Abstract: A laser scanning microscope produces molecular excitation in a target material by simultaneous absorption of three or more photons to thereby provide intrinsic three-dimensional resolution. Fluorophores having single photon absorption in the short (ultraviolet or visible) wavelength range are excited by a beam of strongly focused subpicosecond pulses of laser light of relatively long (red or infrared) wavelength range. The fluorophores absorb at about one third, one fourth or an even smaller fraction of the laser wavelength to produce fluorescent images of living cells and other microscopic objects. The fluorescent emission from the fluorophores increases cubicly, quarticly or even higher power law with the excitation intensity so that by focusing the laser light, fluorescence as well as photobleaching are confined to the vicinity of the focal plane.

Abstract: A scanning force microscope utilizes a probe consisting of a glass stylus, or probe, positioned and oriented by an optical trap. The probe is an optically transparent cylinder having at least one tip on its axis with an apex dimension less than one wavelength of the light used for the trap. An optical displacement sensor utilizing forward scatter or an optical interferometer detects the motion of the probe caused by the force between the tip and an object to be scanned. Mutual scanning displacement between the probe and the object is carried out by moving a support stage along x/y coordinates or by movement of the light beam forming the optical trap along these coordinates. Radiation forces due to the three-dimensional intensity distribution of the light in the optical trap allow the probe to be positioned with precise control and with a low spring constant, allowing resolution in the range of .lambda./100, with the probe being capable of measuring forces smaller than 0.1 pN.

Abstract: In a method of high density (>10.sup.12 bits/cc) optical recording of information in a three-dimensional multilayered format, information is written in a photopolymer as submicron volume elements of altered index of refraction. The index change results from alteration of the photopolymer induced by two-photon excitation of the photo-sensitizer at the waist of a highly focused beam from a subpicosecond colliding pulse modelocked laser. Quadratic dependence of two-photon excitation on incident instantaneous intensity serves to confine crosslinking of the polymer to the focal volume; hence, bit array layers may be written with thicknesses on the order of the confocal parameter. As an example, eight well resolved bit planes can be written in a olymer film about 30 microns thick. Information written in this manner may be read with sufficient axial resolution by differential interference contrast (DIC) or confocal microscopy.

Abstract: A laser scanning microscope produces molecular excitation in a target material by simultaneous absorption of two photons to thereby provide intrinsic three-dimensional resolution. Fluorophores having single photon absorption in the short (ultraviolet or visible) wavelength range are excited by a stream of strongly focused subpicosecond pulses of laser light of relatively long (red or infrared) wavelength range. The fluorophores absorb at about one half the laser wavelength to produce fluorescent images of living cells and other microscopic objects. The fluorescent emission from the fluorophores increases quadratically with the excitation intensity so that by strongly focusing the laser light, fluorescence as well as photobleaching are confined to the vicinity of the focal plane. This feature provides depth of field resolution comparable to that produced by confocal laser scanning microscopes, and in addition reduces photobleaching.

Abstract: A cermet thin film resistor having small particles of a refractory metal embedded in a ceramic insulator at compositions near the percolation transition. The cermets are produced by co-deposition in a dual-electron beam evaporator. The refractory metal is typically Mo or Pt. The insulator is typically a Al.sub.2 O.sub.3, although other insulators, for example SiO.sub.2 may be used. Deposition occurs onto a suitable substrate such as a sapphire under an oxygen environment, typically 10.sup.-5 Torr O.sub.2 with the stage heated in the range of typically 400.degree. C. Such is done to increase the size of the metallic regions. The microstructure is 10-50 .ANG. embedded metal in the ceramic. The resulting films are in the range of 1500 .ANG. thick which provides a film having a typical resistivity of 400 m.OMEGA. - cm which may then be patterned using lithography techniques to form two or four terminal resistors.

Abstract: Improved detector and processing circuitry for use with a vorticity measurement optical probe system is disclosed. The invention makes use of a dual axis position indicating photodetector so that two components of vorticity may be simultaneously measured. Reflective spherical particles are disposed in a fluid whose vorticity is to be measured, and a light beam is reflected off of the particles and onto the photodetector. Analog and digital processing circuitry is connected to the outputs of the photodetector, and generate data that is indicative of the position of the reflected light beam on the photodetector as a function of time. Computer interface circuitry is also provided which enables the beam position data to be read into a digital computer so that the two vorticity components may be calculated therefrom. Embodiments which utilize plural axis photodetectors are also disclosed.

Abstract: The present invention relates to novel compounds which are derivatives of acidic phallotoxins and correspond to the formula: ##STR1## (NBD-acid phallotoxins) their preparation, and their use in fluorescent staining of F-actin.

Abstract: The present invention relates to novel compounds which are derivatives of acidic phallotoxins and correspond to the formula: ##STR1## (NBD-acid phallotoxins) their preparation, and their use in fluorescent staining of F-actin.

Abstract: An optical system for direct measurement of vorticity in a flowing fluid is disclosed. Spherical particles suspended in the flow rotate with an angular velocity that is accurately equal to half the local vorticity; thus, measurements of the rotation rates of such particles indicate the vorticity. The particles are transparent, and preferably are less than 50 .mu.m diameter, and each contains embedded planar crystal mirrors. The particles are suspended in a refractive index matched liquid. Measurement of the particle rotation rate and thus the vorticity of the fluid is preferably accomplished by measuring the rotation rates of reflections of one or more light beams from the planar mirrors. The measurements may be carried out using any system of position sensitive optical detectors such as photo sensitive devices screened by suitable slits or photo diode arrays.