Method and apparatus for measuring the thickness of a transparent object in an automatic production line

摘要

An apparatus (100) and a method for measuring the thickness (s) for a wall (35) of a transparent object (30); the wall (35) comprises a transparent material (35a) arranged between a proximal interface (31), set between an environment (33) and the transparent material (35a), and a distal interface (32), set between said transparent material (35a) and the environment (33). The apparatus (100) comprises a source (1) of a starting light radiation (2) and a means for focusing it (10), in order to obtain an entering light radiation (5) directed towards the wall (35) that hits the proximal interface (31) of the wall (35) of the object and is in part reflected, in order to generate a first reflected radiation (6). A part of the entering light radiation (5) that is transmitted (7), through the transparent material (35a), hitting upon the distal interface (32), is in turn reflected (8) and crosses in an opposite direction the transparent material (35a) through the proximal interface (31), in order to generate a second reflected radiation (9). A collected radiation (15) given by overlapping the first (6) and second (9) reflected radiations have a difference of intensity that is configured to obtain an interference, which allows determining the thickness (s) of the wall (35). In particular, the means for focusing comprises a lens means (10) that have two main meridians (10a, 10b) orthogonal to each other, such that the entering light radiation (5) is focused on a first virtual focus (F1) in the first meridian plane (10a), and on a second virtual focus (F2) in the second meridian plane (10b). This way, it is obtained that the collected radiation (15) is substantially independent from possible movements of the transparent object (30), and this allows a remarkable reliability and robustness of the measurement with respect to fluctuations and vibrations of the object (30).

主权项

1. A method for measuring the thickness of a wall (35) of a transparent object (30), in particular a curved object, said wall (35) comprising: a transparent material (35a), a proximal interface (31) arranged between an external environment (33) and said transparent material (35a), and a distal interface (32) arranged between said transparent material (35a) and said environment (33) opposite to said proximal interface (31),
said method providing the steps of: prearranging a starting light radiation (2); focusing (10,11,22,23) said starting light radiation (2) obtaining an entering light radiation (5) directed towards said wall (35) so that said entering light radiation (5):
hits said proximal interface (31) of said wall (35),is in part reflected by said proximal interface (31), in order to is generate a first reflected radiation (6),crosses (7) in part said transparent material (35a) hitting upon said distal interface (32) and is in part reflected (8) from said distal interface (32);crosses in part in an opposite direction, after the reflection on said distal interface (32), said transparent material (35a) hitting upon again and crossing said proximal interface (31), in order to generate a second reflected radiation (9); collecting (40) an overall exiting light radiation (15) an overlapping of said first (6) and second (9) reflected radiations; analysing (50) said exiting light radiation (15) with spectroscopic methods and for determining the thickness (s) of said wall (35) according to interference characteristics between said first (6) and second (9) reflected radiations in said exiting light radiation (15),
characterised in that said step of focusing (10) provides obtaining said entering light radiation (5) through a non-axisymmetric lens means (10,11,22,23) having two main meridian planes (10a, 10b) such that said entering light radiation (5) is focused on a first virtual focus (F1) in a first main meridian plane (10a), and on a second virtual focus (F2) in a second main meridian plane (10b).