Broadband antireflective structures applied to high resistive float zone silicon in the THz spectral range.

The optimal structural parameters for an antireflective structure in high resistive float zone silicon are deduced for a rectangular and a hexagonal structure. For this the dependence of the effective index from the filling factor was calculated for both grating types. The structures were manufactured by the Bosch-process. The required structural parameters for a continuous profile require an adaption of the fabrication process. Challenges are the depth and the slight positive slope of the structures. Starting point for the realization of the antireflective structures was the manufacturing of deep binary gratings. A rectangular structure and a hexagonal structure with period 50 mum and depth 500 mum were realized. Measurements with a THz time domain spectroscopy setup show an increase of the electric field amplitude of 15.2% for the rectangular grating and 21.76% for the hexagonal grating. The spectral analysis shows that the bandwidth of the hexagonal grating reaches from 0.1 to 2 THz.

Diagnostic value of anti-topoisomerase I antibodies in a large monocentric cohort.

INTRODUCTION: In the present study, the detection of anti-topoisomerase I (anti-topo I) autoantibodies was evaluated for diagnosis and risk assessment of systemic sclerosis (SSc) patients in a well characterized large monocentric cohort. METHODS: Sera from patients with SSc (diffuse n = 96, limited n = 113), from patients with overlap syndromes (n = 51), from patients with other diseases associated with SSc (n = 20), as well as from disease controls (n = 487) were analysed for the presence of anti-topo I antibodies by line immunoblot assay and ELISA. Assessment of organ manifestations was performed as proposed by the European Scleroderma Trial and Research network. RESULTS: The applied test systems for the detection of anti-topo I antibodies revealed a diagnostic sensitivity for SSc of approximately 24% and a diagnostic specificity of at least 99.6%. The sensitivity to identify patients with diffuse SSc amounted to 60%. Patients with anti-topo I antibodies showed a higher burden of skin and lung fibrosis, contractures, electrocardiogram changes, as well as digital ulcers and had more active disease than antibody-negative patients. Signal strengths correlated only weakly with disease activity, with modified Rodnan skin score, with predicted forced vital capacity, and with predicted diffusion capacity levels (P = 0.01, rho = 0.234, rho = 0.413, rho = -0.215, rho = -0.219). High signal intensities were associated with an increased mortality in diffuse SSc patients (P = 0.003). CONCLUSIONS: Diagnosis and risk assessment of SSc patients can be supported by the detection of anti-topo I antibodies. Signal intensities as obtained by line immunoblot assay or ELISA can be used as a surrogate marker for fibrosis, active disease and worse prognosis.

Antibodies against PM/Scl-75 and PM/Scl-100 are independent markers for different subsets of systemic sclerosis patients.

INTRODUCTION: Anti-PM/Scl antibodies are present in sera from patients with polymyositis (PM), systemic sclerosis (SSc), and PM/SSc overlap syndromes. The prevalence of antibodies against the 75- and 100-kDa PM/Scl proteins and their clinical associations have not been studied in SSc patients in detail so far but could provide a valuable tool for risk assessment in these patients. Furthermore, it remains speculative whether commercially available test systems detecting only anti-PM/Scl-100 antibodies are sufficient in SSc patients. METHODS: Two hundred eighty sera from SSc patients, patients with other connective tissue diseases (n = 209), and healthy blood donors (n = 50) were analyzed for the presence of anti-PM/Scl-75 and anti-PM/Scl-100 antibodies by means of line immunoblot assay. For the SSc patients, possible associations between both subsets of anti-PM/Scl antibodies with clinical and laboratory findings were studied. RESULTS: The determination of anti-PM/Scl reactivity revealed a diagnostic sensitivity of 12.5% and a specificity of 96.9% for SSc. Among anti-PM/Scl-positive SSc patients, 10.4% and 7.1% were positive for anti-PM/Scl-75 and anti-PM/Scl-100 antibodies, respectively. The highest prevalences of reactivity to PM/Scl were detected in diffuse SSc (19.8%) and overlap syndromes (17.6%). Patients with diffuse SSc showed mainly an anti-PM/Scl-75 response, whereas most cases of overlap syndromes were characterized by reactivity to both PM/Scl antigens. The presence of anti-PM/Scl-75/100 antibodies was associated with muscular and lung involvements as well as with digital ulcers; pulmonary arterial hypertension was found less frequently. Anti-PM/Scl-75 antibodies were detected more frequently in younger and more active patients with joint contractures. Anti-PM/Scl-100 antibodies were associated with creatine kinase elevation; however, gastrointestinal involvements were observed less frequently. CONCLUSIONS: Anti-PM/Scl antibodies are common in distinct SSc subsets and are associated with several clinical symptoms. They are directed mainly to the PM/Scl-75 antigen. Consequently, the detection of anti-PM/Scl antibodies by tests based only on PM/Scl-100 as an antigen source may miss a relevant number of SSc patients positive for these antibodies.

Design and evaluation of a THz time domain imaging system using standard optical design software.

A terahertz (THz) time domain imaging system is analyzed and optimized with standard optical design software (ZEMAX). Special requirements to the illumination optics and imaging optics are presented. In the optimized system, off-axis parabolic mirrors and lenses are combined. The system has a numerical aperture of 0.4 and is diffraction limited for field points up to 4 mm and wavelengths down to 750 microm. ZEONEX is used as the lens material. Higher aspherical coefficients are used for correction of spherical aberration and reduction of lens thickness. The lenses were manufactured by ultraprecision machining. For optimization of the system, ray tracing and wave-optical methods were combined. We show how the ZEMAX Gaussian beam analysis tool can be used to evaluate illumination optics. The resolution of the THz system was tested with a wire and a slit target, line gratings of different period, and a Siemens star. The behavior of the temporal line spread function can be modeled with the polychromatic coherent line spread function feature in ZEMAX. The spectral and temporal resolutions of the line gratings are compared with the respective modulation transfer function of ZEMAX. For maximum resolution, the system has to be diffraction limited down to the smallest wavelength of the spectrum of the THz pulse. Then, the resolution on time domain analysis of the pulse maximum can be estimated with the spectral resolution of the center of gravity wavelength. The system resolution near the optical axis on time domain analysis of the pulse maximum is 1 line pair/mm with an intensity contrast of 0.22. The Siemens star is used for estimation of the resolution of the whole system. An eight channel electro-optic sampling system was used for detection. The resolution on time domain analysis of the pulse maximum of all eight channels could be determined with the Siemens star to be 0.7 line pairs/mm.

Broadband antireflective surface-relief structure for THz optics.

The requirements for a broadband antireflective structure in the THz spectral region are derived. Optimized structural parameters for a surface-relief grating adapted to the spectrum of an intended THz pulse are deduced. The effect of a structure fabricated into Topas((R)) by a single-point diamond-turning process is demonstrated.