1. A focused ion beam system comprising:
a plasma chamber for containing a plasma;
a source electrode for biasing the plasma;
an extraction electrode for extracting ions from the plasma chamber;
a focusing lens for focusing the ions into a beam directed toward a work piece;
a sample chamber for containing a work piece, the sample chamber connected to a vacuum pump; and
a first intermediary vacuum chamber connected at one end to the plasma chamber and connected to a vacuum pump;
a second intermediary vacuum chamber connected to a vacuum pump;
a first differential pumping aperture connecting the first intermediary vacuum chamber and the second intermediary vacuum chamber; and
a second differential pumping aperture connecting the second intermediary vacuum chamber to the sample chamber or to one or more additional intermediary vacuum chambers.
2. (canceled)
3. The focused ion beam system of claim 1 in which each of the additional intermediary vacuum chamber has a lower pressure than an immediately preceding intermediary vacuum chamber.
4. (canceled)
5. The focused ion beam system of claim 1 in which the first intermediary vacuum chamber has a pressure at least five times lower than the pressure in a plasma chamber.
6. (canceled)
7. The focused ion beam system of claim 1 in which the sample chamber has a pressure higher than an immediately preceding intermediary vacuum chamber.
8. The focused ion beam system of claim 1 in which a sum of products of pressure times path length through each of the intermediary vacuum chambers and the sample chamber is less than 3\xd710\u22123 mbar*mm.
9. The focused ion beam system of claim 8 in which the sum of the products of the pressure times the path length through each of the intermediary vacuum chambers and the sample chamber is less than 3\xd710\u22125 mbar*mm.
10. The focused ion beam system of claim 1 configured such that a probability of energetic neutral creation is less than 1%.
11. The focused ion beam system of claim 1 configured such that a probability of energetic neutral creation is less than 0.01%.
12. The focused ion beam system of claim 1 further comprising means to reduce an energy spread of ions emitted from the plasma chamber to less than 10 eV.
13. A method of improving ion beam processing using a plasma ion source by reducing the number of energetic neutral particles impacting onto a work piece, comprising:
applying energy to a gas in a plasma chamber to produce a plasma, the plasma chamber being maintained at a first pressure;
extracting ions from the plasma chamber into a first intermediary vacuum chamber, the first intermediary vacuum chamber being maintained at a pressure lower than the first pressure;
passing the ions from the first intermediary vacuum chamber through a first differential pumping aperture into a second intermediary vacuum chamber, the second intermediary vacuum chamber being maintained at a pressure lower than that of the first intermediary vacuum chamber;
passing the ions into a sample chamber through a second differential pumping aperture; and
focusing the ions onto a work piece to process the work piece with the focused ions.
14. (canceled)
15. The method of claim 13 in which a product of pressure times path length through each of the intermediary vacuum chambers and the sample chamber is less than 3\xd710\u22123 mbar*mm.
16. The method of claim 13 in which a product of pressure times path length through each of the intermediary vacuum chambers and the sample chamber is less than 3\xd710\u22125 mbar*mm.
17. The method of claim 13 further comprising reducing a probability of energetic neutral creation from the first intermediary vacuum chamber to the work piece to less than 1%.
18. The method of claim 13 further comprising reducing a probability of energetic neutral creation from the first intermediary vacuum chamber to the work piece to less than 0.01%.
19. The method of claim 13 in which the first intermediary vacuum chamber is maintained at a pressure of between 10\u22125 mbar and 10\u22126 mbar and the second intermediary vacuum chamber is maintained at a pressure of between 10\u22126 mbar and 10\u22127 mbar.
20. The method of claim 13 in which extracting ions from the plasma chamber into a first intermediary vacuum chamber includes extracting ions having an energy spread of less than 10 eV.
21. The focused ion beam system of claim 1, wherein:
the vacuum pump connected to the first intermediary vacuum chamber is a different vacuum pump than the vacuum pump connected to the second intermediary vacuum chamber;
the vacuum pump connected to the first intermediary vacuum chamber is capable of maintaining the first intermediary vacuum chamber at a pressure in a range of from about 10\u22125 mbar to about 10\u22126 mbar; and
the vacuum pump connected to the second intermediary vacuum chamber is capable of maintaining the second intermediary vacuum chamber at a pressure in a range of from about 5*10\u22127 mbar to about 1*10\u22127 mbar.
22. The focused ion beam system of claim 1, wherein:
the vacuum pump connected to the first intermediary vacuum chamber is a turbo pump;
the second intermediary vacuum chamber or an additional intermediary vacuum chamber is connected at one end to the second differential pumping aperture and connected to an ion pump.
23. A focused ion beam system comprising a focused ion beam column, the focused ion beam column including:
a plasma chamber;
a sample chamber;
vacuum chambers connected in series between the plasma chamber and the sample chamber, the vacuum chambers separated by pressure limiting apertures and configured to be differentially pumped during operation of the focused ion beam column, as a focused ion beam passes from the plasma chamber to the sample chamber via the vacuum chambers.
24. The focused ion beam system of claim 23, further comprising vacuum pumps connected to the vacuum chambers and configured to carry out the differential pumping, wherein the differential pumping prevents the creation of energetic neutrals in the focused ion beam column during the operation of the focused ion beam column.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A joint prosthesis articulation comprising:
a concave component having a main axis; and
a convex component seated within said concave component;
wherein, in an unloaded state of the articulation, said concave component and said convex component are at least partially congruent over an annular surface area generally centred on an axis of symmetry about which at least a portion of an inner surface of said concave component or an outer surface of said convex component is axisymmetric, and wherein said axis of symmetry is offset from said main axis.
2. The joint prosthesis articulation of claim 1, wherein the concave and the convex components of the articulation, brought into contact, define a closed volume bounded by an inner radius of said annular surface area.
3. The joint prosthesis articulation of claim 1, wherein the convex component of the articulation is spherical in shape.
4. The joint prosthesis articulation of claim 1, wherein the concave component of the articulation is shaped as a body of revolution around the axis of symmetry, the body of revolution defining an arc of the annular surface area with the convex component, wherein the arc is centered at a position angle of contact relative to the axis of symmetry, leaving a gap between the convex component and concave component at a pole defined by the axis of symmetry.
5. The joint prosthesis articulation of claim 4, wherein the position angle of contact of the annular surface area is in a range of 20 to 50 degrees andor wherein an angle of width of the annular surface area is in a range of 10 to 40 degrees.
6. The joint prosthesis articulation of claim 4, wherein the gap is in a range of 0.02 to 2 mm.
7. The joint prosthesis articulation of claim 4, wherein the gap is in a range of 0.3 to 1 mm for UHMWPE-incorporating articulations.
8. The joint prosthesis articulation of claim 4, wherein the gap is in a range of 0.05 to 0.2 mm for metal-metal and ceramic-ceramic articulations.
9. The joint prosthesis articulation of claim 1, wherein the concave component of the articulation is spherical in shape.
10. The joint prosthesis articulation of claim 1, wherein the convex component of the articulation is shaped as a body of revolution around the axis of symmetry, the body of revolution defining an arc of the annular surface area with the concave component, wherein the arc is centered at a position angle of contact relative to the axis of symmetry, leaving a gap between the convex component and the concave component near a pole defined by the axis of symmetry.
11. The joint prosthesis articulation of claim 10, wherein the position angle is in the range of 20 to 50 degrees andor wherein and angle of width of the annular surface area is in the range of 10 to 40 degrees.
12. The joint prosthesis articulation of claim 10, wherein the maximum value of the gap is in the range of 0.02 to 2 mm.
13. The joint prosthesis articulation of claim 10, wherein the maximum value of the gap is in the range of 0.3 to 1 mm for UHMWPE-incorporating articulations.
14. The joint prosthesis articulation of claim 10, wherein the maximum value of the gap is in the range of 0.05 to 0.2 mm for metal-metal and ceramic-ceramic articulations.
15. The joint prosthesis articulation of claim 1, wherein said concave and said convex components of the articulation form an interrupted annular area of contact in an unloaded state and form a closed annular area of contact under physiological loads.
16. The joint prosthesis articulation of claim 1, wherein the annular surface area is bounded by first and second polar angles with respect to the axis of symmetry, the second polar angle being larger than the first polar angle, and wherein a radius of curvature of the concave component at polar angles greater than the second polar angle is greater than the radius of curvature of the concave component between the first and second polar angles.
17. The joint prosthesis articulation of claim 1, comprising one of a hip prosthesis, a spinal disk prosthesis, a knee prosthesis, a prosthesis for a single kneetibia condyle, a shoulder prosthesis, a finger prosthesis, an elbow prosthesis, a wrist prosthesis, and an ankle prosthesis.
18. A joint prosthesis articulation, comprising:
a concave component having a main axis; and
a convex component seated within said concave component;
wherein, in an unloaded state of the articulation and under a tare-load, said concave component and said convex component are at least partially congruent over an annular surface area generally centred on an axis of symmetry about which at least a portion of an inner surface of said concave component or an outer surface of said convex component is axisymmetric, and wherein said axis of symmetry is offset from said main axis.
19. A joint prosthesis articulation, comprising:
a concave component having a main axis; and
a convex component seated within said concave component;
wherein said concave and said convex components of the articulation form an interrupted annular area of contact in an unloaded state and under a tare-load and form a closed annular area of contact under physiological loads, wherein said annular area is generally centered on an axis of symmetry about which at least a portion of an inner surface of said concave component or an outer surface of said convex component is axisymmetric, and wherein said axis of symmetry is offset from said main axis.