Lidar Transceiver Thermal Expansion Matching
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Solution Overview
Problem
Lidar transceivers face challenges in maintaining optimal alignment and performance due to environmental changes, such as temperature fluctuations, which can cause misalignment of collimators over time.
Innovation Solution
A transceiver design featuring a hermetically sealed volume with equal coefficients of thermal expansion for the circuit board, inner housing, and lens, combined with a Risley prism alignment system for the collimator, which minimizes thermal misalignment and ensures stable beam alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional transceiver designs are used without thermal expansion matching, then manufacturing and assembly are simpler, but alignment stability deteriorates due to temperature-induced misalignment
Solution Approach 1:
The patent applies parameter changes by selecting materials for the circuit board, inner housing, and lens that have substantially equal coefficients of thermal expansion. This material parameter selection ensures that all components expand and contract uniformly with temperature changes, maintaining their relative positions and preventing thermal misalignment. The detector is bonded to an integrated circuit on the circuit board, which is attached to the inner housing, creating a thermally matched assembly that preserves alignment stability across temperature variations.
2Ease of manufacture
If components with different thermal expansion coefficients are used, then material selection and manufacturing are easier, but thermal misalignment occurs causing performance degradation
Solution Approach 1:
The patent resolves this contradiction by changing the material parameter selection criterion from convenience to thermal expansion matching. The circuit board, inner housing, and lens are specifically selected to have substantially equal coefficients of thermal expansion. This ensures that during manufacturing and assembly, the components maintain their relative geometric relationships even when subjected to temperature changes, thereby preserving alignment precision without significantly complicating the manufacturing process.
3Ease of operation
If the collimator is rigidly fixed, then alignment is easier to establish, but the system becomes sensitive to thermal expansion differences causing misalignment
Solution Approach 1:
The patent addresses this contradiction by changing the thermal expansion parameter of the materials used in the collimator assembly. The inner housing and lens are selected to have substantially equal coefficients of thermal expansion, which allows the collimator to be rigidly fixed while preventing thermal misalignment. The uniform thermal expansion ensures that the collimator remains properly aligned with the detector across temperature variations, maintaining both alignment ease and reliability.
4Device complexity
If environmental sealing is not implemented, then device complexity is reduced, but thermal and environmental effects cause misalignment and performance degradation
Solution Approach 1:
The patent applies the inert environment principle by hermetically sealing the optical components (detector, integrated circuit, lens, and collimator) within the inner housing. This sealing creates a controlled, stable internal environment that isolates the sensitive optical alignment from external thermal and environmental fluctuations. The sealed enclosure maintains constant temperature and pressure conditions for the optical components, preventing thermal expansion/contraction cycles and environmental contamination that would otherwise cause misalignment and performance degradation.
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 design enhances alignment stability and performance by uniformly expanding components with temperature changes, reducing optical misalignment and preventing cracking, while the Risley prism system allows for precise beam alignment with reduced sensitivity to temperature variations.
Implementation Method 1
the circuit board, the inner housing, and the lens are characterized by substantially equal coefficients of thermal expansion
Implementation Method 2
a window hermetically attached to the second end of the inner housing, wherein the circuit board, the inner housing, and the window form a hermetically sealed volume that encloses the detector
Implementation Method 3
the transmission beam alignment component is a prismatic component; wherein the prismatic component includes a Risley prism
Data Source
AI summary
A transceiver for use in a lidar system includes an optical receiver and a transmitter. The optical receiver includes a circuit board including a detector, a cylindrical inner housing, a C-shaped outer housing that partially surrounds the inner housing, and a lens in the outer housing. The transmitter includes an optical fiber coupled to a light source and a collimator, and a pair of Risley prism rods for adjusting collimator alignment. The collimator and Risley rods sit in a groove formed by the inner housing and the outer housing. A lidar system using the transceiver and a transceiver assembly method are disclosed.