Depth of the probe and orientation of the light source were controlled by a plate attached to the cable within 5 cm of the light sensor.
This observation is only possible because the registration between the recorded 3D data sets is better than the extension of a cone (transverse) and better than the coherence length of the light source (in depth).
These properties of the light source determine the depth resolution of the system, which was measured to be 12.7 μm in air.
In this case, the depth resolution is determined by the coherence length of the light source instead of the focusing properties of a microscope objective, and can reach the micrometer level.
Spatial resolution in the axial (depth) direction of OCT is largely determined by the coherence length of the light source, and high resolution and penetration OCT has been sought to obtain 3D optic nerve head images without averaging.
Because of the low coherence of the light source, interferometric signal is observed only over a limited depth of sample.
The A-line depth profile of the sample is reconstructed by first measuring the spectral interference signal expressed by [ 4, 5]: In this expression, s(k) is the spectral intensity distribution of the light source.
Interference of low-coherence light only occurs when the optical path length of reference and probe are matched within the coherence length of the light source, which means that the difference between the optical path of the reference and the probe light determines the depth in the sample at which the magnitude of reflection is registered.
Aim the light source toward the subject, placing the umbrella in front of the light source.
The main challenges rely on the properties of the light sources, their wavelength, diffusion and absorption, which influence the penetration depth of the light into tissues, as well as the resolution.
