Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
137 words
In a charged particle imaging system of the type having an objective lens; an annular diaphragm behind the objective lens for stopping, except for an annular aperture zone, rays transmitted from a point on the axis in an object plane located in front of the objective lens so as to form a hollow beam, the rays of said beam generating a first annular caustic surface behind the diaphragm; and a first supplementary lens behind the first annular caustic surface for focusing the hollow beam at a point on the axis, the improvement comprising: a second supplementary lens, having a focal length that is large in comparison to that of the objective lens, located between the first caustic surface and the first supplementary lens for generating a second annular caustic surface in front of the first supplementary lens.
Claim 2
Dependent Claim
137 words
In a charged particle imaging system of the type having an objective lens; an annular diaphragm behind the objective lens for stopping, except for an annular aperture zone, rays transmitted from a point on the axis in an object plane located in front of the objective lens so as to form a hollow beam, the rays of said beam generating a first annular caustic surface behind the diaphragm; and a first supplementary lens behind the first annular caustic surface for focusing the hollow beam at a point on the axis, the improvement comprising: a second supplementary lens, having a focal length that is large in comparison to that of the objective lens, located between the first caustic surface and the first supplementary lens for generating a second annular caustic surface in front of the first supplementary lens.
Claim 3
Dependent Claim
29 words
The imaging system of claim 1 wherein the first supplementary lens also has a large focal length as compared to the objective lens for the purpose of magnified imaging.
Claim 4
Dependent Claim
39 words
The imaging system of claim 1 wherein the annular zone of the diaphragm has a radial width such that the wave aberration of the hollow beam is maximally lambda /4, where lambda is the wavelength of the imaging radiation.
Claim 5
Dependent Claim
30 words
The imaging system of claim 1, further comprising: a third supplementary lens having a focal length large as compared to the objective lens and located behind the first supplementary lens.
Claim 6
Dependent Claim
50 words
The imaging system of claim 4 wherein the first supplementary lens focuses the hollow beam virtually at a point on the axis in front of said first supplementary lens so that the image generated by the objective lens and the first and second supplementary lenses is a magnified virtual image.
Claim 7
Dependent Claim
127 words
The imaging system of claim 1 wherein the first and second supplementary lenses are positioned in relation to the objective lens so as to satisfy the condition: CF (ro/fo)2 + CF (r1/f1)2 - CF (r2/f2)2 0, where CF , CF , CF , are the color error coefficients for infinite magnification of the objective and the first and second supplementary lens, respectively; fo, f1 and f2 are the corresponding focal lengths; r1, r2 are the radial distances from the axis of the principal surface of the hollow beam as it enters the supplementary lenses; and ro is the radial distance from the axis of the principal surface of the hollow beam in the plane of the annular diaphragm, which is assumed to be in the field-free space.
Claim 8
Dependent Claim
32 words
The imaging system of claim 1 wherein the objective lens and the first and second supplementary lenses comprise magnetic lenses, and the first and second supplementary lenses have approximately telescopic lens power.