Universität Stuttgart

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Open Access
Zukunft der Optik
(1970) Tiziani, Hans J.
Die Optik hat in den letzten Jahren neuen Aufschwung genommen. Mitverantwortlich für diese Entwicklung sind sowohl die Verwendung von leistungsfähigen Computern als auch die Nachfrage nach immer besserer Auflösung und Bildqualität. Besonders positiv haben sich die Entwicklungen des Laser (1960) und der Holographie ausgewirkt. Immer neue Applikationen des gebündelten, kohärenten Laserlichtes werden erschlossen, doch will ich mich in diesem Zusammenhang auf die mögliche Weiterentwlckung der erwähnten Gebiete beschränken.
Open Access
Speckling in diffraction patterns and optical images formed with the laser
(1970) Hopkins, Harold H.; Tiziani, Hans J.
It has been shown that the known characteristics of speckling in both diffraction patterns and optical images can be explained on the basis of a simple physical model. This explains not only the occurence of a predominant size but also the high contrast in speckle patterns.
Open Access
Prospects of testing aspheric surfaces with computer-generated holograms
(1981) Tiziani, Hans J.
For testing aspheric surfaces, computer generated holograms are frequently used. Some methods of generating the holograms as well as a comparison of in-line and off-axis computer generated holograms will be discussed. Furthermore, examples tested will be analysed from the stand point of an industrial testing procedure.
Open Access
Measurement of small movements and vibrations by laser photography
(1973) Tiziani, Hans J.
Most of the holographic techniques applied so far for non-contacting measurements of surface displacements are highly sensitive. But the interpretation of the interference fringes obtained is usually rather difficult for a non-expert, especially for the study of tilts in the presence of lateral in-plane movements. Moire techniques could be applied to overcome some of the difficulties encountered but they require a relatively flat surface, which needs to be specially prepared. The application of speckling, a well-known phenomenon in coherent optics, was found to be very convenient for the investigation of lateral in-plane displacements and vibrations in the presence of tilts. The speckle pattern can be regarded ,as related to the object and hence will be displaced if the object or part of it is moved. For the analysis of in-plane movements or tilts the speckle pattern is photographed in the image plane or the Fourier transform plane of the object, respectively, before and after the movement has taken place. From the diffraction effects of the recorded speckle patterns the movement of the object is determined. Different techniques to measure rigid-body translations, tilts and surface vibrations will be demonstrated and a comparison with other methods given together with the appropriate experimental results.
Open Access
Dual-wavelength interferometer for surface profile
(1990) Manhart, Sigmund; Maurer, R.; Tiziani, Hans J.; Sodnik, Zoran; Fischer, Edgar; Mariani, A.; Bonsignori, R.; Margheri, Giancarlo; Giunti, C.; Zatti, Stefano
The design and first experimental results of a dual-wavelength heterodyne interferometer (DWHI) for precise surface profile measurements are presented. The DWHI is based on a Mach-Zehnder type interferometer with the surface to be measured in the sensing arm of the interferometer. Two adjacent wavelengths are simultaneously used in the interferometer; the range information is gained from the beat frequency of both heterodyne interferometer signals. Thus, the extreme range ambiguity of classical interferometers and their sensitivity to mechanical distortions are reduced by the ratio of laser frequency to beat frequency. The DWHI is expected to have the good SIN performance a of coherent detection system but also the capability of measuring to diffusely scattering targets. The main features of the system presented here are: - use of a single diode laser in combination with a high frequency Bragg cell to generate two adjacent wavelengths - use of an all-fiber concept for the optomechanical build-up
Open Access
The use of optical transfer function for assessing the quality of optical systems
(1976) Tiziani, Hans J.
The optical transfer function (OTF) has proved to be a highly valuable aid in comparing and evaluating the quality of optical systems. The measuring instrument developed is briefly described. The OTF measurements agreed well with theoretical results obtained from lens data, especially for the modulation transfer function (MTF). With the aid of a model based on experiments, a threshold curve was obtained which enabled the results based on the MTF to be compared with those from conventional resolution tests. To enable workable focusing and quality criteria to be derived, an attempt was made to condense the profuse data resulting from the MTF.
Open Access
Image quality criteria for aerial survey lenses
(1978) Tiziani, Hans J.
An image quality criterion based on MTF is highly desirable. The quality specification should be appropriate for the application of the optical system and simple for the user. The proposed quality criteria look promising and comparisons with subjective image quality techniques commonly used are favourable. Further evaluations are needed before quality specification can be recommended.
Open Access
A review of speckle photography and interferometry
(1977) Tiziani, Hans J.
Laser photography has been found to be a very useful and powerful tool for many applications. The interpretation of the fringes obtained is very much easier than for holography. Speckle techniques for strain, displacement and vibration analysis were found to be very powerful aids. The requirements on coherence of the light source used are moderate. High-resolution, low-scatter film or plates can be used to record the speckle patterns (Kodak or Agfa Scientia).

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