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Introduction to Biophotonics for Medical Applications. Summarized by: Name: AGNES Purwidyantri Student ID No: D0228005. Biophotonics is the science of generating and harnessing light (photons) to image, detect and manipulate biological materials. What is Biophotonics ?.

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introduction to biophotonics for medical applications

Introduction to Biophotonics for Medical Applications

Summarized by:

Name: AGNES Purwidyantri

Student ID No: D0228005

Biophotonics is the science of generating and harnessing light (photons) to image, detect and manipulate biological materials

What is Biophotonics?


The transfer of exogenous DNA into a cell

femtosecond laser mediated cell membrane poration
Femtosecond Laser Mediated Cell Membrane Poration

Photoporation: the use of light to permeabilise cells. First inspired from a Tirlapur and Konig, Nature 2002:

Used a near-infrared, femtosecond-pulsed laser beam (λ 800 nm) from an 80-MHz titanium–sapphire laser, with a mean power of 50–100 mW and tightly focused using a high-numerical-aperture objective

introduction to optical c oherence t omography oct

Introduction to Optical Coherence Tomography (OCT)


The in situ imaging of tissue microstructure with a resolution approaching that of histology, but without the need for tissue excision and processing

optical coherence tomography
Optical Coherence Tomography
  • Three-dimensional imaging technique with ultrahigh spatial resolution even in highly scattering media
  • Based on measurements of the reflected light from tissue discontinuities
    • e.g. the epidermis-dermis junction.
  • Based on interferometry
    • involves interference between the reflected light and the reference beam.
oct vs standard imaging

Resolution (log)

1 mm


100 mm

10 mm


1 mm

Penetration depth (log)

1 mm

1 cm

10 cm

OCT vs. standard imaging




oct in non invasive diagnostics
OCT in non-invasive diagnostics
  • Ophthalmology
    • diagnosing retinal diseases.
  • Dermatology
    • skin diseases,
    • early detection of skin cancers.
  • Cardio-vascular diseases
    • vulnerable plaque detection.
  • Endoscopy (fiber-optic devices)
    • gastrology,
  • Functional imaging
    • Doppler OCT,
    • spectroscopic OCT,
    • optical properties,
    • PS-OCT.
  • Guided surgery
    • delicate procedures
    • brain surgery,
      • knee surgery,
t he oct setup
The OCTsetup







reference mirror




Bandpass filter


Coherent source

Michelson interferometer

light source


Partially coherent source

normal eye
Normal Eye

250 microns


Nominal width of scan: 2.8 mm

uhr oct versus commercial oct
UHR-OCT versus commercial OCT

W. Drexler et al., “Ultrahigh-resolution ophthalmic optical coherence

tomography”, Nature Medicine 7, 502-507 (2001)

system perspective
System perspective
  • Light sources
  • Superluminescent diodes
  • Semiconductor amplifiers
  • Femtosecond lasers
  • Beam delivery and probes
  • Hand-held probe
  • Catheter
  • Ophthalmoscope
  • Microscope
  • OCT imaging engine
  • Resolution
  • Reference delay scanning
  • Doppler/polarization/spectroscopy
  • Detection
  • Frequency domain
  • Computer control
  • Drive system
  • Real-time display
  • Data management
  • Image & signal processing
  • Motion reduction
  • Speckle reduction
  • Image enhancement
  • Rendering algorithms
choosing the light source
Choosing the light source
  • Four primary considerations
    • wavelength,
    • bandwidth,
    • power (in a single-transverse-mode),
    • stability;
      • portability, ease-of-use, etc.
choose light source wavelength
Choose light source – wavelength
  • Light propagation (Monte Carlo simulation)


“Snake” component

Incident light

Ballistic component

Diffuse reflectance

Diffuse transmittance

ultra high resolution oct
Ultra-high resolution OCT
  • Broad bandwidth sources
    • solid-state lasers,
    • sub-5 fs pulse;
      • Ti:Al2O3 (Spectral bandwidth: 350 nm demonstrated),
    • other lasers/wavelengths available or needed.
  • Special interferometers and fiber optics
    • support for broad spectral range,
    • dispersion balanced,
    • current system used for OCT: 260 nm bandwidth, ~1.5µm resolution.
  • Chromatically corrected optics
    • aberrations can decrease resolution and SNR.
  • Broad bandwidth detectors and electronics
    • dual balance detection,
    • low noise circuitry necessary.
s canning devices
Scanning devices
  • Piezo or motorized scanning devices
    • ideal for both longitudinal and lateral scanning.
  • Galvanic mirrors
  • Resonance scanners
  • Helical mirrors
    • longitudinal scanning.
  • Fiber stretcher
    • longitudinal scanning.
rsod in the lab
RSOD in the lab

Peter E. Andersen, Optics and Plasma Research Department

bcc ii
  • Layers
  • Thinning oflayers

L. K. Jensen, MSc thesis (in Danish), 2003 [data obtained atLund Medical Laser Centre, courtesy K. Svanberg].

oct figures of merit summary
OCT: Figures-of-merit – summary
  • Dynamic range
    • 100 dB (or better).
  • Resolution (typical)
    • 1-10 micrometers.
  • Penetration depth
    • depending on wavelength/tissue,
      • 1-2 mm (typically) for 1300 nm in skin tissue.
  • Axial and lateral resolutions are decoupled
    • important for applications.
  • Pixel density is related to spatial resolution and image acquisition time
    • Nz=2*Lz/dz,
    • Nx=2*Lx/dx,
    • image acq. time: T=Nx*fs,
    • scan velocity: vs=Lz*fs.
  • Image acquisition
    • seconds or less,
    • real-time OCT.
  • Clinical adaptation
    • interfaced to standard equipment,
    • fiber-optic devices,
    • endoscopes.