Many aspects must be considered in the design of telescope enclosures. One critical aspect is the floor sensitivity to
movement. The floor moves due to floor-foundation interaction, floor-wall interaction, soil-floor interaction, and
internal enclosure loads. This paper presents the details of the design of an environmental enclosure floor having
minimum rotation due internal laboratory equipment loads, which can have a significant effect on the deformation of the
floor. Floor analysis is presented by finite element methods. An example of a floor design is presented in the context of
a future Navy Prototype Optical Interferometer (NPOI) environmental enclosure.
The Navy Prototype Optical Interferometer (NPOI) in Flagstaff, Arizona, makes use of separate smaller telescopes
spaced along a Y-array and used simultaneously to simulate an equivalent single large telescope. Each telescope is
mounted on a massive reinforced concrete pier tied to bedrock. The mass of the pier dampens most, but not all, of the
unwanted vibration in the required spectrum. The quality and resolution of a stellar image depends on minimizing
movement of the mirrors due to vibration. The main source of pier vibration is due to the soil-pier interaction.
Surrounding environmental and man-made vibration propagates through the soil as body and surface waves, and forces
the pier to move. In this paper, a novel concept based on a sleeve/air gap system to isolate the soil from the pier is used
to minimize the vibration input to the telescope. An example of the concept is presented with respect to the future
implementation of a 1.4-m diameter composite telescope at the Navy Prototype Optical Interferometer.