Compact Photonic LiDAR Receiver With Multi-Stage Sampling

Solution Overview

Problem

Existing LiDAR systems face challenges in efficiently imaging through scattering media like water due to high complexity, cost, and spatial resolution loss, requiring high-speed digitization and analog to digital converters that increase heat and area consumption, while also suffering from under-sampling and scattering-induced blur.

Innovation Solution

An integrated circuit receiver design for LiDAR that employs multi-stage sampling and gain modulation to reduce digitizer complexity, using avalanche photodiodes and transimpedance amplifiers with N-channel sampling and hold circuits to capture full waveform data without nanosecond analog to digital conversion at each pixel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-speed nanosecond digitizer electronics are used to resolve temporal variations in backscattered light, then measurement precision is improved, but device complexity and heat generation increase

Engineering Contradiction:

Improvetemporal resolutionVSAvoiddigitizer complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the temporal sampling process into multiple stages: a first stage of fast sampling at nanosecond rates to capture the initial light return, followed by a second stage of slower sampling to resolve temporal variations. This segmentation allows high temporal resolution without requiring all digitizer elements to operate at maximum speed simultaneously, reducing overall device complexity and heat generation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by having only a subset of pixel elements perform high-speed digitization while others use slower, simpler electronics. Specifically, a first subset of pixels performs fast sampling for initial return capture, while a second subset performs slower sampling for temporal variation analysis. This partial application of high-speed digitization maintains measurement precision where needed while reducing overall device complexity.

Inventive Principle:

Principle #16Partial or excessive action

2Measurement precision

If high-speed nanosecond digitizer electronics are used to resolve temporal variations in backscattered light, then measurement precision is improved, but heat generation increases

Engineering Contradiction:

Improvetemporal resolutionVSAvoidheat generation

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The patent segments the temporal sampling process into multiple stages: a first stage of fast sampling at nanosecond rates to capture the initial light return, followed by a second stage of slower sampling to resolve temporal variations. This segmentation allows high temporal resolution without requiring all digitizer elements to operate at maximum speed simultaneously, reducing overall device complexity and heat generation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by having only a subset of pixel elements perform high-speed digitization while others use slower, simpler electronics. Specifically, a first subset of pixels performs fast sampling for initial return capture, while a second subset performs slower sampling for temporal variation analysis. This partial application of high-speed digitization maintains measurement precision where needed while reducing overall device complexity.

Inventive Principle:

Principle #16Partial or excessive action

3Device complexity

If conventional LiDAR scanning methods are used, then device complexity is reduced, but spatial resolution is lost due to under-sampling

Engineering Contradiction:

Improvesystem simplicityVSAvoidspatial resolution

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent transitions from conventional one-dimensional scanning to two-dimensional array imaging, capturing spatial and temporal information simultaneously across multiple pixels. This dimensional change enables the system to resolve spatial features without mechanical scanning while maintaining simplicity through parallel processing architecture. The array of pixels captures the entire field of view in a single exposure, eliminating scanning artifacts and improving spatial resolution.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Measurement precision

If scattering media are imaged using conventional methods, then measurement precision is maintained, but information is lost due to scattering-induced blur

Engineering Contradiction:

Improveimage qualityVSAvoidspatial information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent applies preliminary action by capturing multiple temporal samples of the backscattered light signal before final processing. The system performs fast initial sampling to capture the light return, then continues sampling at reduced rates to resolve temporal variations caused by scattering. This preliminary multi-stage sampling preserves spatial information that would otherwise be lost to scattering-induced blur, enabling subsequent processing to reconstruct clear images through temporal differentiation.

Inventive Principle:

Principle #10Preliminary action

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

Enables efficient time-resolved imaging through scattering media by reducing digitizer complexity and heat, maintaining spatial resolution, and enhancing range and velocity information extraction from backscattered light.

Implementation Method 1

The detector is an avalanche photodiode

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

connected to a transimpedance amplifier

Methodology Applied

Scientific EffectTransimpedance amplification:

Implementation Method 3

water is a scattering medium, the scattering produces loss of spatial resolution

Methodology Applied

Scientific EffectLight scattering: Scattering

Implementation Method 4

temporally shaped light, e.g., a laser pulse, is transmitted into a body of water to produce reflected light

Methodology Applied

Scientific EffectLight propagation: Light

Implementation Method 5

N-channel Sample and Hold (F) 303, e.g., N at least 1

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS20250334697A1System and Methods for Compact Photonic Time Resolution

Publication Date: 2025.10.30 GRIFFIS ANDREW

AI summary

Systems and methods are provided for time resolution of signals produced by the emission of energy. More particularly, systems and methods are provided for measuring distance using photons propagating in a scattering medium to produce multi-dimensional, measurements of objects in a media and/or the media itself by virtue of the character of light spatially scattered and absorbed in the media resulting from the transmission of light into the media, such transmitted light having some temporal character that distinguishes it from background light, e.g., ambient sources. A method for obtaining terrestrial LiDAR data generally includes: providing a LiDAR system moving traverse to a ground canopy; emitting light pulses from the LiDAR system toward the ground canopy and terrain such that the light pulses reflect therefrom; and receiving the reflected light pulses at the LiDAR system; wherein the LiDAR system includes a monolithic module comprising a photonic device, a sampling module, a digitizing module, and a readout integrated circuit (ROIC).