Form Measuring Apparatus with Phase Shifting and Reference Light Detection

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Solution Overview

Problem

Existing form measuring apparatuses face inefficiencies in generating three-dimensional form data under certain imaging conditions, leading to the need for repeated measurements when imaging conditions change.

Innovation Solution

A form measuring apparatus that uses a phase shifting technique with an N-bucket method to change the initial phase of structured light, taking images with different initial phases and utilizing a reference light to detect target areas based on signal intensity differences, allowing for efficient form measurement even under varying conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If form measurement is performed under certain imaging conditions, then three-dimensional form data can be generated, but measurement efficiency decreases when imaging conditions change requiring repeated measurements

Engineering Contradiction:
Improvethree-dimensional form data generationVSAvoidmeasurement efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system performs a preliminary area determination process before actual form measurement to identify target areas where three-dimensional data can be generated. By pre-determining suitable measurement areas based on imaging conditions, the system avoids attempting measurements in unsuitable areas, thereby improving overall measurement efficiency and reducing wasted measurement attempts.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If repeated measurements are performed under changed imaging conditions, then measurement completeness is maintained, but measurement time increases

Engineering Contradiction:
Improvemeasurement completenessVSAvoidmeasurement time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system determines target areas in advance by evaluating imaging conditions before measurement. This preliminary area determination identifies which regions can successfully generate three-dimensional data under current conditions, allowing the system to proceed directly to measurement only in suitable areas without time-consuming repeated measurements.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from area determination results to guide the measurement process. By evaluating whether imaging conditions are suitable for generating three-dimensional data and using this information to select target areas, the system adapts its measurement strategy to avoid unnecessary repeated measurements while ensuring measurement completeness where conditions permit.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The apparatus improves measurement efficiency by predetermining areas where three-dimensional data can be generated, reducing the need for repeated measurements and enhancing the coincidence between form measurement and area determination processes.

Implementation Method 1

a form measuring apparatus which measures a form of an object by using a phase shifting technique

Methodology Applied
Scientific EffectPhase shifting technique:

Implementation Method 2

projects a structured light having a sinusoidal intensity distribution onto a measuring object

Methodology Applied
Scientific EffectStructured light projection:

Implementation Method 3

irradiating a reference light onto the measuring object, and detecting a target area for the form measurement from pickup images taken by imaging the measuring object irradiated with the reference light

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP2770295B1Shape-measuring device, system for manufacturing structures, shape-measuring method, method for manufacturing structures, shape-measuring program
Publication Date: 2019.11.27 NIKON CORP
  • EP2770295B1 patent drawingFigure 1
  • EP2770295B1 patent drawingFigure 2
  • EP2770295B1 patent drawingFigure 3

AI summary

It is possible to improve a measurement efficiency of a form measuring apparatus. There is provided a form measuring apparatus including: an imager configured to take an image of a object, an irradiator configured to irradiate a measurement light from a projection direction different from the direction along which the imager performs imaging to form a predetermined light amount distribution on the object, a reference light generator configured to generate a reference light to irradiate the object, and a detector configured to detect a target area for form measurement of the object based on a pickup image taken by the imager as the reference light is irradiated on the object.