A scanner which includes a gradient index lens for passing and focusing beams from a radiation emitter to a cantilevered member reflective surface of a probe and from the reflective surface to a radiation detector. The lens also serves as a mechanical support for attachment of the radiation emitter and the radiation detector and is also attached to a support for the cantilevered member. The resulting fixed positions of the radiation emitter and the radiation detector relative to the reflective cantilevered member surface allows the scanner to be compact and factory focally alignable.