A surgical device for treating target tissue, comprising: a light source assembly for generating a treatment beam of light; a microscope including: a delivery mirror for directing the treatment beam onto target tissue; and a plurality of second optical elements (56, 58, 60, 62) for generating an image of the target tissue from light emanating from the target tissue, the plurality of second optical elements including at least an objective lens and a magnification stage; a translation device; and control electronics for controlling the translation device to cause the treatment beam to move along the target tissue in a predetermined pattern, characterised in that the translation device is arranged to translate: (i) the delivery mirror and the plurality of second optical elements (56, 58, 60, 62), (ii) the light source assembly, the delivery mirror, the objective lens and the magnification stage, (iii) the light source assembly, the delivery mirror and the objective lens, or (iv) the objective lens, the objective lens being located on the target side of the delivery mirror, relative to the target tissue to simultaneously move both the treatment beam along the target tissue and a field of view of the target tissue defined by the plurality of second optical elements (56, 58, 60, 62). a light source assembly for generating a treatment beam of light; a microscope including: a delivery mirror for directing the treatment beam onto target tissue; and a plurality of second optical elements (56, 58, 60, 62) for generating an image of the target tissue from light emanating from the target tissue, the plurality of second optical elements including at least an objective lens and a magnification stage; a delivery mirror for directing the treatment beam onto target tissue; and a plurality of second optical elements (56, 58, 60, 62) for generating an image of the target tissue from light emanating from the target tissue, the plurality of second optical elements including at least an objective lens and a magnification stage; a translation device; and control electronics for controlling the translation device to cause the treatment beam to move along the target tissue in a predetermined pattern, characterised in that the translation device is arranged to translate: (i) the delivery mirror and the plurality of second optical elements (56, 58, 60, 62), (ii) the light source assembly, the delivery mirror, the objective lens and the magnification stage, (iii) the light source assembly, the delivery mirror and the objective lens, or (iv) the objective lens, the objective lens being located on the target side of the delivery mirror, relative to the target tissue to simultaneously move both the treatment beam along the target tissue and a field of view of the target tissue defined by the plurality of second optical elements (56, 58, 60, 62). (i) the delivery mirror and the plurality of second optical elements (56, 58, 60, 62), (ii) the light source assembly, the delivery mirror, the objective lens and the magnification stage, (iii) the light source assembly, the delivery mirror and the objective lens, or (iv) the objective lens, the objective lens being located on the target side of the delivery mirror,