Near infrared interference filter design and the production with ion-assisted deposition techniques

Aydoğdu, Selçuk
Near infrared region (NIR) of the electromagnetic spectrum (EM) is defined as 700nm to 1400nm wavelength interval by International Commission on Illumination(CIE). This wavelength interval is extensively used for target acquisition, night vision, wireless communication etc. Therefore, filtering the desired portion of EM spectra becomes a need for that kind of applications. Interference filters are multilayer optical devices which can be designed and produced for the desired wavelength intervals. The production of near infrared interference filters is a process of depositing thin material layers on the suitable substrates. In this thesis, a multilayer NIR filter will be designed for a selected wavelength interval by the use of di erent materials. Then, transmission quality, thermal stability, dependence of the transmission values on the incoming beam angle, performance and durability of the filter will be studied.


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Hasanlı, Nızamı (Wiley, 2002-11-01)
The frequencies and linewidths of five Raman-active modes in a GaS0.75Se0.25 layered crystal have been measured in the 10-300 K temperature range and in the 10-380 cm(-1) frequency region. We observed softening and broadening of the optical phonon lines with increasing temperature. The analysis of the experimental data showed that the temperature dependencies of frequencies and linewidths are well described by considering the contributions from thermal expansion and lattice anharmonicity. The purely anharmo...
Infrared and Raman scattering spectra of layered structured Ga3InSe4 crystals
IŞIK, MEHMET; Hasanlı, Nızamı; KORKMAZ ÖZKAN, FİLİZ (2013-03-01)
The infrared reflectivity and transmittance and Raman scattering in Ga3InSe4 layered crystals were investigated in the frequency ranges of 100-400, 400-4000 and 25-500 cm(-1). The refractive and absorption indices, the frequencies of transverse and longitudinal optical modes, high- and low-frequency dielectric constants were obtained from the analysis of the IR reflectivity spectra. The bands observed in IR transmittance spectra were interpreted in terms of two-phonon absorption processes.
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Güler, Işıkhan; Hasanlı, Nızamı (2007-12-01)
The optical properties of TlGaSeS layered single crystals have been investigated by measuring the transmissions and the reflections in the wavelength region between 400 and 1100 nm. The optical indirect transitions with a band gap energy of 2.27 eV and direct transitions with a band gap energy of 2.58 eV were found by means of the analysis of the absorption data at the room temperature. The rate of change of the indirect band gap with temperature, that is, gamma = -3.2 x 10(-4) eV/K, was determined from the...
Specific features of the optical spectra in Tl2In2S3Se layered single crystals
Hasanlı, Nızamı; Güler, Işıkhan (2007-06-01)
The optical properties of Tl2In2S3Se layered single crystals have been studied by means of transmission and reflection measurements in the wavelength range of 450-1100 nm. The analysis of the absorption data revealed the presence of both optical indirect and direct transitions with energy band gaps of 2.16 and 2.42 eV, respectively. The observed coexistence of indirect and direct energy band gaps is related to the anisotropy of the TI-containing layered crystals. The dispersion of the refractive index is di...
Multi-channel thin film piezoelectric acoustic transducer for cochlear implant applications
YÜKSEL, MUHAMMED BERAT; İlik, Bedirhan; Koyuncuoğlu, Aziz; Külah, Haluk (2019-10-27)
This paper presents a multi-channel piezoelectric acoustic transducer that is working within the audible frequency band (250- 5500 Hz). The transducer consists of eight cantilevers with thin film PLD-PZT piezoelectric layers. The transducer is well suited to be implanted in middle ear cavity with an active volume of 5x5x0.6 mm(3) and mass of 4.8 mg excluding the test frame. Finite Element Method (FEM) is used for modelling cantilever resonance frequencies and piezoelectric outputs. This model and shaker-tab...
Citation Formats
S. Aydoğdu, “Near infrared interference filter design and the production with ion-assisted deposition techniques,” M.S. - Master of Science, Middle East Technical University, 2012.