Abstract: A method for creating a retroreflective image of a surface (or transparent medium) is provided where the retroreflective image is produced by illuminating an area of the surface with light which is reflected therefrom to a retroreflector which returns this light to the surface area. At the surface area, the retroreflected light is then reflected again and imaged to thus form the retroreflected image. In one embodiment, a broad light source is used to image a secondary image of the surface. In another embodiment, the light field produced by the surface is larger than the retroreflective element or group of elements which are then moved. In still another embodiment, a single retroreflective element is used together with a divergent light source.

Abstract: Methods for improving and calibrating a retroreflection defects determination system are disclosed. The retroreflection system includes a light source which directs light to an area of a surface such that the light is reflected therefrom, a retroreflective member positioned such that the reflected light from the surface area impinges thereon and is thus returned to the surface area and re-reflected therefrom and an imaging device whereby the re-reflected light is imaged as a retroreflection image and scanned for intensity variations. In the identifying method, the retroreflective member of the system has a divergence angle, and the imaging step is repeated after the divergence angle has been appropriately changed. According to the calibrating methods, a first retroreflection image of a system is obtained. Then, one of the test conditions of the system is changed or the test surface is changed. The subsequent retroreflection image is then compared to the first in order to calibrate the system.

Abstract: Disclosed are improvements in the surface inspection method and apparatus invention of our copending application "Panel Surface Flaw Inspection", Ser. No. 579,971, U.S. Pat. No. 4,629,319, which has now come to be described as "DiffractoSight". Particularly disclosed are semi and full automatic techniques for quantifying and locating localized surface distortions. Applications for determination of scratches, paint finish defects and other surface problems are also described.The primary area of application is to cosmetic defects on automobile bodies, appliances, and furniture, and the dies, molds and models and other surfaces used in their manufacture.