Methods to ensure frequency stability of laser marking machine

1. Active frequency stabilization method for laser marking machine. This frequency stabilized laser has a mirror fixed on a piezoelectric ceramic. When the frequency of the laser deviates from a specific standard frequency, a servo control system converts the frequency deviation into an error signal that drives the piezoelectric ceramic. The cavity length is controlled by the expansion and contraction of the piezoelectric ceramic to bring its oscillation frequency closer to the specific standard frequency, in order to achieve frequency stabilization. According to the different principles underlying this method, it can be further divided into several active frequency stabilization methods, such as Lam concave frequency stabilization, Zeeman effect frequency stabilization, and saturation absorption frequency stabilization.

2. Passive frequency stabilization method for laser marking machine. This method involves using materials with low expansion coefficients to make the spacers between the mirrors of the laser resonant cavity, while controlling the coefficient of the entire laser resonant cavity at a constant temperature. Alternatively, two materials with positive and negative expansion coefficients can be combined in a certain length ratio to form a resonant cavity spacer. Within a certain temperature range, the length changes of the two materials compensate for each other. Usually, quartz with a positive expansion coefficient and glass or ceramic with a negative expansion coefficient are used in combination to produce a frequency stable laser. When the temperature variation range reaches ± 1.5 ℃, the relative frequency change does not exceed 5.5 × 10-8.