We left the 300um to allow adequate room for Fabrinet to use active alignment to position and adjust the lenses. We were not planning for the vertical position to be set by the shims alone. However, if Fabrinet believes that the 300um is too large (and we will differ to Fabrinet’s expertise on this point), we can adjust the height of the shims to achieve the gap that Fabrinet believes to be appropriate. What gap does Fabrinet want to achieve in order to (1) allow enough room for the alignment process and (2) be possible to fill with epoxy?