Project Alma Mater

Absorption of Light, Macro algae and Atmosphere

 

Marie Curie Intra European Fellowship (IEF)

 

Project No: 3012109

 

Persons in Charge: Dr. Ranjini Raghunandan, Dr. Andy Ruth

 

 

 

Background Methodology Outreach Project Output

 

           IBBCEAS FT-IBBCEAS Off-Axis CEAS

 

 

 

Off-Axis CEAS

 

Off-axis alignment can be used in conjunction with CEAS to increase the re-entrant length and produce a denser cavity-mode structure. An off-axis injection of the input beam relative to the optical cavity creates a long, folded path whereby the light retraces the same path only after a number of traversals of the cavity. As the re-entrant length increases, the free spectral range for the cavity in off-axis alignment is much smaller than in the on-axis case. To preserve the finesse of the cavity, the width of the fringes also decreases and an extremely dense mode pattern is observed. The transmission of a cavity in on-axis and off-axis alignment is compared in Figure 4. By employing an off-axis configuration, components such as piezo electric actuators (PZT) for cavity length modulation are no longer required in CEAS.