Stacked zone plates for pitch frequency multiplication
A compound x-ray lens and method of fabricating these lenses are disclosed. These compound lenses use multiple zone plate stacking to achieve a pitch frequency increase for the resulting combined zone plate. The compound equivalent zone plate includes a first zone plate having an initial pitch frequency stacked onto a second zone plate to form an equivalent compound zone plate. The equivalent zone plate has a pitch frequency that is at least twice the initial pitch frequency. Also, in one example, the equivalent zone plate has a mark-to-space ratio of 1:1.
1. A method for fabricating a compound zone plate comprising:
fabricating a first zone plate by depositing zones on sidewalk of a first patterned resist template using a conformal thin film coating process;
fabricating a second zone plate by depositing zones on sidewalls of a second patterned resist template using a conformal thin film coating process, wherein the second patterned resist template provides complementary zone placement relative to the zones of the first zone plate; and
stacking the first zone plate on the second zone plate to form a compound zone plate and aligning the first zone plate with the second zone late so that the zones of the first zone plate are interlaced with the zones of the second zone plate, wherein the resist templates have been retained in the stacked first zone plate and second zone plate.
2. A method as claimed in claim 1 , wherein the
first zone plate has an initial pitch frequency and
when the zone plates are mechanically stacked together to form the compound zone plate, the compound zone plate has a pitch frequency that is greater than the initial pitch frequency.
3. The method as claimed in claim 1 , wherein the compound zone plate has a mark-to-space ratio of 1:1 in the outermost zones, and the first and second zone plates have a mark-to-space ratio of 1:2n+1, wherein n is an integer equal to 1 or higher.
4. The method as claimed in claim 1 , wherein zones of the first and second zone plates include Gold.
5. The method as claimed in claim 1 , wherein zones of the first and second zone plates include Platinum.
6. The method as claimed in claim 1 , wherein zones of the first and second zone plates include Tungsten.
7. The method as claimed in claim 1 , wherein zones of the first and second zone plates include Iridium.
8. The method as claimed in claim 1 , further including a third zone plate mechanically stacked with the first and second zone plates.
9. The method as claimed in claim 8 , further including a fourth zone plate mechanically stacked with the first, second, and third zone plates.
10. The method as claimed in claim 1 , wherein the compound zone plate has a mark-to-space ratio of 1:1 in the outermost zones.
11. The method as claimed in claim 1 , wherein fabricating the first zone plate and the second zone plate comprises using atomic layer deposition to deposit Gold zones.
12. The method as claimed in claim 1 , wherein fabricating the first zone plate and the second zone plate comprises using atomic layer deposition to deposit Platinum zones.
13. The method as claimed in claim 1 , wherein fabricating the first zone plate and the second zone plate comprises using atomic layer deposition to deposit Tungsten zones.
14. The method as claimed in claim 1 , wherein fabricating the first zone plate and the second zone plate comprises using atomic layer deposition to deposit Iridium zones.
15. The method as claimed in claim 1 , further comprising:
fabricating a third zone plate using atomic layer deposition to deposit zones on sidewalk of a third patterned resist template; and
stacking the third zone plate with the first zone plate and the second zone plate to form the compound zone plate.
16. The method as claimed in claim 15 , further comprising:
fabricating a fourth zone plate using atomic layer deposition to deposit zones on sidewalls of a fourth patterned resist template; and
stacking the fourth zone plate with the first zone plate, the second zone plate, and the third zone plate to form the compound zone plate.