Optical measuring method for obtaining surface topography by calibrating the direction of measuring head and measuring device with measuring head

Abstract

The invention relates to an optical measurement method for obtaining a surface topography (1) of a measured object (2). For this reason, a kind of measuring device (3) is provided, and the measuring device (3) comprises a measuring head (4) located on the measuring head guide (5), which is used for spectral confocal acquisition of surface topography (1), or with Spectro-interferometric OCT distance measurements for obtaining surface topography (1). The spectral light of the light source (6) is applied to the measured object (2) in the form of i measurement light spots (12 to 15) from the fiber array (7) including i optical fibers (8) through the common measuring head lens (10) , wherein the i measurement spots (12 to 15) form a spot array (11). Next, i reflection spectra of i measurement channels are obtained and digitized. Estimation of the digitized reflectance spectrum by calculating the time variation of the system measurement error and the time-induced bias movement of the measuring head guide (5) consists of the following steps: At time t(j), the geometric distance values ​​of the i measuring channels are obtained (a, b, c), obtain the three-dimensional position value of the i measurement spot on the measured object surface (16); obtain the measured object surface (16) with respect to the triangle that includes projection onto the measured object surface (16) (17) the local inclination of the measuring head (4) of at least three measuring light spots (12, 13, 14) to correct the measured value; the measuring head guiding device (5) is guided by the three-dimensional acceleration sensor on the measuring head (4) ) to correlate the local topography; generate the corrected local topography.

Description

technical field [0001] The invention relates to an optical measurement method for obtaining the surface topography of a measured object. For this purpose, a measuring device is provided which has a measuring head on a measuring head guide in order to obtain a surface topography. Background technique [0002] A measuring device for measuring surfaces is known from publication DE 10 2008 041 062 A1. Known measuring devices generate a measuring beam which, after passing through three separate focusing optics, is incident on the surface of the object, is reflected by the object, and is then detected by a spatially resolved light detector together with interferometrically superimposed reference light. [0003] For this purpose, known measuring devices have an optical assembly comprising at least three separate focusing optical elements. The major axes of these separate focusing optics are offset relative to each other and are arranged side by side. Furthermore, known measuring...

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Problems solved by technology

[0006] A disadvantage of the known device is that the known device requires a considerable amount of space since the optical elements of the known device are arranged separately and side by side

Another disadvantage is that in the known embodiments no measures are taken to take into account systematic measurement errors, secular changes in absolute distance values ​​or Deviation from the reference path

As a result, known measuring devices cannot provide reliable data, especially at the nanometer scale, to obtain surface topography of this size

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