Mirror substrates

Internal thermal noise of mirrors. Mirror substrates are transparent material cylinders. They are affected by thermal noise and each one of their modes of vibration can be represented by an harmonic oscillator. The study of thermal noise in solids is a complex task, made difficult because no... 

Does Epitope Specificity of Gliadin Antibodies of CD Patients Mirror Substrate Specificity of tTG ... 

To achieve a point focus the mirror substrate can be ground to a fixed radius of curvature, i H, in one direction (for the horizontal focussing) and then bent to a curvature i v (equation (5.24)) for the vertical focussing. The equation for i H is... 

A large batch coating system especially designed to coat astronomical telescope mirrors with A1 films is shown in Fig. 37. The mirror substrate to be coated is made of glass ceramics, its thickness is 60 cm and the weight is about 14 tons. 

Soufli, S.L. Baker, D.L. Windt, E.M. Gullikson, J.C. Robinson, W.A. Podgorski, and L. Golub, Atomic force microscopy characterization of Zerodur mirror substrates for the extreme ultraviolet telescopes aboard NASA s Solar Dynamics Observatory, Appl. Opt. 46(16), 3156 3163 (2007). 

Berezhinsky et al. used SMS to measure the effects of thermal annealing on bulk and interface properties of ZERODUR glass ceramics [67]. ZERODUR is used as the mirror substrate for large-scale telescopes. Components of devices made of ZERODUR can be connected by diffusion welding using an aluminium film of lOOnm thickness. This film is then annealed. The performance of the weld depends on chemical and physical phenomena occurring at the aluminium-ZERODUR... 

Thermal expansion The thermal expansion properties, particularly the low expansions, are the primary properties that have been exploited commercially. The low expansion materials have been used for applications where thermal shock resistance is important such as cookware, stove tops, heat exehangers etc. They have also been used in applications such as mirror substrates where minimal thermally indueed distortions are important. Higher expansion materials have been used for sealing various metals and alloys. 

The Mach-Zehnder interferometer has found a wide range of applications. Density variations in laminar or turbulent gas flows can be seen with this technique and the optical quality of mirror substrates or interferometer plates can be tested with high sensitivity [4.29,4.30]. 

Moving away from the dispersion relation for infinite layers, the transmissivity or reflectivity of an A-repeat ADBR can be calculated using the theory of Mizuno and Tamura (Mizuno and Tamura 1992) which extracts the net transmission from transfer matrix theory for waves passing from a mirror substrate to a detector. For a fuller model that can include the details of transducer layers and coupling fluids used to couple acoustic waves into an ADBR, the matrix model of Mitsas and Siapkas has been used (Mitsas and Siapkas 1995). At normal incidence for acoustic waves and when... 

Alternatively, hollow spheres could be prepared that consisted of a thick inner layer of core-shell CdSe/CdS nanoparticles that are surrounded by a thicker siUca nanoparticle layer (41). The latter spheres allow for microcavity lasing without the use of additional mirrors, substrate spheres, or gratings. 

A mirror substrate should maintain its shape at a given temperature after many cycles of temperature changes. The specific Young s modulus should be high so that the thickness necessary for the substrate not to deform under gravity forces would be small the values to compare it with are those for borosilicate glass E = 63 GPa, p = 2.22 x 10 kg/m ) and fused silica E = 72 GPa, p = 2.20 x 10 kg/m ), materials which serve successfully as telescope mirror substrates. 

J/(kgK), A is the thermal conductivity in W/mK. The higher the FOMs of a material the more sensitive it is to thermomechanical loads. If a is taken as 0.05 x 10 K , the values of FOMt sind FOMg for Zerodur are 1.6 X 10 sec /m K and 0.8 x 10 sec /W/m, respectively. These values are among the best values obtained for potential mirror substrate materials. Further, it should be noted that these FOMs are very sensitive to variations in the GTE values for all low-expansion materials with GTE values close to zero. If Zerodur of expansion class 0 is taken, the FOMs improve at least by a factor of 2.5. 

All testing and control steps are integrated into the manufacturing process. The elements of the quality assurance system are designed according to ISO 9001. Thus, it is ensured that the manufactured products comply with specifications. This is demonstrated by a process such as the one specially used for 8 m class mirror substrates. Correspondingly, the process is less complicated for Zerodur produced as for blocks and bars with smaller dimensions. 

Thin menisci made of Zerodur are used as mirror substrates in astronomical telescopes (see Sect. 4.6.1). For massive conventional mirror substrates, a thickness diameter ratio of 1 6 was a usual rule. With this ratio, the mirror substrate is adequately stiff. This means that its function is not restricted by deviations in the contour caused by weight, wind pressure, temperature inhomogeneities, etc. 

In both cases, the thickness diameter ratio is approximately 1 20 to 1 50. These mirror substrates are called thin menisci. 

R 1 cooling and ceramizing facilities for mirror substrates up to 4.4 m diameter. 

The quality of the glass to be fed into the mould had to be improved for the manufacturing of the 8 m mirror substrates. In the spin casting technique, there is no longer the possibility to avoid glass faults such as bubbles, solid inclusions, crystals, and striae in the final machining, as there is with the conventional technique. 

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