Electro-Optic Deflector Wavelength Swept Light Source

Solution Overview

Problem

Current wavelength swept light sources used in SS-OCT struggle to achieve linear wavelength variation, leading to non-linear OCT images due to the difficulty in controlling the rotational speed of polygon mirrors, which results in poor image sharpness and linearity.

Innovation Solution

A wavelength swept light source is developed using an electro-optic deflector with a controlled voltage generator that applies a sawtooth waveform with superimposed exponential and squared components, allowing for precise control of wavelength variation, ensuring the wavenumber varies linearly with time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a polygon mirror is used to sweep the wavelength, then the device structure is relatively simple, but the rotational speed control becomes difficult resulting in non-linear wavelength variation

Engineering Contradiction:

Improvedevice structureVSAvoidwavelength variation linearity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical polygon mirror system with an electro-optic deflector that uses electric fields to control light deflection. This substitution eliminates the need for precise rotational speed control of a mechanical component, as the electro-optic deflector can be controlled electronically to achieve linear wavelength variation with respect to time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from mechanical rotational speed to applied voltage. By controlling the voltage applied to the electro-optic deflector, the system achieves precise control over the wavelength sweep rate, ensuring linear variation of wavelength with time without the limitations of mechanical rotation control.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the rotational speed of polygon mirror is increased to improve scan speed, then productivity increases, but the difficulty of controlling rotational speed increases leading to worse wavelength linearity

Engineering Contradiction:

Improvescan speedVSAvoidwavelength variation linearity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical polygon mirror system with an electro-optic deflector that uses electric fields to control light deflection. This substitution eliminates the need for precise rotational speed control of a mechanical component, as the electro-optic deflector can be controlled electronically to achieve linear wavelength variation with respect to time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from mechanical rotational speed to applied voltage. By controlling the voltage applied to the electro-optic deflector, the system achieves precise control over the wavelength sweep rate, ensuring linear variation of wavelength with time without the limitations of mechanical rotation control.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If a simple sawtooth waveform is applied to the electro-optic deflector, then the control is simple, but the wavelength sweep becomes non-linear resulting in poor image sharpness

Engineering Contradiction:

Improvecontrol simplicityVSAvoidimage sharpness

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent modifies the voltage waveform parameters by superimposing exponential and squared components on the sawtooth waveform. This adjustment changes the time-dependency of the voltage applied to the electro-optic deflector, achieving linear wavelength variation with time while maintaining relative simplicity in the control approach.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite waveform consisting of multiple mathematical components (sawtooth, exponential, and squared terms) combined together. This composite voltage waveform achieves the desired linear wavelength sweep by compensating for non-linearities in the electro-optic deflector's response characteristics.

Inventive Principle:

Principle #40Composite materials

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 achieves a linear wavelength sweep, significantly improving the linearity and sharpness of OCT images by correcting the controlled voltage applied to the electro-optic deflector, resulting in a more accurate and clear image in SS-OCT.

Implementation Method 1

an oscillator part including an electro-optic deflector

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Implementation Method 2

a wavelength swept light source using a polygon mirror in the well-known art... enters the diffraction grating 106

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS9372339B2Wavelength swept light source

Publication Date: 2016.06.21 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

A wavelength swept light source includes a sawtooth waveform as a main waveform and an exponential component of the sawtooth waveform to the controlled voltage of the electro-optic deflector. The controlled voltage is controlled so that, as an oscillation wavelength to be swept is swept towards a longer wavelength side, a change rate of the oscillation wavelength is increased.