Abstract: A device for providing an output beam in a direction, the device including a plate including an exit pupil; a plurality of rows of optical elements disposed substantially in a first plane, each row of optical elements in the first plane including: at least one beam splitter; and a plurality of rows of optical elements disposed substantially in a second plane, the optical elements in the second plane include mirrors, wherein the second plane is disposed between the exit pupil and the first plane, wherein the at least one beam splitter at the first plane is configured to transmit an incident beam to one of a subsequent optical element at the first plane and a subsequent optical element at the second plane before being reflected to exit through the exit pupil.

Abstract: A method for detecting lens cleanliness of a lens disposed in a flat-field optical path, the flat-field optical path including a light source, the lens, a camera, the light source is a narrow-band multispectral uniform surface light source, the camera's light-sensitive surface is disposed perpendicular to an optical axis of the lens and in the light position of the lens, the method including collecting the bright-field image data and dark-field image data in a plurality of spectra through the lens; for each pixel, performing a spectral differential flat-field correction operation to yield a plurality of spectral differentials; and displaying the spectral differentials in the form of a plurality of images to show a uniformity of each of the plurality of images, wherein a non-uniform area on each of the plurality of images is determined to have been caused by an impurity of the lens.

Abstract: A method for detecting lens cleanliness of a lens disposed in a flat-field optical path, the flat-field optical path including a light source, the lens, a camera, the light source is a narrow-band multispectral uniform surface light source, the camera's light-sensitive surface is disposed perpendicular to an optical axis of the lens and in the light position of the lens, the method including collecting the bright-field image data and dark-field image data in a plurality of spectra through the lens; for each pixel, performing a spectral differential flat-field correction operation to yield a plurality of spectral differentials; and displaying the spectral differentials in the form of a plurality of images to show a uniformity of each of the plurality of images, wherein a non-uniform area on each of the plurality of images is determined to have been caused by an impurity of the lens.

Abstract: A method for detecting lens cleanliness of a lens in a flat-field optical path, the flat-field optical path includes a light source, the lens, a camera, the light source is a narrow-band multispectral uniform surface light source, the camera's light-sensitive surface is disposed perpendicular to an optical axis of the lens and in the light position of the lens and a pupil interposed between the lens and the light source, the method including collecting the bright-field image data and dark-field image data for a plurality of pupil aperture sizes through the lens; for each pixel, performing a pupil differential flat field correction to yield a plurality of PiPj pupil differentials; and displaying the pupil differentials in the form of a plurality of images to show uniformity of each the image, wherein a non-uniform area on each the image is determined to have been caused by an impurity of the lens.

Abstract: A method for detecting lens cleanliness of a lens in a flat-field optical path, the flat-field optical path includes a light source, the lens, a camera, the light source is a narrow-band multispectral uniform surface light source, the camera's light-sensitive surface is disposed perpendicular to an optical axis of the lens and in the light position of the lens and a pupil interposed between the lens and the light source, the method including collecting the bright-field image data and dark-field image data for a plurality of pupil aperture sizes through the lens; for each pixel, performing a pupil differential flat field correction to yield a plurality of PiPj pupil differentials; and displaying the pupil differentials in the form of a plurality of images to show uniformity of each image, wherein a non-uniform area on each image is determined to have been caused by an impurity of the lens.

Abstract: A method for detecting lens cleanliness of a lens in a flat-field optical path, the flat-field optical path includes a light source, the lens, a camera, the light source is a narrow-band multispectral uniform surface light source, the camera's light-sensitive surface is disposed perpendicular to an optical axis of the lens and in the light position of the lens, the method including disposing the camera such that the camera's light-sensitive surface is located a distance from the focal plane of the lens and measuring the bright-field image data and the dark-field image data; for each pixel, performing an out-of-focus differential flat field correction to yield a plurality of DiDj out-of-focus differentials; repeating the disposing and performing steps by altering the distance at least two more times; and displaying the out-of-focus differentials in the form of a plurality of images to show uniformity of each of the plurality of images.