Transcript Document

Centre for Medical Science
&Technology
Optical Developments in Medical Engineering
Prof. P.J. Bryanston-Cross
Presentation of research interests
Belfast 2001
4:30pm, Friday 14th September
A series of Optical & Medical Engineering
innovations have been developed through the
interaction between Engineering, Computer and
Medical Sciences.
In particular there are areas of exchange between
medical
instrumentation and aerospace science,
.
which promise to create new types of intelligent
optical diagnostic technology.
Synthetic Intelligence
Synthetic intelligence is gaining use in optical diagnostics.
• low cost processing power
• allowing for highly sophisticated signal processing software
• hardware programmed into embedded systems
Example: solving highly complex image connectivity problems.
Application of Fuzzy Logic
in Fluid Dynamics
Raw PIV particle Image
Processed Velocity Map of the Flow
Holographic Interferometry
The movement in the face has been
contoured using holographic
interferometry.
The fringe spacing represents a
movement of 30 m and was created
by two pulses from a ruby laser.
Opera Singer
Miniature Instrumentation
Optical system:
Developed for delivering a high power ‘Q’ switched laser beam into a
gas turbine engine at MIT to visualise airflows.
The probe exit beam diameter was 4 mm delivering a 200 mJ laser pulse
in 10 ns.
Similar construction has been developed for application to surgery.
Medical Applications
•Fundus Camera Technology
•Tonometer
•Diabetes probe
•Vitrectomy
Fundus Camera
The resolution must be a minimum
of 10 line pairs/mm.
The colour contrast must be
calibrated.
The colour balance must be
compared to a stored standard.
The pixel integrity/optical
cleanliness of the system must be
checked, on both the camera and
the monitors used.
The camera test should be carried
out under the same conditions
weekly.
A flat resolution test chart can
be used to evaluate the camera
Active Non-Contacting
Diabetes Probe
• 1 Year of research and the subject of a DTI Smart
Award.
• Design and implementation of a low cost, on-line, noncontact, spectral testing device to be used as a Diabetes
Probe.
Diagnostic sensors for testing for diabetes
Colour intensity plot: spectral
variation through the lens
Laboratory demonstration system
Normal eye illuminated with blue light
fluorescent green glow: glucose retention
Optical Tonometer
•
•
Active Non-Contacting Glaucoma Probe (AGP)
3 years of research, laboratory prototype tested on human
subjects
•
Design and implementation of an active Non-Contacting
Glaucoma Probe which has the potential to be used as a low cost,
on-line testing device.
The objective is to provide a low cost probe which could be used
by mobile medics, small practices and surgeons in the third
world, eliminating in some cases the need for contact methods of
testing methods
•
Non-invasive, non-contact, intelligent
tonometer for the detection of glaucoma
Warwick has recently been exploring the early detection of glaucoma. In this
case the objective is to measure the intra-ocular pressure. This can be
achieved using acoustic resonance.
The measured curve with digital filter
340
Experiment data
Fitted curve y=1.08x+293.50
Standard deviation of the residuals is 1.99
335
Resonance frequency in Hz
330
325
320
315
310
305
300
295
290
0
5
10
15
20
25
30
Intraocular pressure in mmHg
35
40
45
Laser Eye Surgery Instrumentation
Test and prototyping a series of probes for application to ophthalmic surgery.
Criteria: external diameter < 0.8mm
debris suction
preferably disposable
optical fibre illumination
cutting capability
Further research: spectral analysis and proximity detection while retaining a
disposable fibre optic construction.
New Laser Cutting Tools for Vitrectomy
Suitability of IR (Infra Red) laser wavelengths has been investigated.
FTIR spectral plot shows 6.1 and 6.45 m to be particularly suited to soft tissue
ablation.
FELIX Free Electron Laser facility in the Netherlands is being used to characterise
the thermal, mechanical and molecular dynamics of the ablation process in swine
vitreous.
A high resolution low cost
Loupe system
•
•
•
•
•
1 year Smart Award, 2 years research as part of an EU grant.
The loupe is for use in the third world as a low cost operating
stereoscopic system.
It uses low cost plastic aspheric lenses. The lens system has been
designed with a magnification of 3 at an object distance of 300 mm.
Its optical resolution is 20 lines/mm
It has been designed to be viewed by the eye, which requires the exit
pupil of the lens to be focused at infinity.
The operation of the lens is to minimise spherical and chromatic
aberrations. This is achieved by a complex surface curvature and a
specially designed spectral spatial filter.
Surgical Loupe
Cumulative Effect of Technological Advances
If the innovations discussed are applied, then:
Cameras provide a visual history and library for surgeons and a map for operations
where vision is restricted.
Intelligent cameras will assist in aiding the pre-diagnostics.
Images of the eye placed into a 3-D drawing model would allow the surgeon to
evaluate the complexity of the operation.
Self-illuminating probes make surgery simpler and easier; they also free the surgeon,
in that he no longer needs to control the position of the light source.
Active probes make training in surgery safer and can provide direct feedback, e.g.
power delivery during laser ablation.
Disposable surgical instrumentation and non-contact diagnostics considerably lower
risk of infection.
Intelligent non-contacting low cost intelligent diagnostics make the early detection of
potentially sight threatening diseases possible.
The probes are still at an early research stage; but with the
falling costs of computer technology and innovations in
optical design and laser technology, the prospect of lower
cost, synthetically intelligent, accurate optical diagnostics
are starting to emerge.
Industrial Applications
Tomographic array
Spectral probe
Small Engine
Tomographic measurement of
heat release
•
Part of a 3 year Faraday Intersect project with Rolls-Royce, CORUS
and DERA as the industrial partners.
•
The Aim here is to find a SME partner interested to develop the
approach as a testing instrument for Rolls Royce.
•
The probe is constructed from a ring of fibre optics which record the
light emitted from the within the combustor. A tomographic
reconstruction is used to capture the emitted light and a 40 fibre optics
placed in a ring around the combustor. The objective of the work is to
measure the heat release from the combustor to a spatial resolution of
10mm and a temporal resolution of 600Hz.
Tomographic array:
Modified Burner
Thermocouple
Result
Array Result
Colour Intensity photograph
Fibres
Tomographic array
Spectral Measurements in
a Gas Turbine Engine
•
A spectrometer on a chip has been fibre optic linked to a diagnostic
probe. The probe has been used in the fuel injector within the
combustion chamber of a gas turbine engine. Tests have been made at
RAe Farnborough to show how a engine can be run at a minimal
running condition with switching off the engine.
•
This work is part of the INTErSECT faraday Centre project: The
Application of Data Fusion to a Multi Sensored Intelligent Engine.
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•
Its industrial partners are: Rolls-Royce, CORUS and DERA.
The project represents 2 years of research work in the area.
Spectroscopic Measurements on a DERA Reverse Flow
Combustor
Spectroscopic Measurements on a
DERA Reverse Flow Combustor
Fuel Injector
INLET
Fibreoptic
Primary Holes
Combustor Wall
OUTLET
Optical Access Through Injector
Spectroscopic Measurements on a
DERA Reverse Flow Combustor
Three-way
Beam Splitter
Combustor Rig
25m UV Fibre Optic
25m VIS-IR Fibre Optic
Twin Channel
Spectrometer
Spectroscopic Measurements on a
DERA Reverse Flow Combustor
UV Fibre Idle Condition
250
Intensity
200
430nm
CH
470nm
CHO
150
590nm
H2O
394nm
S2
100
50
0
200
308nm
OH
516nm
C2
300
400
500
Wavelength (nm)
600
559nm
C2
700
800
The Small Engine project
•
The operating pressure and temperature of a I.C. engine is very similar
to those of a gas turbine engine. As a result of this a small low cost test
bed engine has been develop on which a series of novel instruments
are in the process of development. In particular the engine is optically
instrumented and has heat transfer gauges mounted on its head and
piston. It is possible to also investigate the fundamental aspects of,
for example direct injection.
•
This work is part of the INTErSECT faraday Centre project: The
Application of Data Fusion to a Multi Sensored Intelligent Engine.
•
It represents 2 years of research.
Heat Transfer
• Thin film,
constant current,
Platinum resistance,
thermometers.
• 90 kHz response
• Measure Heat Flux (Not
capacity)
Heat Transfer - Results
• Fired
(note noise)
• Wall temp
increases
• Interpretation
Firing Probe
Electrode
Fibreoptic
Coupling
GRIN lens
Plano-concave
lens
Spark
tip
Quartz Protection
Window
• Spectroscopy
• Conveys light to
Spectrometer
• 3mm lenses
• Overall optics diameter
4mm
Spectral Results
Emission Spectra. TDC.
Emission Spectra. 15 ATDC.
Inten
sity
(coun
ts)
Intensity
(counts)
Wavelength
(nm)
Wavelength
(nm)