Precise measurement of the resolution in light microscopy using Fourier transform

Area of Science:

• Optics
• Microscopy
• Image Analysis

Background:

• Accurate measurement of microscope resolution is crucial for scientific imaging.
• Traditional methods often rely on specific calibrated targets, which may not be suitable for all microscopy techniques, especially super-resolution.
• There is a need for a versatile and accessible method to determine resolution power.

Purpose of the Study:

• To develop and validate a simple, direct method for measuring the resolution power of light microscopes.
• To demonstrate the applicability of this method across various light microscopy techniques, including super-resolution.
• To provide an alternative to conventional resolution testing using calibrated line patterns.

Main Methods:

• Utilizing Fourier transform of object images to analyze the highest spatial frequency in the Fourier spectrum.
• Employing unknown shape plane objects with features smaller than the resolution to be measured as test objects.
• Validating results by comparing them with standard resolution measurements using calibrated periodic line patterns.
• Implementing the method using a compact disk as a test object and free IMAGEJ software.

Main Results:

• The developed method accurately measures light microscope resolution power with a precision of +/-5%.
• The technique reliably determines resolution using simple, non-standard objects.
• The approach was successfully applied to super-resolution light microscopy (transmission, reflection, and fluorescence).

Conclusions:

• A straightforward and accurate method for measuring light microscope resolution power has been established.
• This technique offers a practical and broadly applicable alternative to traditional resolution testing methods.
• The method is particularly valuable for super-resolution microscopy where standard targets are often unavailable.