Laser-based controlled-intensity light source using reflection from a convex surface and method of making same

An integrated laser-based light source for illuminating an optical fibre with an output light beam having a controlled intensity, the light source comprising:

• a laser/sensor assembly, including:
• a header,
• light sensor means for generating an electrical signal representing an intensity of light energy falling thereon, the light sensor means including a light-receiving face and being mounted on the header,
• a laser having one and only one light-emitting face from which a light beam is radiated as a radiated light beam, the laser being mounted adjacent the light sensor means with the light-emitting face substantially parallel to the light-receiving face;
• a ball lens;
• and
• a package, including:
• an axial bore in which the ball lens is mounted, the bore including a portion dimensioned to receive the optical fibre and to position the optical fibre accurately relative to the ball lens, and
• a body portion optically aligned with the axial bore and dimensioned to adjustably accommodate the laser/sensor assembly in a position relative to the ball lens at which the ball lens reflects a fraction of the radiated light beam towards the light sensor means as a reflected light beam, the ball lens transmits a remainder of the radiated light beam as the output light beam, and the intensity of the output light beam is maximized.

A method of making an integrated laser-based light source for illuminating an optical fibre with an output light beam having a controlled intensity, the method comprising steps of:

• providing:
• a laser/sensor assembly, the laser/sensor assembly including:
• a header;
• light sensor means for generating an electrical signal representing an intensity of light energy falling thereon, the light sensor means including a light-receiving face and being mounted on the header;
• a laser having one and only one light-emitting face from which a light beam is radiated as a radiated light beam, the laser being mounted in the package adjacent the light sensor means with the light-emitting face substantially parallel to the light-receiving face,
• a lens, the lens having a convex surface, and
• a package, the package including:
• an axial bore including portions dimensioned to receive the lens and the optical fibre such that the optical fibre is positioned accurately in a predetermined position relative to the lens;
• and
• a body portion optically aligned with the axial bore and dimensioned to receive the laser/sensor assembly with a clearance fit;
• mounting the lens in the axial bore of the package;
• inserting the laser/sensor assembly into the body portion to a position at which the convex surface of the lens reflects a fraction of the radiated light beam towards the light sensor means as a reflected light beam, and the lens transmits a remainder of the radiated light beam as the output light beam;
• adjusting the position of the laser/sensor assembly relative to the lens to maximize the intensity of the output light beam;
• and
• fixing the laser/sensor assembly in the body portion at the position attained in the adjusting step.