Sample Shape Measuring Apparatus Tilt Calculation

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Solution Overview

Problem

Current methods for measuring the tilt and shape of a sample surface, such as those using fringe projection and interference between non-diffracted and diffracted light, face challenges with low reflectance surfaces and smooth shapes, where accuracy is compromised due to the reliance on contrast and interference patterns.

Innovation Solution

A method and apparatus utilizing illumination light that passes through a predetermined region, including an optical axis at a pupil position, where the light is transmitted through the sample and received by an observation optical system, calculating the difference or ratio of light quantities to determine the tilt and shape of the sample surface, without relying on contrast or interference patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fringe projection method is used to measure three-dimensional shape, then measurement capability is provided, but measurement precision deteriorates on low reflectance surfaces and smooth shapes due to reliance on contrast and interference patterns

Engineering Contradiction:

Improvemeasurement precisionVSAvoidlow reflectance and smooth surface effects

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention changes the measurement parameter from relying on optical contrast and interference patterns to relying on light transmission intensity variations. By measuring the intensity of light transmitted through different regions of the sample and comparing it to reference intensity, the system can accurately measure surfaces with low reflectance and smooth shapes that were previously difficult to measure.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the optical interference-based measurement mechanism with a direct light transmission intensity measurement mechanism. Instead of using complex interference patterns between non-diffracted and diffracted light, the system directly measures transmitted light intensity to determine surface shape and tilt.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If interference between non-diffracted light and diffracted light is utilized for measurement, then three-dimensional shape measurement is enabled, but measurement reliability deteriorates when contrast is insufficient

Engineering Contradiction:

Improvemeasurement reliabilityVSAvoidimage contrast

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The invention introduces an intermediary measurement approach by using a beam splitter to separate transmitted light into measurement light and reference light paths. The measurement light passes through the sample while the reference light provides a stable reference intensity, allowing reliable comparison even when sample contrast is low.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention segments the light path into distinct measurement and reference components using a beam splitter. This allows independent optimization of the measurement path (through the sample) and reference path (bypassing the sample), enabling reliable measurements by comparing the two separate light paths.

Inventive Principle:

Principle #1Segmentation

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

Enables accurate measurement of tilt and shape on low reflectance and smooth surfaces by utilizing light transmission through the sample, improving measurement precision and reliability.

Implementation Method 1

illumination light applied to the sample by the illumination optical system is transmitted through the sample

Methodology Applied

Scientific EffectLight transmission: Light

Implementation Method 2

light transmitted through the sample is incident on an observation optical system

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS10697764B2Sample shape measuring apparatus for calculating a shape of a sample disposed between an illumination optical system and an observation optical system

Publication Date: 2020.06.30 EVIDENT CORP

AI summary

A sample shape measuring method includes a step of preparing illumination light passing through a predetermined illumination region, a step of applying the illumination light to a sample, and a predetermined processing step. The predetermined illumination region is set so as to include an optical axis at a pupil position of an illumination optical system. Light transmitted through the sample is incident on the observation optical system. The predetermined processing step includes a step of receiving light emerged from the observation optical system, a step of obtaining a quantity of light of the received light, a step of calculating a difference or a ratio between the quantity of light and a reference quantity of light, and a step of calculating an amount of tilt in a surface of the sample from the difference or the ratio.