Phase-space reconstruction of focused x-ray fields

We apply the method of phase-space tomography to reconstruct x-ray beams focused using a compound refractive lens. We show that it is possible to decouple the effect of aberrations in the optical system from the field and hence measure both them and the original field. We recover the complex coherence function and find that it is consistent with expectations.     

Overcoming SU-8 stiction in high aspect ratio structures

Deep X-ray lithography is a well known technique used for making high aspect ratio structures (HARS). However, well known difficulties arise in the creation of some HARS; adhesion of the developed resist structures to the plating base commonly fails, and when resist structures are densely packed features can clump together. This in turn can exacerbate adhesion failure. The problem of clumping is sometimes known as stiction. In this paper we describe an idea involving a low dose UV second exposure that can help overcome stiction in certain designs and thus promote adhesion and the retention of the designed structure.AGP acknowledges receipt of an Australian Research Council QEII fellowship. This work was supported by the Australian Synchrotron Research Program, which is funded by the Commonwealth of Australia under the Major National Research Facilities Program.     

The dominance of the disease theory in American ideas about and treatment of alcoholism.

Comments on R. M. Dreger's (see record 1986-20021-001) and W. P. Reich and W. J. Filstead's (see record 1986-20050-001) comments concerning the present author's (see record 1985-28347-001) article on the cultural context of psychological approaches to alcoholism. In answer to the question of whether anyone really believes alcohol is a disease, it is asserted, based on practice, that every clinician in the US does. The question of the most appropriate view of alcoholism is addressed in terms of the debate over controlled drinking vs abstinence. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Standards and quality control: problems and pitfalls

The proliferation of standards and quality assurance programs is posing a major problem for mental health administrators. The authors review some of these problems and emphasize the differences between cost and quality controls. They propose that quality controls be judged on their ability to improve patient care and suggest that administrators consider the establishment of quality control offices.     

Side wall roughness in ultradeep X-ray lithography

 An experimental characterization of the roughness of side walls in ultradeep, hard X-ray lithography was performed. Several sources of roughness were distinguished: the roughness of the absorber layer on the mask, the roughness of the mask substrate, nonhomogeneities in the X-ray beam, incomplete developing, cracks generated in the PMMA, and the thermal treatment of PMMA. The intrinsic roughness of the correctly developed PMMA was estimated to about 4 nm rms. The best results showed an anisotropy of roughness with minimal values of 4 nm rms along the Oz direction (parallel with the X-ray beam) and 25 nm rms in the Ox direction. Received: 10 August 2001/Accepted: 24 September 2001 This work is supported by the U.S. Department of Energy, Office of Science, under Contract No. W-31-109-ENG-38. This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2001 in June 2001.     

Production issues for high aspect ratio Lobster-eye optics using LIGA

We have previously considered some of the parameters for, and production issues involved in making, a useful Lobster-eye prototype using X-ray lithography. Due to the high aspect ratio and dense packing of the array features, we were unable, in our initial attempts to produce optimal Lobster-eye optics using X-ray lithography and a PMMA resist, to consistently overcome adhesion issues between the substrate and the resist. In recent work we have overcome this problem by using SU-8 as the resist instead. In the light of this advance we reconsider the relevant parameters and production issues when using SU-8 and lower-energy exposures.     

Direct quantitative tomographic reconstruction for weakly absorbing homogeneous phase objects

We examine a direct filtered back projection approach that is suitable for the reconstruction of weakly absorbing homogeneous phase objects. Like recent similar approaches this method needs only one intensity image in each projection without the requirement for an intermediate step of phase retrieval. We tested the method using simulation and experimental results. Simulation results show good quantitative reconstruction which includes the correct refractive index value and distribution of the sample. However, experimental result still indicates the presence of artifacts.     

Sidewall slopes and roughness of SU-8 HARMST

In recent years we have investigated the feasibility of deep X-ray lithography in SU-8 as a means of fabricating very high aspect ratio and densely packed arrays of square channels. We have demonstrated how to overcome the problems in adhesion and stiction accompanying the fabrication of such high aspect ratio structures. We have also examined how to calculate the development time of these structures and how this can be used to optimize the dimensional fidelity of the resulting structures. More recently we have considered the effect of the non-uniform dose deposition and beam hardening as a function of depth in the resist on factors such as the surface roughness and the sidewall taper. In this paper we describe our experimental program, review these results and discuss their implications for the operation of our target device—the lobster-eye telescope.