Optical device for use during climbing sports, has holder attached before eyes of observer so that part of visual field/complete visual field is deviated in desired direction by using ray process, which corresponds to that in penta prism
摘要
<p>The device has a penta prism utilized for lateral deviation of light source around ninety degree. Two mirror surfaces are attached in an angle around forty five degree. An eyeglass shaped holder is attached before an eye or the eyes of an observer so that a part of a visual field or complete visual field is deviated in a desired direction by using a ray process, which corresponds to that in a penta prism.</p>
