Microscope illuminator

An illuminator for use with a microscope having a base, a slide holder configured to accept a slide, and an objective having a Field Of View (FOV) covering a portion of an accepted slide, the illuminator comprising a light-emitting surface and configured to be movably coupled to the base, wherein a clear and focused image can be provided by the objective with no light-shaping optical element disposed along an optical path from the illuminator to the accepted slide;

• wherein:
• the illuminator is movable with respect to the base to selectably determine a separation distance between the light-emitting surface and the slide;
• the light emitting surface configured to project light on the optical path;
• the projected light has a peak intensity on an axis perpendicular to the light-emitting surface and a 90% intensity at a determined first half-angle from the perpendicular axis;
• the projected light has an intensity over the entire FOV that is within a range of 10% of the peak intensity when the separation distance is at least the arcsine of the half-angle.

A method of operating a microscope, comprising:

• projecting light from a planar light-emitting surface directly onto an underside of a slide accepted by the microscope;
• and
• adjusting a separation distance between the light-emitting surface and the underside of the slide to achieve a selected value of a realized numerical aperture of the microscope;
• wherein:
• the light emitted by the light-emitting surface has an intensity that is uniform within a defined range over a dispersion cone having a defined half-angle;
• the projected light is not shaped between the light-emitting surface and the underside of the slide;
• and
• increasing the separation distance reduces a maximum half-angle of the emitted light that enters an entrance aperture of an objective of the microscope.