IR (Infrared) Night VisionIR (Infrared) Night Vision

Weapon Detection

Security Monitoring

Firefighting

IR SensingIR Sensing

– Photonic – absorbed photon excites electronic transitions• Cryogenic cooled (77K) • Most sensitive IR sensor (NETD = 5mK)

– Thermal – absorbed radiation changes device temperature

• Operate at room temperature (uncooled)• Less sensitive (NETD ~ 20 mK)

Thermal IR sensors

Supporting Leg

SensorRadiation Signal

Supporting Substrate

CCD

BeamSplitter

Low PowerVisible Laser

ImagingLens

Focal Plane Array (FPA) of Bi-material Cantilever Temperature Sensors

Infrared (IR)Source

IR AntireflectionCoating

IR Absorber

VisibleReflector

FPA SideView

IR Radiation

ImagePlane

Image Process System

InfraredLens

Cantilever IR Sensor ArraysCantilever IR Sensor Arrays

Cantilever DesignCantilever Design

• Material selection – SiNx/Al

• IR optics ( SiNx )– Resonant cavity (m / 2)

• Thermal design– IR absorption area– Minimum thermal conductance

• Thermomechanical design– Long bimaterial beam– Vacuum Packaging

Bi-material Cantilever

Anchor

Thermal Isolation Leg

Si SubstrateIR absorber

Microfabrication ProcessMicrofabrication Process

• High temperature process• Metal deposition simultaneously on both

layers after release

Si substrate

LPCVD PSG

LPCVD SiNx

LPCVD Poly Si

Al

Pt

18

10121416

20

(oC)Pixel size: 110 m

Pixel Layout and Pixel Layout and Temperature ResponseTemperature Response

Thermomechanical Response ~ 2 m/K

Experiment Setup and IR Imaging ResultExperiment Setup and IR Imaging Result

CCD

He-Ne Laser

Beam Splitter

FPA

Vacuum Chamber

Temperature Control System

IR Lens

Beam Expander

Imaging Lens

IR imaging with background subtraction

Linearization CalibrationLinearization Calibration

Original image Linearly corrected

Zhao, Mao, Horowitz, Majumdar, Varesi, Norton, Kitching, J. MEMS (2001)

Summary

10 m

• Nanotube

• Thermal Imaging

• Cancer Detection

• IR Night Vision

An Example for ME381R:Micro-Nano Thermal-Fluid

Science and Technology