Patent ID: 7499161

Claim:
A method of obtaining spectroscopic data from a target in a specific depth layer of a specimen, comprising: providing a fiber-optic probe comprising: a first excitation source emitting a first output light; a collection fiber configured to receive an optical signal in a detection region; an end; and a ball lens proximal to the end, wherein the ball lens has a central axis and the collection fiber is proximal to the central axis; locating the fiber-optic probe such that the ball lens is proximal to the specimen; redirecting the first output light with the ball-shaped lens, wherein: the first output light intersects the detection region in the specific depth layer of the specimen; and the first output light illuminates the target, wherein the target is located both in the specific depth layer of the specimen and in the detection region; generating the optical signal from the target; and receiving the optical signal in the collection fiber.