Absorbing Mirror Substrate for Laser Saturation Suppression
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Solution Overview
Problem
Laser range finders face detector saturation issues due to scattered laser pulse light, which complicates the design and increases recovery time, necessitating a compact and efficient solution to manage both reference and laser light paths effectively.
Innovation Solution
A mirror substrate is designed with a reflective coating on one side for laser light and a transmissive coating on the other for reference light, using materials like samarium or praseodymium-doped glass to absorb laser light and transmit reference light, minimizing internal reflections and scattering, thereby preventing detector saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mirror substrate with reflective coating is used to reflect laser light, then the laser beam path is effectively managed, but scattered laser light causes detector saturation and increases recovery time
Solution Approach 1:
The substrate exhibits different optical properties at different locations/wavelengths: it is absorptive at the laser wavelength (1550 nm) and transmissive at the reference light wavelength (635 nm). This local quality differentiation allows the same substrate to simultaneously prevent detector saturation from laser light while transmitting reference light for alignment purposes.
Solution Approach 2:
The substrate's absorption of laser light, which could be considered harmful (causing saturation), is converted into a beneficial effect by preventing scattered laser light from reaching the detector. The harmful scattering is eliminated by designing the substrate to be inherently absorptive at the laser wavelength, turning potential damage into protective functionality.
2Ease of operation
If separate paths for reference light and laser light are implemented, then light path management is achieved, but device complexity and size increase
Solution Approach 1:
The substrate merges the functions of reference light transmission and laser light reflection into a single optical component. The front surface reflects laser light while the back surface transmits reference light, eliminating the need for separate optical paths and reducing overall device complexity.
Solution Approach 2:
The single substrate performs multiple functions: it acts as a beam splitter, a reflector for laser light, and a transmitter for reference light. This multi-functionality simplifies the overall optical system design by replacing what would traditionally require multiple separate optical components.
3Object-generated harmful factors
If internal reflections within the substrate are reduced, then scattered light is minimized, but manufacturing precision requirements increase
Solution Approach 1:
Instead of trying to eliminate all internal reflections through ultra-precise manufacturing, the substrate is designed to be absorptive at the laser wavelength. This converts the potentially harmful effect of internal reflections into a beneficial absorption effect, where scattered light is absorbed rather than reflected back to the detector.
Solution Approach 2:
The optical parameters of the substrate are changed by selecting materials with specific absorption characteristics at the laser wavelength. This parameter change (from reflective to absorptive) fundamentally alters how internal reflections are handled, reducing the need for extreme manufacturing precision.
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 reduces detector saturation by eliminating scattered laser light, allowing for a compact laser range finder design with reduced recovery times and improved sensitivity to return signals.
Implementation Method 1
the substrate is absorptive at a first wavelength... the substrate is absorptive at a first wavelength and transmissive at a second wavelength
Implementation Method 2
a transmissive coating on the other for reference light... the substrate is absorptive at a first wavelength and transmissive at a second wavelength
Implementation Method 3
the reflective coating is reflective at the first wavelength... the reflective coating is arranged on a first side of the substrate opposite a second side of the substrate
Data Source
AI summary
Provided for herein is a mirror including a substrate and a reflective coating, wherein the substrate is absorptive at a first wavelength and transmissive at a second wavelength, wherein the reflective coating is reflective at the first wavelength; and wherein the reflective coating is arranged on a first side of the substrate opposite a second side of the substrate; a first radiation source configured to transmit radiation at the first wavelength incident on the first side of the substrate; and a second radiation source configured to transmit radiation at the second wavelength incident on the second side of the substrate.