Laser Diode Firing Circuit With Inductive Timing Feedback
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Solution Overview
Problem
Existing LIDAR systems face challenges in accurately determining the pulse emission time due to delays and jitter in the transistor switching process, which affects the precision of distance measurements to reflective objects.
Innovation Solution
The implementation of a laser diode firing circuit with an inductively coupled feedback system, where a conductive loop detects changes in current flow to determine the pulse emission time, thereby reducing the impact of transistor delays and jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a transistor is used to control current through the laser diode, then the laser diode can be switched on and off rapidly, but there is delay and jitter in the transistor switching process that reduces timing precision
Solution Approach 1:
The patent introduces a feedback loop as an intermediary element that senses the actual current flow through the laser diode and provides timing information. This feedback mechanism mediates between the transistor switching action and the timing measurement, allowing the system to capture the true emission time despite transistor delays and jitter.
Solution Approach 2:
The patent implements a feedback loop that continuously monitors the current flow through the laser diode and feeds this information back to the timing circuit. This feedback enables the system to determine the actual pulse emission time by detecting when current truly flows through the laser diode, rather than relying on the initiating signal timing that is affected by transistor delays.
2Device complexity
If the initiating signal timing is used to determine pulse emission time, then the timing measurement is simple, but the transistor delays and jitter cause inaccuracies in the emission time determination
Solution Approach 1:
The feedback loop monitors the actual current flow through the laser diode and provides timing information that reflects the true emission time. This feedback mechanism improves emission time accuracy by capturing when current actually flows, rather than relying on the initiating signal that is affected by transistor delays.
Solution Approach 2:
The patent replaces the mechanical/electrical timing method (using initiating signal timing) with an optical/electromagnetic sensing method (using the feedback loop to detect current flow). This substitution allows for more accurate timing measurement by directly sensing the electromagnetic phenomenon associated with laser diode operation.
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 solution allows for more accurate determination of pulse emission times, reducing timing uncertainties and improving the spatial resolution of distance measurements in LIDAR systems.
Implementation Method 1
a feedback loop is positioned to be inductively coupled to a current path of the firing circuit that includes the laser diode. As such, a change in current flowing through the laser diode (e.g., during firing of the laser diode) induces a current in the feedback loop.
Data Source
AI summary
A laser diode firing circuit for a light detection and ranging (LIDAR) device that includes an inductively coupled feedback system is disclosed. The firing circuit includes a laser diode coupled in series with a transistor, such that current through the laser diode is controlled by the transistor. The laser diode is configured to emit a pulse of light in response to current flowing through the laser diode. A feedback loop is positioned to be inductively coupled to a current path of the firing circuit that includes the laser diode. As such, a change in current flowing through the laser diode induces a voltage in the feedback loop. A change in voltage across the leads of the feedback loop can be detected and the timing of the voltage change can be used to determine the time that current begins flowing through the laser diode.