In an optical amplifying device, an optical beam passes multiple times through a grazing-incidence bounce amplifier, accessing different parts (G1,G2) of the gain region on each transit. This provides improved characteristics in beam quality, with higher power scalability. The multipass configuration can operate as a high gain amplifier device and, with the addition of suitable feedback such as reflectors (M1-M4), as a laser oscillator to provide an optical source.