There is also a Hornix distributer in Vancouver BC, Canada. This guy distributes the Hornix glass, but he’s also really good at designing systems like you are using. You might give him a call.
Thanks John for your great answer, I would like to add some important information : the material is important for the crosstalk performance but the cover glass width and the air gap (the space between the top surface of the sensor and the cover glass) are determinant and main contributors for the crosstalk performances.