An apparatus comprising: an excitation light source configured to produce excitation light ; wherein the excitation light comprises light having a wavelength that corresponds to an excitation wavelength of a fluorophore, wherein the fluorophore is configured to emit emission light at an emission wavelength in response to receiving light at the excitation wavelength; an ablation light source configured to produce ablation light ; wherein the ablation light is configured to ablate tissue; a beam combiner optically coupled to the excitation light source and the ablation light source; a beam scanner optically coupled to the beam combiner, an exit aperture, wherein the apparatus is configured such that excitation light produced by the excitation light source and ablation light produced by the ablation light source exit the apparatus via the exit aperture; a camera ; and a controller, wherein the controller comprises a computer programmed to carry out instructions, the instructions comprising: causing the excitation light source to emit excitation light via the exit aperture; causing the camera to capture an image of at least a particular tissue location; characterised in that the instructions further comprise the step of: using a triangulation method to determine at least one of (i) a focal length for the ablation light source such that the ablation light is provided in-focus to the particular tissue location or (ii) a distance to the particular tissue location from the exit aperture. an excitation light source configured to produce excitation light ; wherein the excitation light comprises light having a wavelength that corresponds to an excitation wavelength of a fluorophore, wherein the fluorophore is configured to emit emission light at an emission wavelength in response to receiving light at the excitation wavelength; an ablation light source configured to produce ablation light ; wherein the ablation light is configured to ablate tissue; a beam combiner optically coupled to the excitation light source and the ablation light source; a beam scanner optically coupled to the beam combiner, an exit aperture, wherein the apparatus is configured such that excitation light produced by the excitation light source and ablation light produced by the ablation light source exit the apparatus via the exit aperture; a camera ; and a controller, wherein the controller comprises a computer programmed to carry out instructions, the instructions comprising: causing the excitation light source to emit excitation light via the exit aperture; causing the camera to capture an image of at least a particular tissue location; characterised in that the instructions further comprise the step of: using a triangulation method to determine at least one of (i) a focal length for the ablation light source such that the ablation light is provided in-focus to the particular tissue location or (ii) a distance to the particular tissue location from the exit aperture. causing the excitation light source to emit excitation light via the exit aperture; causing the camera to capture an image of at least a particular tissue location; characterised in that the instructions further comprise the step of: using a triangulation method to determine at least one of (i) a focal length for the ablation light source such that the ablation light is provided in-focus to the particular tissue location or (ii) a distance to the particular tissue location from the exit aperture. <EOS>