Optical element and method of making an optical element

Patent metadata

Field	Value
Publication number	US-10698135-B2
Application number	US-201715614122-A
Country	US
Kind code	B2
Filing date	Jun 5, 2017
Priority date	Jun 3, 2016
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A method for producing an optical element having a main body with a first side surface, which has a first optical coating, and at least one second side surface, which is not plane-parallel to the first side surface and has a second optical coating, is proposed. The method includes the steps of: determining the stress induced in the optical element by the first optical coating of the first side surface; determining a counter-stress, so that the resultant overall stress induced in the optical element is as small as possible; determining the second optical coating while taking into account the determined counter-stress and the optical parameters of the second optical coating; applying the first optical coating on the first side surface; and, applying the second optical coating on the at least one second side surface.

First claim

What is claimed is:

1. An optical element comprising:
a main body having a first side surface and at least one second side surface;
said first side surface and said at least one second side surface being non-plane-parallel;
a first optical coating applied to said first side surface, wherein said first coating induces a first stress on the optical element;
a second optical coating having optical parameters and being applied to said at least one second side surface, wherein said second optical coating induces a counter-stress on the optical element;
said second optical coating being selected with said counter-stress induced by said second optical coating and said optical parameters of said second optical coating being taken into account; and,
the optical element being a polarizer for operation in an infrared wavelength range.

2. The optical element of claim 1 , wherein said at least one second side surface adjoins said first side surface.

3. The optical element of claim 1 , wherein said main body or a subunit of said main body is formed as a prism or a wedge-shaped plate.

4. The optical element of claim 1 , wherein at least one of said first optical coating and said second optical coating is formed as an antireflection coating, as a reflection coating or as a filter layer.

5. The optical element of claim 1 , wherein said first optical coating and said second optical coating are made of different materials.

6. The optical element of claim 1 , wherein
the optical element is configured to be operated in a wavelength range having a main wavelength;
at least one of said first side surface with said first optical coating and said second side surface with said second optical coating has an RMS value of at most 10% of the main wavelength; and,
said at least one of said first side surface with said first optical coating and said second side surface with said second optical coating has a Strehl ratio of at least 0.8.

7. The optical element of claim 1 , wherein said polarizer is configured exclusively for operation in the infrared wavelength range.

8. An optical element comprising:
a main body having a first side surface and at least one second side surface;
said first side surface and said at least one second side surface being non-plane-parallel;
a first optical coating applied to said first side surface, wherein said first coating induces a first stress on the optical element;
a second optical coating having optical parameters and being applied to said at least one second side surface, wherein said second optical coating induces a counter-stress on the optical element;
said second optical coating being selected with said counter-stress induced by said second optical coating and said optical parameters of said second optical coating being taken into account;
said first optical coating or said second optical coating being formed as a fluorescence filter or, a polarization filter; and,
the optical element being configured for operation in an infrared wavelength range.

9. An optical element comprising:
a main body having a first side surface and at least one second side surface;
said first side surface and said at least one second side surface being non-plane-parallel;
a first optical coating applied to said first side surface, wherein said first coating induces a first stress on the optical element;
a second optical coating having optical parameters and being applied to said at least one second side surface, wherein said second optical coating induces a counter-stress on the optical element;
said second optical coating being selected with said counter-stress induced by said second optical coating and said optical parameters of said second optical coating being taken into account;
the optical element being a polarizer, an optical prism, a beam splitter or a beam combiner for operation in an infrared wavelength range and/or a visible wavelength range; and,
wherein said second optical coating is formed as an antireflection coating combined with an optically neutral silicon dioxide layer so as to cause a predetermined Strehl ratio to be maintained both at said first side surface and said at least one second side surface.

10. The optical element of claim 9 , wherein said Strehl ratio is at least 0.79.

11. A method for making an optical element, the optical element including a main body having a first side surface and at least a second side surface, the first side surface and the at least one second side surface being non-plane-parallel, the optical element further including a first optical coating applied to the first side surface, wherein the first coating induces a first stress on the optical element, and a second optical coating having optical parameters and being applied to the at least one second side surface, wherein the second optical coating induces a counter-stress on the optical element, the second optical coating being selected with the counter-stress induced by the second optical coating and the optical parameters of the second optical coating being taken into account, the optical element being a polarizer for operation in an infrared wavelength range, the method comprising the steps of:
determining the stress induced in the optical element by the first optical coating of the first side surface;
determining a counter-stress, so that the resultant overall stress induced in the optical element is as small as possible;
determining the second optical coating while taking into account the determined counter-stress and the optical parameters of the second optical coating;
applying the first optical coating on the first side surface; and,
applying the second optical coating on the at least one second side surface.

12. The method of claim 11 , wherein the second optical coating is determined under the condition that the RMS value of at least one of the first side surface and the second side surface with the respective coating is limited to a maximum of 10% of at least one of the main wavelength and its Strehl ratio or their Strehl ratios is or are at least 0.8.

13. The method of claim 11 , wherein methods of calculation of the finite element method are used for at least one of determining the counter-stress, determining the stress induced by the optical coating of the first side surface in the optical element and determining the second coating.

14. The method of claim 11 , further comprising the steps of:
experimentally ascertaining an overall stress actually induced in the optical element after applying the first optical coating on the first side surface and the second optical coating on the at least one second side surface;
comparing the overall stress actually induced to a desired overall stress; and,
locally working at least one of the first optical coating, the second optical coating, and a further side surface of the optical element in the case of an excessive deviation between the overall stress actually induced and the desired overall stress.

15. The method of claim 14 , wherein the local working is carried out via magnetorheological polishing or ion-beam polishing.

16. The method of claim 11 further comprising the step of modifying the main body of the optical element.

17. The method of claim 11 , wherein the optical coatings are applied by ion- or plasma-assisted physical deposition from the vapor phase or by sputtering.

Assignees

• Zeiss Carl Meditec Ag

Inventors

• Beder Christian
• Zaczek Christoph
• Gaber Erwin
• Tonova Diana
• Sundermann Michael

Classifications

• G02B27/0012

  Optical design, e.g. procedures, algorithms, optimisation routines · CPC title

• G02B1/115 Primary

  Multilayers · CPC title

• G02F1/09

  based on magneto-optical elements, e.g. exhibiting Faraday effect · CPC title

• G02B1/12

  by surface treatment, e.g. by irradiation · CPC title

• H01Q15/006

  Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces · CPC title