Determining at least one of alignment and bond line thickness between an optical component and a mounting surface

A method comprising:

• bonding a bottom surface of an optical component to a mounting surface, wherein the bottom surface comprises a first opaque feature and the mounting surface comprises a second opaque feature, wherein the first and second opaque features are hidden between the bottom surface and the mounting surface after the bonding;
• obtaining an infrared image via at least one window region over the first and second opaque features and through a top surface of the optical component that is opposed to the bottom surface, the infrared image comprising a view through at least part of the bottom surface of a region proximate the first and second opaque features, the at least one window region formed of GaAs and being transparent to infrared light;
• and
• determining, via the same infrared image, an optical alignment between the optical component and the mounting surface and a difference in distance between measurements of the first and second opaque features along a direction normal to the mounting surface, the difference in distance corresponding to a bond line thickness between the optical component and the mounting surface.