Abstract
In this paper we analyze the capability of adaptive lenses to replace mechanical axial scanning in confocal microscopy. The adaptive approach promises to achieve high scan rates in a rather simple implementation. This may open up new applications in biomedical imaging or surface analysis in micro- and nanoelectronics, where currently the axial scan rates and the flexibility at the scan process are the limiting factors. The results show that fast and adaptive axial scanning is possible using electrically tunable lenses but the performance degrades during the scan. This is due to defocus and spherical aberrations introduced to the system by tuning of the adaptive lens. These detune the observation plane away from the best focus which strongly deteriorates the axial resolution by a factor of ~2.4. Introducing balancing aberrations allows addressing these influences. The presented approach is based on the employment of a second adaptive lens, located in the detection path. It enables shifting the observation plane back to the best focus position and thus creating axial scans with homogeneous axial resolution. We present simulated and experimental proof-of-principle results.
Highlights
Confocal microscopy (CM) was originally invented by Minsky in 1957 [1] on his search to overcome limitations of traditional wide-field fluorescence microscopes
The technique achieved its breakthrough as confocal laser scanning microscopy (CLSM) [2] which is mainly used in life-sciences for imaging cells or tissues that are marked with fluorescent probes [3, 4]
In this paper we investigate the usage of adaptive lenses to overcome the need for mechanical axial scanning in confocal microscopy
Summary
Confocal microscopy (CM) was originally invented by Minsky in 1957 [1] on his search to overcome limitations of traditional wide-field fluorescence microscopes. Supported by the technological progress in recent years a variety of approaches came up that overcome these limitations by using adaptive optical elements to implement the axial scan or to change the focus position, including deformable mirrors and tunable lenses [17,18,19,20] The latter have undergone a rapid development in the last years [20,21,22], which led to several applications like e.g. in extended depth-of-field imaging [23], in fast axial focusing in two-photon microscopy [24], optical coherence microscopy [25, 26] and light-sheet microscopy [27]. Experimental and simulated proof of principle results show that it this approach is sufficient to create a homogeneous axial resolution
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