Telescopic glasses

Telescopic glasses with adjustment options for different distances

A telescopic spectacles is at the most a miniaturized glasses Galilean telescope is mounted with dimensions in the one- to two-digit millimeter range.

Designs

There are telescopic glasses in which the optical system is permanently connected to the glasses. In most cases, the telescopes (only one telescope in monocular systems) are fitted into the spectacle lenses where the near-vision range is to be found in bifocal glasses . These systems must be adapted to the wearer by an optician - the telescopes must be aligned with the pupils and the distance between the eye and the eyepiece must be set. There are also systems in which the telescope optics are attached to the actual glasses with a clip. With other telescopic glasses, the optical system is held by a headband. In the strict sense, it is then no longer a question of telescopic glasses because the glasses are missing. These two systems do not require any special adjustment by an optician.

Telescopic glasses are used in many areas in which small structures have to be recognized and at the same time it is advantageous to have both hands available for work. Examples are medicine and dentistry (e.g. in hand surgery ), precision mechanics and watchmaking, etc. They are also used as visual aids for the visually impaired and to control model aircraft.

Optical background

Galileo telescope with collecting and diverging lens and Kepler telescope with two collecting lenses in comparison. In the Galilei telescope, the distance between the lenses is smaller, which enables a shorter and more compact design of such systems

Galileo systems have the advantage over Kepler telescopes that they can be implemented with a shorter design, because the image with the Galileo system is upright and does not have to be rotated by mirrors or prisms .

Telescopic glasses with a Galileo system can focus in a wide range from near to infinity . This distinguishes them from the much cheaper loupes , in which the focus range is fixed, which means that you have a fixed working distance.

literature

• Hans Boegehold : To Lambert telescope glasses. In: Journal for ophthalmological optics including instrument science. Vol. 31, H. 5/6, 1943, ISSN  0931-0088 , pp. 135-140 (also special print).
• Felix Auerbach : The Zeisswerk and the Carl Zeiss Foundation in Jena. Their scientific, technical and social development and importance. 5th revised edition. G. Fischer, Jena 1925 (reprint. Rockstuhl, Bad Langensalza 2010, ISBN 978-3-86777-291-4 ).

Individual evidence

1. ^ Franz Grehn: Ophthalmology . 30th, revised and updated edition. Springer-Medizin-Verlag, Heidelberg 2008, ISBN 978-3-540-75264-6 , p. 347 ( limited preview in Google Book search).
2. ↑ Telescopic glasses and model airplanes  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. (PDF; 1.6 MB)  
3. ↑ Did you know that ... there are glasses with a built-in telescope?  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. Company information Carl Zeiss AG, Germany