Patent Number: 
Section: claims

1. A method, comprising: changing a size of an electron object image with a set of electron lenses;  creating an interference pattern from the electron object image; and  imaging interference fringes of the interference pattern onto an image plane, while not changing a magnification of the interference pattern,  wherein changing the size of the electron object image includes maintaining a rotation of the electron object image defined by an astigmatic object illumination with respect to a final image plane constant by adjusting the astigmatic object illumination by adjusting a condenser. 2. The method of  claim 1 , wherein changing the size of the electron object image includes maintaining an aspect ratio defined by an astigmatic object illumination with respect to the final image plane constant by adjusting the astigmatic object illumination by adjusting a condenser electron lens set. claim 1 3. The method of  claim 1 , wherein changing the size of the electron object image includes demagnifying the electron object image at a power of {fraction (1/20)}. claim 1 4. The method of  claim 1 , wherein changing the size of the electron object image includes demagnifying the electron object image. claim 1 5. A method, comprising: changing a size of an electron object image with a set of electron lenses;  creating an interference pattern from the electron object image; and  imaging interference fringes of the interference pattern onto an image plane, while not changing a magnification of the interference pattern,  wherein changing the size of the electron object image includes maintaining an aspect ratio defined by an astigmatic object illumination with respect to the final image plane constant by adjusting the astigmatic object illumination by adjusting a condenser electron lens set. 6. The method of  claim 1 , wherein changing the size of the electron object image includes maintaining an intensity distribution with respect to a final image plane by adjusting an illumination. claim 1 7. The method of  claim 5 , wherein changing the size of the electron object image includes maintaining the aspect ratio as well as an intensity distribution defined by an astigmatic object illumination with respect to a final image plane by adjusting the astigmatic object illumination. claim 5 8. The method of  claim 5 , wherein changing the size of the electron object image includes maintaining rotation of the electron object image with respect to a final image plane constant. claim 5 9. An apparatus, comprising an electron beam emitter;  a condenser electron lens set coupled to the electron beam emitter;  a first set of electron lenses coupled to the condenser electron lens set, the first set of electron lenses adapted to change an electron object image size;  an electron biprism coupled to the first set of electron lenses; and  a second set of electron lenses coupled to the electron biprism, the second set of electron lenses adapted to image interference fringes of an interference pattern created by the electron biprism onto an image plane without changing a magnification of the interference pattern,  wherein the condenser electron lens set, which may include the pre-field of the objective lens, is sufficiently strong to maintain an astigmatic illumination condition with respect to a final image plane independent of a selected magnification of the first set of electron lenses and the astigmatic illumination condition includes rotation of the electron object image with respect to the final image plane. 10. The apparatus of  claim 9 , wherein the first set of electron lenses includes a wide-gap objective lens. claim 9 11. The apparatus of  claim 10 , further comprising a spherical aberration corrector coupled to the wide-gap objective lens. claim 10 12. The apparatus of  claim 9 , wherein the condenser electron lens set is sufficiently strong to maintain another astigmatic illumination condition with respect to a final image plane independent of the selected magnification of the first set of electron lenses and the another astigmatic illumination condition includes an aspect ratio with respect to the final image plane. claim 9 13. The apparatus of  claim 9 , wherein the condenser lens set includes stigmators that maintain the astigmatic illumination condition of rotation of the electron object image with respect to the final image plane. claim 9 14. The apparatus of  claim 9 , wherein the first set of lenses demagnify the electron object image. claim 9 15. The apparatus of  claim 9 , wherein the condenser electron lens set is sufficiently strong to maintain another astigmatic illumination condition with respect to a final image plane independent of the selected magnification of the first set of electron lenses and the another astigmatic illumination condition includes an intensity distribution with respect to the final image plane. claim 9 16. The apparatus of  claim 17 , wherein the condenser electron lens set is sufficiently strong to maintain another astigmatic illumination condition with respect to a final image plane independent of the selected magnification of the first set of electron lenses and the another astigmatic illumination condition includes an intensity distribution with respect to the final image plane. claim 17 17. An apparatus, comprising an electron beam emitter;  a condenser electron lens set coupled to the electron beam emitter;  a first set of electron lenses coupled to the condenser electron lens set, the first set of electron lenses adapted to change an electron object image size;  an electron biprism coupled to the first set of electron lenses; and  a second set of electron lenses coupled to the electron biprism, the second set of electron lenses adapted to image interference fringes of an interference pattern created by the electron biprism onto an image plane without changing a magnification of the interference pattern,  wherein the condenser electron lens set, which may include the pre-field of the objective lens, is sufficiently strong to maintain an astigmatic illumination condition with respect to a final image plane independent of a selected magnification of the first set of electron lenses and the astigmatic illumination condition includes an aspect ratio with respect to the final image plane. 18. The apparatus of  claim 17 , wherein the first set of electron lenses demagnify the electron object image. claim 17 19. The apparatus of  claim 17 , wherein the condenser electron lens set is sufficiently strong to maintain another astigmatic illumination condition with respect to a final image plane independent of the selected magnification of the first set of electron lenses and the another astigmatic illumination condition includes rotation of the electron object image with respect to the final image plane. claim 17 20. The method of  claim 5 , wherein changing the size of the electron object image includes demagnifying the electron object image. claim 5 21. The method of  claim 1 , wherein maintaining rotation of the electron object image with respect to a final image plane constant includes adjusting stigmators that are incorporated in the condenser. claim 1