Fibre-optic apparatus for the photodynamic treatment of tumors

Claim 1

A fibre-optic apparatus for the photodynamic treatment of tumours in a patient, which apparatus has an optical fibre connected to a laser for conveying light to a site of the tumour in a patient, wherein first and second lenses comprising a pair of lenses (14, 15) which are similar plano-convex microlenses (14, 15), each microlens having a planar side and a convex side; a focal length which locates a focal point relative to the lens; a central ray axis; and a diameter the focal length of which is smaller than the diameter thereof, said microlenses being arranged such that the convex sides (19, 20) thereof are facing each other and which are at a distance from one another that is smaller than the focal length of the microlenses (14, 15), and including means for locating said microlenses coaxially with respect to a light (13)-emitting end face (9) of the fibre (8) and are so adjusted and have a spherical aberration such that edge rays (23) having an angle of divergence (β) of a divergent pencil of light rays (23) emerging from the end face (9) of the fibre (8) are so greatly refracted by the first lens (14) of the lens pair, owing to the spherical aberration of said first lens (14), that, after traversing radially the central ray axis of the pair of lenses (14, 15) before the focal point (24'), said edge rays enter the convex side (20) of the second lens (15) of the lens pair (14, 15) at a site (25) lying diametrically opposite a site of emergence (26) from the convex side (19) of the first lens (14), as a result of which the angle of divergence (β) of the edge rays (23) is reduced.