Abstract: Optical systems providing any or all of better images, brighter images, better optical usability, and better mechanical flexibility are made available to users of catalog lenses. These systems are enabled by apparatus including field compressor/corrector lenses and coordinated groups of field compressor/corrector lenses, and methods which include teaching the user how to make effective use of the apparatus. In preferred embodiments, the field compressor/corrector lenses are newly designed and are adapted to correct a field aberration of standard achromatic doublets. The apparatus may also be extracted from prior art lens combinations by separating these combinations into discrete components. These discrete components are then provided to the user and the user is taught how to combine these components to meet the user's specific requirements.

Abstract: Focusing systems for which variation of magnification with focus is either inherently compensated, or is calibrated and corrected. The required conditions for inherent compensation are determined, and the desired state is called constant relative magnification. It is shown that telecentricity does not guarantee constant relative magnification. Both telecentric and non-telecentric accessory cameras for endoscopes are disclosed that have constant relative magnification, as are additional optical systems for general metrological purposes. Methods for calibrating change in relative magnification and deviation of the optical axis with focal shift are disclosed, as are methods for incorporating these changes into perspective dimensional measurements. Embodiments are disclosed in which only a single quantity need be measured to perform the correction, and these embodiments require only a low-resolution position transducer to provide accurate measurements.

Abstract: Focusing systems for which variation of magnification with focus is either inherently compensated, or is calibrated and corrected. The required conditions for inherent compensation are determined, and the desired state is called constant relative magnification. It is shown that telecentricity does not guarantee constant relative magnification. Both telecentric and non-telecentric accessory cameras for endoscopes are disclosed that have constant relative magnification, as are additional optical systems for general metrological purposes. Methods for calibrating change in relative magnification and deviation of the optical axis with focal shift are disclosed, as are methods for incorporating these changes into perspective dimensional measurements. Embodiments are disclosed in which only a single quantity need be measured to perform the correction, and these embodiments require only a low-resolution position transducer to provide accurate measurements.

Abstract: Focusing systems for which variation of magnification with focus is either inherently compensated, or is calibrated and corrected. The required conditions for inherent compensation are determined, and the desired state is called constant relative magnification. It is shown that telecentricity does not guarantee constant relative magnification. Both telecentric and non-telecentric accessory cameras for endoscopes are disclosed that have constant relative magnification, as are additional optical systems for general metrological purposes. Methods for calibrating change in relative magnification and deviation of the optical axis with focal shift are disclosed, as are methods for incorporating these changes into perspective dimensional measurements. Embodiments are disclosed in which only a single quantity need be measured to perform the correction, and these embodiments require only a low-resolution position transducer to provide accurate measurements.

Abstract: Three-dimensional endoscopic measurements are made by adding an array of reference target points to the scene viewed by an endoscopic camera and characterizing the image formed by the camera when it views the scene from two or more viewing positions. Methods and apparatus are taught which allow one to make accurate measurements with any endoscope, without requiring any modification to the endoscope. Under certain circumstances, the measurements can be made without any pre-calibration of the endoscopic camera. A general measurement reference apparatus comprises a reference target array which is placed near to and fixed with respect to an object of interest inside an enclosure by means of a reference array holding apparatus and a reference array insertion apparatus. This measurement reference apparatus can be used to make either perspective dimensional measurements or to make conventional photogrammetric measurements of the object of interest.

Abstract: An improved system of perspective dimensional measurement uses complementary reference surfaces on a camera and on a camera translating unit to provide a repeatable relative orientation between the perspective displacement and the camera's measurement coordinate system while still allowing a rotational and an optional translational degree of freedom for alignment of the camera with an object of interest. In one set of embodiments the rotational axis is accurately aligned with the translation axis. In a second set of embodiments, the geometry of the system is determined in an expanded alignment calibration procedure, the rotation of the camera about the rotational axis is measured, and these additional data are incorporated into the perspective measurement procedure.

Abstract: Spatial locations of individual points on an inaccessible object are determined by measuring two images acquired with one or more cameras which can be moved to a plurality of positions and orientations which are accurately determined relative to the instrument. Once points are located, distances are easily calculated. In distinction to prior art, which uses a fixed separation of camera viewpoints, this new system offers smaller errors, measurement over a larger range of object distances, and measurement of distances which cannot be contained in a single camera view. Random errors are minimized by use of an optimum measurement geometry. Systematic errors are minimized by use of a complete and robust set of calibration procedures. A standard measurement procedure automatically obtains the optimum measurement geometry. A least squares calculation uses all of the image location and calibration data to derive the true three dimensional positions of the selected object points.