CO2 laser sources

Working principle: CO2 molecules are linearly symmetric molecules, with two oxygen atoms located on either side of the carbon atom, indicating the equilibrium position of the atoms. The atoms in the molecule are always in motion, constantly vibrating around their equilibrium position. According to molecular vibration theory, CO2 has three different modes of vibration:

① Two oxygen atoms vibrate in opposite directions along the molecular axis, meaning that both oxygen atoms reach their maximum and equilibrium values during vibration, while the carbon atoms in the molecule remain stationary, hence their vibration is called symmetric vibration.

② Two oxygen atoms vibrate perpendicular to the molecular axis in the same direction, while carbon atoms vibrate perpendicular to the molecular axis in the opposite direction. Due to the synchronous vibration of three atoms, it is also known as deformation vibration.

③ Three atoms vibrate along the axis of symmetry, where the vibration direction of carbon atoms is opposite to that of two oxygen atoms, also known as the antisymmetric vibrational kinetic energy. Among these three different modes of vibration, different groups of energy levels were determined.

The operating frequency of CO2 laser is 27~40MHz according to ISM regulations; Its main categories are as follows:

(1) Divided by output method

1) Continuous output;

2) Pulse output - modulation frequency up to 1MHz;

3) Q-switch output - electro-optic Q-switching and acousto-optic Q-switching.

(2) According to the working classification of the resonant cavity

1) Waveguide cavity - aperture D=1-3mm;

2) Free space cavity - aperture D=4-6 mm.

(3) Divided by excitation polarity

1) Single phase;

2) Reverse phase.

(4) Classified by cavity structure

1) Single chamber;

2) Multi chamber; (a) Folding cavity: V-shaped -2 folds; Z-type -30% off; X-shaped -40% off. (b) Array cavity: short shoulder array; Staggered array. (c) Building block type: parallel connection -2 chambers; Triangle connection -3 chambers.

3) Large area discharge (a) flat plate type, (b) concentric ring type.

(5) Divided according to the distribution of uniform inductance

1) Quasi inductive resonance technology - used for low capacitance laser heads; 2) Parallel distributed inductance resonance technology - used for high capacitance laser heads.

(6) Divided by resonant cavity material

1) Ceramic metal hybrid type; 2) All ceramic type; 3) All metal type.

(7) Divided by cooling method

1) Air cooling; 2) Water cooling.

(8) Divided by packaging method

1) Sealing off type; 2) Flowing type. The material of the resonant cavity is generally metal A1. Ceramics - BeO, BN, AIN, Al2O3, etc