Abstract: Underfill voids and solder ball defects are detected via laser generation and laser detection of an ultrasonic wave at the top surface of flip chips. High resolution is provided by using small laser spot sizes and closely-spaced laser beams of wavelengths that are absorbed near the surface of the semiconductor. Alternatively, the generation laser beam may be absorbed in the bulk of the semiconductor. Improved spatial resolution and rejection of unwanted scattered waves can be attained by limiting the time frame of the ultrasonic waveform to the time required for the first longitudinal wave reflection from the bottom of the flip chip. The laser beam spacing can be reduced by using overlapping probe and detection beams of different wavelengths. Resolution of less than 100 ?m features was demonstrated for silicon flip chips.

Abstract: Distributed fiber optic chemical and physical sensors provide a relatively highly uniform response over the length of the fiber by, for example, varying such properties as the core/cladding index of refraction ratio to compensate for the non-linearity in sensitivity due for example to the loss of higher order modes in multi-mode fibers. The variation of the ratio changes the absorption coefficient of the fiber and can be used to compensate for any non-linearity in response. Other techniques for compensation also are disclosed.

Abstract: Apparatus and method for using an light source to incapacitate a subject in which the light source strobes by a spatial scanning through a pattern and a temporal flashing at a rate sufficient to cause incapacitation. The strobing (meaning both spatial scanning and temporal flashing is in a pattern to prevent the subject from escaping the strobing effect. The flashing is timed so that each flash point in the pattern will flash at a rate and sequence to cause incapacitation. In a preferred embodiment, the light source is an array of LEDs or laser diodes.

Abstract: Methods and apparatus for producing an optical waveguide illuminator are disclosed. By controlling the propagation of light in the core and cladding regions of the waveguide, distributed light emission along a length of an optical fiber or along a planar waveguide surface can be achieved by varying the core/cladding refractive index ratio and introducing light scattering centers in the core.

Abstract: A method and apparatus for processing an optical signal in an optical waveguide using a closed loop wavelength dependent active tuning system. A tunable fiber Bragg grating, optical processor and a controller provide feedback control of the central wavelength of the tunable fiber Bragg grating. Changes in wavelength of the processed signal are followed to keep the tunable fiber Bragg grating tuned to a peak wavelength for maximum sensitivity.

Abstract: A surface plasmon resonance device includes a metal thin film, a dielectric thin film on an optical member and, in addition, an electro-optically active thin film either between the metal thin film and the dielectric thin film or between the optical member and the metal thin film. The electro-optically active thin film is subject to a voltage which is varied to tune the resonance condition of the device.

Abstract: A porous glass rod is treated to include tungsten oxide and palladium in an arrangement that is sensitive to hydrogen to produce a color change that is a function of the hydrogen concentration. The rod is attached to the tip of a double fiber into one of which light is launched by a light source. A detector at the end of the second fiber is responsive to light reflected by the rod. The process for forming the rod includes the steps of doping the glass with a tungsten compound and a palladium compound with intervening and subsequent heating steps to bond the tungsten oxide and palladium to available oxygen atoms of the porous glass.