Photogrammetric camera and method for the two-dimensional measurement of objects

Patent metadata

Field	Value
Publication number	US-12546583-B2
Application number	US-202318216552-A
Country	US
Kind code	B2
Filing date	Jun 29, 2023
Priority date	Jun 29, 2022
Publication date	Feb 10, 2026
Grant date	Feb 10, 2026

Abstract

A photogrammetric camera for the two-dimensional measurement of objects has a lens, an image sensor and a pupil filter configured as a micromirror, each of which is transferable into a first and second tilted position. An illumination system produces light. A micromirror in the first tilt position reflects light produced by the illumination system such that the light cannot reach the object while light reflected at the object is guided to the image sensor. Conversely, a micromirror in the second tilt position reflects light such that the light can reach the object while light reflected at the object is supplied to the image sensor. To implement a recording of an image with coaxial dark or coaxial reflected light illumination, the micromirror device is controlled such that the light produced by the illumination system is incident on the surface at different angles within an angular range of at least arcsin(NA).

First claim

What is claimed is:

1 . A photogrammetric camera for a two-dimensional measurement of objects, the photogrammetric camera comprising:
an object-side telecentric lens which has a pupil plane; a two-dimensional image sensor; a variable pupil filter which includes a micromirror device arranged in the pupil plane and which has a plurality of micromirrors, each of which is transferable into a first stable tilted position and into a second stable tilted position; an illumination system configured to produce light and direct the light at an object with the micromirror device; a controller configured to control the micromirror device, wherein a micromirror in the first stable tilted position reflects light produced by the illumination system such that the light cannot reach the object and reflects light reflected at the object such that the light can reach the image sensor, wherein a micromirror in the second stable tilted position reflects light produced by the illumination system such that the light can reach the object and reflects light reflected at the object such that the light cannot reach the image sensor, wherein the object-side telecentric lens has a numerical aperture (NA), wherein, to implement a recording of an image of a surface of the object with coaxial dark field illumination or coaxial reflected light illumination, the controller is configured to control the micromirror device such that the light produced by the illumination system is incident on the surface of the object at different angles within an angular range of at least arcsin (NA)/10, wherein the angular range is between 70° and 90°, wherein to record an image with coaxial dark field illumination, the controller is further configured to control the micromirror device such that all micromirrors within a first region in the pupil plane are in the second stable tilted position and all micromirrors within a second region surrounding the first region are in the first stable tilted position, and wherein the first region is not point symmetric.

2 . The photogrammetric camera according to claim 1 , wherein the first region has the shape of a circular disc segment.

3 . The photogrammetric camera according to claim 1 , wherein to record an image with coaxial reflected light illumination, the controller is configured to control the micromirror device such that different first regions are produced successively at different locations in the pupil plane.

4 . The photogrammetric camera according to claim 3 , wherein k different first regions are produced in succession and each have a shape of circular disc segments with a respective angular range of 360/k°, and
wherein the different first regions are oriented such that the different first regions add up to a complete circular disc.

5 . The photogrammetric camera according to claim 1 , wherein the photogrammetric camera has a deflection mirror arranged in the light path between the micromirror device and the image sensor, and
wherein the micromirrors are arranged in an assembly plane which extends at an inclination with respect to a sensor plane in which the image sensor extends.

6 . The photogrammetric camera according to claim 1 , wherein the controller is configured to successively produce different first regions at different locations in the pupil plane to record the image of the surface of the object.

7 . A method for a two-dimensional measurement of objects with a photogrammetric camera, the photogrammetric camera including an object-side telecentric lens which has a pupil plane and a numerical aperture (NA), and which images a surface of an object onto an image sensor, a variable pupil filter which includes a micromirror device arranged in the pupil plane and which has a plurality of micromirrors, each of which is transferable into a first and into a second stable tilted position, an illumination system which produces light and directs the latter at the object with the aid of the micromirror device, a micromirror in the first stable tilted position reflecting light produced by the illumination system such that the light cannot reach the object and reflecting light reflected at the object such that the light can reach the image sensor, a micromirror in the second stable tilted position reflecting light produced by the illumination system such that the light can reach the object and reflects light reflected at the object such that said light cannot reach the image sensor, the method comprising:
producing and directing light at the object with the micromirror device; to implement a recording of an image with coaxial dark field illumination or coaxial reflected light illumination, controlling the micromirror device such that the light produced by the illumination system is incident on the surface at different angles within an angular range of at least arcsin (NA)/10, wherein the angular range is between 70° and 90°; storing an image of the surface of the object recorded by the image sensor; calculating dimensions of structures on the surface based on the stored image of the surface; and to record an image with coaxial dark field illumination, controlling the micromirror device such that all micromirrors within a first region in the pupil plane are in the second stable tilted position and all micromirrors within a second region surrounding the first region are in the first stable tilted position, wherein the first region is not point symmetric.

8 . A non-transitory computer-readable storage medium on which a computer program comprising program code is stored, which, when executed on a processor causes the processor to:
produce light with an illumination system and direct the light at an object with a micromirror device; to implement a recording of an image with coaxial dark field illumination or coaxial reflected light illumination, control the micromirror device such that the light produced with the illumination system is incident on a surface of the object at different angles within an angular range of at least arcsin (NA)/10, wherein the angular range is between 70° and 90°, and wherein NA is a numerical aperture of an object-side telecentric lens; store an image of the surface of the object recorded by an image sensor; calculate dimensions of structures on the surface based on the stored image of the surface of the object; and to record an image with coaxial dark field illumination, control the micromirror device such that all micromirrors within a first region in the pupil plane are in a second stable tilted position and all micromirrors within a second region surrounding the first region are in a first stable tilted position, wherein the first region is not point symmetric, wherein a micromirror in the first stable tilted position reflects light produced by the illumination system such that the light cannot reach the object and reflecting light reflected at the object such that the light can reach the image sensor, and wherein the micromirror in the second stable tilted position reflects light produced by the illumination system such that the light can reach the object and reflects light reflected at the object such that said light cannot reach the image sensor.

Assignees

• Zeiss Carl Industrielle Messtechnik Gmbh
• Zeiss Carl Meditec Ag

Inventors

• Göhnermeier Aksel

Classifications

• G03B9/02

  Diaphragms · CPC title

• G01B11/022

  by means of tv-camera scanning · CPC title

• G03B7/095

  for control of aperture · CPC title

• G03B35/02

  by sequential recording · CPC title

• G02B13/22

  Telecentric objectives or lens systems · CPC title