Optical arrangement for camera modules, camera modules with optical arrangements, and method of manufacture
An optical arrangement for a camera module with an image sensor is provided. The optical arrangement includes optical components having a transparent cover element; an infrared absorbing cut-off filter; and an optical lens. The optical components are arranged, along an incident optical beam path going through the optical components onto the image sensor, in a sequence through the transparent cover element, then the infrared absorbing cut-off filter, and then the optical lens.
1. An optical arrangement for a camera module with an image sensor, comprising a plurality of optical components having an incident optical beam path towards the image sensor, the plurality of optical components comprising a first antireflection layer arranged on one face of a transparent cover element, an IR reflecting layer arranged on an opposite face of the cover element, a near infrared absorbing cut-off filter on the IR reflecting layer, a second antireflection layer arranged on the cut-off filter, and an optical lens, the plurality of optical components being arranged, along the incident optical beam, in a sequence from the cover element to the cut-off filter, then to the optical lens, and then to the image sensor.
2. A camera module, comprising a camera module with an optical arrangement and an image sensor, the optical arrangement comprising a plurality of optical components having an incident optical beam path towards the image sensor, the plurality of optical components comprising a transparent cover element, a near infrared absorbing cut-off filter, and an optical lens, the plurality of optical components being arranged, along the incident optical beam, in a sequence from the cover element to the cut-off filter, and then to the optical lens, wherein the optical lens is an objective lens having a minimum back focal length of 3.6 mm.
3. The optical arrangement according to claim 2 , wherein the cover element is formed as a sheet made of a material selected from the group consisting of sapphire, chemically strengthened glass, spinel, aluminium oxynitride, moissanite, corundum, and quartz.
4. The optical arrangement according to claim 2 , wherein the cut-off filter is formed as a near infrared absorbing filter glass element.
5. The optical arrangement according to claim 4 , wherein the near infrared absorbing filter glass element comprises a filter glass sheet or substrate.
6. The optical arrangement according to claim 5 , wherein the near infrared absorbing filter glass element comprises blue glass or an infrared absorbing layer made of an organic ink or organic film.
7. The optical arrangement according to claim 2 , further comprising an IR reflecting layer.
8. The optical arrangement according to claim 7 , wherein the IR reflecting layer is arranged on the opposite face of the cover element between the cover element and the cut-off filter.
9. The optical arrangement according to claim 7 , wherein the IR reflecting layer is arranged on the one face of the cover element between the cover element and the first antireflection layer.
10. The optical arrangement according to claim 2 , wherein the cut-off filter has a thickness of less than 0.3 mm.
11. The optical arrangement according to claim 2 , wherein the cover element and the cut-off filter are cemented together.
12. A camera module comprising the optical arrangement according to claim 2 .
13. The camera module according to claim 12 , wherein the optical lens is an objective lens having a minimum back focal length of 3.6 mm.