Obtaining a copy of R. W. O'Brien's PhD thesis I have read lots of papers about high-contrast material, but lots of them cite the PhD thesis by R. W. O'Brien (see, for example Reference 2 here), but I couldn't find this dissertation. Can anyone help me?
 A: I did my PhD at Cambridge at around that time, and I recall having to provide a copy of the thesis for the University Library. If you contact the library I would guess a mechanism exists for providing copies of theses, though presumably they will charge for the service.
Later:
See this page How do I access a dissertation from the University of Cambridge? from the library web site.

The University Library holds all Cambridge dissertations from 1921 onwards and they can be ordered from the Manuscript Reading Room (01223 333143, mss@lib.cam.ac.uk). They can't be borrowed or supplied for inter-library loan.
Information on finding theses and dissertations can be found on the Theses Libguide.   Details of all Cambridge theses approved since 1970 can be found using iDiscover. They are also listed in the EThOS database.
Copying of Cambridge dissertations is subject to regulations made by the Board of Graduate Studies. Personal applications for the purchase of copies of dissertations for private research can be directed to the Digital Content Unit (http://www.lib.cam.ac.uk/collections/departments/digital-content-unit ; email photo@lib.cam.ac.uk). There is a charge for this. To purchase dissertations on behalf of an institution (e.g. for library stock) the author's permission is required before a copy can be supplied.

