In one embodiment, a block for a physics package of an atomic sensor is provided. The block comprises one or more sections of optically transparent material defining a vacuum sealed chamber, and including a plurality of transmissive and reflective surfaces to define a plurality of light paths intersecting the vacuum sealed chamber. The one or more sections of optically transparent material include a first monolithic section defining at least a portion of the vacuum sealed chamber. The first monolithic section includes a first portion disposed across a first light path of the plurality of light paths such that light in the first light path is incident on the first portion of the first monolithic section.