Congratulations to Philip Koch for successfully defending his PhD thesis titled “Design, Suspension and Optical Characterization of the Beam Splitter and Output Mode Cleaner for the AEI 10 m Prototype”. Philip’s thesis work covered a range of topics including:

• the thickness homogeneity of crystalline AlGaAs/GaAs high reflectivity coatings
• the design, construction and characterisation of the main sub-SQL Interferometer beam splitter and it’s triple suspension
• building the “scatterometer” – an apparatus to characterise the scattered light produced by optics by measuring the bidirectional reflectivity distribution function (BRDF)
• the design and construction of an outpupt mode cleaner cavity for the sub-SQL interferometer, with a measured intra-cavity loss of < 0.5%