Precise measurement of the resolution in light microscopy using Fourier transform

The resolution power of light microscope has been accurately measured (+/-5%) by Fourier transform of various object images and further evaluation of the highest spatial frequency in Fourier spectrum. Any unknown shape plane object with a shape feature's size smaller than the resolution to be measured was shown to provide a reliable resolution test. This simple method gives a direct measurement of the resolution power as defined by Abbe [Archiv. F. Mikroskopische Anat. 9, 413 (1873)].

The results have been justified by comparison to a standard resolution measurement by using calibrated periodic line patterns. Notably, the approach is applicable in super-resolution light microscopy (transmission, reflection, and fluorescence), where calibrated resolution targets do not occur. It was conveniently implemented by using a compact disk as a test object and free IMAGEJ imaging software.

The article was published in: Review of Scientific Instruments 79(4): 046112.

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This work was supported (in part) by the Fetzer Franklin Fund of the John E. Fetzer Memorial Trust.