In an optical scanning system for detecting particles and pattern defects on a sample surface, a light beam is focused to an illuminated spot on the surface and the spot is scanned across the surface along a scan line. A detector is positioned adjacent to the surface to collect scattered light from the spot where the detector includes a one- or two-dimensional array of sensors. Light scattered from the illuminated spot at each of a plurality of positions along the scan line is focused onto a corresponding sensor in the array. A plurality of detectors symmetrically placed with respect to the illuminating beam detect laterally and forward scattered light from the spot. The spot is scanned over arrays of scan line segments shorter than the dimensions of the surface. A bright field channel enables the adjustment of the height of the sample surface to correct for errors caused by height variations of the surface. Different defect maps provided by the output of the detectors can be compared to identify and classify the defects. The imaging function of the array of sensors combines the advantages of a scanning system and an imaging system while improving signal/background ratio of the system.

Optical scanning system for surface inspection

A high sensitivity and high throughput surface inspection system directs a focused beam of light at a grazing angle towards the surface to be inspected. Relative motion is caused between the beam and the surface so that the beam scans a scan path covering substantially the entire surface and light scattered along the path is collected for detecting anamolies. The scan path comprises a plurality of arrays of straight scan path segments. The focused beam of light illuminates an area of the surface between 5-15 microns in width and this system is capable of inspecting in excess of about 40 wafers per hour for 150 millimeter diameter wafers (6-inch wafers), in excess of about 20 wafers per hour for 200 millimeter diameter wafers (8-inch wafers) and in excess of about 10 wafers per hour for 300 millimeter diameter wafers (12-inch wafers).

Scanning system for inspecting anamolies on surfaces

An automotive trim product is made as follows. A single or multiple layer sheet is extruded so as to include at least one color pigmented and/or metallized layer therein. The sheet is then thermoformed into a three-dimensionally shaped preform via vacuum forming or the like. The preform is placed into a cavity of an injection molding apparatus and heated semi-molten material is injected thereinto. The semi-molten material bonds to the preform in the cavity. After cycling, the molding apparatus ejects a final automotive trim part. Optionally, some processing (e.g. trimming) may be performed following ejection.

Extruded automotive trim and method of making same

A method and apparatus for analyzing the appearance features of a surface with a spatially coherent beam of uniformly distributed collimated polychromatic light that is directed through a beam limiting means (or mask) and onto the surface at an acute angle of incidence. A scanned imaging detector, translatable through a sequence of focal plane positions along the optic axis between the mask and surface, measures the reflectance values associated with the scanned pixel intensities. After standardization, the scan intensity values are Fourier transformed into the spatial frequency domain to obtain an optical transfer function (OTF) and power and amplitude spectra. The visual spatial frequency response characteristic V(f) and standard psychophysical methodology is applied to mathematically determine surface appearance attributes such as orange peel, microwrinkle, cracks and crazes, distinctness of image (DOI), gloss, haze, contrast, luster, fog and texture.

Method and apparatus for analyzing the appearance features of a surface

A spectrophotometer apparatus (200) is adapted to provide spectral reflectance measurements of object, particularly optical characteristics of colored surfaces comprising metallic or pearlescent particles. The apparatus (200) comprises a source light and a reflection optics assembly. Signals representative of reflected light are analyzed and data is generated representative of the spectral response characteristics of the object sample. The apparatus employs a plurality of fiber optic bundles for receiving light reflected from the object sample, with each of the fiber optic bundles being positioned at one of a corresponding plurality of fixed angles different from the angle of illumination by the source light. Reflectance is measured at each angle by sequential switching such that light is impaired from being received from all but one of the plurality of multiple angles. Light received from the fiber optic bundles is transferee to a single array of integral interference-filter/photodiode devices which modulate the light and determine the spectro characteristics thereof. With the use of fiber optic devices, a single source of illumination and a single optical detector arrangement, the spectrophotometer apparatus is employed within an optimally small packaging configuration, and the apparatus can be maintained in a portable mode while maintaining relatively high accuracy and repeatability.

Multiangular color measuring apparatus

Electrical stock removal apparatus

In order to obtain an objective measurement of paint gloss on a flat or slightly curved surface, a distinctness of image instrument is provided having a light source for projecting a light beam onto the test surface, a detector responsive to reflected light from the surface, an aperture at the detector, a chopper near the light source and a lens for imaging the chopper blade on the plane of the aperture so that the sharpness of the image depends upon the reflective quality of the test surface. The rate of change of the detector output signal is large for a high glass surface while the rate of change is low for a low gloss surface. For use of the instrument on curved as well as flat surfaces the chopper is provided with a plurality of blades spaced at different distances from the light source. The blade image which is more nearly focussed on the aperture will produce a larger rate of change in the detector signal and the signal with the largest rate of change is chosen as the one representative of the surface quality.

Distinctness of image meter

Orange peel or texture of a painted surface (10) is measured by scanning a light beam (14) across the surface and receiving the reflected beam on an area detector (38) generating a signal having a first component varying with surface slope variations in the painted surface and a second component due to scan rate Apparatus is provided for orienting the light beam (14) relative to the painted surface (10) so as to be reflected therefrom to the detector area without re-reflection from the painted surface; and a converging lens (24) converges the light beam (14) on the area detector (38) A portable, surface contacting embodiment uses a plurality of projecting feet (74) for orientation to the painted surface (10) and relies on the converging lens (24) for convergence In a non-contact embodiment, variations in orientation and curvature of the surface are detected by the second component of the signal and compensated for in closed loop control of a mirror (22) and the converging lens (24) to dynamically converge the beam (14) on the area detector (38)

Method and apparatus for measuring orange peel and texture in painted surfaces

A single meter measures the gloss and the distinctness of image (DOI) of a painted surface for quality evaluation of the finish. A DOI signal is obtained by a prior method of focusing the reflected image of a moving shutter onto a slit and measuring the light passing through the slit. The rate of increase of the resulting signal is used as a measure of DOI. The same signal is integrated over a preset time period covering the upper part of the signal rise to yield a value proportional to gloss.

Combined distinctness of image and gloss meter

The surfaces of large (approximately 1-m) diffusely reflecting objects can be mapped by automatic following of the holographic real image of the object. Large aperture, low f number holograms give the shallow depth of focus required for this method. The ability to apply the technique to situations requiring a pulsed laser is demonstrated. Unity magnification real images from holograms made with a Q-switched ruby laser have a measured metric fidelity of at least one part in 104 over an object field of 60 deg. A sinusoidal optical interference pattern projected onto the object when the hologram is taken provides the type of contrast pattern necessary for unambiguous determination of the location of the focused image surface and facilitates automatic focus detection. The image is scanned by an image dissector that is moved about the image by a 3-axis slide system. A computer analyzes the video signals, directs the machine motions to follow the image, and provides an output of surface dimensions in digital form. A prototype machine using cw helium–neon lasers for object illumination and image reconstruction is described and performance data presented.

Thomas T. Stapleton

Papers

Electrical stock removal apparatus

Distinctness of image meter

Method and apparatus for measuring orange peel and texture in painted surfaces

Combined distinctness of image and gloss meter

Holographic System for Automatic Surface Mapping