Industrial Technology Institute

Other

Insutrial Technology Institute

Kevin G Harding

Albert J Boehnlein

Leonard H Bieman

An optical method and system for measuring bore hole diameter, out-of-roundness and lobing and a probe for use therein are provided. A ring of structured light is initially formed or projected on the inner surface of a bore hole by optical components supported within a housing of the probe. A lens system also supported within the housing images the ring of light. Image merging lenses of the lens system reform the image at a video camera located at a window of the housing such that two or more arcs of the ring form a magnified image with the image of the arcs being shifted in space such that all the arcs can be viewed by the camera. The video camera image is captured by a frame grabber/computer. A computer calculates the location of the arcs and from this information determine bore diameter and other bore properties such as out-of-roundness and lobing. The method, system and probe have the ability to capture information around the entire bore without movement of the camera or any of the optical components supported within the housing.

Method and system for measuring cavities and probe for use therein

A moire interferometry system and method are provided for achieving full field surface contouring with an extended depth of view of image. The moire interferometry system includes a projection system generally made up of a light source, imaging lens and a square wave grating pattern. The imaging lens is configured to filter higher order light rays passing through the square wave grating pattern so as to project a sine wave like pattern onto a desired surface. The moire interferometry system also includes a viewing system generally made up of an imaging lens, a submaster grating and a camera. The submaster grating is preferably a customized grating that may be produced by recording a grating pattern in relation to a reference surface. The camera is able to view an image anywhere within the extended depth of image and analyze the moire fringes. A determination of deviation between a test part and a reference surface provides a part inspection system.

Moire interferometry system and method with extended imaging depth

A filter for a laser gaging system that significantly increases the accuracy of the system when measuring scattering or translucent surfaces by reducing deviations caused by skewed speckle patterns. The filter limits the field of view of the sensor to light rays originating along the detection axis of the laser gaging system, thereby reducing the effects of noise such as halos, star patterns and beat patterns. The filter can comprise a slit filter or preferably a slit filter in combination with a grated filter, such as a tandem holographic filter.

Filter for laser gaging system

A method of evaluating defects in a surface as compared with a reference surface by providing a surface for defect evaluation, illuminating and projecting a pattern of lines on the surface having a periodic configuration with features having a separation period, providing a camera for recording a reflected image of the pattern of lines projected and reflected from the surface, and evaluating and quantifying the image by calculating a slope of a defect observed by the camera using a specified relationship. The distance between the illuminated pattern and the surface are used to calculate the defect slope and a defect depth value is generated using a specified relationship dependent on length of a defect area visually recognizable from the reflected image and the calculated defect slope.

Highlighted panel inspection

A moire interferometry system for detecting defects in a surface of a panel. The moire interferometry system is adapted to be used as a defect detection tool and not specifically as a surface measurement tool. The system includes a moire projection system having a light source and master grating projecting grating lines onto a surface panel to be inspected. A viewing system with a detection means records an image of the surface with the master grating lines on it as viewed through a submaster grating. The intersection of the projected lines on the panel and the lines in the submaster grating produce moire fringes. Phase shift interferometry techniques are used to produce a phase map of the surface for a plurality of phase shifted moire fringes. A derivative operation is performed on the image, and that image thresholded to identify areas of pixels having the greatest change in contour. The resulting image can then be used to locate and quantify deviations in the contour of the panel which exceed predetermined tolerances to identify defects. The system provides an unambiguous quantitative means for characterizing defects which does not require skilled operators or the application of highlighting fluid to the surface.

Moire inspection system

A moire contouring imaging device for small field moire imaging in which both the illumination and viewing optical beam paths pass through a common primary lens and optical grating. The use of such common optical elements improves optical stability and accuracy since magnification and focal length and other mismatching between discrete optical elements in the viewing and illumination paths are avoided. The device is assembled in a rugged elongated housing. The device further incorporates mechanisms for either translating the grating to generate a moire phase shift, or translating the folding mirror of the system to provide a moire field shift.

Moire contouring camera

A moire contouring imaging device for small field moire imaging in which both the illumination and viewing optical beam paths pass through a common primary lens and optical grating. The use of such common optical elements improves optical stability and accuracy since magnification and focal length and other mismatching between discrete optical elements in the viewing and illumination paths are avoided. The device is assembled in a rugged elongated housing. Additional features are provided to avoid the effects of unwanted stray light reflected off rear surfaces of optical elements within the system.

An optical gauging system for evaluating the surface shape of a workpiece along a particular cross section. The gauging system includes an illumination system which projects a line of light onto the workpiece surface. A viewing system is focused along a line which is illuminated when a workpiece surface is intersected by the line of light. The focused line of the viewing system is imaged onto a linear detector array. A translation mechanism is provided which moves the line of light and the focused line of the viewing system into the workpiece along the plane of the cross section of interest. The relationship between the translation mechanism and the output of the array is related to the profile shape of the workpiece along the cross section of interest.

High accuracy structured light profiler

A non-contact dimensional gage for turned parts which permits in-process gaging for closed loop machine operations. The gage locates three points on the circumference of the cylindrical workpiece which are formed by shadowing the part onto three photo detectors receiving collimated light along three angled optical axes. The photo detectors evaluate the extent of shadowing of the light beams caused by the presence of the workpiece. The output of the photo detectors is a function of the degree of shadowing and accordingly provides a measure of the location of the tangent points of the workpiece. When the workpiece is positioned within the working range of the device such that three of the light beams are partially blocked by the workpiece, the three circumferentially spaced points can be located and consequently the part's diameter can be determined.

Non-contact dimensional gage for turned parts

An optical structured light profiler for evaluating the surface shape of a workpiece along a particular cross section of interest. The profiler includes an illumination optical system which projects a sheet of light onto the workpiece surface along the cross sectional plane of interest. The viewing system has its optical axis perpendicular to the optical axis of the illumination systems such that it images the illuminated portion of the workpiece off-axis from its optical axis. In this manner the entire image illuminated on the workpiece surface is within the same depth-of-field plane of the viewing system, which provides advantages in selecting and designing the optics of the viewing system. In a first embodiment, a conventional wide angle lens is used in which only a portion of the lens is used to form an image. In accordance with a second embodiment, an optimized optical system for the viewing system is provided which images only in the off-axis region where the workpiece image is present. Many forms of the detector may be used including a two dimensional video camera or a translated linear detector array.

Growing community of inventors

Ann Arbor, MI, United States of America

Kevin G Harding