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					 OPTOELECTRONICS AND MEASUREMENTS GROUP (OPME)
    Professor Risto Myllylä and Professor Markku Moilanen, Optoelectronics and Measurement
Techniques Laboratory, Department of Electrical and Information Engineering, University of Oulu
Dr. Jouni Tornberg, Professor Harri Kopola and Professor Aarne Mämmelä, VTT Electronics, Oulu
    Juha Kalliokoski, Research Director of the Measurement and Sensor Laboratory (Kajaani),
                                           University of Oulu
            risto.myllyla@ee.oulu.fi,markku.moilanen@ee.oulu.fi, jouni.tornberg@vtt.fi,
                 harri.kopola@vtt.fi, aarne.mammela@vtt.fi, juha.kalliokoski@oulu.fi
                                   http://www.infotech.oulu.fi/opme


Background and Mission                                      the group also focuses its efforts on arranging lecture
                                                            series and graduate school courses for graduate stu-
The Optoelectronics and Measurements Group
                                                            dents. During 2005, the group organized the traditional
(OPME) comprises an intensive collaboration network
                                                            Infotech Oulu Workshop on Optoelectronic Devices
of researchers at the Optoelectronics and Measure-
                                                            and Instrumentation for the fifth time, concentrating
ment Techniques Laboratory at the University of Oulu,
                                                            this time on ‘MEMS, NEMS and Optical Micro-
the Measurement and Sensor Laboratory (MILA) in
                                                            systems’. The group also organized the IEEE/LEOS
Kajaani and VTT Electronics. OPME employs 38
                                                            International Conference on Optical MEMS and Their
postgraduate students and 38 other persons in the re-
                                                            Applications, and the 2nd Finnish-Russian Meeting:
search work. The main research activities are in the
                                                            Photonics and Laser Symposium. In addition, three
fields of optoelectronic measuring and electronics test-
                                                            international lectures and courses were held in the
ing techniques and communication systems, with par-
                                                            group, ‘the development of wireless sensor network
ticular emphasis on the practical applications of these
                                                            platform in Korea and some basic research results on
techniques. The group work includes pursuing new
                                                            ubiquitous health care’, ‘Mechanical properties of
methodologies in sensing and measurement, develop-
                                                            great arteries of cardiovascular system: a) theoretical
ing new devices and instruments for basic research
                                                            investigation, b) clinical applications’ and ‘Laser mea-
purpose, and helping companies and enterprises to
                                                            surements’.
improve their designing and process controlling.
                                                            It is worth noting that optical and electrical compo-
In these undertaking, the group focuses on measuring
                                                            nents used in low end products like disposable sen-
and modeling the propagation of light in turbulent and
                                                            sors, product packages, flexible displays etc. will be
scattering media such as the atmosphere, human tis-
                                                            based more and more on organic materials in the near
sues, pulp and paper. Interesting basic properties of
                                                            future. These so called ‘polytronics’ can be manufac-
light are, for example, scattering, absorption, reflec-
                                                            tured using roll-to-roll and printable techniques like
tion, refraction, diffraction and polarization when light
                                                            gravure, offset, screen and inkjet printing, which re-
propagates through non-homogenous media. The tech-
                                                            duces remarkably the manufacturing period and costs.
niques developed for measuring these optical proper-
                                                            Integration of traditional optoelectronic measurement
ties are absorption spectroscopy, diffuse-reflection
                                                            techniques to polymer platforms is a great challenge,
spectroscopy, Raman spectroscopy, photon time-of-
                                                            but it opens up a lot of new solutions in different bio-
flight, a scattering photoacoustic approach, and high
                                                            medical and industrial measurement applications. One
and low coherent interferometry. Optical and micro-
                                                            example of this may be different biosensor applica-
sensors including MEMS technology, and camera and
                                                            tions where a biomolecular recognition process could
machine vision in optical measurement are the focuses
                                                            be performed using polymer waveguides. The sub-
of the group research. Looking for new materials, tech-
                                                            group of VTT Electronics has engaged in this work
nologies, integration of the systems and customized
                                                            and the achievement thus far is encouraging.
micro-optical devices, optoelectronic devices and
novel packaging technologies are still activities in the
OPME group. All this work and achievements are
                                                            Scientific Progress
being applied in biomedicine, and in the pharmaceu-         The following research examples illustrate the scien-
tical, paper, pulp and mechanical wood industries, as       tific progress of the OPME group. These research
well as in wireless communication and instrumenta-          projects have been carried out in active collaboration
tion.                                                       with both domestic and international research institu-
As a participant in the Infotech Oulu graduate school,      tions and industrial partners.


                                                                                     INFOTECH OULU Annual Report 2005   51
Miniature Michelson Interferometer Based on                 Biosensor Based on Young Interferometer
an LTCC Platform                                            Principle
A miniature Michelson interferometer based on a low         Conventional biochemical analyses are carried out in
thermal co-fired ceramics (LTCC) platform was dem-          chemical laboratories with relatively large and expen-
onstrated. The interferometer was implemented on a          sive equipment; they are also time consuming. The
25 mm × 25 mm ceramic optical table, which a thick-         objective of this project was to develop a miniatur-
ness of 0.5 mm. The interferometer can be used in           ized biosensor, which is cheap to produce and quick
high-precision displacement measurements. An imag-          to use. The sensor should also have sufficient sensi-
ing lens was used to image a laser diode facet on the       tivity. Because interferometric methods can be ex-
surface of a measurement mirror and a reference mir-        tremely sensitive and such sensors are very well suited
ror. Controlled displacement of the measurement mir-        to compact sizes, a Young interferometer structure was
ror was achieved by attaching the measurement mir-          chosen for the sensor.
ror on top of a piezo actuator. Driving the laser diode
                                                            The integrated Young interferometer sensor is based
in a LED mode, the optical path difference (OPD)
                                                            on confining light in a waveguide structure. This
between optical arms was adjusted to zero by moving
                                                            waveguide structure guides the light inside the sensor
the second mirror along the optical axis and simulta-
                                                            and divides the light to go through a sample area and
neously monitoring the interference pattern. The mir-
                                                            a reference area. Although light is confined inside the
ror was then attached to an LTCC substrate with ep-
                                                            waveguide layer, a small part of it, called an evanes-
oxy. The OPD after the reference mirror attachment
                                                            cent wave, reaches through the physical boundary of
was smaller than 200 nm.
                                                            the waveguide into the sample/reference area. This
                                                            interaction between the light and the sample causes a
                                                            phase change in the propagating light, because the re-
                                                            fractive index of the sample area differs from the re-
                                                            fractive index of the reference area. When the light
                                                            leaves the sensor, it is superimposed on an observa-
                                                            tion screen or a detector, where it creates an interfer-
                                                            ence pattern. The shift of this interference pattern is
                                                            directly proportional to the change in the phase of the
                                                            light, and thus we can observe changes happening in
                                                            the sample area. For example, an antibody-antigen
                                                            binding event on the sample area can be detected from
                                                            the interferogram shift.
                                                            The waveguide chip in this project was fabricated from
                                                            siloxane material, which can be processed by UV-li-
                                                            thography to have a channel like waveguide structure.
                                                            The sensitivity of the integrated Young interferom-
Miniature interferometer schematic and Implemented inter-   eter was studied and found to be in the order of 10-6
ferometer.                                                  refractive index unit.
A 128-element CMOS detector, pixel size 62.5 µm ×
200 µm, was used to detect interferogram modulation
due to measurement mirror displacement. Measured
analog pixel values were digitized by 16-bit and the
corresponding displacement was calculated using a
laptop. The displacement of the mirror as a function
of piezo driving voltage was characterized using an         Principle of the Young interferometer sensor and waveguide
                                                            structure.
atomic force microscope (AFM). When using a 100
Hz sinusoidal piezo driving signal introducing a 1 nm       Electronics Testing Techniques
peak-to-peak mirror movement and using 1 s integra-
                                                            Miniaturization and new manufacturing technologies
tion time, a displacement resolution of 20 pm was
                                                            will make testing of electronic products difficult in
achieved. Theoretical investigations based on the cal-
                                                            the future. Access to certain locations in the device
culated SNR achieved by FFT measurements suggest
                                                            will be impossible with traditional measurement tech-
that displacement resolution below 5 pm should be
                                                            niques, or the access will require new, possibly ex-
possible to attain via increasing integration time to
                                                            pensive, and time consuming methods.
100 s.


52   INFOTECH OULU Annual Report 2005
One way to address these concerns is to incorporate         which will be used for manual steering of the robot
measurement capabilities into the product itself. In        head. With the help of personnel at the Mechatronics
this, so-called embedded testing, new test-specific cir-    and Machine Diagnostics Laboratory of the Depart-
cuit structures and existing parts of the product are       ment of Machine Engineering, the handle design was
used together to perform parameter, functional, inter-      modeled, but then it proved to be too complex to solve
connect and component self-tests on different parts         by using only Bragg gratings: the solution was then
of the product.                                             focused on 1-dimensional needle force sensor (Bragg-
                                                            grating) and an optical joystick. Commercial MRI-
Basic concepts for such embedded testing have been
                                                            compatible angle encoders were charted. Development
developed in the research group. Principles of com-
                                                            of our own solution based on a high precision fiber
ponent and interconnect testing via analogue bound-
                                                            optical displacement sensor with an eccentric cam-
ary scan test architecture have been developed, the
                                                            shaft (spiral) was started. The availability of a small
frequency range of the test bus has been extended to
                                                            sized, MRI-compatible video camera was charted. One
RF with the use of simple integrated radio-frequency
                                                            of them was ordered for further evaluation. Prelimi-
detectors, and the basic phenomena related to the
                                                            nary tests within an MR-imaging room were carried
breaking-up of solder joints of ball grid arrays have
                                                            out.
been studied.
Embedded testing forms one of the cornerstones on
which the concurrently developed ideas on tests serv-
ing the entire life-cycle of products from development
to field repair are laid upon. Since in this kind of sce-
nario, test instruments and measurement equipment
are embedded as part of the product, a method to re-
motely initiate and control the tests, and to access the
measurement results is needed. Groundwork leading           Measurement setup and sensitivity curves of the fiber optic
towards standardized ways of performing such remote         displacement sensor.
testing and data telemetry is being done by the on-
going effort in the Wireless Test Standard (WTS)
workgroups. This work will provide the network pro-
tocols and infrastructure for communication between
the embedded test enabling circuitry, the software in-
side the device under test, and the remote user.

Optical Measurements for Steering a Surgi-
cal, Interactive Robot in an MRI-Environment
A surgical robot will take biopsy samples of soft tis-
sue or bone, and works on the basis of MRI-image
and ordinary camera information. The purpose is to
design miniaturized optical angle and position sen-
sors for measuring the robot’s arm position accurately
inside arm joints. Also, a three dimensional force sen-
sor for a robot head to sense biopsy needle forces is       Electronics for measuring displacement differentially. One
one of the main research topics. In addition, aim is to     fiber is transmitting light and two fibers are collecting re-
                                                            flected light. The difference of the amplitude is amplified.
transmit measurement data out to the controller unit
optically by using fibre optical link or using UWB
(Ultra Wide Band)-technology. The whole robot sys-          Scattering Photoacoustic Measurement in
tem will be tested in the EMC-laboratory to ensure          Turbid Suspensions
electromagnetic compatibility.                              The scattering photoacoustic (SPA) method is based
Theories and different measurement setup possibili-         on the photoacoustic (PA) effect produced in the stud-
ties for developing fiber optic 3D-sensors were pre-        ied medium and external absorbers. A light beam is
sented. One of them, based on the strain of the Bragg       used to illuminate a scattering medium and then a part
gratings, was used to make a demonstration. In addi-        of the optical energy is absorbed at an incident point
tion, the mechanical structure (POM-material) for           to generate a PA source. When the scattering sample
sense needle forces was machined. At that point, re-        is weakly absorbed, another part of light energy is scat-
search was refocused to sense forces in the handle,         tered outside the illuminated region.


                                                                                        INFOTECH OULU Annual Report 2005   53
The SPA method uses absorbers with a high absorp-          Paper Research Using Optical Coherence
tion coefficient at the irradiation wavelength, located    Tomography
outside of the sample, to accept the scattering light.     The growth of the paper making industry has triggered
Therefore, other PA sources are produced at the re-        a continuous search for improved methods for diag-
ception surfaces of the absorbers, whose intensities       nosing and characterizing paper properties. By and
are strongly dependent upon the scattering property        large, testing tends to be focused on the goal of ensur-
of the sample with low absorption. All PA sources emit     ing that the paper produced meets end-user specifica-
acoustic waves and can be detected by an ultrasonic        tions at the lowest possible cost. On the macroscopic
transducer which acoustically contacts with an ab-         level, paper can be characterized by numerous param-
sorber. Analyzing these wave amplitudes may sense          eters, including, for example, density, bulk, porosity,
the sample change or its optical properties. Moreover,     thickness, roughness and gloss. All these parameters
SPA detection can also be used to simultaneously study     have an effect on paper quality, and can be used to
acoustic properties, such as acoustic speed and attenu-    classify different types of paper as suitable for par-
ation, on the basis of acoustic waves propagating          ticular purposes.
through the sample. In this case, two absorbers, lo-
cated symmetrically at the same distance from the in-      Surface analysis, including roughness, porosity and
cident light beam, will generate two photoacoustic         gloss estimation, is particularly important in printing
sources with an equal intensity. The ratio of both sig-    papers, because parameters like roughness and sur-
nal amplitudes received is proportional to the acous-      face porosity affect such optical properties of paper
tic attenuation of the sample, because one wave goes       as gloss and ink absorption. There are several ap-
directly through the sample, while the other one does      proaches for non-contact surface analysis of paper,
not, before being received by the ultrasonic transducer.   but the need to see through a paper surface calls for
                                                           more sophisticated methods. Current measurement
Apparently, an advantage of SPA is that it can study       methods for structural analysis of paper tend to be
optical and acoustic properties of scattering materials    either slow, labor-intensive, expensive or invasive.
simultaneously, merely by applying an ultrasonic trans-
ducer to fulfil optical and acoustic measurements. The     The latest Optical Coherence Tomography - OCT de-
apparatus is convenient for practical application and      vices are fast and have a resolution which competes
has high ratio between function and price. Currently,      with conventional laboratory structural analysis meth-
we are using it in measuring optical parameters of         ods of paper. The advantage is the non-contact and
intralipid suspension, in determining fibre and fine       non-invasive approach. A resolution of 1 - 2 µm can
consistencies in paper pulp, in monitoring the lipid       be reached by the new Nd:YAG pumped Ti:Sapphire
content in milk, and in sensing the glucose effect on      source based OCT-system shown in the figure below.
the scattering properties of milk, intralipid and poly-    Such a high resolution enables the imaging of single
styrene micro-sphere suspensions. The results show         fibers, coating paste and color layers.
that currently the SPA approach is effective in near
infrared wavelengths for aqueous suspensions where
reduced scattering coefficients are in the range of 0.2
mm-1 to 3 mm-1.




                                                                         TISSA-50 Ti:Sapphire laser.
                                                           In OCT-imaging of paper, there is a need for knowl-
                                                           edge of many areas such as paper physics, photon
                                                           migration in paper, paper chemistry, signal process-
                                                           ing and automation control of the imaging device,
                                                           which means that the collaboration between several
                                                           scientists and research groups has to be active. In ad-
                                                           dition to the imaging of paper, the technique has been
                                                           applied to fluid mechanics evaluation by using the
                                                           ability of the method to determine the velocity pro-
                                                           files of flowing suspensions like pulp and coating paste
Scheme of an SPA measurement and a typical signal re-      suspensions.
ceived by an acoustic detector.



54   INFOTECH OULU Annual Report 2005
Pulp and Paper Research
Research on a new imaging technology utilizing
diodelaserstroboscopy, the DILA-project was a joint
effort with Tampere University of Technology’s Op-
tics laboratory. During the project, this technology was                           On the left is the 3D-model of a
tested in four case studies with industrial partners.                              log and on the right a cross sec-
                                                                                   tion from the same log. A is a
Diodelaserstroboscopy is an efficient technology for                               photograph of the cross section,
imaging very fast phenomena. In the case studies, the                              B represents a calculated density
light pulses used were between 0.1 - 10 ms. The cases                              estimate, C shows the moisture
were                                                                               distribution measured with near-
                                                                                   infrared spectroscopy, D the mi-
• Measuring the speed profile of fibers in a high speed                            crowave absorption and E the mi-
   steam flow                                                                      crowave reflectance map of the
• Measuring the speeds and sizes of air bubbles in an                              cross section.
   AOD converter
                                                           Wireless Instrumentation
• Visualization of the collapse of cavitation bubbles
   in an ultrasonic washer                                 In the System-on-Chip project, our Wireless instru-
• Visualization of wood fibers in a wood fiber-air flow    mentation team has applied the latest SoC-technolo-
                                                           gies in different environments in research and industry.
The technique proved to be very effective in all of
                                                           SoC, System-on-Chip, is a circuit where a large em-
these case studies.
                                                           bedded system has been integrated into one single chip.
                                                           The increased capacity of FPGA’s has made it pos-
                                                           sible to use them as SoC’s. This technology enables
                                                           us to develop more complicated measurement solu-
                                                           tions, where calculations can be effectively executed
                                                           with SoC’s.

                                                           Sports Technology Measurements
                                                           The Meibi project aims to apply the SPR method for
                                                           bio-measurements of human physiology. In this project
                                                           we focus on developing the required optical solutions
                                                           for a measurement device that is being developed to-
                                                           gether with the Laboratory of Biotechnology in
                                                           Sotkamo. The goal is to develop a prototype of a fully
                                                           operational SPR device for laboratory conditions. The
                                                           developed measurement method is non-invasive, and
                                                           it will be used to measure different factors of human
                                                           physiology using sweat and saliva as the source of
                                                           information. The long term vision is to develop a por-
       The light source used in the DILA project.          table, multi channel on-line measurement device that
                                                           can be applied in health care as well as in environ-
Mechanical Wood Research                                   mental measurements.
During 2005, the research on wood properties took
some notable steps forward. Data-analysis techniques       Exploitation of the Results
were studied in the METRI project, and in August a         Active interaction with industry ensures the rapid ap-
large development project called PLOMMI was                plication of research results. The work of the group
started. PLOMMI utilizes the results from earlier          paves the way for the introduction of a new genera-
projects and aims to further develop our competence        tion of optoelectronic sensors and instruments based
in non-destructive testing and measurements of wood        on micro-optics, micromechanics and microelectron-
and microwave measurement techniques. The                  ics, and polymer-based manufacturing technology.
PLOMMI project aims to detect accurately the knots
and decayed parts in trunks, utilizing microwaves and      The research results of the group have been presented
infrared spectroscopy. During the project, a prototype     at scientific conferences and published in professional
of a measurement device will be built for measuring        journals. In projects funded by TEKES, the acquired
knots and decay from spruce and pine in the longitu-       knowledge has been directly transferred to the par-
dinal direction.                                           ticipating enterprises. Also commissioned research has


                                                                                    INFOTECH OULU Annual Report 2005   55
been directly reported to the enterprises concerned,        As a participant of the Infotech Oulu graduate school,
and several senior and junior researchers have taken        the group will continue effective education of gradu-
up employment with them.                                    ate students. The aim is to continue the traditional
                                                            workshop series on Optoelectronics Devices and In-
Future Goals                                                strumentation. In addition, internationally well known
                                                            scientists will continuously be invited to give lectures
Attaining an acknowledged position as a top Euro-           to the students.
pean research unit in its own field forms a key objec-
tive for the group. Another important goal involves
                                                            Personnel
becoming a central cooperation partner for Finnish
industry in the development and application of mea-
                                                            professors & doctors                                    22
suring techniques and instrument technology. In ad-
dition, the group advances the scientific understanding     graduate students                                       39
of optoelectronics and measurement applications, and
produces high-quality dissertations and publications.       others                                                   15
Finally, the highly applicable, in-depth, information       total                                                    76
produced by the group also makes a contribution to
product development and the creation of new busi-           person years (univ. 70%, VTT 30%)                        54
ness opportunities.
The research activities are still focusing or will be       External Funding
focused on:
1) modeling and simulating of the propagation of light       Source                                               EU R
   in turbulent and scattering media, especially in pa-
   per, pulp, process suspension and human tissue,           Academy of Finland                               171 000

2) pursuing new measuring and testing techniques or          Ministry of Education                            230 000
   combining them with traditional ones to new ap-
                                                             Tekes                                          1 582 000
   plications,
3) improving the OCT for industrial application, es-         other domestic public                          1 552 000
   pecially in measuring paper thickness and internal
                                                             domestic private                                 636 000
   structure,
4) continuing the scattering photoacoustic measure-          EU + other international                         869 000
   ment in paper pulp and other turbid suspensions
                                                             total                                          5 040 000
   and following biomedical imaging based on
   photoacoustics,
5) developing optical high and low coherent interfer-       Doctoral Theses
   ometry for trace detection and particle behavior in
                                                            Kataja K (2005) Numerical modelling of near field optical
   a turbid medium,
                                                            data storage. VTT Publications 570.
6) applying pico-second and femto-second lasers to
   study the impulse response of paper and bio-             Selected Publications
   materials in the time domain,
                                                            Olkkonen J, Kataja K & Howe D (2005) Light transmis-
7) combining customized photonic devices, and ad-           sion through a high index dielectric-filled sub-wavelength
   vanced materials and packaging technologies for          hole in a metal film. Optics Express 13: 6980-6989.
   their implementation in novel systems for optical        Heikkinen V, Heikkinen M, Keränen K, Mitikka R, Putila
   communications, wireless instrumentation, machine        VP & Tukkiniemi K (2005) Laser profilometer module
   automation, and biomedicine,                             based on a low-temperature cofired ceramic substrate, Op-
8) continuing to develop polymer devices and bio-           tical Engineering 44: 093603, 7 p.
   sensors to be used in low end products like dispos-      Keränen K, Karppinen M, Lenkkeri J, Mäkinen JT, Ollila J
   able sensors, product package, flexible display, etc.,   & Karioja P (2005) LTCC technology for photonic and
   and                                                      millimeter wave module integration. International Journal
                                                            of Software Engineering and Knowledge Engineering
9) developing non-destructive testing and measure-          15:215-224.
   ments of wood to detect accurately the knots and
                                                            Heikkinen V, Aikio J, Alajoki Y, Kautio K, Ollila J & Karioja
   decayed parts in trunks, utilizing microwaves and        P (2005) Wavelength-tunable laser module using low-tem-
   infrared spectroscopy.


56   INFOTECH OULU Annual Report 2005
perature cofired ceramic substrates. IEEE Transactions on    Popov AP, Lademann J, Priezzhev AV & Myllylä R (2005)
Advanced Packaging 28:121-127.                               Effect of size of TiO2 nanoparticles embedded into stratum
Kinnunen M, and Myllylä R (2005) Effect of glucose on        corneum on UVA and UVB sun-blocking properties of the
photoacoustic signals at the wavelengths of 1064 and 532     skin. Journal of Biomedical Optics 10:064037-(1-9).
nm in pig blood and Intralipid. Journal of Physics D: Ap-    Sorvoja H, Kokko VM, Myllylä R & Miettinen J (2005)
plied Physics 38:2654-2661.                                  Use of EMFi as a blood pressure pulse transducer. IEEE
Popov AP, Priezzhev AV, Lademann J & Myllylä R (2005)        Transactions on Instrumentation and Measurement 54: 2505-
TiO2 nanoparticles as effective UV-B radiation skin-pro-     2512.
tective compound in sunscreens. Journal of Physics D: Ap-    Sarén M-P, Peura M & Serimaa R (2005) Interpretation of
plied Physics 38:2564-2570.                                  microfibril angle distributions in wood using micro-
Kirillin YM, Priezzhev AV, Tuchin VV, Wang RK & Myllylä      diffraction experiments on single cells. Journal of X-Ray
R (2005) Effect of red blood cell aggregation and sedimen-   Science and Technology 13:191-197.
tation on optical coherence tomography signals from blood    Peura M, Müller M, Serimaa R, Vainio U, Sarén M-P,
samples. Journal of Physics D: Applied Physics 38:2582-      Saranpää P & Burghammer B (2005) Structural studies of
2589.                                                        sigle wood cell walls by synchrotron, X-ray microdiffraction
Hast J, Krehut L & Myllylä R (2005) A displacement sen-      and polarised light microscopy. Nuclear Instruments and
sor based on optical feedback interferometry in a GaN di-    Methods in Physics Research B 238:16-20.
ode laser. Optical Engineering, 44(8):080504.                Jaakkola T, Mäkinen H, Sarén M-P & Saranpää P (2005)
Zhao Z & Myllylä R (2005) Measuring the optical param-       Does thinning intensity affect the tracheid dimensions of
eters of weakly absorbing, highly turbid suspensions by a    Norway spruce. Canadian Journal of Forest Research 35:
new technique: photoacoustic detection of scattered light.   2685-2697.
Applied Optics 44: 7845-7852.                                Suhonen R, Tuomikoski M, Maaninen A & Kopola H (2005)
Alarousu E, Krehut L, Prykäri T & Myllylä R (2005) Study     Roll-to-roll manufacturing technologies of OLEDs for
on the use of optical coherence tomography in measure-       signage and lighting. Printed Electronics USA 2005 Con-
ments of paper properties. Measurement Science and Tech-     ference Proceedings.
nology 16:1131-1137.                                         Känsäkoski M, Kivimäki L, Maaninen A, Leinonen M,
Popov AP, Priezzhev AV & Myllylä R (2005) Effect of glu-     Kopola H, Takkinen K & Pulli T (2005) Bioactive
cose concentration in model light-scattering suspension on   nanoparticulate hybrid materials for diagnostic applications.
propagation of ultrashort laser pulses. Quantum Electron-    New trends in research and development in the areas
ics 35:1075-1078.                                            medicine-biotechnology-nanotechnology. Biotechnica,
                                                             Hannover.




                                                                                         INFOTECH OULU Annual Report 2005   57

				
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