An Experiment to Test the Mechanical Losses of Different Bonding Techniques in Fused Silica

TL;DR

This paper compares the mechanical losses of various bonding techniques in fused silica, crucial for optical systems, by conducting experiments on different bonding methods to identify the most suitable for low-noise applications.

Contribution

It introduces an experimental setup to measure and compare mechanical losses of multiple bonding techniques in fused silica, highlighting their impact on displacement noise.

Findings

Hydroxide catalysis bonding shows higher mechanical loss due to the enclosed medium layer.

Initial results from the first test sample are presented.

The experiment provides a basis for selecting low-loss bonding methods in optical systems.

Abstract

High-purity glasses are used for their low optical and mechanical loss, which makes them an excellent material for oscillators in optical systems, such as inertial sensors. Complex geometries often require the assembly of multiple pieces of glass and their permanent bonding. One common method is hydroxide catalysis bonding, which leaves an enclosed medium layer. This layer has different mechanical properties to the bulk glass around it. The higher mechanical loss of this layer makes it more susceptible to displacement noise originating from the conversion of energy from oscillation to heat and vice versa. Therefore, other methods are needed to bond together glass assemblies. To investigate this, we have set up an experiment to measure the mechanical losses of several different types of bond commonly used in fused silica manufacturing, namely; plasma activated direct bonding, hydroxide catalysis bonding, laser welding, and adhesive bonding. In this paper we present the experimental design and show initial results of the first test sample.