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Development of Large Size Direction Controlled α-NiSO4. 6H2O Single Crystals and its Optical Studies for Bandpass Filters

Rajesh Paulraj ,  Ramasamy Perumalsamy 

Centre for Crystal Growth,SSN College of Engineering,Kalavakkam,Chennai, Chennai 603110, India

Optical band pass filters need normally a cylindrical plate crystal and perpendicular to the optical axis (0 0 1) and the crystal is directly applicable for the fabrication of the filters.Highly transparent single crystals of α- Nickel sulphate hexahydrate were grown by Sankaranarayanan-Ramasamy method. The size of the grown crystal is 150 mm in length and 25 mm in diameter.  The grown crystals are shown in the Fig. 1. The element applied for filter, α -NSH crystal is normally a cylindrical sheet and perpendicular to the optical axis (0 0 1), while all the crystals grown by conventional method have a bitetragonal shape. The Sankaranarayanan-Ramasamy (SR) method has given the solution, and it is possible to grow bulk-size single crystals along a desired orientation needed for device fabrication.  Its parameters of transmission spectrometry in the range from UV to near IR wavelengths, Microhardness, dislocation density, laser damage threshold and thermal properties are reported.  It has the transmission of specific spectral wavelengths and rejection of others. The laser damage threshold studies show that SR method grown crystal has high laser stability compared to other crystals.  Similar behaviour was reflected on the hardness measurements also.



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Related papers

Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 2, by Rajesh Paulraj
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-04-05 09:56
Revised:   2013-04-05 09:56