Laser Interference Structuring of a-GeN for the Production of Optical Diffraction Gratings

2003 ◽  
Vol 762 ◽  
Author(s):  
M. Mulato ◽  
A. R. Zanatta ◽  
D. Toet ◽  
I. E. Chambouleyron

AbstractIn this work, we study the pulsed laser crystallization of hydrogen-free amorphous germanium-nitrogen alloys (a-GeN). We discuss the role of nitrogen during phase transitions and the possible application of the resulting structure as an optical diffraction grating. The crystallized region results of pure microcrystalline germanium (μc-Ge). An indication that Ge-N bonds have broken and nitrogen outdiffused of the film is obtained from infrared spectroscopy and confirmed by Raman spectra. A pattern of alternating a-GeN and μc-Ge lines with a period of about 4 μm acts as an optical diffraction grating due to the difference in optical properties between the two materials, and the three dimensional surface profile, caused by N2 effusion, that is formed on the sample.

2017 ◽  
Vol 164 (2) ◽  
pp. 385-393 ◽  
Author(s):  
Rachel L. O’Connell ◽  
Rosa Di Micco ◽  
Komel Khabra ◽  
Lisa Wolf ◽  
Nandita deSouza ◽  
...  

2007 ◽  
Vol 8 (5) ◽  
pp. 9-17 ◽  
Author(s):  
A. Rüya Yazici ◽  
Gerard Kugel ◽  
Ali Müftü

Abstract Aim The aim of this study was to investigate the surface roughness of different types of flowable restorative resins and compare the effectiveness of diamond finishing burs followed by aluminum oxide discs with aluminum oxide discs alone in producing smooth surfaces. Methods and Materials Twenty-four specimens (10 mm X 2 mm) for each flowable resin (flowable microhybrid composite, flowable liquid microhybrid composite, flowable compomer, and flowable ormocer) were fabricated in an acrylic mold and randomly assigned to three groups. In group I samples were left undisturbed after the removal of a Mylar strip (control). In group II samples were polished with diamond finishing burs, followed by aluminum oxide discs. In group III samples were finished with only aluminum oxide discs. The mean surface roughness (Ra, μm) was determined with 3-D non-contact interferometry. Data were subjected to one way analysis of variance (ANOVA), and post hoc comparison was accomplished using Tukey's HSD. Results Although significant differences in surface roughness (Ra) values were observed among the materials using a Mylar strip (control), no significant differences between restorative materials were found when all finishing/polishing methods were combined. For all flowable restorative resins tested, the Mylar strip produced surfaces smoother than those produced by a diamond finishing bur followed by a disc or by using discs alone. Surface roughness values were statistically similar for a diamond finishing bur followed by a disc and for disc treated surfaces within each material except for Dyract Flow, a flowable compomer. Conclusion Although the surface roughness of flowable restorative resins differs among the types, this difference can be overcome with different finishing/polishing methods. Citation Yazici AR, Müftü A, Kugel G. Three-dimensional Surface Profile Analysis of Different Types of Flowable Restorative Resins Following Different Finishing Protocols. J Contemp Dent Pract 2007 July;(8)5:009-017.


Author(s):  
Barbara E. Barich

This chapter discusses the collection of objects, in clay and stone, from various pastoral Saharan sites whose original core area lay between Libya (Tadrart Acacus) and Algeria (Tassili- n-Ajjer). The chapter starts from the general theme of the relationship between the figurines and the subjects they represent, and the difference between two-dimensional and three-dimensional representation. It goes on to discuss the manufacturing process of the clay specimens (dating from between 7000 and 4000 years ago) and the significance of the changes introduced by the Neolithic. Most of the items studied fall into the category of zoomorphic figurines, with only two anthropomorphic examples, and find in the depiction of cattle their most striking subject. These representations possess an evident symbolic content which must be framed within the pastoral ideology of the Saharan Neolithic. In the anthropomorphic figurines the representation of the human body also plays the role of recapturing the sense of wholeness.


2000 ◽  
Vol 266-269 ◽  
pp. 1015-1020 ◽  
Author(s):  
Xinfan Huang ◽  
Li Wang ◽  
Jian Li ◽  
Wei Li ◽  
Ming Jiang ◽  
...  

2009 ◽  
Vol 14 (3) ◽  
pp. 034045 ◽  
Author(s):  
Sylvain Gioux ◽  
Amaan Mazhar ◽  
David J. Cuccia ◽  
Anthony J. Durkin ◽  
Bruce J. Tromberg ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document