Semiconductor Laser Light Source With Conversion Medium
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Solution Overview
Problem
Existing light sources and projectors face challenges in achieving high luminance with reduced speckle patterns, as conventional coherent radiation sources can produce interference patterns that affect image quality.
Innovation Solution
The use of an optoelectronic semiconductor chip-based light source that generates primary radiation in the ultraviolet or visible spectrum, with a conversion medium to produce incoherent secondary radiation, reducing optical coherence length and eliminating speckle patterns by decoupling the phase relationship between color centers, resulting in a homogeneous and high-luminance output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a semiconductor laser is used to generate primary radiation, then high luminance and spectral precision are achieved, but optical coherence length increases causing speckle patterns
Solution Approach 1:
A conversion medium is introduced as an intermediary between the semiconductor laser and the final radiation output. This conversion medium absorbs the coherent primary radiation from the laser and re-emits it as incoherent secondary radiation, thereby eliminating speckle patterns while maintaining high luminance. The conversion medium acts as a mediator that transforms the harmful coherent radiation into useful incoherent radiation.
Solution Approach 2:
The patent changes the optical parameters of the radiation by using a conversion medium that alters the coherence length and spectral characteristics. The conversion medium is designed to reduce the optical coherence length from millimeter/centimeter scale (harmful for projections) to micrometer scale (beneficial for eliminating speckle), while maintaining high luminance output.
2Object-affected harmful factors
If the optical coherence length is reduced to eliminate speckle patterns, then image quality improves, but luminance may decrease
Solution Approach 1:
The conversion medium serves as an efficient intermediary that maintains energy conservation while transforming radiation properties. It absorbs primary radiation and re-emits secondary radiation with comparable intensity, ensuring that luminance is preserved even as coherence length is reduced to eliminate speckle patterns.
3Stability of the object's composition
If homogeneous radiation output is achieved across the beam cross section, then color consistency improves, but device complexity increases
Solution Approach 1:
The conversion medium is designed with spatially varying properties to achieve uniform radiation output. By carefully controlling the local characteristics of the conversion medium (such as phosphor distribution, concentration, or thickness), the patent ensures that each region contributes appropriately to produce homogeneous radiation across the entire beam cross section, maintaining color consistency without requiring complex additional components.
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 solution achieves high luminance with minimal speckle patterns, ensuring improved image quality and coherence length reduction, suitable for projection applications.
Implementation Method 1
The semiconductor chip can be a light-emitting diode or a semiconductor laser
Implementation Method 2
The semiconductor chip can be a light-emitting diode or a semiconductor laser
Implementation Method 3
The conversion means is arranged downstream of the semiconductor laser in the beam direction of the primary radiation and is set up to convert at least part of the primary radiation into secondary radiation
Implementation Method 4
The publication WO 2006/129211 A2 relates to a spectrally broadband emitting laser light source with a reduced speckle pattern
Implementation Method 5
An incoherent secondary radiation is generated through the use of the conversion medium, which in particular contains a large number of color centers or luminous points that are independent of one another
Data Source
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AI summary
In at least one embodiment of the luminous means (1), the latter comprises at least one semiconductor laser (2) which is designed to emit a primary radiation (P) having a wavelength of between 360 nm and 485 nm inclusive. Furthermore, the luminous means (1) comprises at least one conversion means (3) which is disposed downstream of the semiconductor laser (2) and is designed to convert at least part of the primary radiation (P) into secondary radiation (S) having a greater wavelength that is different from the primary radiation (P). In this case, the radiation (R) emitted by the luminous means (1) exhibits an optical coherence length amounting to at most 50 μm.