# Comparison of beam divergence between laser diode and DPSS laser

I'm currently comparing a pulsed laser diode and a pulsed DPSS laser. For the DPSS laser, the beam divergence is listed as "beam divergence (80% of total energy): $$<4 \text{mr}$$". The laser diode is said to already be collimated, and has a beam divergence angle of "$$\theta_\perp$$: $$\le 10^\circ$$" and "$$\theta_\parallel \le 12^\circ$$". I know that plain laser diodes have more divergent beams than DPSS lasers, but I want to understand the differences here and whether I can lower the beam divergence of the laser diode to be closer to the DPSS laser. What is meant by "beam divergence (80% of total energy)"? And what is meant by a beam divergence angle of "$$\theta_\perp$$: $$\le 10^\circ$$" and "$$\theta_\parallel \le 12^\circ$$"? Furthermore, how do I compare "beam divergence (80% of total energy): $$<4 \text{mr}$$" to a divergence angle of "$$\theta_\perp$$: $$\le 10^\circ$$" and "$$\theta_\parallel \le 12^\circ$$"? And, lastly, how can I decrease the beam divergence of the LD so that it is closer to the DPSSL? The experiment is over relatively short distances (varying between 10-100cm).

## EDIT

This datasheet seems to have the same parameters.