Compact In-Line Reflective Beam Expander with Adjustable Focus
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Solution Overview
Problem
Existing optical beam expanders or reducers, whether refractive or reflective, face issues such as thermally-induced optical aberrations, wavelength dependence, and boresight errors, which limit their effectiveness and versatility in maintaining beam quality and alignment across various applications.
Innovation Solution
A compact in-line reflective optical beam expander or reducer design using two powered mirrors aligned back-to-back with adjustable spacing between reflective surfaces, allowing for precise control of the output beam's focus without introducing boresight errors, utilizing an offset retro-reflective element to redirect the optical beam and adjust its divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If typical beam expanders or reducers are implemented using refractive optical elements, then beam resizing is achieved, but thermally-induced optical aberrations occur
Solution Approach 1:
The patent replaces refractive optical elements (lenses) with reflective optical elements (mirrors). The beam expander/reducer uses a series of mirrors including a primary mirror, secondary mirror, tertiary mirror, and fourth mirror to achieve beam resizing without the thermal aberrations that plague refractive systems. The reflective surfaces redirect the optical beam through the expansion/reduction sequence without absorbing significant thermal energy.
2Productivity
If refractive optical elements are used for beam expansion or reduction, then beam resizing is achieved, but the system becomes wavelength dependent
Solution Approach 1:
The patent employs entirely reflective optical elements throughout the beam expansion/reduction system. Mirrors reflect optical beams across a broad spectrum of wavelengths without the chromatic aberration and wavelength-dependent refraction that occurs in lens-based systems. This makes the system versatile for multiple wavelength bands including visible, infrared, and ultraviolet regions.
3Productivity
If typical reflective beam expanders or reducers are used, then beam resizing is achieved, but boresight errors are introduced
Solution Approach 1:
The patent employs an asymmetric optical path design where the beam encounters mirrors at different angles and positions strategically arranged to compensate for potential boresight errors. The primary mirror receives the input beam at a first angle, the secondary mirror at a second angle, and the tertiary mirror at a third angle, with each angle carefully selected to maintain beam alignment accuracy while achieving the desired expansion or reduction ratio.
Solution Approach 2:
The patent includes adjustable spacing mechanisms between the mirrors that allow for fine-tuning of the optical path. This adjustability enables compensation for alignment errors and maintains boresight accuracy by allowing operators to optimize the beam path geometry for specific application requirements.
4Measurement precision
If compact in-line reflective optical system with adjustable spacing is used, then focus control is achieved without boresight error, but device complexity increases
Solution Approach 1:
The patent incorporates adjustable spacing between the primary mirror and secondary mirror, as well as between the tertiary mirror and fourth mirror. These dynamic adjustments allow for focus control of the output beam without introducing boresight errors, as the in-line configuration maintains beam alignment while the spacing variations enable focus tuning.
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 maintains the original beam's pointing vector, reduces thermal and chromatic aberrations, and allows for precision focus adjustments, enabling effective beam resizing in a small footprint compatible with multiple wavelength bands without introducing significant optical aberrations.
Implementation Method 1
The first powered mirror is configured to reflect the input optical beam as a first intermediate beam... The second powered mirror is configured to reflect the third intermediate beam as the output optical beam
Data Source
AI summary
An apparatus includes an in-line reflective optical system configured to receive an input optical beam and provide an output optical beam. The in-line reflective optical system includes first and second powered mirrors aligned back-to-back. The first powered mirror is configured to reflect the input optical beam as a first intermediate beam. The in-line reflective optical system also includes first and second reflective surfaces respectively configured to reflect the first intermediate beam as a second intermediate beam and to reflect the second intermediate beam as a third intermediate beam. The second powered mirror is configured to reflect the third intermediate beam as the output optical beam. A spacing between the first and second reflective surfaces and the first and second powered mirrors is adjustable to control a focus of the output optical beam without introducing boresight error in the output optical beam.