The ER20 erbium glass laser operates at a wavelength of 1535 nm, providing Class 1 eye-safe performance. It delivers pulse energy of ≥20 μJ with a 5 ns pulse width at a 2 kHz repetition rate. Featuring excellent pulse stability (10%), a raw beam diameter of 0.2 mm, and a beam divergence of less than 15 mrad in TEM mode, the ER20 ensures high-quality beam output. It is designed for rugged environments, withstanding temperatures from -45°C to +65°C, impacts up to 1500 G, and vibrations from 20–2000 Hz/20 G. The compact design (17×8×7 mm, 6 g) and long lifespan (>5 million pulses) make it ideal for portable systems, widely used in military range-finding, handheld rangefinder, LIDAR, laser communication, and ophthalmology devices where compact size, high stability, and eye safety are critical.