photon welding devices of this invention comprise a non - coherent photon source , and a light pipe coupled to the photon source at one end . a thin mask is positioned at another end of the light pipe that defines a weld location for photon delivery . a work piece to be bonded by the device comprises a top layer of transparent plastic and a base layer of absorbing plastic . the thin mask is in the form of a reflective coating positioned on the end of the light pipe over all surfaces that are not in contact with the work piece . a device includes a member that imposes a controlled , compressive force to the work piece while it is being welded and during a short time thereafter . the device also includes a member that maintains a desired alignment of the light pipe , top layer of the work piece , and base layer of the work piece during the bonding cycle .