Confocal microscopy with a volume holographic filter


A confocal scanning microscopy in which a matched volume holographic filter replaces the pinhole is described. Hologram recording is such that the field generated by an in-focus object is maximally diffracted, whereas out-of-focus objects are filtered out due to Bragg mismatch. This decouples dynamic range and axial resolution. The dynamic range is determined by the diffraction efficiency of the hologram, and the axial resolution by the numerical aperture of the objective lens and the hologram thickness. Additional benefits include ease of alignment and improved aberration performance.