High-speed off-axis Cavity Ring-Down Spectroscopy with a re-entrant configuration for spectral resolution enhancement.
Opt Express
; 18(5): 4845-58, 2010 Mar 01.
Article
en En
| MEDLINE
| ID: mdl-20389497
ABSTRACT
Monitoring of changing samples by Cavity Ring-Down Spectroscopy (CRDS) is possible using fast frequency scans of the laser and/or the cavity resonance. Mode-matched cavity excitation improves performance of fast CRDS but data-points result separated by the cavity Free Spectral Range (FSR) low pressure samples demand long cavities. We demonstrate fast CRDS with off-axis injection of a "re-entrant" resonator yielding FSR/N data-points separation. Our N = 4 short-cavity setup is found to perform well compared with other fast-CRDS implementations. Interestingly, the intrinsic chirped ringing affecting ring-down signals in mode-matched fast-CRDS disappear with off-axis injection. This is due to a fine splitting of the re-entrant-cavity degenerate groups of modes by astigmatism.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Idioma:
En
Revista:
Opt Express
Asunto de la revista:
OFTALMOLOGIA
Año:
2010
Tipo del documento:
Article
País de afiliación:
Francia