Abstract: A process for the nondestructive inspection of chromium-plated or coated metal parts. The process uses an uncomplicated electrolytic technique to etch selectively the surface of the part to thereby develop indications of thermal damage which are readily detectable by a simple visual inspection without the requirement for any further processing of the part for inspection. The process is particularly suitable for the nondestructive detection of thermal damage in hard chromium plating on a high-strength steel base metal. Damage in the base metal of the part itself, particularly that resulting from abusive grinding or other machining operations on the plating, can also be detected in the chromium plating on the part because of the excellent correlation between chromium damage and base metal damage. In the process, after the part has undergone normal pre-etch preparation, it is immersed anodically in a conventional electrolytic solvent of the plating metal and is etched for a short period of time.

Abstract: The method of determining the change in the spacing between two positions on a single object or a position on each of two objects, by affixing two linear scatterers at the two positions; illuminating the scatterers with coherent monochromatic light from a source such as a He-Ne laser and obtaining an indication of the relative movement from changes in the interference pattern.In one apparatus, linear scatterers are positioned on opposite sides of an adhesive in a lap joint. The scatterers are illuminated with light from a He-Ne laser to produce an interference pattern on a screen. Movement of a preselected fringe on the screen will provide an indication of strain in the adhesive lap joint.In another apparatus, fibers are attached to the ends of a standard bar specimen and a test bar specimen which are placed in a furnace. The fibers are then illuminated with light from a helium neon laser to produce an interference pattern.

Abstract: A method and apparatus for determining fatigue in a structural part. The fatigue sensor comprises, for example, a thin silver zinc film affixed to a structural member that is to be monitored for fatigue damage. Upon sufficient flexing or other cold working, the silver zinc film undergoes a color change, pink to silver, to thereby indicate that the structural member has reached predetermined fatigue levels.

Abstract: The method of determining the change in the spacing between two positions on a single object or a position on each of two objects, by affixing two linear scatterers at the two positions; illuminating the scatterers with coherent monochromatic light from a source such as a He-Ne laser and obtaining an indication of the relative movement from changes in the interference pattern.In one apparatus, linear scatterers are positioned on opposite sides of an adhesive in a lap joint. The scatterers are illuminated with light from a He-Ne laser to produce an interference pattern on a screen. Movement of a preselected fringe on the screen will provide an indication of strain in the adhesive lap joint.In another apparatus, fibers are attached to the ends of a standard bar specimen and a test bar specimen which are placed in a furnace. The fibers are then illuminated with light from a helium neon laser to produce an interference pattern.

Abstract: A method and devices for sensing changes in separation of a first member relative to a second member, as well as variables causing such changes is disclosed. Electromagnetic waves diffracted by means included in said first member interact with waves from means included in said second member to form a characteristic interference pattern. Measured changes in this pattern allow determination of changes in separation.

Abstract: An optics module for use in a holographic borehole instrument which is operable to determine the stress in the wall of a borehole by recording successively on the same holographic recording medium two holograms of a selected surface region of the wall and, in the interval between the two recordings, drilling a stress relief hole in the wall in stress relieving relation to the selected surface region to produce on the recording medium a double exposure hologram containing holographic information representing the stress. The optics module embodies a frame which adjustably mounts the optical elements of the holographic system of the instrument in a manner which facilitates initial alignment of the system and preserves the alignment during instrument operation.

Abstract: A method and apparatus are provided for testing containers such as glass bottles. The container is filled with an opaque material and then immersed in a bath having two parallel walls of light transmitting material. The bath contains a light transmitting liquid having a refractive index comparable with that of the material of the container and a light transmitting efficiency different from that of the material of the container. Light is projected through the parallel walls of the bath to illuminate the walls of the container so that the wall thickness is clearly visible and the distribution of wall thickness can be studied.

Abstract: A highly sensitive process for measuring fine deformation comprises a stage of illumination with beam to on a periodic structure having diffractive function as well as lacking in diffractive function, a stage of selecting wave of diffraction order having conjugate or nearly conjugate relation among diffracted wave fronts projected from the periodic structure by means of said illumination with beam so as to cause mutual interference, thus, the amount of deformation is measured by the interference fringe formed by said mutual interference when the basic period of periodic structure is displaced or periodic structure is deformed.

Abstract: A method is disclosed for measuring in-plane deformation in a surface of an article, which includes attaching to the surface a grid pattern which is periodic in relief, allowing the grid pattern to become deformed and thereafter taking a cast replica of the deformed grid pattern and processing the replica under laboratory conditions to produce Moire fringes from which the deformation can be measured. The cast replica is taken by loading a rigid carrier in the form of a glass plate with a layer of silicone rubber which is a curable shape-retentive material, impressing the silicone rubber layer upon the deformed relief grid pattern and curing the silicone rubber so that the replica is a faithful and permanent reproduction of the deformed pattern.

Abstract: An instrument for determining the stress in the wall of a borehole by recording successively on the same holographic recording medium two holograms of a selected surface region of the wall, and, in the interval between the two recordings, forming a stress relief in the wall in stress relieving relation to the surface region to produce on the recording medium a double exposure hologram. This hologram contains holographic information which represents the stress in the wall in the vicinity of the surface region and may be converted to data defining the magnitude and direction of the stress.