Rhomboid prism can displace a laser beam without change the image orientation, the input beam is totally internal reflected by two 45degree faces and goes out from the output face. Then, a lateral displacement is produced. Higher transmission rate can be achieved by anti-reflective coating on the input and output faces. Rhomboid prism is always used in stereoscopic system and periscope system. Currently we can make angle tolerance<5 arc seconds, total beam deviation <30 arc seconds. Large size is also available.