Exposure Device Beam Splitter for UV Light Utilization

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Solution Overview

Problem

Existing exposure devices using high-pressure discharge lamps for ultraviolet light production face issues with electrode evaporation leading to reduced lamp lifetime and inefficient use of ultraviolet light due to the need for openings in elliptical reflectors, which can cause energy density problems and vessel damage.

Innovation Solution

The exposure device incorporates a beam splitter in the optical path to allow laser light to be incident on the light source from the open side of the elliptical reflector, eliminating the need for openings and using a collimator or converging lens to ensure efficient light utilization, with the light source positioned at the first focal point of the elliptical reflector and a hollow light profile to reduce direct irradiation and heat.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If openings are provided on the side faces of the elliptical reflector to supply laser light to the electrodeless discharge lamp, then the lamp can be energized without electrodes, but the ultraviolet light condensing function of the elliptical reflector is compromised

Engineering Contradiction:
Improvelamp lifetimeVSAvoidultraviolet light utilization efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

A beam splitter is introduced as an intermediary component in the optical path. The beam splitter allows laser light to pass through to energize the electrodeless discharge lamp while simultaneously allowing the elliptical reflector to maintain its ultraviolet light condensing function. This mediator resolves the conflict between enabling electrodeless operation and preserving optical efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical path is segmented into separate channels: one for laser light input (through the beam splitter) and another for ultraviolet light output (reflected by the elliptical reflector). This segmentation allows each function to operate independently without interfering with the other, maintaining both lamp reliability and UV light utilization efficiency.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If the openings on the elliptical reflector are made small to reduce laser energy density, then vessel damage is prevented, but the angle of incidence of laser light on the lamp becomes small reducing energy transfer efficiency

Engineering Contradiction:
Improvevessel damage from high energy densityVSAvoidlaser energy transfer efficiency to lamp
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The laser beam is directed through the opening from a different spatial dimension (through the beam splitter plane) rather than from the side. This dimensional change allows the use of larger effective opening areas without increasing the linear dimensions of the opening in the reflector surface, thereby maintaining low energy density while improving energy transfer efficiency.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The beam splitter acts as an intermediary that redistributes the laser energy across a larger effective area. By passing the laser light through the beam splitter before it reaches the lamp, the energy is spread out, reducing peak energy density at any single point on the vessel while still delivering sufficient total energy to excite the lamp effectively.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Use of energy by moving object

If the openings are made large to improve laser light incidence angle and energy transfer, then energy transfer efficiency improves, but ultraviolet light from the lamp cannot be effectively utilized

Engineering Contradiction:
Improvelaser energy transfer efficiency to lampVSAvoidultraviolet light utilization efficiency
Core Design Contradiction:
Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The beam splitter serves as a wavelength-selective intermediary that is transparent to laser light (infrared) but reflective to ultraviolet light. This allows large effective openings for laser energy input while the elliptical reflector maintains its UV light condensing function, preventing UV light loss.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

Different regions of the optical system are assigned different functional qualities: the beam splitter region handles laser light transmission while the elliptical reflector region handles ultraviolet light reflection and condensing. This local differentiation allows each component to optimize its performance for its specific wavelength range without compromising the other function.

Inventive Principle:
Principle #3Local quality

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 configuration enhances the utilization of ultraviolet light, reduces energy density, and prevents vessel damage, while maintaining a compact design and efficient energy transfer, thereby extending lamp lifetime and improving exposure device performance.

Implementation Method 1

a beam splitter having a wavelength selecting function is provided in an optical path of light reflected by the elliptical reflector to allow laser light from the laser device to be incident on the light source from an open side of the elliptical reflector

Methodology Applied
Scientific EffectWavelength selective reflection and transmission: Dichroic Filter

Implementation Method 2

an elliptical reflector for reflecting ultraviolet light emitted from the light source

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 3

laser light is used as a means for supplying energy to the light source

Methodology Applied
Scientific EffectLaser excitation: Laser

Implementation Method 4

to excite a discharge gas sealed inside the discharge vessel

Methodology Applied
Scientific EffectLight emission from excited gas: Luminescence

Data Source

PatentEP2172962B1Exposure device
Publication Date: 2014.08.20 USHIO INC
  • EP2172962B1 patent drawingFigure 1~2
  • EP2172962B1 patent drawingFigure 3~4
  • EP2172962B1 patent drawingFigure 5~6

AI summary

An exposure device (1) for producing semiconductors and liquid crystals has an optical system capable of effectively using light generated without making a hole in a lamp discharge vessel when high energy laser light is supplied to it for emitting light, such as ultraviolet light. The exposure device has a light source (30) for emitting ultraviolet light, a laser device (30) for emitting laser light, an elliptical reflector (2) for reflecting ultraviolet light emitted from the light source, and an optical system for directing light reflected by the elliptical reflector to an article (11) to be treated via optical elements including a collimator lens (6) and an integrator lens (7), and a beam splitter (4) having a wavelength selecting ability provided in the optical path for light reflected by the elliptical reflector to allow laser light to be incident on the light source from and opening side of the elliptical reflector.