Optical Photon Reassignment Microscopy (OPRA)

TL;DR

Optical Photon Reassignment Microscopy (OPRA) is an all-optical method that enhances confocal microscope resolution by reassigning photons without image processing, using an intermediate optical beam expansion to improve detection efficiency.

Contribution

This paper introduces OPRA, a novel all-optical implementation of photon reassignment that simplifies super-resolution imaging in confocal microscopes.

Findings

Achieves enhanced resolution without image processing

Uses an intermediate optical beam expansion

Potential to improve various laser scanning microscopes

Abstract

To enhance the resolution of a confocal laser scanning microscope the additional information of a pinhole plane image taken at every excitation scan position can be used [C. J. R. Sheppard, Super-resolution in confocal imaging, Optik 80, 5354 (1988)]. This photon reassignment principle is based on the fact that the most probable position of an emitter is at half way between the nominal focus of the excitation laser and the position corresponding to the (off centre) detection position. Therefore, by reassigning the detected photons to this place, an image with enhanced detection efficiency and resolution is obtained. Here we present optical photon reassignment microscopy (OPRA) which realises this concept in an all-optical way obviating the need for image-processing. With the help of an additional intermediate optical beam expansion between descanning and a further rescanning of the detected light, an image with the advantages of photon reassignment can be acquired. Due to its simplicity and flexibility this method has the potential to enhance the performance of nearly every laser scanning microscope and is therefore expected to play an important role in future systems.