title: Temperature-compensated cryogenic Fabry-Perot cavity.
abstract: We show that temperature compensation based on differential thermal expansion between sapphire and fused silica can be used to create a Fabry-Perot cavity with an exceptionally low coefficient of thermal expansion at low temperatures. We describe the design of such a cavity that utilizes shaped fused silica mirrors and a sapphire spacer. The geometry of the fused silica mirror was designed using a finite element model to have a small platform, giving a frequency temperature turning point of 16.6 K. The measured turning point was 16.2 K and the curvature was 6 x 10(-10) K(-2), both of which were consistent with the model.
authors.forename: E K
authors.initials: EK
authors.lastname: Wong
authors.forename: M
authors.initials: M
authors.lastname: Notcutt
authors.forename: C T
authors.initials: CT
authors.lastname: Taylor
authors.forename: A G
authors.initials: AG
authors.lastname: Mann
authors.forename: D G
authors.initials: DG
authors.lastname: Blair