VCSEL Holographic Sight Wavelength Stabilization
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Solution Overview
Problem
Holographic gun sights face inaccuracies due to wavelength shifts in laser diodes caused by temperature changes, leading to parallax mismatch and requiring bulky and energy-intensive thermoelectric controllers for stabilization.
Innovation Solution
A compact holographic gun sight using a wavelength-tunable VCSEL light source with smart light control, which adjusts the laser current to maintain stable wavelength output, and fine adjustment mechanisms for windage and elevation to minimize image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a standard laser diode is used in a holographic gun sight, then the device can be compact and simple, but the wavelength shifts with temperature changes causing inaccurate reticle positioning
Solution Approach 1:
The patent uses a VCSEL (vertical-cavity surface-emitting laser) which has fundamentally different temperature-wavelength characteristics compared to standard laser diodes. The VCSEL's wavelength shifts only 0.05 nm/°C versus 0.30 nm/°C for standard diodes, providing inherent temperature stability without requiring additional control mechanisms. This parameter change in the laser type resolves the contradiction by maintaining simplicity while improving precision.
2Reliability
If a thermoelectric cooler is added to stabilize laser diode wavelength, then wavelength stability improves, but the device size and energy consumption increase significantly
Solution Approach 1:
The patent extracts the temperature control function entirely from the system by using a VCSEL that inherently resists temperature-induced wavelength shifts. Instead of adding a thermoelectric cooler to control a standard laser diode, the solution removes the need for active cooling by choosing a laser type whose operating characteristics naturally provide wavelength stability across temperature variations.
Solution Approach 2:
The VCSEL serves itself by providing inherent temperature compensation through its physical characteristics. The laser type's design naturally compensates for temperature effects without requiring external control systems, making the system self-regulating regarding wavelength stability.
3Reliability
If a thermoelectric cooler is added to stabilize laser diode wavelength, then wavelength stability improves, but energy consumption increases by more than 0.5 amps
Solution Approach 1:
The patent removes the energy-intensive thermoelectric cooling system entirely by using a VCSEL that provides passive temperature stability. The high current draw of 0.5+ amps required by TEC coolers is eliminated, reducing power consumption while maintaining wavelength stability through the laser type's inherent characteristics.
4Measurement precision
If achromatic holographic elements are used to compensate for wavelength changes, then reticle accuracy is maintained, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent performs preliminary action by selecting a VCSEL that inherently maintains stable wavelength across temperature ranges. This prevents wavelength shifts before they can affect the holographic elements, eliminating the need for complex achromatic compensation systems and simplifying the overall design.
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 provides a compact, energy-efficient, and accurate holographic gun sight with reduced parallax mismatch, improving shooting precision by stabilizing the reticle image and reducing the need for complex achromatic systems.
Implementation Method 1
A compact holographic gun sight using a wavelength-tunable VCSEL light source, which adjusts the laser current to maintain stable wavelength output
Implementation Method 2
A holographic optical element (HOE) in communication with the light source and the display hologram, the HOE diffracting the light beam onto the display hologram
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
A sight assembly for mounting to a weapon is provided. A holographic optical element and a light source are provided in a fixed angular configuration with respect to one another, but may be adjusted either together or individually in a horizontal or vertical direction. A mirror or lens may also be provided. An adjustment mechanism is provided where a shaft includes at least two portions wherein the two portions of the shaft of the screw have different pitch directions and/or pitch dimensions allowing for slight adjustment the assembly. The light source is typically a vertical-cavity surface emitting laser (VCSEL). The wavelength of the VCSEL is controlled by controlling the current it is given. The assembly further allows for perceived image distance adjustment using parallax mismatch. Further, a chassis is provided for holding holographic elements.