Abstract: The present invention provides a laser processing and autofocusing system that measures the position of the work-piece at the machining spot, to allow the laser processing of work-pieces which are not flat and have surface variations, with the autofocusing system being able to compensate for these variations. During laser machining, it is desirable to keep the laser focus at the same height with respect to the surface of the sample for the best possible machining quality. Not all samples are flat, though, and it thus becomes necessary to map the surface of the sample accurately and to correct the focusing of the laser beam on the fly. The system includes a processing laser beam directed onto the surface at normal incidence and a light line projected onto the surface in the vicinity of the area being machined but at an angle with respect to the surface normal. The focusing optics for the machining laser and light line generator are fixed relative to each other on a positioning stage.

Abstract: A method and circuit is disclosed for providing a control signal to a laser cavity controller. The cavity has two completely reflective surfaces. A long lived laser medium stores energy within the cavity. A computer generated waveform generated from enough values to appear substantially smooth after being amplified is provided to a control circuit having a Pockels cell or a Bragg cell. By controlling the amplitude of the computer generated waveform, the output pulse of the laser cavity is controlled.

Abstract: A multitasking optical fiber probe for collecting dosimeter information from more than one position in a sample. The basic principle of the present invention involves using one or more different sensor zones along the length of the fiber each with a different photoactive constituent having a sufficiently unique emission spectra (spectral or temporal) to enable deconvolution of the emission spectra by the computer and therefore correlation of the detected parameter with the position of the sensor zone along the length of the optical fiber. In the broadest form of the invention the probe is embodied by only one sensor zone located at some point along the length of the fiber spaced away from the end face of the fiber.

Abstract: Optical fiber diffusers for emitting light cylindrically along a length of the fiber diffuser with preselected light intensity distributions along the length of the diffuser. The diffuser portion is defined by forming a Bragg grating in a section of the optical fiber core having a modulated index of refraction which acts to couple light radially out of the fiber along the diffuser section. The intensity distribution of light coupled out of the diffuser section of the fiber is controlled by controlling the profile of the modulated index of refraction, namely the coupling coefficient, along the length of the grating. For photodynamic therapy type II strong Bragg gratings are preferred which give higher intensity output over short distances. Multiple Bragg gratings can be written into a multimode fiber for emission of light at several positions along the fiber.

Abstract: The present invention provides a method for measurement of concentration of fluorophores in turbid media. The method uses a fluorescence plus reflectance technique to measure quantitatively the in vivo concentration of a fluorescent drug independent of the tissue optical properties. The method involves using the reflectance measurement as a means of correcting for tissue scattering and absorption in the fluorescence measurement. Light directed to the tissue by means of an optical fiber to excite the fluorophores. Fluorescence from the fluorophores is measured by another fiber at a distance (D1) from the source in the turbid medium, while the excitation light is simultaneously collected at a distance (D2) from the source. The ratio fluorescence/reflectance will be approximately constant for a fixed concentration of the fluorophore and a judicious choice of D1 and D2, regardless of the optical properties of the tissue.

Abstract: A grating-in-etalon wavelength division multiplexing device is disclosed. In one aspect the device includes an etalon structure with a single volume (or Bragg) diffraction grating, multiple superimposed volume diffraction gratings or a binary volume supergrating is interposed between the reflective opposed faces of the etalon. The etalon includes a tilt mechanism for tilting one or both of the reflective faces at a preselected angle with respect to each other from the parallel. A multiple wavelength light beam is directed through the volume grating in different preselected directions so that light of wavelengths satisfying the Bragg condition on each traversal of the grating is diffracted in a direction different from the direction of the incident beam. The diffracted beam exits the etalon and is wavelength interrogated in a detector while the undiffracted wavelengths propagate through the grating to be reflected from the opposed mirror face back through the volume grating.