Optical Probe Head Sealing to Prevent Condensation Failure

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Solution Overview

Problem

Conventional probes fail to maintain reliability and durability in warm, humid environments, such as machining areas where condensation and high temperatures are common, leading to frequent failures.

Innovation Solution

A probe design featuring a light source and photodetector assembly with a deflection element having a lens housed in a transparent metal-walled housing, allowing light beam transmission and generating a switching signal upon deflection, while being hermetically sealed with glass plates to prevent condensation and maintain functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the probe is used in warm, humid environments, then the operational capability is maintained, but condensation forms on optical components leading to failure

Engineering Contradiction:
ImprovereliabilityVSAvoidcondensation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The probe is divided into separate functional modules: the optical assembly with lens is hermetically sealed in a metal housing, while the light source and photodetector remain outside. This segmentation allows the optical components to be protected from humid environments while maintaining overall probe functionality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A transparent wall (glass plate) serves as an intermediary barrier between the humid external environment and the internal optical components. This transparent barrier allows light transmission while preventing condensation on the optical surfaces, resolving the contradiction between environmental exposure and condensation protection.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the lens is hermetically sealed in a metal housing, then condensation is prevented, but light transmission must be maintained

Engineering Contradiction:
ImproverobustnessVSAvoidlight transmission
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The metal housing is made transparent in specific regions where light transmission is required. The wall containing the lens features transparent sections (glass plates) that allow light to pass through while the rest of the metal housing provides hermetic sealing and structural integrity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The housing combines metal material for structural strength and hermetic sealing with transparent glass plate material for light transmission. This composite construction allows the housing to simultaneously provide robustness and maintain optical functionality.

Inventive Principle:
Principle #40Composite materials

3Reliability

If the light source and photodetector are placed outside the hermetic housing, then condensation is avoided on optical components, but the assembly complexity increases

Engineering Contradiction:
Improvefailure rateVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The probe is segmented into an internal hermetic housing containing only the lens and optical path, with external light source and photodetector components. This segmentation simplifies the internal housing design while allowing external components to remain exposed to the environment without causing condensation issues.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The light source and photodetector are extracted from the hermetic housing and placed externally. This extraction eliminates the need for complex hermetic sealing of these components while maintaining protection for the critical optical lens, reducing overall assembly complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

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 design significantly reduces failure rates by minimizing condensation on optical components and ensuring robustness in humid conditions, maintaining reliable operation in high-humidity environments.

Implementation Method 1

The wall is designed to be transparent at least in regions, so that the wall is permeable to a light beam emitted by the light source and reaches the photodetector through the lens

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

a lens which is attached to the carrier body... reaches the photodetector through the lens

Methodology Applied
Scientific EffectLens refraction: Lens

Implementation Method 3

a photodetector... When the light beam impinging on the photodetector shifts, a switching signal can be generated

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP3971516B1Probe
Publication Date: 2022.11.09 DR JOHANNES HEIDENHAIN GMBH
  • EP3971516B1 patent drawingFigure 1
  • EP3971516B1 patent drawingFigure 2

AI summary

The invention relates to a probe head comprising an assembly (1) having a light source (1.1) and a photodetector (1.2), and a deflection element (2) comprising a carrier body (2.1) to which a lens (2.2) is attached. The carrier body (2.1) is mounted on the assembly (1) such that, upon contact with the deflection element (2), movement of the deflection element (2) relative to the assembly (1) is permitted. The lens (2.2) is located in a housing (H) which is bounded by a wall (2.11), while the light source (1.1) and the photodetector (1.2) are arranged outside the housing (H). The wall (2.11) of the housing (H) is designed to be transparent at least in some areas, so that the wall (2.11) is transparent to a light beam emitted by the light source (1.1) and passes through the lens (2.2) to the photodetector (1.2).