  Near-concentric cavities are excellent tools for enhancing atom--light
interaction as they combine a small mode volume with a large optical access for
atom manipulation. However, they are sensitive to longitudinal and transverse
misalignment. To address this sensitivity, we present a compact near-concentric
optical cavity system with a residual cavity length variation $\delta L_{C,
rms}$=36(9) pm. A key part of this system is a cage-like tensegrity mirror
support structure that allows to correct for longitudinal and transverse
misalignment. The system is stable enough to allow the use of mirrors with
higher cavity finesse to enhance the atom--light coupling strength in
cavity-QED applications.
