US 12480789 B1Patent grantUnited States

Ultraprecision Free-Space Optical Sensing

Official patent title

Hybrid free space oscillators for ultraprecision sensor applications

Arabic title: مذبذبات هجينة في الفضاء الحر لتطبيقات المستشعرات فائقة الدقة

Invention

Problem

Small changes in gas density, temperature, composition, or material thickness can create optical phase shifts too subtle for simple amplitude-based sensing. A stable noncontact readout is needed.

Why it matters

Sensitive free-space measurements could support process control, environmental monitoring, gas identification, thickness inspection, and scientific metrology without placing a sensor on the sample.

Approach

An optoelectronic oscillator passes modulated laser light through a sensing zone, amplifies the phase-shifted signal, stabilizes it with a fiber delay and PZT stretcher, and maps measured frequency shifts to substance changes through a lookup table.

Who may benefit

Potential beneficiaries include optical-instrument manufacturers, process-control companies, gas-sensing developers, nondestructive-testing laboratories, and precision-metrology researchers.

Potential value

The architecture converts free-space phase perturbations into frequency-domain signals and combines optical amplification, controllable phase stabilization, spectral analysis, and lookup-based interpretation.

Background

Optical free-space sensing can detect changes in refractive index or path length without contacting the sample. Direct phase measurements can be vulnerable to noise and small signal excursions. Oscillator feedback recirculates the signal so phase changes appear as frequency shifts that may be easier to resolve. Stable operation still requires gain, filtering, delay, and phase control. The disclosed system uses an optical amplifier and a PZT fiber stretcher, then compares the spectrum with calibration data to infer gas or material changes.

Technology overview

A laser diode feeds a 50/50 coupler and two collimating lenses around a free-space sensing zone. A semiconductor optical amplifier boosts the returned signal. A phase loop contains a fiber delay and PZT fiber stretcher that inserts controlled phase; a measurement loop converts light to an electrical signal, amplifies and filters it, and adjusts electrical phase. A spectrum analyzer identifies frequency shifts, and a computer compares them with a lookup table to infer gas formula, density, temperature, or object thickness.

Potential applications

Gas identity and density sensing.
Noncontact temperature measurement.
Material-thickness inspection.
Industrial process monitoring.
Optical metrology research.

Evidence-supported advantages

Provides noncontact free-space sensing.
Converts phase shifts to frequency shifts.
Uses optical amplification to compensate loss.
Includes controllable PZT phase adjustment.
Supports lookup-based identification of several properties.

Development stage

A system architecture, control loops, signal processing, and proposed measured properties are described; calibrated prototype sensitivity, resolution, selectivity, drift, and field performance were not established. The development stage was not independently verified.

Commercial opportunity

The system may interest gas-sensor, process-control, and metrology vendors. Product development requires a calibrated prototype, sensitivity and resolution by measurand, selectivity among gases and environmental effects, frequency stability and drift, response time, reference-instrument comparison, alignment tolerance, optical safety, component-cost reduction, and field validation in the intended process environment.

Patent classifications

WIPO IPC

G01D5/353Measuring not adapted to a specific variable; measuring multiple variables; tariff metering; transferring or transducing arrangements; measuring or testing not otherwise provided for
G01C9/02Measuring distances, levels or bearings; surveying; navigation; gyroscopic instruments; photogrammetry or videogrammetry

CPC

G01C19/64Measuring distances, levels or bearings; surveying; navigation; gyroscopic instruments; photogrammetry or videogrammetry
G01C9/02Measuring distances, levels or bearings; surveying; navigation; gyroscopic instruments; photogrammetry or videogrammetry
G01D5/35329Measuring not adapted to a specific variable; measuring multiple variables; tariff metering; transferring or transducing arrangements; measuring or testing not otherwise provided for

Inventors

First inventorMohamed Yehia Mohamed Shalaby
InventorAbdulrahman M. Shalaby

Keywords

optical oscillator
free-space sensing
phase shift
frequency shift
PZT fiber stretcher
gas sensing
thickness measurement
spectrum analyzer

Patent document and drawings

The patent publication is mapped to this record. Patent drawings remain within that publication; no separately cleared public media package has been supplied.