Abstract: This invention relates to a simple, compact, and robust, cylindrical microlens external cavity for laser diode frequency control. The microlens system makes possible a tunable laser diode that utilizes an orthogonal pair of collimating microlenses to form a short external cavity for longitudinal mode and frequency control. The resulting system generates a circular, collimated beam of single frequency, tunable laser radiation. A cylindrical microlens collimator has a powered surface that semi-collimates (i.e., collimates in one axis only) the light from a laser diode. This powered surface is placed so as to be the surface closest to the laser facet. A second lens surface opposite the powered surface, is located in the semi-collimated beam is planar. The second surface of the lens is flat and has a reflective coating. Hence, it provides feedback that is refocused (in one axis) onto the laser aperture.

Abstract: Disclosed is a lens assembly having a first cylindrical microlens having a first microlens longitudinal axis. A flat sheet of material having a hole therein is attached to the microlens, with the microlens traversing the hole. The microlens is oriented with the first microlens longitudinal axis being parallel to the flat sheet, such that the microlens can be illuminated through the hole. In a second embodiment, a second microlens is attached on the opposite side of the sheet and is oriented at an angle relative to the first microlens.

Abstract: A new cylindrical minilens and a new lens system for collimating and circularizing the output beam from a laser diode are provided which can be mounted outside the can of a laser diode. The system is made up of two lens elements. The first lens element is a collimating lens which is located to receive the output beam from the laser diode. The collimating lens is typically a standard small lens used in the art for collimating the output beam on a first axis, such that the output beam when it leaves the collimating lens has a desired amount of collimation and has a desired dimension on a second axis that is orthogonal to the first axis.