Method for zero-contact measurement of topography

A method for zero-contact measurement of the topography of a spherically or aspherically curved air-glass surface of an optical lens or of an optical lens system, comprising the following steps:

• a) providing a rotatably mounted hollow shaft rotatable about its axis and operatively associated with an optical measurement unit having at least one measurement head including means for generating at least a first optical measurement beam,
• b) fastening the optical lens or lens system having the spherically or aspherically curved air-glass surface to be measured on an end side of the rotatably mounted hollow shaft such that the optical axis of the lens or lens system is at least approximately aligned with the rotation axis of the hollow shaft;
• c) arranging focusing optics for the optical measurement beam inside the hollow shaft;
• d) sampling a plurality of measurement points on the spherically or aspherically curved air-glass surface to be measured with the optical measurement beam through another air-glass surface having known optical characteristics, the another air-glass surface also being fastened to the hollow shaft and lying in the measurement direction before the curved air-glass surface to be measured;
• and
• e) using an absolutely measuring multiwavelength interferometer to determine for each approached measurement point on the surface to be measured, a distance from a fixed front surface of the optical measurement head, the distance determination being carried out sequentially for approached measurement points on the entire surface to be measured.