A scanning device, comprising: a scanner, which comprises: a base; a gimbal, mounted within the base so as to rotate relative to the base about a first axis of rotation; and a transmit mirror and at least one receive mirror, which is separate from the transmit mirror, wherein the transmit mirror and the at least one receive mirror are both mounted within the same gimbal so as to rotate in mutual synchronization about respective second axes, which are parallel to one another and perpendicular to the first axis; a transmitter, which is configured to emit along an optical transmit channel a beam comprising pulses of light within a predefined wavelength range toward the transmit mirror, which reflects the beam so that the scanner scans the beam over a predefined angular range toward a scene; and a receiver, which is configured to receive, by reflection from the at least one receive mirror along an optical receive channel, which is parallel to but separate from the optical transmit channel, the light reflected from the scene and to generate an output indicative of the time of flight of the pulses to and from points in the scene, characterized in that the device comprises; a reflector, wherein the reflector comprises an interference filter, which is positioned between the scanner and the scene and is configured to pass the light between the scanner and the scene within the predefined wavelength range that is incident on the interference filter at angles within the predefined angular range, while reflecting the light within the predefined wavelength range that is incident on the interference filter outside the predefined angular range, wherein the transmitter and receiver are located so that the reflector reflects the light emitted by the transmitter onto the transmit mirror and reflects the light reflected from the scene from the at least one receive mirror to the receiver at reflection angles that are outside the predefined angular range. a scanner, which comprises: a base; a gimbal, mounted within the base so as to rotate relative to the base about a first axis of rotation; and a transmit mirror and at least one receive mirror, which is separate from the transmit mirror, wherein the transmit mirror and the at least one receive mirror are both mounted within the same gimbal so as to rotate in mutual synchronization about respective second axes, which are parallel to one another and perpendicular to the first axis; a base; a gimbal, mounted within the base so as to rotate relative to the base about a first axis of rotation; and a transmit mirror and at least one receive mirror, which is separate from the transmit mirror, wherein the transmit mirror and the at least one receive mirror are both mounted within the same gimbal so as to rotate in mutual synchronization about respective second axes, which are parallel to one another and perpendicular to the first axis; a transmitter, which is configured to emit along an optical transmit channel a beam comprising pulses of light within a predefined wavelength range toward the transmit mirror, which reflects the beam so that the scanner scans the beam over a predefined angular range toward a scene; and a receiver, which is configured to receive, by reflection from the at least one receive mirror along an optical receive channel, which is parallel to but separate from the optical transmit channel, the light reflected from the scene and to generate an output indicative of the time of flight of the pulses to and from points in the scene, characterized in that the device comprises; a reflector, wherein the reflector comprises an interference filter, which is positioned between the scanner and the scene and is configured to pass the light between the scanner and the scene within the predefined wavelength range that is incident on the interference filter at angles within the predefined angular range, while reflecting the light within the predefined wavelength range that is incident on the interference filter outside the predefined angular range, wherein the transmitter and receiver are located so that the reflector reflects the light emitted by the transmitter onto the transmit mirror and reflects the light reflected from the scene from the at least one receive mirror to the receiver at reflection angles that are outside the predefined angular range.