Laboratory for Medical Optics

 

Laboratory description

Figure 1: View into the laboratory for medical optics

The Medical Optics Laboratory at the BMTI is used for the optical, optomechanical, colorimetric and radiation-physical characterization of light and radiation sources, optomechanical and electrooptical components and assemblies up to complete ophthalmological systems. Commercial devices and components, modified systems as well as complete in-house developments are analyzed. Figure 1 gives an insight into the laboratory.

 

Laboratory equipment

  • Room darkening system
  • Optical tables and plates (passively damped)
  • Optical components (lenses, filters, mirrors), mechanical and piezo-active components (holders, mounts, linear one-, two-, and three-axis drives, etc.), electro-optical components (LC displays, high-power LEDs, DMD displays)
  • Non-coherent light sources (incandescent lamps, xenon lamps, LED light sources), for free beam applications or with fiber output (multifiber as well as liquid light guides)
  • Spectral programmable light source in the VIS range
  • Measuring station for measuring the modulation transfer function MTF (in-house development)
  • Measuring station for photogoniometric measurement of the radiation characteristics of point light sources (in-house development)
  • Camera measuring station for the characterization of digital cameras and image sensors according to EMVA standard 1288 R3.0 (in-house development)
  • Array spectroradiometer CAS140B (350-1050nm) and CAS140C (200-800nm)
  • SPECTRO 320 scanning spectroradiometer (190-1700nm)
  • Detectors for array and scanning spectroradiometers: EOP120 for measuring spectrally resolved irradiance and illuminance, TOP100 for measuring spectrally resolved radiance and luminance, ISP75 and ISP250 for spectrally resolved measurement of luminous flux and radiant power.
  • Multi-channel oscilloscopes and photodiodes for measuring temporal processes, e.g. switch-on and switch-off behaviour of light stimulators and light sources
  • Measuring station for recording 3D objects using light field measuring technology

Example application:Figure 2 shows how a color flicker stimulus (here magenta) is generated and characterized. Exact wavelength properties (wavelengths, one could say colors, and their intensities) are very important for color channel selective stimulations for color sense research, but also targeted diagnostic procedures for various eye diseases, such as for glaucoma. If the temporal component of the stimulus is also addressed, the exactness and knowledge of the energetic, colorimetric and temporal nature of the stimulus must ultimately be determined. In Figure 2, according to additive color mixing, magenta is generated from blue and red using a spectrally programmable light source (software interface in Figure 1, top left). This color is applied with a rectangular gradient at 15 Hz, which is also done with the light source. The software surface of the light source can be seen in the top left of the picture.The wavelength spectrum and light output are recorded using a radiospectrometer and integrating sphere (Figure 2, top right). The temporal behaviour of the stimulus is recorded and analysed with a storage oscilloscope and a fast Si photodiode.

Figure 2 Example of characterization of a color flicker stimulus at 15 Hz.