Design optimization of Cassegrain telescope for remote explosive trace detection.

Bhavsar, Kaushalkumar; Eseller, K.E.; Prabhu, Radhakrishna

Abstract

The past three years have seen a global increase in explosive-based terror attacks. The widespread use of improvised explosives and anti-personnel landmines have caused thousands of civilian casualties across the world. Current scenario of globalized civilization threat from terror drives the need to improve the performance and capabilities of standoff explosive trace detection devices to be able to anticipate the threat from a safe distance to prevent explosions and save human lives. In recent years, laser-induced breakdown spectroscopy (LIBS) is an emerging approach for material or elemental investigations. All the principle elements on the surface are detectable in a single measurement using LIBS and hence, a standoff LIBS based method has been used to remotely detect explosive traces from several to tens of metres distance. The most important component of LIBS based standoff explosive trace detection system is the telescope which enables remote identification of chemical constituents of the explosives. However, in a compact LIBS system where Cassegrain telescope serves the purpose of laser beam delivery and light collection, need a design optimization of the telescope system. This paper reports design optimization of a Cassegrain telescope to detect explosives remotely for LIBS system. A design optimization of Schmidt corrector plate was carried out for Nd:YAG laser. Effect of different design parameters was investigated to eliminate spherical aberration in the system. Effect of different laser wavelengths on the Schmidt corrector design was also investigated for the standoff LIBS system.

Citation

BHAVSAR, K., ESELLER, K.E. and PRABHU, R. 2017. Design optimization of Cassegrain telescope for remote explosive trace detection. In Bourma, H., Carlysle-Davies, F., Stokes, R.J. and Yitzhaky, Y. (eds.) Proceedings of the 1st Counterterrorism, crime fighting, forensics and surveillance technologies conference 2017: co-located with the Society of Photo-optical Instrumentation Engineers (SPIE) Security and defence 2017 conference, 11-12 September 2017, Warsaw, Poland. Proceedings of SPIE, 10441. Bellingham, WA: SPIE [online], article number 1044103. Available from: https://doi.org/10.1117/12.2277932

• Conference Name: 1st Counterterrorism, crime fighting, forensics and surveillance technologies conference 2017: co-located with the Society of Photo-optical Instrumentation Engineers (SPIE) Security and defence 2017 conference
• Conference Location: Warsaw, Poland
• Start Date: Sep 11, 2017
• End Date: Sep 12, 2017
• Acceptance Date: May 26, 2017
• Online Publication Date: Oct 5, 2017
• Publication Date: Oct 12, 2017
• Deposit Date: Oct 12, 2017
• Publicly Available Date: Oct 12, 2017
• Print ISSN: 0277-786X
• Electronic ISSN: 1996-756X
• Publisher: Society of Photo-optical Instrumentation Engineers
• Article Number: 10441 03
• Series Title: Proceedings of SPIE
• Series Number: 10441
• Series ISSN: 1996-756X
• ISBN: 9781510613461
• DOI: https://doi.org/10.1117/12.2277932
• Keywords: LIBS; Spectroscopy; Schmidt-Cassegrain; Aberrations
• Public URL: http://hdl.handle.net/10059/2546