The present invention provides an optical filter assembly that reduces the phase and amplitude noise of a detection laser used to detect ultrasonic displacements. The annealing diffuses out any contaminant existing in an area near andor contacting the trench on a surface between a semiconductor substrate and a pad oxide film. The tip section comprises a segment of flexible tubing with a tip electrode fixedly attached to its distal end. A keyboard and mouse input is included for inputting control signals to operate the processing means and the computer program or for altering control parameters of same. The weight average molecular weight of each arm of the hyper-branched SBS block copolymer is less than about 100,000. Light is made incident on a diffraction grating so that specular resonance can occur in two or more light scattering units including, for example, bispheres, and by the specular resonance, a fraction of diffracted light 52 that is diffracted by the first layer and the second layer is selectively enhanced.