Abstract: System and method for detecting and measuring chemical perturbations in a sample. The system and method are useful for non-invasive pH monitoring of blood or blood products sealed in storage bags.

Abstract: System and method for detecting and measuring chemical perturbations in a sample. The system and method are useful for non-invasive pH monitoring of blood or blood products sealed in storage bags.

Abstract: System and method for detecting and measuring chemical perturbations in a sample. The system and method are useful for non-invasive pH monitoring of blood or blood products sealed in storage bags.

Abstract: System and method for detecting and measuring chemical perturbations in a sample. The system and method are useful for non-invasive pH monitoring of blood or blood products sealed in storage bags.

Abstract: System and method for detecting and measuring chemical perturbations in a sample. The system and method are useful for non-invasive pH monitoring of blood or blood products sealed in storage bags.

Abstract: System and method for detecting and measuring chemical perturbations in a sample. The system and method are useful for non-invasive pH monitoring of blood or blood products sealed in storage bags.

Abstract: Methods and apparatus for testing the sterility of a product to be administered to a patient. The sterility of the product is tested by monitoring the pH change of a culture medium in contact with any culturable organisms (e.g., bacteria) that are collected by filtration of the product to be tested.

Abstract: Methods and apparatus for testing the sterility of a product to be administered to a patient. The sterility of the product is tested by monitoring the pH change of a culture medium in contact with any culturable organisms (e.g., bacteria) that are collected by filtration of the product to be tested.

Abstract: An adjustable laser light beamsplitter and fiber optic coupler apparatus and method comprising a plurality of splitter modules placeable into an optical path, each module comprising: a splitter to split off a selectable portion of an incident polarized laser beam; a fiber coupler to capture the split-off portion into an optical fiber; and a beam transmitter element to transmit a remainder of the incident beam to serve as an incident polarized laser beam for any subsequent splitter module.

Abstract: A multi-beam Velocity Interferometer System for Any Reflector (VISAR) which can measure velocity histories at multiple locations simultaneously. A VISAR's interferometer accepts laser signal light which has been reflected from a specimen surface, and produces light fringes in proportion to the reflecting surface velocity by virtue of the Doppler shift in wavelength. The invention uses a reflected-light fiber optic bundle to supply the signal light for the VISAR. The bundle has multiple optical fibers, each carrying light reflected from a separate measurement location. The light emerging from the reflected-light fiber bundle is transformed into a beam by a collimator. The beam travels through the conventional VISAR interferometer, emerging usually in two or four exit beams. Imaging optics in the exit beams, together with the collimator, create real images of the end of the reflected-light fiber bundle.

Abstract: A multi-etalon VISAR interferometer with variable velocity-per-fringe constant, capable of measuring the velocity of a diffusely-reflecting surface, having design innovations which preserve the fringe alignment of the interferometer even when its velocity-per-fringe constant is changed or when it is exposed to environmental stress such as substantial temperature changes or being moved from one location to another. The interferometer stability is enhanced by using a very stiff interferometer frame, to which the alignment-sensitive components of the interferometer are attached. The movable interferometer components are attached to a relatively long slide bar which can be attached to the interferometer frame at various locations in a slide bar track in the interferometer frame. Delay leg spacers allow the slide bar, with its movable interferometer components, to be positioned easily and accurately when changing the velocity-per-fringe constant.

Abstract: A fiber optic probe for supplying and collecting instrumentation light in shock experiments. The fiber optic probe comprises two optical fibers and the necessary lens elements to concentrate laser light coming from one of the fibers onto a specimen, and to collect reflected laser light from the specimen into the second fiber. The fibers and lens elements are mounted in a special frame which facilitates better alignment of the lens/fiber arrangement by precise control of the flexing of the fiber optic probe's frame. Improved reflected light gathering efficiency and improved depth of field are achieved by the choices of the optical fiber diameters and by using good optical design practice. Inexpensive components and fabrication techniques allow for the economical use of these probes even when one is destroyed with each experiment.

Abstract: An isentropic compressive wave generator and method of making same. The w generator comprises a disk or flat "pillow" member having component materials of different shock impedances formed in a configuration resulting in a smooth shock impedance gradient over the thickness thereof for interpositioning between an impactor member and a target specimen for producing a shock wave of a smooth predictable rise time. The method of making the pillow member comprises the reduction of the component materials to a powder form and forming the pillow member by sedimentation and compressive techniques.

Abstract: The present invention involves a new method for measuring plane strain fracture toughness (K.sub.Ic) of a somewhat non-elastic material uniquely suitable for use on specimens that are smaller than have formerly been required for performing valid K.sub.Ic tests. The present invention involves selecting a short-rod specimen configuration in which the specimen material at a crack front or tip therein would be constrained during loading to a plane strain state and, from the measurement and anelastic analysis of a load-displacement curve that includes at least two unloading slopes the energy per unit crack area that is required to slowly advance a steady state crack can be determined, which data, along with measurement of the critical load when the crack passes through a known location, and considering the specimen geometry, is used to determine the fracture toughness, K.sub.Ic, of the specimen.

Abstract: The gauge of the present invention consists of a three-pronged spring clip for arrangement between the grips of a conventional grip-loading fracture specimen loading machine, which grips are inserted into the mouth of a standard slotted fracture toughness test specimen, the gauge to monitor the specimen mouth opening displacement thereof during a test for fracture toughness. The spring clip preferably is formed from a single sheet of material that is bent appropriately to produce two aligned legs or prongs with a center leg or prong there between. In operation the outside prongs are essentially stationary while the center prong is arranged to flex with respect to grip movement apart, which center movement is sensed electrically by a strain gauge secured thereto at its point of bending.

Abstract: A constant point of load application fracture specimen loading machine for applying a load between grips that engage opposite grip groove faces of a slotted specimen that preferably has as a remainder portion in that slot a "V" shaped slot root whereby, when the machine grips are moved apart, they rotate so as to apply a constant point of load application to pull the specimen apart at that slot root. The machine of the present invention is useful for measuring the fracture toughness, fatigue-crack growth resistance, or stress corrosion crack growth resistance of slotted specimens providing a unique force application system whereby sliding friction losses are minimized, and other introduced effects, such as from specimen grip machining tolerances, or the like, are largely automatically compensated for.

Abstract: An improved method for testing fracture toughness of tungsten carbide, and more particularly sintered tungsten carbide, consists of preparing a specimen from a short rod of sample material by cutting thin longitudinal slots forming a V within the slotted portion of the sample. An initial crack is started at the tip of the V formed by the slots. After the initial crack is started, the specimen is loaded with a force perpendicular to the slot plane and the peak force required in advancing the crack is recorded. The peak force is linearly related to the critical stress intensity factor (fracture toughness) of the specimen material.

Abstract: An improved method for testing fracture toughness of tungsten carbide, and more particularly sintered tungsten carbide, consists of preparing a specimen from a short rod of sample material by cutting thin longitudinal slots forming a V within the slotted portion of the sample. An initial crack is started at the tip of the V formed by the slots. After the initial crack is started, the specimen is loaded with a force perpendicular to the slot plane and the peak force required in advancing the crack is recorded. The peak force is linearly related to the critical stress intensity factor (fracture toughness) of the specimen material.