Abstract: A low stress reflective optic is provided. The reflective optic includes a substrate, a spectral thin-film stack, and a stress-compensation thin-film stack. The stress-compensation stack is positioned between the spectral stack and the substrate and is designed to include internal stresses that offset or counteract internal stresses present in the spectral stack. Reduced stresses in the spectral stack lead to a reduction or elimination of surface distortions of the optic. Reflective optics with superior performance characteristics are achieved.

Abstract: A hydraulic chain or belt tensioner includes a ratchet-pawl interface on the piston skirt that can be reset to a locked position by rotating the piston and compressing it until locked. The tensioner preferably includes at least one flat on the piston. The flat prevents the piston from rotating axially and locks the piston into place. The locked position is especially useful for shipping the tensioner.

Abstract: A hydraulic chain or belt tensioner includes a ratchet-pawl interface on the piston skirt that can be reset to a locked position by rotating the piston and compressing it until locked. The tensioner preferably includes at least one flat on the piston. The flat prevents the piston from rotating axially and locks the piston into place. The locked position is especially useful for shipping the tensioner.