A diffraction limited confocal microscope includes an energy source to provide focusable illuminating energy and a single mode energy guide comprising a core, an energy receiver and an energy exit. The energy guide is operationally associated with the energy source so that illuminating energy from the energy source is received by the energy receiver and coupled into the core and guided to the energy exit so as to emerge from the core at the energy exit. A first focuser is operationally associated with the energy exit to focus at least a portion of the illuminating energy emerging from the core into a diffraction limited spot pattern volume having a central portion which in use intersects an object. A second focuser is operationally associated with the first focuser to collect outgoing energy from the volume resulting from interaction between the illuminating energy in the volume and the object and/or resulting from transmission or reflection of illuminating energy from the volume. The microscope includes a detector with an aperture and a detecting element wherein the detector is operationally associated with the second focuser whereby the second focuser images the aperture onto the central portion wherein the numerical aperture, NA, of the outgoing energy originating from the central portion focused onto the aperture, the wavelength of the outgoing energy. Lambda., and the average diameter, d, of the aperture are related by the equation: NA<0.6 X lambda / d whereby the detector detects the outgoing energy.
