Patent ID: 7102817

Claim:
An objective lens for a microscope comprising: a casing being tubular and having an inner surface, an inner open end having an edge, an outer open end, a through hole defined longitudinally through the casing, an inner surface and a window defined through the casing; a telescopic tube assembly mounted in the casing and having an outer tube mounted rotatably in the casing and having two open ends, a through hole defined longitudinally through the outer tube, an inner surface, an inner thread formed in the inner surface of the outer tube and an annular knob extending radially outward from one of the open ends of the outer tube and aligned with the window in the casing; an inner tube mounted rotatably and movably in the outer tube and having two open ends, a through hole defined longitudinally through the inner tube, at least two engaging elements defined on the inner tube and at least two tabs protruding from the inner tube and engaging the inner thread in the outer tube; and an objective lens mounted in said through hole of the inner tube; and a cap being tubular and mounted securely on the inner open end of the casing and having two open ends, a through hole defined longitudinally through the cap, an inner surface and at least two guides mounted securely between the casing and the cap and slidably engaging respectively the at least two engaging elements of the inner tube.