle of reflection confocal microscopes (RCM), and uses the property of RCM light intensity curves being almost invariant with the offset of a pinhole. It also uses a heterodyne confocal light path arrangement and intensity normalization technique to improve the linearity and resolution of RCM and to suppress the common-mode noise caused by the disturbance in light source intensity, different environmental conditions and electric drifts of detectors. Analyses and experimental results indicate that, when a microscope objective of 40 × 0.65 is used, the LHCP has a measurement range of 7 µm and a resolution of better than 2 nm. After nonlinear compensation, its residual nonlinear error is less than 13 nm in the full range. The application of the LHCP to ultraprecision measurement of discontinuous contours made it possible to measure the inner and outer contours of a groove in a revolving body at higher precision.

Lateral resolution in confocal microscope is limited by the size of pinhole. In this paper, we attempt to introduce a new method to achieve structured detection through using spatial light modulator (SLM) to improve it. SLM modulates the Airy disk amplitude distribution according to the detection function in collection arm. Instead of using CCD to capture spot images and modulate them with numerical analysis in virtual structured detection (VSD), this method uses SLM to accomplish these aims with higher imaging rates. Based on simulation and the experiment results, it can be found that coherent transfer function expands and the resolution is 1.6 times as large as that of conventional confocal microscope.

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