US 9,958,267 B2Granted

Apparatus and method for dual mode depth measurement

AssigneeIndustrial Technology Research Institute

InventorsLudovic Angot, Kun-Lung Tseng, Yi-Heng Chou

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Abstract

An apparatus and a method for dual mode depth measurement are provided. The apparatus is used for measuring a depth information of a specular surface in a depth from defocus (DFD) mode or measuring a depth information of a textured surface in a depth from focus (DFF) mode. The apparatus includes a light source, a controller, a processor, a lighting optical system, an imaging optical system, a beam splitter and a camera. The controller is for switching between the depth from defocus mode and the depth from focus mode. The lighting optical system is used to focus a light from the light source on an object surface in the depth from defocus mode, and the lighting optical system is used to illuminate the object surface with a uniform irradiance in the depth from focus mode.

Claims13

Dependent claims

An apparatus for dual mode depth measurement, wherein the apparatus is used for measuring depth information of an object presenting a specular surface in a depth from a defocus (DFD) mode or measuring depth information of an object presenting a textured surface in a depth from a focus (DFF) mode, and the apparatus comprises:

a light source;
a controller for switching between the depth from the defocus mode and the depth from the focus mode;
a processor for processing a plurality of images and performing a plurality of computations;
a lighting optical system used to control a light from the light source, wherein the lighting optical system is used to focus the light from the light source on an object surface in the depth from the defocus mode, the lighting optical system is used to illuminate the object surface with a uniform irradiance in the depth from the focus mode, and the lighting optical system controls a focus distance of the light in the depth from the defocus mode and a focus distance of the light in the depth from the focus mode to be different;
an imaging optical system, wherein the imaging optical system is used to capture images and also used to further control the light from the light source;
a beam splitter;
and
a camera.

5 more elements

A method for dual mode depth measurement, wherein the method is used for measuring depth information of a specular surface in a depth from a defocus mode or measuring depth information of a textured surface in a depth from a focus mode, and the method comprises:

illuminating an object with a coherent light;
and
analyzing an image of the object surface captured by an imaging system to determine whether the object presents a specular surface or a textured surface according to an amount of speckle reflected by the object, wherein if the amount of speckle is smaller than a predetermined threshold, the object presents a specular surface, and if the amount of speckle is larger than or equal to the threshold, the object presents a textured surface
measuring the depth information of the specular surface of the object with a depth from a defocus method in the depth from the defocus mode if the object presents a specular surface;
and
measuring the depth information of the textured surface of the object with a depth from a focus method in the depth from the focus mode if the object presents a textured surface;
wherein a focus distance of the light in the depth from the defocus mode and a focus distance of the light in the depth from the focus mode are controlled to be different.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/977,628Filed 21 Dec 2015
Published: US 2017/0178334 A122 Jun 2017
Granted: 1 May 2018
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

G01C 3/08
Use of electric means to obtain final indication: use of electric radiation detectors
G01B 11/026
For measuring length, width or thickness: by measuring distance between sensor and object
G01B 11/0608
For measuring thickness ; e.g. of sheet material: height gauges
G02B 21/36
Microscopes: arranged for photographic purposes or projection purposes or digital imaging or video purposes including associated control and data…