High reflected cubic cavity as long path absorption cell for infrared gas sensing

One direct and efficient method to improve the sensitivity of infrared gas sensors is to increase the optical path length of gas cells according to Beer-Lambert Law. In this paper, cubic shaped cavities with high reflected inner coating as novel long path absorption cells for infrared gas sensing were developed. The effective optical path length (EOPL) for a single cubic cavity and tandem cubic cavities were investigated based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) measuring oxygen P11 line at 763 nm. The law of EOPL of a diffuse cubic cavity in relation with the reflectivity of the coating, the port fraction and side length of the cavity was obtained. Experimental results manifested an increase of EOPL for tandem diffuse cubic cavities as the decrease of port fraction of the connecting aperture f’, and the EOPL equaled to the sum of that of two single cubic cavities at f’<0.01. The EOPL spectra at infrared wavelength range for different inner coatings including high diffuse coatings and high reflected metallic thin film coatings were deduced.

[1]  Ralph P. Tatam,et al.  Gas cells for tunable diode laser absorption spectroscopy employing optical diffusers. Part 2: Integrating spheres , 2010 .

[2]  Roderic L Jones,et al.  A compact broadband cavity enhanced absorption spectrometer for detection of atmospheric NO(2) using light emitting diodes. , 2006, The Analyst.

[3]  P Elterman.  Integrating cavity spectroscopy. , 1970, Applied optics.

[4]  Jack J. Hsia,et al.  NBS Measurement Services: Spectral Reflectance , 1987 .

[5]  S Andersson-Engels,et al.  Analysis of gas dispersed in scattering media. , 2001, Optics letters.

[6]  Shaohua Wu,et al.  Effective optical path length investigation for cubic diffuse cavity as gas absorption cell , 2014 .

[7]  S. Chernin,et al.  Optical multipass matrix systems. , 1991, Applied optics.

[8]  Perry Ping Shum,et al.  Cavity ring-down long period grating pressure sensor , 2010 .

[9]  Ralph P. Tatam,et al.  Gas cells for tunable diode laser absorption spectroscopy employing optical diffusers. Part 1: single and dual pass cells , 2010 .

[10]  Albert Manninen,et al.  Compact multipass optical cell for laser spectroscopy. , 2013, Optics letters.

[11]  A. O’Keefe,et al.  Cavity ring‐down optical spectrometer for absorption measurements using pulsed laser sources , 1988 .

[12]  J T Kirk.  Modeling the performance of an integrating-cavity absorption meter: theory and calculations for a spherical cavity. , 1995, Applied optics.

[13]  Lazo M. Manojlović,et al.  On the integrating cavity transfer function and decay time , 2011 .

[14]  Jia Yu,et al.  Diffuse reflectivity measurement using cubic cavity. , 2014, Optics letters.

[15]  Jane Hodgkinson,et al.  Using integrating spheres as absorption cells: path-length distribution and application of Beer's law. , 2009, Applied optics.

[16]  John U. White.  Long Optical Paths of Large Aperture , 1942 .

[17]  Elfed Lewis,et al.  CO2 monitoring and detection using an integrating sphere as a multipass absorption cell , 2007 .

[18]  Gabriel Somesfalean,et al.  Concentration evaluation method using broadband absorption spectroscopy for sulfur dioxide monitoring , 2006 .

[19]  George W Kattawar,et al.  Integrating cavities: temporal response. , 2006, Applied optics.

[20]  J. Destombes,et al.  Sensitive trace gas detection with near-infrared laser diodes and an integrating sphere. , 1996, Applied optics.

[21]  Herwig Kogelnik,et al.  Off-Axis Paths in Spherical Mirror Interferometers , 1964 .