Variable-focal length microlens arrays in confocal microscopy

Microlenses have been implemented in confocal systems successfully as components of aperture arrays and as arrays of objective lenses. The use of the novel technology of variable focal length (VFL) microlenses in the confocal system is investigated. The use of VFL microlenses as an aperture array in conjunction with an optical fiber as a pinhole array is examined. Axial responses of the system where measured and the Full-Width Half Maximum (FWHM) found to be ∼16μm. VFL microlenses as an array of objective lenses is investigated with a novel method for scanning in the axial direction presented. By variation of the focal length of the lenses the focal plane can be scanned through the sample without the mechanical movement of the sample or the objective lens, we have named this 'focal scanning'. It is shown that the limiting factor with this type of scanning is the low numerical aperture (NA) of the microlenses available. Both focal scanning and conventional scanning are examined for this experimental set-up.