A head-mounted extended reality display device comprising: - a frame configured to be worn by a user's head; - a rigid mounting element coupled to the frame; - a right-side visible light camera coupled to the rigid mounting element; - a left-side visible light camera coupled to the rigid mounting element; - a right-side near-infrared camera coupled to the rigid mounting element; - a left-side NIR camera coupled to the rigid mounting element; and - at least one NIR light-emitting diode configured to illuminate a region within a field of view of the right-side NIR camera and the left-side NIR camera, - wherein the right-side visible light camera and the left-side visible light camera are configured to capture stereoscopic visible light images within a field of view of the user when the user is wearing the frame, and - wherein the right-side NIR camera and the left-side NIR camera are configured to capture stereoscopic NIR images within the field of view of the user when the user is wearing the frame, characterised in that the right-side visible light camera defines a field of view having a first center in a first direction extending away from the frame, wherein the left-side visible light camera defines a field of view having a second center in a second direction extending away from the frame, and wherein the first direction and the second direction intersect at an intersection point within a field of view of the user when the user is wearing the frame and wherein - the frame defines a substantially horizontal reference plane when the frame is being worn by the user, and wherein the first direction and the second direction are angled downwardly with respect to the horizontal reference plane at a downward angle that is greater than 50 degrees and less than 60 degrees when the frame is being worn by the user. - a frame configured to be worn by a user's head; - a rigid mounting element coupled to the frame; - a right-side visible light camera coupled to the rigid mounting element; - a left-side visible light camera coupled to the rigid mounting element; - a right-side near-infrared camera coupled to the rigid mounting element; - a left-side NIR camera coupled to the rigid mounting element; and - at least one NIR light-emitting diode configured to illuminate a region within a field of view of the right-side NIR camera and the left-side NIR camera, - wherein the right-side visible light camera and the left-side visible light camera are configured to capture stereoscopic visible light images within a field of view of the user when the user is wearing the frame, and - wherein the right-side NIR camera and the left-side NIR camera are configured to capture stereoscopic NIR images within the field of view of the user when the user is wearing the frame, characterised in that the right-side visible light camera defines a field of view having a first center in a first direction extending away from the frame, wherein the left-side visible light camera defines a field of view having a second center in a second direction extending away from the frame, and wherein the first direction and the second direction intersect at an intersection point within a field of view of the user when the user is wearing the frame and wherein - the frame defines a substantially horizontal reference plane when the frame is being worn by the user, and wherein the first direction and the second direction are angled downwardly with respect to the horizontal reference plane at a downward angle that is greater than 50 degrees and less than 60 degrees when the frame is being worn by the user.