WO1998013665B1

WO1998013665B1 - Process and device for measuring a bump on a surface, in particular on the retina of the eye

Info

Publication number: WO1998013665B1
Application number: PCT/EP1997/005270
Authority: WO
Filing date: 1997-09-25
Publication date: 1998-06-11
Anticipated expiration: 1999-03-27

Abstract

A process and device are disclosed for measuring a bump of a surface (32) of an object arranged behind a lens (13), for example the retina of an eye (30). A video image (50) of the surface (32) is taken by a camera (10). The objective (13) of the camera (10) is half covered by a substantially semicircular diaphragm (14). The surface (32) is lighted by a plurality of light sources (20) arranged in front of the diaphragm (14). The brightness curve of the video image (50) is measured along an axis substantially normal to the diaphragm-limiting diameter (15). The rise of the brightness curve is sensed. The bump is determined from the rise on the basis of a particular characteristic curve (82) which takes into account the refraction (R) of the lens relative to the surface.

Claims

24

CHANGED CLAIMS

[received by the International Bureau on April 28, 1998 (Apr. 24, 1998), added new claims 6-10; all other claims unchanged (3 pages)]

2. The method according to claim 1, characterized in that for measuring the topography of the upper surface of the survey (z) at a plurality of points of the surface is measured.

3. The method according to claim 1 or 2, characterized in that the lens is a retina (32) of an eye (30).

4. The method according to claim 2 or 3, characterized in that for determining the position of individual measuring points on the retina (32) first the optical axes (26) of the camera (10) and the eye (30) are brought into line and then a brand ( 71) is moved along coordinates (y, x) substantially perpendicular to the optical axis (26), the viewing direction of the eye (30) following the marker (71) being seen from the position of the Purkinje appearing in the video image (50) Reflexes (72) on the lens (31) of the eye (30) is determined.

5. The method according to claim 1 or 2, characterized in that the object is a lifeless object to be measured (105).

6. The method according to claim 2 and 5, characterized in that for determining the position of individual measuring points on the measuring object (105) whose surface is arranged at right angles to the optical axis (26) of the camera (10) and a lens (106) on the optical axis ( 26) is fixed in space between the camera (10) and the test object (105) is positioned, that the test object

(105) is moved along from the optical axis (26) substantially rectangular coordinates (y, x) and that the position of the intersection of the optical axis (26) with the surface of the position of one with the DUT (105) rigidly connected luminous point (104) is determined in the video image.

7. The method according to claim 5 or 6, characterized in that the measuring object is an integrated circuit.

8. The method according to one or more of claims 5 to 7, characterized in that the test object is an imprint of an object.

9. The method according to claim 8, characterized in that the impression is a Gebißabdruck.

10. An apparatus for measuring an elevation (z) of a surface of an object (32, 105) arranged behind a lens (31, 106):

a) a camera (10) whose objective (12) is substantially half covered by a substantially semicircular aperture (14);

b) a plurality of light sources (20 to 23) arranged in front of the diaphragm (14);

c) means for measuring the brightness progression (56 to 58) of a video image (50) of the surface taken by the camera (10) along an axis (y) that is substantially perpendicular to the diameter (15) delimiting the diaphragm (14) ;

d) means for detecting the slope (tan α) of the brightness profile (56 to 58); and 26

e) means for determining the elevation (z) from the slope (tan a) based on a predetermined, the refraction (R) of the lens (31; 106) relative to the surface considering characteristic (60; 82).

11. The device according to claim 10, characterized in that for surveying the topography a retina (32) of an eye (30) are provided:

a) an arrangement for fixing the eye (30) on the optical axis (24) of the objective (12),

b) an arrangement for moving a mark (71) along the optical axis (24) substantially perpendicular coordinates (y, x), - and

c) an arrangement for determining the Purkinje reflex (72) appearing in the video image (50) on the lens (31) of the eye (30).

12. The apparatus according to claim 10, characterized in that are provided for measuring the topography of a surface of a lifeless object to be measured (105):

a) an arrangement for aligning the surface perpendicular to the optical axis (24) of the camera (10);

b) an evacuation test between the chamber (10) and the object to be measured (105) on the optical axis (24) positioned object (106);

c) an arrangement for moving the measurement object (105) along the optical axis (24) substantially