Abstract: A method of and an apparatus for adjusting the focal point of a working laser beam onto a microscopic target region of a transparent biological object to locate the focal point a spaced predetermined microscopic distance from an interface of the object is described. Separate working and auxiliary laser beams are produced which are then collinearly superimposed in parallel relationship, the auxiliary laser beam having a wavelength within the visible range and different from the wavelength of the working laser beam. The superimposed laser beams are focused jointly through the objective of a microscope onto the object. First variable focusing means placed in the path of one of the laser beams is controlled to produce a spacing between the focal spots equal to the predetermined distance.

Abstract: Disclosed is a slide for supporting matter to be observed under a microscope, including a base, a plurality of electrical conductors disposed on the base, an insulating coating distributed over the base to isolate the matter from the conductor, and a plurality of microscopic perforations through the coating and communicating with the conductors, thereby permitting electrical contact between the conductors and a plurality of precise areas of the matter. The slide further includes a plurality of attraction zones on the surface of the coating adapted to cause matter to accumulate on the slide in a predetermined pattern with respect to the perforations.