Beam Dump Curved Surface Reduces Stray Light

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Solution Overview

Problem

Conventional beam dumps for particle counters and fluorescence detectors fail to effectively prevent reflected and stray light from entering the optical chamber, leading to erroneous measurements of weak light signals due to incomplete light absorption and scattering.

Innovation Solution

A beam dump design featuring a focal lens assembly, pin hole assembly, and a light source output detector inclined at a specific angle, which directs the beam through a pin hole and a cavity to minimize reflection and scattering, ensuring that reflected light and stray light are absorbed within the beam dump and do not enter the optical chamber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a simple flat surface is used to dump the beam, then the direct reflection is effectively reduced, but unacceptably large amounts of light are scattered

Engineering Contradiction:
Improvedirect reflectionVSAvoidscattered light
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The beam dump employs a curved reflective surface instead of a flat surface. The curved geometry redirects scattered light away from the optical chamber and detection path, eliminating the scattering problem inherent in flat surfaces while maintaining low direct reflection.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

Different regions of the beam dump have different surface properties optimized for their specific functions. The reflective surface has specific curvature characteristics, while other regions may have absorptive or diffuse properties, creating local quality variations that collectively solve both reflection and scattering issues.

Inventive Principle:
Principle #3Local quality

2Loss of energy

If a black interior coating is applied to the beam dump, then some light absorption is improved, but reflected light and stray light are not completely blocked

Engineering Contradiction:
Improvelight absorptionVSAvoidreflected light and stray light
Core Design Contradiction:
Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The beam dump uses a composite structure combining a curved reflective surface with selective absorptive regions. This composite approach leverages both reflection and absorption mechanisms to comprehensively eliminate harmful light while maintaining useful beam transmission.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The beam dump surface is segmented into different functional zones: reflective regions that redirect light away from the optical path, absorptive regions that capture stray light, and transmission regions that allow the beam to pass. This segmentation enables each zone to optimize its specific function.

Inventive Principle:
Principle #1Segmentation

3Volume of moving object

If the beam dump is positioned close to the optical chamber to improve compactness, then the device size is reduced, but reflected light and stray light can enter the optical chamber

Engineering Contradiction:
Improvedevice sizeVSAvoidreflected light and stray light incident on optical chamber
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The curved surface geometry of the beam dump is specifically designed to redirect stray light and reflections away from the optical chamber direction. This allows the beam dump to be positioned close to the optical chamber for compactness while the curved surface actively prevents harmful light from entering the chamber.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The beam dump converts potentially harmful reflected and stray light into beneficially redirected light paths using its curved surface. The light that would otherwise enter the optical chamber is redirected away, transforming a harmful effect into a functional feature that protects the optical system.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Object-affected harmful factors

If a complex beam dump structure with multiple components is used to improve light blocking performance, then reflected light and stray light are better prevented, but the device complexity increases

Engineering Contradiction:
Improvereflected light and stray light preventionVSAvoidbeam dump structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Multiple functional elements (reflective surfaces, absorptive regions, light redirecting geometries) are merged into a single integrated beam dump component. This consolidation achieves comprehensive light blocking performance while avoiding the complexity of assembling multiple separate parts.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The beam dump is designed as a multi-functional component that simultaneously performs beam dumping, stray light rejection, reflection control, and spatial positioning. This universal design eliminates the need for separate components for each function, reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

This design significantly reduces reflected light and stray light incidence, enhancing the signal-to-noise ratio and measurement accuracy by ensuring that only the intended light signal is measured by the detectors, thereby improving the precision of particle or fluorescence detection.

Implementation Method 1

as the beam passed through the pin hole of the pin hole assembly becomes gradually near the light source output detector, the width of the beam becomes spread

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

a focal lens assembly adapted to be fitted to an insertion hole penetrating into the center of the body

Methodology Applied
Scientific EffectFocusing: Focusing

Implementation Method 3

a beam dump is a device that absorbs a beam of light, and major design concerns in the beam dump typically include the reduction of reflections and scattering of the beam of light as well as the dissipation of heat generated by absorption of the beam of light

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentEP2602645B1Beam dump for particle counter or fluorescence detector
Publication Date: 2014.03.26 AGENCY FOR DEFENSE DEV
  • EP2602645B1 patent drawingFigure 1
  • EP2602645B1 patent drawingFigure 2a
  • EP2602645B1 patent drawingFigure 2b

AI summary

The present invention relates to a beam dump for a particle counter or a fluorescence detector that is mounted on one side of an optical chamber in such a manner as to be opposite to a beam-forming part mounted on the other side of the optical chamber, so as to dump the beam irradiated from the beam-forming part, the beam dump including: a body adapted to be fixed to the optical chamber; a focal lens assembly adapted to be fitted to an insertion hole penetrating into the center of the body; a pin hole assembly adapted to be inserted into a concave portion formed on the rear surface of the body in such a manner as to pass a light axis of the focal lens assembly through a pin hole; a housing adapted to be fixed to the rear surface of the pin hole assembly; and a light source output detector adapted to be fixed to the rear surface of the housing in such a manner as to be inclined to a given angle with respect to a reference plane perpendicular to the light axis of the focal lens assembly, wherein the pin hole assembly and the housing have a cavity formed in the center portions thereof, such that as the beam passed through the pin hole becomes gradually near the light source output detector, the width of the beam becomes spread.