Computational imaging and modelling

Computational imaging and modelling

The group is part of Computational Physics and Inverse Problems research at the Department of Applied Physics. It belongs to the Institute of Photonics. The group is also a member of the Academy of Finland’s Flagship on Photonics Research and Innovation (PREIN) and Centre of Excellence in Inverse Modelling and Imaging. Furthermore, it holds an ERC Consolidator grant.

The research topics of the group include computational inverse problems and modelling with special interests in quantitative imaging, Bayesian inverse problems and uncertainty quantification. Furthermore, the group has strong expertise on computational modelling of light and ultrasound propagation. The group is especially interested in development of light, ultrasound and coupled physics based imaging modalities and therapy.

We have a strong international collaboration network with partners, for example, in the University College London, Politecnico di Milano and Sunnybrook Research Institute in Toronto.

Laboratory

Biomedical Optical Imaging and Ultrasound Laboratory (OPUS) is located at the Department of Applied Physics, Kuopio campus. The laboratory is equipped to perform versatile and demanding ultrasonic measurements. The facilities can be used to tune and calibrate commercial and prototype-level transducers and to measure acoustic pressure fields. The laboratory premises and equipment are available for in vitro, ex vivo, and in vivo experiments. Furthermore, the laboratory has facilities for diffuse optical tomography and photoacoustic tomography experiments and research. These can be applied for different measurement scenarios and they can be applied with e.g. biological samples and phantom targets.

The laboratory includes, for example, the following devices:

  • Two motorized and one manual 3D position systems, μm scale movements. Motorized positioners are under computer control.
  • Calibrated hydrophones for MHz range ultrasonics
  • Transducer from 0.5 MHz up to approximately 12 MHz
  • Ultrasound pulser and receiver electronics
  • RF generators and amplifiers
  • Computer controlled radiation force balance with forwarded/reflected electric power measurement
  • Schlieren system for 0.8 to 80 MHz frequency bandwidth
  • Laser vibrometer for surface velocity and displacement measurements up to 10 MHz
  • Nd:YAG – OPO laser with fiber optic coupling. Optical energies up to several hundreds of millijoules, wavelength range from 660 to 2600 nm, pulse duration ≈ 5 ns.
  • Sensors and meters for optical energy measurement from nanojoules to joules
  • Optical detectors for pulse duration measurement from < 1 ns
  • High-definition oscilloscope with 2.5 GHz bandwidth
  • Commercial and in-house built drive circuits for LEDs and laser diodes

See the full list of devices here: https://sites.uef.fi/opus/

Open software

We have an open source optical Monte Carlo code and MATLAB toolbox ValoMC for simulating light transport in scattering medium.

Group members

List of publications

See the list of publications here: https://sites.uef.fi/inverse/publications/

Services

Our instruments and facilities can be used for characterisation of ultrasound transducers. 3D hydrophone measurements and other available methods provide detailed information of acoustic field structure and amplitude. We can offer services for acoustical characterisation of materials such as speed of sound and attenuation measurements. Services can be tailored to meet the specific requirements.

Keywords: Inverse problems; radiative transfer; light transport; ultrasound; photoacoustics; optical imaging; optical tomography; photoacoustic imaging; tomography; ultrasonics; ultrasound therapy; HIFU; schlieren