Canon Patent Application: Irradiated Resin optical element

The optical element described in this patent application, seems similar in nature to the BR element, with a different purpose.  The title is perhaps a little more exciting than the patent application itself :)

Canon is proposing sandwiching an ultraviolet curable resin in between two elements and lightly irradiating it to cure it.  Back in the 60's when obscure elements where being created for fast lenses, glass was slight radioactive having contained rare earth elements such as Thorium, and actually made slightly radioactive in the process.  Nothing of that sort is happening here.  As Canon simply bombards the element with UV radiation to cure the resin.

Part of the difficulty discussed and the reason for the patent is to bond to irregular surfaces such as a diffractive element surface to aspherical surfaces.  The resin also after curred makes an optical element of its own right.

Interestingly as well, this seems to be a PowerShot small sensor lens, with a diffractive optics component. 

focal length   3.65 16.16 27.91 
F Number       2.06  3.58  4.12 
angle of view 34.97 10.52  6.14 
Image height   2.55  3.00  3.00 
total length  48.67 48.18 48.67 
BF             3.01 13.01  3.01 

Japan Patent Application 2018-180364