A construction method of the quasi-monolithic compact interferometer based on UV-adhesive bonding

Quasi-monolithic interferometers play a crucial role in high-precision measurement experiments, including gravitational wave detection, inertial sensing, vibrometry, and seismology. Achieving high stability and accuracy in such interferometers requires a method for bonding the optical components to a baseplate. While optical contact bonding and silicate bonding are common methods, UV adhesives offer advantages such as controlled curing and low geometrical requirements for optical components and baseplates. This paper presents a detailed construction method for a quasi-monolithic compact interferometer based on UV-adhesive bonding. We built two types of interferometers using this method: a 100 × 100 × 20 mm3 Mach-Zender homodyne interferometer with unequal arm lengths of about 100 mm for laser frequency noise monitoring and a heterodyne interferometer as a displacement sensing head, sizing 20 × 30 × 20 mm3. Our Mach-Zender interferometer achieved a phase noise level of 2μradHz at 1 Hz and an equivalent laser frequency noise monitoring sensitivity of about 1kHz/Hz at 1 Hz. The compact heterodyne interferometer sensing head showed a sensitivity level of 1pm/Hz in translation and 0.2nrad/Hz in two tilts above 0.4 Hz. Our tests demonstrate that quasi-monolithic compact interferometers based on UV-adhesive bonding can achieve high sensitivity levels at the pico-meter and nano-radian scales.