Q-Switched Optical Timing Detection for Compact Distance Sensors
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Solution Overview
Problem
Existing distance measuring devices using Q-switched laser elements face challenges in reducing size, improving impact resistance, and accurately detecting emission times of oscillation light due to the need for high-priced detectors and mirrors, especially when configuring arrays, leading to light leakage between pixels.
Innovation Solution
An optical device incorporating a light emitting element with a semiconductor section and solid-state laser medium, along with a saturable absorber, allows for detecting emission timing of oscillation light using a detector and drive current, enabling accurate distance measurement by integrating reflective layers and detectors within the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a Q-switched laser element is used in dToF to achieve high peak power, then the power is improved, but high-priced photodetectors and mirrors are necessary which increases device complexity and size
Solution Approach 1:
The patent uses the excitation light (first wavelength) as a copy or proxy to detect the emission timing of the oscillation light (second wavelength). Instead of directly detecting the expensive-to-detect oscillation light with complex photodetectors, the system detects the excitation light which has correlated timing characteristics, thereby achieving the same timing detection function with simpler, less expensive components.
Solution Approach 2:
The excitation light acts as an intermediary between the Q-switched laser element and the detector. By detecting the excitation light timing instead of the oscillation light timing directly, the system uses this intermediate measurement to infer the emission timing, avoiding the need for complex high-performance photodetectors and mirrors designed for the oscillation wavelength.
2Measurement precision
If mirrors and photodetectors are added to detect emission time of oscillation light, then measurement precision is improved, but device size increases and impact resistance decreases
Solution Approach 1:
The system detects the excitation light as a proxy for the oscillation light timing. This copying approach allows emission time detection without adding external mirrors and photodetectors, thereby maintaining compact device dimensions while achieving the required measurement precision through the timing correlation between excitation and oscillation light.
3Productivity
If Q-switched laser elements are configured as an array to improve pixel detection, then productivity is improved, but light leakage between pixels occurs making accurate detection difficult
Solution Approach 1:
By detecting the excitation light timing for each pixel in the array rather than the oscillation light timing, the system avoids cross-talk and light leakage issues between adjacent pixels. The excitation light detection provides a clean timing signal for each pixel element that can be accurately measured without interference from neighboring pixels, enabling precise array-based distance measurement.
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 enables compact, robust, and accurate distance measurement by detecting emission timing using low-cost detectors, reducing light leakage, and facilitating array configurations for improved pixel detection.
Implementation Method 1
a semiconductor section that is included in a first resonator causing light of a first wavelength to resonate and causes the light of the first wavelength to oscillate
Implementation Method 2
a solid-state laser medium that is included in the first resonator and a second resonator causing light of a second wavelength to resonate and causes the light of the second wavelength to oscillate
Implementation Method 3
a saturable absorber included in the second resonator and emitting the light of the second wavelength
Implementation Method 4
a detector detecting the light of the first wavelength or a drive current of the light emitting element
Data Source
AI summary
An optical device and a distance measuring device capable of appropriately detecting an emission timing of oscillation light are provided. An optical device according to the present disclosure includes: a light emitting element including a semiconductor section that is included in a first resonator causing light of a first wavelength to resonate and causes the light of the first wavelength to oscillate, a solid-state laser medium that is included in the first resonator and a second resonator causing light of a second wavelength to resonate and causes the light of the second wavelength to oscillate, and a saturable absorber included in the second resonator and emitting the light of the second wavelength; a detector detecting the light of the first wavelength or a drive current of the light emitting element; and an emission timing detecting unit detecting an emission timing of the light of the second wavelength on the basis of a detection result of the light of the first wavelength or the drive current of the light emitting element acquired using the detector.