A laser-based light source comprising a light conversion module, a laser module and an optical device, wherein the light conversion module is arranged between the laser module and the optical device, wherein the light conversion module comprises: - a transparent substrate, having a light entrance side and a light exit side, wherein the laser-based light source is arranged such that laser light in the first wavelength range emitted by the laser module enters the substrate via the light entrance side and leaves the substrate via the light exit side, - a conversion layer, arranged to convert a part of laser light of a first wavelength to converted laser light of a second wavelength range different from the first wavelength range, and to transmit another part of the laser light, - wherein the substrate is arranged such that converted laser light entering the substrate is inhibited to re-enter the conversion layer via the light exit side, and wherein the laser-based light source is further arranged such that at least a part of the converted laser light and transmitted laser light which passes the conversion layer is imaged by means of the optical device to a target region. characterized in that, the conversion layer is attached to a light exit side of the substrate and is arranged to convert a part of laser light entering the substrate via the light entrance side of the substrate, the substrate is arranged such that converted laser light entering the substrate which is totally reflected at the light entrance side of the substrate is inhibited to re-enter the conversion layer via the light exit side by arranging a thickness of the substrate perpendicular to the light exit side such that said converted laser light entering the substrate which is totally reflected at the light entrance side of the substrate does not hit the conversion layer after one total reflection at the light entrance side, and that a mixture of the transmitted laser light and of a part of the converted laser light leaves the conversion layer in forward direction opposite to the side where the conversion layer is attached to the light exit side of the substrate. - a transparent substrate, having a light entrance side and a light exit side, wherein the laser-based light source is arranged such that laser light in the first wavelength range emitted by the laser module enters the substrate via the light entrance side and leaves the substrate via the light exit side, - a conversion layer, arranged to convert a part of laser light of a first wavelength to converted laser light of a second wavelength range different from the first wavelength range, and to transmit another part of the laser light, - wherein the substrate is arranged such that converted laser light entering the substrate is inhibited to re-enter the conversion layer via the light exit side, and wherein the laser-based light source is further arranged such that at least a part of the converted laser light and transmitted laser light which passes the conversion layer is imaged by means of the optical device to a target region. characterized in that, the conversion layer is attached to a light exit side of the substrate and is arranged to convert a part of laser light entering the substrate via the light entrance side of the substrate, the substrate is arranged such that converted laser light entering the substrate which is totally reflected at the light entrance side of the substrate is inhibited to re-enter the conversion layer via the light exit side by arranging a thickness of the substrate perpendicular to the light exit side such that said converted laser light entering the substrate which is totally reflected at the light entrance side of the substrate does not hit the conversion layer after one total reflection at the light entrance side, and that a mixture of the transmitted laser light and of a part of the converted laser light leaves the conversion layer in forward direction opposite to the side where the conversion layer is attached to the light exit side of the substrate. the conversion layer is attached to a light exit side of the substrate and is arranged to convert a part of laser light entering the substrate via the light entrance side of the substrate, the substrate is arranged such that converted laser light entering the substrate which is totally reflected at the light entrance side of the substrate is inhibited to re-enter the conversion layer via the light exit side by arranging a thickness of the substrate perpendicular to the light exit side such that said converted laser light entering the substrate which is totally reflected at the light entrance side of the substrate does not hit the conversion layer after one total reflection at the light entrance side, and that a mixture of the transmitted laser light and of a part of the converted laser light leaves the conversion layer in forward direction opposite to the side where the conversion layer is attached to the light exit side of the substrate.