tailoring lasers for specific swept source oct applications · axsun technologies inc. • a wholly...

Bill Ahern

Axsun Technologies, Inc.

Bio Opto Japan 2013

Tailoring Lasers for Specific Swept

Source OCT Applications

Outline

• Axsun Overview

• Axsun Technology and Manufacturing

• OCT Laser Platform

• Imaging Subsystems

• Laser Operation

• Advanced System Development

• Summary

Axsun Technologies Inc.

• A wholly owned subsidiary of Volcano

Corporation (Nasdaq: VOLC)

• Founded in 1998, located in Billerica, MA

• Producing more than ten thousand

optical engines annually into Telecom,

Industrial Spectroscopy and Medical

Imaging applications

• Unique tunable MEMS and optical

integration technology

• Telecom and Industrial products have

strong synergy with Medical Imaging

• 115 employees

• 110 Issued Patents

AXSUN MODULE ASSEMBLY FACILITY

Optical Engine

MEMs Technology and

Manufacturing Platform

High Capacity, Automated

Manufacturing

The Axsun Platform – Unique Devices,

Assembly, and Products

Unique Devices Optical Bench Optical Engine

Module

Complete Subsystem

The Axsun Platform – Unique Devices,

Assembly, and Products

Unique Devices Optical Bench Optical Engine

Module

Complete Subsystem

The Axsun Platform – Unique Devices,

Assembly, and Products

Unique Devices Optical Bench Optical Engine

Module

Complete Subsystem

The Axsun Platform – Unique Devices,

Assembly, and Products

Unique Devices Optical Bench Optical Engine

Module

Complete Subsystem

Swept Source OCT

Axsun Swept Laser Technology

and Performance

Optical Coherence TomographyOCT Techniques

1. Time-domain OCT

2.Frequency-domain OCT• Spectral-domain OCT

• Swept-source OCT

Swept-Source OCT advantages

– Enables balanced and polarization diverse detection

schemes

– Longer Wavelengths, such as 1060nm and 1300nm, enable

deeper penetration into tissue

– Increased imaging depth range from slower signal roll-off

– High SNR and Resolution in a compact, rugged package

SSOCT

Axsun MEMs External Cavity Tunable Laser

14 mm

SOA

Tunable FP Filter

Laser Cavity

GainOutput

Optical

Fiber

Fiber

Reflector

Lens Lens

Micro-Electro-Mechanical System

(MEMS) Tunable Filter

Tethered

Membrane

Filter Assembly

Wafer Scale Processing

HR Coated

Flat Mirror

Electrode Gap

Optical Cavity

HR Coated Curved

Mirror on Tethered

Membrane

Si

MEMS Fabry-Perot Filter Structure

V

Micro-Optical Bench Packaging Platform

SOA gain chip

Output Fiber pigtail

LIGA alignment structure

Si micro lens

MEMS tunable filter

Micro-optical bench

x

y

z

Micro-

lens

fiber

Enables the most compact, highest

speed tunable laser for OCT

Axsun Swept Laser

Performance

Axsun Laser Tuning Range (Bandwidth)

BW >110 nmBW >100 nm

Axsun Laser Coherence Length

0 2 4 6 8 10 12 14 16 18 20 22-60

-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

5

Full Length (mm)

Sig

nal F

FT

(dB

=20*l

og10)

<Down Tune Wavelength> <oct 0243 CohLen 1mm.dat>

Coherence Length = 13.5 mm

Operating conditions:

– l ~ 1060nm

– 110nm tuning

range

– 100kHz scan rate

Axsun’s slow signal rolloff enables longer imaging depth

range than competitive swept lasers and Spectral Domain

OCT systems

SNR over Imaging Depth

Slow SNR rolloff enables

longer imaging depth

range

Ref:

Benjamin Potsaid, Bernhard Baumann,

David Huang, Scott Barry, Alex E. Cable,

Joel S. Schuman, Jay S. Duker, and

James G. Fujimoto, "Ultrahigh speed

1050nm swept source / Fourier domain

OCT retinal and anterior segment imaging

at 100,000 to 400,000 axial scans per

second," Opt. Express 18, 20029-20048

(2010)

1060nm 47kHz

InGaAs Camera 850nm 91kHz

CMOS CameraAxsun 1060nm

100kHz Engine

-60

-40

-20

0

20

40

60

80

100

120

0.001 0.01 0.1 1 10 100 1000 10000

dB

Reference Power (uW)

Sensitivity for 2.5 mW sample power

Noise

Signal

SNR

SNR + Loss

OCT System Performance

Operating conditions:

– l ~ 1060nm

– 110nm tuning range

– 100kHz scan rate

– System includes

Axsun BD and DAQ

Shot Noise Limited

sensitivity of 102dB

Axsun OCT Engine

Current products

Axsun OCT Imaging Products• OCT Engines

– Enabling element for next generation Frequency Domain

OCT systems

– Industry leading speed, imaging depth and resolution

– Small, rugged and reliable

Swept Laser Swept Laser with Integrated Optics Complete OCT Engine

OCT system with Axsun SS Laser &

Axsun Data Acquisition Board

Swept Laser

20

80

50

50

Balanced

Receiver

Variable Delay

10

90

Clock

Clock interferometerDAQ Board

Sweep

Trigger

Signal

1060 nm OCT “Engine”

Probe

Axsun OCT products

Axsun Swept Laser OEM EngineAxsun Camera Link DAQ Board

Axsun Swept Laser Benchtop

EngineAxsun Swept Laser Engine with

integrated DAQ

New 2 Channel DAQ Overview

500MS/s PCIe DAQ

x8 PCIe

Bra

cket

Cut

out

regi

on (

end

view

)4

GTXs

8 GTXs

DSP

TI ADC

TI ADC

BracketMtg Hole

MaximADC

Virtex-6Xilinx

XC6VLX130T-1FFG784C

+ Aavid374324B60023G(27x27x10mm)

spring-clip

anchor

Flash

FRAM

LED

StandoffMtg Hole

(on Engineand heatsink)

Engine PCB Outline

PHY

1Gb

PHY

PHY

JTAG1 J6

QSFP cageMolex 0747500021

Module

AvagoAFBR-79Q4Z

PCB Bracket

Strut

Mtg HoleStrut

CLOCK LOGIC

12V SUPPLY FILTER,

DIGITAL VOLTAGE REGULATORS

(5VD, 3.3VD, 2.5V, 1V)

ANALOGVOLTAGE

REGULATORS(6V, 5VA, 3.3VA

-5V)

SATA

J1

SATAJ2

PowerJ3

USBJ4

MBJ5

0.124

SDRAM

SMA J10

Hand-pieceJ11

RJ-45J9

(R/A)

COMJ7

7.000”

4.376”

FAN J16

AUX

J15

F/O

J8

JTAG J12J14

J13

• 2 Channel PCIe based DAQ Board

– Specifically designed to work

seamlessly with Axsun 100kHz and

future 200kHz sources

– 2 Channel 500MS/s 12-bit DAQ– 1024-2048 samples per A-scan

– Xilinx Virtex-6 FPGA gives added

signal processing capability– Image processing (FFT, Pol. Mixing,

Windowing)

– Image compression

– Multiple high speed data interfaces– PCIe x 8, Ethernet, GBE, RS232,

– In-house expertise to provide custom

algorithms

– Quick turn customization capability

will be a differentiator and speed

TTM for our customers

New Wide Bandwidth 1310nm Engine> 40% Wider Tuning BW

150nm Axsun 1310nm Source

Axsun Proprietary and Confidential Information

• 140nm 1310nm Engine– 50 or 100kHz Sweep Rate

– High Output Power (20mW Average)

– Wide (>140nm) Tuning Range

– >12 mm Coherence Length

– Enables 10um Axial Resolution and High

Signal to Noise Ratio

– Compact OEM Module design

– USB Interface

– Optional MZI Clock output

Axsun OCT Real World

Imaging Examples

Axsun SS-OCT engines used in broad range of

clinical applications

World Class Retinal Imaging

Image Courtesy of

Topcon

(Healthy Subject)

1,050 nm 840 nm

Courtesy of Topcon, healthy Subject

Comparison of 1060nm SSOCT vs 840nm

SDOCT

Scan length : 12 mm

1,050nm

High Myopia

強度近視 High Myopia Patient

脂肪組織

硝子体

強膜 脈絡膜

Scan length : 12 mm

Scan length : 12 mm

中心性漿液性脈絡網膜症（central serous

chorioretinopathy:CSC）

Enhanced Depth Imaging with Axsun SL

Engine

• SSOCT Imaging of the

entire Anterior Segment,

Kitasato University

showing dynamic

accommodation 1

• Full Anterior Segment

Imaging using fast

Optical Switching – Univ.

of Luebeck 2

1. Biomedical Optics Express Vol. 1, Issue 5, Nov. 2010

2. ARVO Meeting, May 2011

12mm

OCT Assisted Micro-Surgery

• The use of OCT as

guidance for Micro-

surgery in the eye or

elsewhere in the body

makes the procedure

faster with better

outcomes

Biomedical Optics Express, Vol. 4, Issue 7, pp. 1045-1050 (2013)

Corneal Prosthesis Imaging

• 1060nm OCT Precisely

measures the anterior

segment and can be

used to assess the

integrity of the

keratoprosthesis (KPRO)

implant

• The speed and depth

range of SSOCT minimize

motion artifacts and

provide a more complete

image than SDOCT

systems

JBO 18(8) 086002 August 2013, Zawadzki et al

Doppler Imaging with Axsun SL Engine

• Retinal Blood flow with Axsun 200kHz SSOCT demonstrated by MIT 1

• Doppler OCT blood flow measurement data from Duke University 2

– Axsun 1060nm SSOCT demonstrated a more than 60% improvement in Doppler dynamic range over SDOCT

MIT Retinal Blood Flow with 200kHz Doppler OCT

1. Biomedical Optics Express Vol. 2, Issue 6, May 2011

2. Biomedical Optics Express Vol. 2, Issue 8, August 2011

High Velocity Doppler OCT retinal blood flow

comparison of Axsun 1060nm SSOCT vs 830nm

SDOCT

Non-Ophthalmic 1310 images

J. de Boer group, "High speed miniature motorized endoscopic probe for optical frequency domain imaging," Opt. Express 20, 24132-24138 (2012);

D. Sampson group, "High-sensitivity anastigmatic imaging needle for optical coherence tomography," Opt. Letters 37, 5247-9 (2012);

Non-Ophthalmic 1310 images

J. de Boer group, "High speed miniature motorized endoscopic probe for optical frequency domain imaging," Opt. Express 20, 24132-24138 (2012);

D. Sampson group, "High-sensitivity anastigmatic imaging needle for optical coherence tomography," Opt. Letters 37, 5247-9 (2012);

Speed of SSOCT Enables Dynamic Measurement

• OCT Doppler Imaging of

Vibrating porcine Vocal

Chords – UC Irvine (1)

38

1. June 2011 / Vol. 19, No. 12 / OPTICS

EXPRESS 2010

OCT in Dermatology

Images courtesy of Michelson Diagnostics

20kHz 1310-Wideband with K-Clock

OCT in Dentistry• OCT offers dentists a

new high resolution

modality enabling

earlier detection of

decay and true

preventive dentistry

Images generated by Axsun 1310 Engine

Biometric Measurement with OCT

• OCT can be used for

Spoof Proof fingerprint

detection, displaying

the fingerprint,

detecting vascular

pattern and blood

flow, scars and

scratches and sweat

duct patterns for a fast

ultra secure image with

many unique attributes

Flexible laser platform

14 mm

SOA

Tunable FP Filter

Laser Cavity

GainOutput

Optical

Fiber

Fiber

Reflector

Lens Lens

Tailoring of tunable filter finesse, FSR and cavity length optimizes

our laser to image a range of depth, resolution, and sweep speed

Extended Coherence Length• High speed extended depth

imaging

• 1060nm SS-OCT

• 30nm tuning BW

• 30kHz Speed

• Designs up to 100mm Lc

have been demonstrated Lc = ~70mm

Enables new applications such as whole eye imaging

Current Axsun SS-OCT lasers

A-line rate (kHz)

Tunin

g B

andw

idth

(nm

)

20 2001005030

140

110

30

1310

1060 long Lc

1060

Ping-Pong

Laser Operation and Advanced

System Development

Basic Operation

Laser tuning driven by non-

linear phase shift

Fig. 7CitationAl-Hafeez Dhalla, Derek Nankivil, Joseph A. Izatt, "Complex conjugate resolved heterodyne swept source optical coherence tomography using coherence revival," Biomed. Opt. Express 3, 633-649 (2012); http://www.opticsinfobase.org/boe/abstract.cfm?uri=boe-3-3-633

Coherence Revival

Fig. 8

Laser Operation Summary

• Axsun laser is passively mode-locked

• Non-linear tuning mechanisms promote short to

long tuning (blue -> red)

• Cavity modes do not have to build up from

spontaneous emission

• Enables high-speed tuning

• Coherence revival shown both theoretically and

experimentally

Approaches for increased A-line

rate

52

• Faster filter drive

• Utilize both up and down wavelength tuning

• New fast tunable laser regime (FDML)

• Multi-spot imaging

• Time-delayed optical buffering

Time-delayed optical buffering

increases A-line rate

53

Huber et al., Optics Letters 2006

2x buffering (370 kHz) Huber et al., Optics Letters 2007

2x buffering (236 kHz)

Long fiber lengths required: ~1km

4/8/16x buffering has also been demonstrated

Booster amplifier typical

Proposed buffering alternative –

Dual source “Ping Pong” approach

54

• Two lasers are time-multiplexed into one output

• Output A-line rate is twice the rate of individual

lasers

Drive Electronics

Laser 1

Laser 2

50/50

95/5

Output 2

Imaging

k-Clock MZI

Ping-Pong Timing

Ping

Pong

Trigger

Output 200kHz 1060 SS-Engine

1060-200kHz PP Images

Finger Tip Tape Roll Kiwi Fruit

Sweat Gland 60 um Layers

Integrated design: Dual Source

“Ping-Pong” Laser

• Shared laser cavity = “1.5 cavities”

• Ping/Pong orthogonal output polarization

SOA

SOAPBC

HWPOutput

Optical

Fiber

Fiber

Reflector

Filter Lens Lens

Lens

Ping-Pong vs. Buffering

Summary

• Axsun’s Core Technology provides distinct

advantages in size, speed, imaging depth range

and reliability for our OCT Engine Products

• Axsun’s Swept Laser OCT Engine products are

leading the way in the next generation of OCT

imaging systems

• The Axsun OCT Swept Laser platform is flexible and can be configured to meet requirements for a wide range of imaging applications

Acknowledgements

Dale Flanders, PhD

Randy Murdza

Peter Whitney, PhD

Walid Atia, PhD

Mark Kuznetsov, PhD

Bart Johnson, PhD

Brian Goldberg, PhD

Chris Cook

Vaibhav Mathur

Ranko Galeb

Bill Wells

Noble Larson

Eric McKenzie

Ed Mallon

Steve Conover

Carlos Melendez

Tom Williams

Seungbum Woo

Axsun Team

Systems engineering booth B-165

Thank you!