Parabolic multi-pass cell with high detection sensitivity and compact structure.

Area of Science:

• Optics
• Spectroscopy
• Optical Engineering

Background:

• Multi-pass cells (MPCs) are crucial for enhancing sensitivity in tunable diode laser absorption spectroscopy (TDLAS).
• Traditional MPC designs often rely on approximations, limiting ray tracing accuracy.
• There is a need for compact, high-performance MPCs with adjustable optical path lengths.

Purpose of the Study:

• To propose and analyze a novel multi-pass cell design utilizing two parabolic mirrors.
• To develop an accurate analytical method for ray tracing within the parabolic MPC without paraxial approximations.
• To demonstrate a flexible design approach for adjusting optical path length and volume for gas sensing applications.

Main Methods:

• Derivation of analytical expressions for ray transmission between parabolic mirrors using vector reflection theory.
• Detailed design process of the parabolic MPC, including simulation validation using TracePro.
• Introduction of a spot pattern scaling method for adjustable optical path length and volume.

Main Results:

• Accurate ray tracing achieved without paraxial approximations.
• Simulations validated the design process and calculating method.
• Parabolic MPCs demonstrated the potential for optical path lengths up to 128.7 m within a compact volume (<100 mL).

Conclusions:

• The proposed parabolic multi-pass cell offers high detection sensitivity and a compact structure.
• The design method provides flexibility for adjusting optical path length and volume, crucial for gas sensing.
• This work is significant for advancing MPC design and gas sensing technologies.