Asymmetric TIR lenses producing off-axis beams

DETAILED DESCRIPTION The following description of the presently contemplated best mode of practicing the invention is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention.
The scope of the invention should be determined with reference to the claims.
The problem addressed by the present embodiment is how to produce an off-axis beam with a TIR lens while retaining a smooth exterior surface and without the requirement of a second lens.
The present embodiment overcomes the limitations of the prior art lenses, which cannot deliver an off-axis beam without the installation of additional deflection means or additional lenses on their surfaces.
This external auxiliary deflector limits the range of applications of the TIR lens.
The output beam of a TIR lens will generally share its symmetry.
Most pertinent to the present embodiment, TIR lenses with a smooth exterior surface will typically emit beams centered about the normal to that surface.
Slanted output beams require additional deflection means, such as linear refractive facets, to be installed on the external surface.
External Fresnel faceting in the form of linear grooves will deflect light towards their upward slope.
As deflections approach a practical limit of 30° (for the typical refractive index in the range 1.
4-1.
7), the finite size of the light source increases the risk of internal reflection trapping light within the lens body.
Unlike with the teachings of the present embodiment, deflections greater than 30° are completely unattainable by a single refraction.
The present embodiment generally comprises an asymmetric transparent lens that employs a precise internal faceting design.
This lens utilizes total internal reflectance (TIR) in conjunction with refraction In order to concentrate and redirect electromagnetic radiation at a desired deflected angle from exterior surface normal (i.
e.
off-axis).
Radiant energy (i.
e.
light) is redirected to or from a predetermined zone or zones wherein such redirection has a predetermined degree of concentration