Abstract: A focus detecting system for detecting focus state of an image forming optical system relative to an object, includes a beam splitter assembly for forming at least three coplanar two-dimensional images of a scene, each image having a different focus setting. An area array image sensor senses the images at the image forming plane. Signal processing electronics determine the sharpness of the three images and calculates an optimum focus setting for the optical system by deterring the variances of the three images and calculating a position of maximum variance corresponding to a best focus setting of the optical system.

Abstract: The Foucault or knife-edge method may be employed for testing an optical surface defined by an imaging device, for example, a mirror surface, to ascertain its characteristics, for example, whether or not it is a source of optical aberrations. To this end, the traditional Foucault knife-edge method typically employs a knife-edge that comprises a metal razor blade. The present method, in contrast, provides an improved Foucault method, and features a novel optical element suitable for employment in the method. The optical element comprises a transparent substrate, and a coating material that can adhere to at least a portion of the transparent substrate, thereby forming at least one knife-edge pattern.

Abstract: The Foucault knife-edge test has been traditionally employed for testing a monolithic imaging device, for example, a mirror, to ascertain its characteristics, for example, whether or not it is a source of optical aberrations. The present invention, in contrast to the traditional Foucault employment, discloses a Foucault testing of a segmented optic, thereby significantly extending the utility of the Foucault test.

Abstract: A method for providing corrections of distortions of an imaging device. Initial corrections may be provided through the use of active optics, to apply forces to the imaging device, or to a compensator device in a common optical path with the imaging device, so as to introduce deformations that cancel out the distortions. This action, in turn, may induce undesirable, secondary aberrations. The method of the invention provides steps for identifying, isolating and removing the undesirable secondary aberrations, and computing new applied forces that cannot induce the secondary aberrations.

Abstract: The historical Foucault knife-edge test enables one to passively ascertain an optical imaging device's characteristics, for example, whether or not it is a source of optical aberrations. The historical Foucault knife-edge test corresponds to an open loop control system, since a control action, which is that quantity responsible for producing the imaging device characteristic, or open loop output, is independent of that output. The present invention, in sharp contrast to the historical Foucault knife-edge test, discloses a method for closing the Foucault open loop, so that the control action is somehow dependent on the output. In this way, accordingly, dynamic steps can be taken to compensate for, or remove the optical aberrations.

Abstract: The historical Foucault knife-edge test enables one to qualitatively ascertain an optical imaging device's characteristics, for example, whether or not it is a source of optical aberrations. The novel method of the present invention, in sharp contrast, complements the historical Foucault knife-edge test, by expanding the test so as to develop a quantitative interpretation of the imaging device's characteristics. In particular, the novel method is suitable for determining a wavefront aberration over an entire surface of the imaging device.

Abstract: The historical Foucault knife-edge test enables one to qualitatively ascertain an optical imaging device's characteristics, for example, whether or not it is a source of optical aberrations. The novel method of the present invention, in sharp contrast, complements the historical Foucault knife-edge test, by expanding the test so as to develop a quantitative interpretation of the imaging device's characteristics.

Abstract: Method and system for wavefront reconstruction from an image plane intensity distribution profile. An imaging device may be an agent for producing the image plane intensity distribution profile, for example, a point spread function. In one embodiment, the method and system include defining a feature vector from the point spread function, and employing an adaptive computational architecture for associating the feature vector with at least one identifying characteristic of the imaging device, e.g., such as an amount of astigmatism.

Abstract: A method for providing corrections of distortions of a mirror. Initial corrections may be provided through the use of active optics, to apply forces to the mirror to introduce deformations that cancel out the distortions. This action, in turn, may induce undesirable aberrations. The method of the invention provides steps for identifying, isolating and removing the induced undesirable aberrations, and computing new applied forces that cannot induce the undesirable aberrations.

Abstract: An assembly that can provide corrections of distortions of a mirror. The assembly uses the method of active optics to apply forces to the mirror to introduce deformations that cancel out the distortions. An important feature of the assembly is the employment of a force actuator which comprises a closed feedback loop that closes around the force actuator. An advantage of this novel feature is that, in response to a disturbance to the force actuator, the feedback loop can maintain a desired controlled force for application to the mirror.