Harald Boettner

Bio: Harald Boettner is an academic researcher. The author has contributed to research in topics: Tunable diode laser absorption spectroscopy & Photoresist. The author has an hindex of 1, co-authored 1 publications receiving 3 citations.

Monitoring processes in photoresist using infrared optical fibers and tunable diode lasers

Abstract: A novel approach for the problem of in-situ and real time monitoring processes in thin film photoresists is presented. The approach is based on the fact that all the essential processing steps, such as softbaking, exposure, hardbaking, and development, can be monitored by the induced spectral modifications in the infrared spectrum of the resist film. The technique of fiber-optic-based evanescent field spectroscopy, is proposed as the method for measuring these spectral changes. The technique is demonstrated using a silver halide infrared transmitting optical fiber coated with thin photoresist film, as the sensing element, and a tunable lead salt diode laser, as the infrared monochromatic source. As an example, immense changes in the resist IR spectrum, induced by thermolysis, are measured. The advantages of using all-fiber technology for remote real time sensing is further discussed, and the possibility to monitor the resist film temperature and thickness, using the same silver halide fibers, is emphasized.

Infrared Optical Fiber Sensors

Abstract: Notably improved performance as well as extended application areas is expected in the technology of optical fiber sensors using infrared fibers that transmit radiation in a wavelength range beyond 2 μm. Measurement of infrared radiation is particularly important in thermometry and spectrometry. In these areas, the use of infrared fibers has been studied extensively not only as a transmission waveguide but also as a sensor chip. Of various infrared fibers, fluoride glass fibers exhibit the lowest transmission loss and hence are useful for remote sensing that requires light transmission over a long distance. The wide transmission range of chalcogenide glass fibers and halide crystalline fibers is valuable for thermometry in a low temperature range and for spectrometry of various molecules. Hollow waveguides are useful as a capillary flow cell that realizes fast-response spectrometry. The advantages and disadvantages of infrared fibers must be considered carefully in the development of fiber sensors. In this paper, the progress of infrared optical fiber sensors is reviewed with particular interest in thermometry and spectroscopy.

Research and development on silver halide fibers at Tel Aviv University

Abstract: This paper presents a survey of current work at Tel Aviv University on properties and applications of silver halide infrared transmitting fibers. Various infrared spectral features of core-only fibers, extruded from pure mixed halide crystals of composition AgClBr1(O < x < 1), are presented and discussed. In the best fibers, total loss is as low as 0.15 dB per meter at a wavelength of 10.6 jim. The fibers can be repetitively bent on a 5 cm radius without degrading the transmission, up to thousands of bends. Fibers witha smooth core-clad structure have also been fabricated, but the optical losses are still relatively high. Novel applications of these fibers in spectrophotometry and radiometry are described.

Remote spectroscopy using mid-IR fiber-coupled laboratory apparatus

Abstract: Instrument accessories for remote infrared spectroscopy have been developed employing chalcogenide fiber. The fiber probes, designed for immersion in standard laboratory hardware, provide scientists with new possibilities for acquiring spectral signatures between 3400 cm-1 and 850 cm-1 for quantitative analysis of a wide variety of solutions, mixtures, sludge, mud, creams, and gels, including biological samples.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.