optical safety device with a transparent screen element

An optical safety device, comprising:

• a casing with an inner volume and a lens opening,
• an image sensor arranged in the inner volume, behind the lens opening,
• a lens element fitted in the lens opening and configured to focus on the image sensor an optical image of an environment outside the casing,
• a control system configured to receive and process digital image data collected by the image sensor,
• wherein:
• a screen element mounted to the casing and having a transparent area, the screen element being configured to switch between an active configuration and an inactive configuration,
• wherein:
• in the active configuration, the screen element is arranged in an active position in front of the lens element, such that the environment is visible from the image sensor through the lens element and the transparent area, and the screen element has a marker image on the transparent area, the marker image being arranged to be visible from the image sensor through the lens element,
• in the inactive configuration, no marker image on the screen element is visible from the image sensor and the screen element leaves the vision of the environment by the image sensor through the lens element unobstructed, and
• the control system is configured to command switching of the screen element between the active and inactive configurations, and is further configured, in the active configuration, to identify the marker image in the digital image data and use the marker image for a predetermined calibration or diagnostic processing.