1. What is Laser Beam Divergence?

Laser beam divergence refers to the increase in beam diameter with distance from the beam waist. It's a measure of how much the laser beam spreads out as it propagates, typically measured in radians or milliradians.

2. How Temperature Affects Beam Divergence

The calculator uses the temperature-dependent divergence equation:

Where:

• \( \theta \) — Resulting beam divergence (rad)
• \( \theta_0 \) — Initial beam divergence (rad)
• \( \alpha \) — Thermal expansion coefficient (1/K)
• \( \Delta T \) — Temperature change (K)

Explanation: Temperature changes affect optical components and laser cavity dimensions, altering the beam divergence angle through thermal expansion effects.

3. Importance of Thermal Expansion Coefficient

Details: The thermal expansion coefficient (α) is material-specific and determines how much the optical components expand or contract with temperature changes, directly affecting beam characteristics.

4. Using the Calculator

Tips: Enter initial divergence in radians, thermal expansion coefficient in 1/K, and temperature change in Kelvin. All values must be valid (θ₀ > 0).

5. Frequently Asked Questions (FAQ)

Q1: Why does temperature affect beam divergence?
A: Temperature changes cause thermal expansion/contraction of optical components, altering the laser cavity dimensions and optical path lengths.

Q2: What are typical values for α in laser systems?
A: Common values range from 5×10⁻⁶ 1/K for invar to 23×10⁻⁶ 1/K for aluminum, depending on materials used.

Q3: Is this effect reversible?
A: Yes, if temperature returns to original value and no permanent changes occurred, divergence should return to original value.

Q4: Are there other temperature effects on lasers?
A: Yes, temperature also affects wavelength, output power, and mode structure through various mechanisms.

Q5: How can I minimize temperature effects?
A: Use materials with low α, maintain temperature stability, or use active temperature compensation systems.