Hyperspectral Camera Design Project D3 Engineering definition - - PowerPoint PPT Presentation

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Hyperspectral Camera Design Project D3 Engineering definition - - PowerPoint PPT Presentation

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Hyperspectral Camera Design Project D3 Engineering definition design development Team Members Will Shaffer Electrical Engineering Sponsored by: Jeff Sidoni D3 Engineering Electrical Engineering 222 Andrews Street

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definition • design • development

D3 Engineering

Hyperspectral Camera Design Project

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definition • design • development

D3 Engineering

Team Members

  • Will Shaffer

– Electrical Engineering

  • Jeff Sidoni

– Electrical Engineering

  • Dan Scorse

– Mechanical Engineering

  • Jordan Gartenhaus

– Mechanical Engineering

  • Sponsored by:

D3 Engineering

222 Andrews Street Rochester, NY 14604

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D3 Engineering

Hyperspectral Overview

  • Imaging system capable of capturing several tens to

several hundreds of narrow, contiguous bands of the electromagnetic spectrum.

  • Covers visible spectrum, extends from NIR to long

wave IR.

  • Data sets are large, but allow for the detection of

subtle differences overlooked by traditional and multispectral systems.

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D3 Engineering

Spectral Reflectance

  • Defined as the ratio of

reflected energy to incident energy as a function of wavelength

  • Materials have a unique

spectral signature that is used for identification after a data set is acquired.

5 10 15

  • 10

10 20 30 40 50 60 70 Wavelength λ (μm) % Reflectance Asphalt Dry Grass Granite Grass Dark Soil

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Data Acquisition

  • Hyperspectral images are obtained using an imaging

spectrometer; a device used to measure various properties of light over the spectrum.

  • Typically contains an optical system, a dispersing

element, possibly in the form or a prism or grating and an array of detectors.

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Linear Array Spectrometer

  • Uses a single row of detectors. Allows for the spectrum of a given point

in a target to be acquired.

  • Scanning mirror adds a dimension to capture an entire row of the

target.

  • Second dimension is typically accomplished by the movement of a

plane or satellite.

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D3 Engineering

2D Sensor Method

  • Using a two dimensional sensor, an entire row can be captured

in a single frame.

  • Scanning mirror adds second dimension.
  • In remote sensing applications where the camera is in a plane,

data sets can be captured without the need of a scanning mirror.

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D3 Engineering

Data Organization

  • Hyperspectral data sets, by

nature, are very large

  • Usually consist of several

hundred bands of the spectrum.

  • Organized in a cube where

two of the axes are spatial and one is spectral.

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D3 Engineering

Identification of Materials

  • Unique spectral signature for materials
  • Many libraries available containing hundreds or

thousands of signatures for natural and man-made materials

  • Research and evaluation of algorithms to improve

classification and identification

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D3 Engineering

Applications

  • Remote Sensing Applications

– Military

  • Terrain Mapping
  • Target Detection

– Agricultural

  • Crop Yield Prediction
  • Soil Quality Evaluation

– Mineral Exploration – Environmental Research

  • Close Range Applications

– Medical

  • Early cancer detection

– Food Industry

  • Bacteria detection and

illness prevention

– Counterfeit Currency

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D3 Engineering

Defense Applications

  • Used for target identification in combat areas
  • Target below is a camouflaged tank, hidden to traditional and

even multispectral imaging systems.

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D3 Engineering

Project Outline

  • Purpose is to design and build a functional

hyperspectral camera system for use by D3 Engineering’s design staff.

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D3 Engineering

Project Requirements

  • Prototype a Hyperspectral Camera that

– Uses a single CMOS or CCD imager – Captures spectra from ~400 to ~850nm (Visible Light) – Has spectral resolution of 25-50nm – Develop back end software to acquire and process a hyperspectral data set and extract basic information such as material identification – Utilizes hardware already developed and tested by D3 Engineering for the image acquisition and motor control for the scanning mirror

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D3 Engineering

System Block Diagram

Processing Board Motion Board Imager Board

Image Sensor DSP

Video Data USB Communication I2C Serial Communications

Motion Control SDRAM FLASH

5VDC

M i r r

  • r

Target

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D3 Engineering

Project Timeline

ID Task Name Duration Start Finish 1 Hyperspectral Camera Design 124 days Mon 12/5/05 Thu 5/25/06 2 Requirements Generation 2 w ks Mon 12/5/05 Fri 12/16/05 3 Design Documentation 2 w ks Mon 12/19/05 Fri 12/30/05 4 Initial Prototyping w / CDK 2 w ks Mon 12/19/05 Fri 12/30/05 5 Working Camera 2 w ks Mon 1/2/06 Fri 1/13/06 6 Preliminary Design R eview 1 day Fri 2/24/06 Fri 2/24/06 7 CDK 61 days Mon 1/2/06 Mon 3/27/06 8 Camera Softw are D evelopment 9.2 w ks Mon 1/2/06 Mon 3/6/06 9 1Mpixel 1 w k Tue 3/7/06 Mon 3/13/06 10 Frequency registration 2 w ks Tue 3/14/06 Mon 3/27/06 11 Optical Subsystem 40 days Mon 2/27/06 Fri 4/21/06 12 Use Spectrograph Optics 7 w ks Mon 2/27/06 Fri 4/14/06 13 Optical Design 2 w ks Mon 2/27/06 Fri 3/10/06 14 Lightpath Diagram 2 w ks Mon 3/13/06 Fri 3/24/06 15 Simulation 2 w ks Mon 3/27/06 Fri 4/7/06 16 Testing 2 w ks Mon 4/10/06 Fri 4/21/06 17 Scanning Mirror 20 days Mon 2/27/06 Fri 3/24/06 18 Linear stepper motor 4 w ks Mon 2/27/06 Fri 3/24/06 19 Mechanical Structure 4 w ks Mon 2/27/06 Fri 3/24/06 20 Software 45 days Mon 2/27/06 Fri 4/28/06 21 Raw Data Dow nlaod 1 w k Mon 2/27/06 Fri 3/3/06 22 Conversion to Matlab 2 w ks Mon 3/6/06 Fri 3/17/06 23 Frequency Resolution 3 w ks Mon 3/20/06 Fri 4/7/06 24 Create data Cube 3 w ks Mon 4/10/06 Fri 4/28/06 25 Mechanical 50 days Mon 2/27/06 Fri 5/5/06 26 Mirror 2 w ks Mon 2/27/06 Fri 3/10/06 27 Enclosure 4 w ks Mon 3/13/06 Fri 4/7/06 28 Optical Mounts 4 w ks Mon 4/10/06 Fri 5/5/06 29 Intergration 20 days Mon 4/24/06 Fri 5/19/06 30 Testing 3 w ks Mon 4/24/06 Fri 5/12/06 31 Verify vs Requirements 1 w k Mon 5/15/06 Fri 5/19/06 32 Final Report 1 w k Fri 5/19/06 Thu 5/25/06 1/2 4 11 18 25 1 8 15 22 29 5 12 19 26 5 12 19 26 2 9 16 23 30 7 14 21 28 4 11 Dec '05 Jan '06 Feb '06 Mar '06 Apr '06 May '06 Jun '06

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D3 Engineering

Task Partitioning

  • Four main design areas

– Optics System

  • Development of custom optics system
  • Evaluation of ImSpector Optics System

– Image System / Algorithm Development

  • Interfacing image capture to MATLAB
  • Algorithms to normalize capture data and identification

– Scanning Mirror Motor Control

  • Precise movement of scanning mirror

– Mechanical Components

  • Enclosure and mounting system for optics
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D3 Engineering

Optical Design

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D3 Engineering

Background

  • As a part-time employee at ITT Space Systems

Division basic knowledge in optics is benificial

  • Took on optical design as a learning experience
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D3 Engineering

Requirements

  • Initially minimal
  • Achieve a wavelength of 400-700nm
  • Resolution 25-50nm
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D3 Engineering

Initial Research

  • Initial inquiries made at ITT about optical design
  • Dr. Conrad Wells assisted with providing relevant

books and guidance to understanding calculations

  • Dr. Wells also provided initial design paths as

possibilities

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D3 Engineering

Initial Optical Path

TARGE T

MIRROR ENCLOSUR E BAFFLE PRISM LENS (3) PLACE S

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D3 Engineering

TARGE T MIRROR ENCLOSUR E BAFFLE PRIS M LENS (3) PLACES

Alternate Path

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D3 Engineering

Relevant Work

  • Upon looking into existing companies who make hyperspectral

camera’s, Specim, a company in Finland was brought to attention by Scott Reardon

  • On the website, the dispersion element, prism-grating-prism

(PGP) was discussed

  • Searching PGP turned up Mauri Aikio’s dissertation on

hyperspectral imaging and his invention of the PGP

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D3 Engineering

Work Continued

  • Calculations for optimization of focal length while
  • ptimizing a prism size were preformed.
  • Focal length results were in the range of one meter

which was unacceptable for making a compact design.

  • Alternate dispersion elements looked at.
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D3 Engineering

lamda vs. h

  • 30
  • 20
  • 10

10 20 30 . 4 . 4 5 . 5 . 5 5 . 6 . 6 5 . 7 . 7 5 . 8 . 8 5 . 9 . 9 5 1 1 . 5 lamda (nm) h (mm) Series1

Lambda vs. Height

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D3 Engineering

Wavelength vs. Optimized Refracted Angle

  • 0.03
  • 0.02
  • 0.01

0.01 0.02 0.03 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 Lamda (nm) Theta_t2-theta_not (deg) Series1

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D3 Engineering

Detector size Vs Input angle

10 20 30 40 50 60 70 80 90 100 10 20 30 40 50 60 70 Incident Angle (deg) Focal Plane Size (mm) Series1

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D3 Engineering

detector size vs. prism angle

5 10 15 20 25 30 35 40 45 50 10 20 30 40 50 60 70 80 prism angle (deg) detector size (mm) Series1 Series2 Series3 Series4 Series5 Series6 Series7 Series8 Series9 Series10 Series11 Series12 Series13 Series14 Series15

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Work Continued

  • Research on dispersion elements and spectrographs performed
  • Result of research turned up prism-grating-prism (PGP) element
  • Correspondences with Edmund Optics (E.O.): suggested a

monochromator

  • Additional searching turned up handheld spectrograph
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D3 Engineering

Dispersion Elements

  • Two different dispersion elements considered
  • Prism
  • Blazed holographic grating
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D3 Engineering

Prism Applications

Littrow Prism

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D3 Engineering

Prism Apps. Cont.

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D3 Engineering

Prism Apps. Cont.

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Prism Test Sets

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D3 Engineering

Prism Test Sets Cont.

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D3 Engineering

Prism Test Sets Cont.

  • This test set utilizes the

Edmund Optics handheld spectrograph.

  • The light source is an Hg pencil

lamp.

  • The video camera is recording

the spectrum.

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D3 Engineering

Prism-Grating-Prism

  • Design discovered by Mauri Aikio of Finland
  • A mate of a prism, longpass filter, covering glass,

grating, substrate glass, shortpass filter, and another prism

  • Provides for a compact and straight thru design for

spectrographs

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D3 Engineering

PGP Element

Prism 1 LPF Covering glass Grating SPF Prism 2 Substrate glass

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D3 Engineering

Handheld Spectrograph

  • This unit is approximately 4” long and 7/8” in diameter.
  • It utilizes a multiple prism alignment or mate similar to the PGP

element in the ImSpector.

  • Very easy to use and test.
  • Can easily be adapted to an existing system.
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D3 Engineering

Handheld Spectrograph Prism Element Concept

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D3 Engineering

Monochromator

  • E.O. suggested a monorchromator in place of
  • rdering a holographic grating and slit separately.
  • Using the monochromator E.O. suggested allows you

to tune it to what wavelength you want to look at.

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D3 Engineering

Solution Guidelines

  • Prism calculations yielded a large focal length
  • D3 is attempting to demonstrate data acquisition
  • Calibration of optics must be done by optical

technician

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D3 Engineering

Optical Design Solution

  • The Handheld spectroscope, monocromator, or

ImSpector camera all stood out to be the best optical solutions to meet requirements

  • An optical system will be created in parallel by D.

Scorse utilizing a Littrow prism as the dispersion element.

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D3 Engineering

Imaging System

  • Embedded System comprised of an imager and a

DSP to capture and process frames

  • Initial design will use USB to send acquired data to

MATLAB for processing

– Ease development of algorithms for normalization and classification – Eventually move final processing inside the DSP

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D3 Engineering

Imaging Hardware

  • Several tradeoffs while choosing hardware for this

application

– CMOS vs. CCD

  • Pre-existing interface hardware to CMOS sensor
  • CCD has complex circuitry, but better dynamic range and bit

depth

  • Preliminary design will use CMOS, future revisions may

implement a CCD sensor

– Texas Instruments DSP

  • C6416 vs. DM642
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D3 Engineering

Image Acquisition

Processing Board Imager Board

1.3 MegaPixel 10 Bit CMOS Imager DSP C6416

Video Data USB I2C Serial Communications

SDRAM FLASH

5VDC

Imager0 Optics

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D3 Engineering

Image Classification

  • Initial development of algorithms done using

MATLAB

  • Several associated issues

– Camera calibration – Reflectance conversion – Image normalization – Spectral Mixing Correction – Material Classification against reference libraries

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D3 Engineering

Scanning Mirror Control

Stages of Development:

  • Generate PWM signals to rotate and stop mirror at 1° increments as a

baseline for data acquisition

  • Increase resolution to achieve a smooth steady rotation while varying

angular velocity to accommodate imager

  • Implement close-loop Kruse control to maximize resolution and provide

rotor position feedback

  • Incorporate additional interrupts to handle serial communications and

external velocity control

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D3 Engineering

Driver Schematic for Stepper Motor Phase A

100 10k 100 10k 10k 100 10k 100 47k 47k 1k 1k .033 .033 IRFZ44E IRFZ44E IRFZ44E IRFZ44E 1uF IN 2 SHDN 3 LO 5 HO 7 COM 4 VB 8 VCC 1 VS 6 IR2104 PWM_A1+ 820nF ZMM5251B 100 uF 1uF

Vdd Vdd

3 1 2

  • +

MtrDA1- MtrDA1+ 820nF

Vmm

IN 2 SHDN 3 LO 5 HO 7 COM 4 VB 8 VCC 1 VS 6 IR2104

V3_3/2 ViA1

Motor Current Sense Half - Bridge Driver Half - Bridge Driver

PWM_A1-

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D3 Engineering

PWM Generation

  • The top waveform is generated by selecting a base PWM carrier

frequency

  • The bottom waveform is the modulated signal produced through

comparison with the percentage values stored in a table

  • Thus, the angular velocity of the rotor can be controlled by slowing

down the transition through the look-up table

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PWM Generation

  • Motor windings are modeled as a series LC circuit; and thus a low-pass filter
  • Each PWM signal drives one half-bridge driver – need four signals per motor
  • Other signals are generated identically except for either inversion or 90° phase shift

Effective Driver Signal

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D3 Engineering

Mechanics

  • Mirror is required to rotate +/- 20° relative to the center of the target image
  • The distance between the mirror and the target is remains variable to allow

for optimized data acquisition

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D3 Engineering

Slit Width Analysis

tan(20 ) y d = ⋅ °

Target Width 2y =

1

tan( ) y d Δ = ⋅ ΔΘ

2 1

tan(2 ) y d y Δ = ⋅ ΔΘ − Δ

3 2 1

tan(3 ) y d y y Δ = ⋅ ΔΘ − Δ − Δ

( )

1 1

tan( ) 1

i i j j

y d i y i

− =

Δ = ⋅ ΔΘ − Δ ∀ >

∑

( )

( )

1 2 2 1 1 1

tan( ) tan( ) tan ( 1)

i i i i j j j j j j

y d i y d i d i y y

− − − = = =

⎛ ⎞ Δ = ⋅ ΔΘ − Δ = ⋅ ΔΘ − − ΔΘ − Δ − Δ ⎜ ⎟ ⎝ ⎠

∑ ∑ ∑

( ) ( )

tan tan ( 1)

i

y d i d i Δ = ⋅ ΔΘ − ⋅ − ΔΘ

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d [m] y [m] μStep Size Δθ # Slits/ Half Image

  • Avg. Δy

[mm] Min Δy [mm] Max Δy [mm] 0.0625 0.225 88 4.136 3.927 4.430 0.03125 0.1125 177 2.056 1.963 2.220 0.015625 0.05625 355 1.025 0.982 1.111 0.0078125 0.028125 711 0.512 0.491 0.556 0.00390625 0.0140625 1422 0.256 0.245 0.278 0.0625 0.225 88 8.272 7.854 8.860 0.03125 0.1125 177 4.113 3.927 4.439 0.015625 0.05625 355 2.051 1.963 2.222 0.0078125 0.028125 711 1.024 0.982 1.112 0.00390625 0.0140625 1422 0.512 0.491 0.556 0.0625 0.225 88 12.408 11.781 13.289 0.03125 0.1125 177 6.169 5.890 6.659 0.015625 0.05625 355 3.076 2.945 3.333 0.0078125 0.028125 711 1.536 1.473 1.667 0.00390625 0.0140625 1422 0.768 0.736 0.834 0.0625 0.225 88 16.544 15.708 17.719 0.03125 0.1125 177 8.225 7.854 8.878 0.015625 0.05625 355 4.101 3.927 4.444 0.0078125 0.028125 711 2.048 1.963 2.223 0.00390625 0.0140625 1422 1.024 0.982 1.112 0.0625 0.225 88 20.680 19.635 22.149 0.03125 0.1125 177 10.282 9.817 11.098 0.015625 0.05625 355 5.126 4.909 5.555 0.0078125 0.028125 711 2.560 2.454 2.779 0.00390625 0.0140625 1422 1.280 1.227 1.390 1.092 5 1.820 4 1.456 3 3.6 ° per Full Step: 0.364 1 2 0.728

Comparison of Open-Loop Control Variables

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Close-Loop Kruse Control

  • Technique for accurately calculating the rotor angle in real-time and

without the use of an encoder

  • Achieved by feeding back emf from sense windings and integrating to

produce voltage signals proportional to the rotor’s displacement angle

  • Allows for 40,000-60,000 micro-steps per revolution
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d [m] y [m] μSteps / Full Rev. Δθ # Slits/ Half Image

  • Avg. Δy [mm] Min Δy [mm]

Max Δy [mm] 40000 0.00900 2222 0.163802986 0.1570796 0.1778740 45000 0.00800 2500 0.145588094 0.1396263 0.1581152 50000 0.00720 2777 0.131065983 0.1256637 0.1422943 55000 0.00655 3055 0.119139193 0.1142397 0.1293622 60000 0.00600 3333 0.109201990 0.1047198 0.1185849 40000 0.00900 2222 0.327605971 0.3141593 0.3557479 45000 0.00800 2500 0.291176187 0.2792527 0.3162304 50000 0.00720 2777 0.262131966 0.2513274 0.2845886 55000 0.00655 3055 0.238278386 0.2284795 0.2587244 60000 0.00600 3333 0.218403981 0.2094395 0.2371698 40000 0.00900 2222 0.491408957 0.4712389 0.5336219 45000 0.00800 2500 0.436764281 0.4188790 0.4743456 50000 0.00720 2777 0.393197948 0.3769911 0.4268829 55000 0.00655 3055 0.357417579 0.3427192 0.3880866 60000 0.00600 3333 0.327605971 0.3141593 0.3557547 40000 0.00900 2222 0.655211943 0.6283185 0.7114959 45000 0.00800 2500 0.582352375 0.5585054 0.6324608 50000 0.00720 2777 0.524263931 0.5026548 0.5691772 55000 0.00655 3055 0.476556772 0.4569589 0.5174488 60000 0.00600 3333 0.436807962 0.4188790 0.4743396 40000 0.00900 2222 0.819014929 0.7853982 0.8893698 45000 0.00800 2500 0.727940469 0.6981317 0.7905761 50000 0.00720 2777 0.655329914 0.6283185 0.7114715 55000 0.00655 3055 0.595695964 0.5711987 0.6468111 60000 0.00600 3333 0.546009952 0.5235988 0.5929245 Kruse Control 1 0.364 2 0.728 5 1.820 3 1.092 4 1.456

Slit Width Analysis for Kruse Controlled System

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Mechanical Components

Main components:

– Project enclosure – Scanning mirror fixture – Optical mounts

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ImSpector Imager Mount

  • Threaded for standard C-mount fixture
  • Tapped for mounting of an imager adapter plate
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Hyperspectral Enclosure

  • Optical breadboard based
  • Light-weight lift-off aluminum box top
  • Draw latches for easy open/close
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D3 Engineering

Scanning Mirror Fixture

  • Machined mounting plate
  • Attached to stepper motor shaft
  • Adjustability of mirror height and angle
  • Set screw allows for easy manipulation
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D3 Engineering

Lenses

  • Commercially available mounting hardware
  • Modified to suit requirements