Air-gap optical structure with a nonreflective air-gap spacer
An air-gap optical structure includes a first transmissive optical element, a second transmissive optical element, and a spacer structure disposed between the first transmissive optical element and the second transmissive optical element so as to define an air gap therebetween. The spacer structure includes a spacer having a spacer body, and a nonreflective multilayer interference coating between the spacer body and the second transmissive optical element.
1. An air-gap optical structure comprising:
a first transmissive optical element;
a second transmissive optical element; and
a spacer structure disposed between the first transmissive optical element and the second transmissive optical element so as to define an air gap therebetween, wherein the spacer structure comprises a spacer having
a spacer body, and
a substantially nonreflective multilayer interference coating between the spacer body and the second transmissive optical element.
2. The air-gap optical structure of claim 1 , wherein the first transmissive optical element and the second transmissive optical element are each made of glass.
3. The air-gap optical structure of claim 1 , wherein the spacer body is metallic and comprises
a first layer made of a first metal, and
a second layer made of a second metal overlying and contacting the first layer.
4. The air-gap optical structure of claim 1 , wherein a spacer thickness is from about 5 to about 15 micrometers.
5. The air-gap optical structure of claim 1 , wherein the spacer structure comprises at least three coplanar and laterally spaced-apart spacers.
6. The air-gap optical structure of claim 1 , wherein
the first transmissive optical element is a first prism, and
the second transmissive optical element is a second prism.
7. The air-gap optical structure of claim 1 , wherein the multilayer interference coating comprises at least three layers.
8. The air-gap optical structure of claim 1 , wherein the multilayer interference coating comprises
a first layer of yttrium oxide,
a second layer of titanium oxide,
a third layer of chromium, and
a fourth layer of titanium oxide.
9. An air-gap optical structure comprising:
a first transmissive prism;
a second transmissive prism; and
a spacer structure disposed between the first transmissive prism and the second transmissive prism so as to define an air gap therebetween, wherein the spacer structure comprises a spacer having
a metallic spacer body, and
a substantially nonreflective multilayer interference coating between the spacer body and the second transmissive prism, wherein the multilayer interference coating has at least three layers.
10. The air-gap optical structure of claim 9 , wherein the first transmissive optical element and the second transmissive optical element are each made of glass.
11. The air-gap optical structure of claim 9 , wherein the spacer body is metallic and comprises
a first layer made of a first metal, and
a second layer made of a second metal overlying and contacting the first layer.
12. The air-gap optical structure of claim 9 , wherein the spacer thickness is from about 5 to about 15 micrometers.
13. The air-gap optical structure of claim 9 , wherein the spacer structure comprises at least three coplanar and laterally spaced-apart spacers.
14. The air-gap optical structure of claim 9 , wherein the multilayer interference coating comprises at least three oxide layers.
15. The air-gap optical structure of claim 9 , wherein the multilayer interference coating comprises
a first layer of yttrium oxide about 39 nanometers thick,
a second layer of titanium oxide about 32 nanometers thick,
a third layer of chromium about 10 nanometers thick, and
a fourth layer of titanium oxide about 37 nanometers thick.