Optical coherence tomography methods and systems

A spectral domain optical coherence tomography (SD-OCT) system, the system comprising:

• an illumination system having a light source for illuminating an object region with measuring light,
• wherein a spectral width of a spectrum of the measuring light is adjustable;
• a spectrometer having an adjustable dispersion for spectrally dispersing measuring light returned from the object region and superimposed with reference light into plural spatially separated different spectral portions;
• and
• a controller which is configured to switch between a first and a second operation mode of the system by adjusting the adjustable spectral width and adjusting the adjustable dispersion of the spectrometer based on an input signal;
• wherein in the first operation mode, the measuring light illuminating the object region is spectrally distributed according to a first spectrum having a first spectral width;
• and
• in the second operation mode, the measuring light illuminating the object region is spectrally distributed according to a second spectrum having a second spectral width;
• wherein the first spectral width is at least 10% greater than the second spectral width;
• wherein the first spectral width is determined to be a minimum of a difference between a first upper wavelength and a first lower wavelength;
• wherein in the first operation mode, an intensity of the measuring light having wavelengths between the first lower wavelength and the first upper wavelength amounts to 90% of a total intensity of the measuring light;
• wherein the second spectral width is determined to be a minimum of a difference between a second upper wavelength and a second lower wavelength;
• wherein in the second operation mode, an intensity of the measuring light having wavelengths between the second lower wavelength and the second upper wavelength amounts to 90% of a total intensity of the measuring light;
• and
• wherein a width of a wavelength range comprised in each of the spectral portions in the first operation mode is greater than a width of a wavelength range comprised in each of the spectral portions in the second operation mode.

A Swept source domain optical coherence tomography (SSOCT) method comprising:

• performing a first measurement and a second measurement, each measurement comprising:
• illuminating an object region with first measuring light;
• superimposing first measuring light returned from the illuminated object region with reference light, to form first superimposed light;
• and
• detecting an intensity of the first superimposed light;
• then
• illuminating the object region with second measuring light;
• superimposing second measuring light returned from the illuminated object region with reference light, to form second superimposed light;
• and
• detecting an intensity of the second superimposed light;
• wherein each of the first and the second measuring lights has a spectral distribution having a peak wavelength and a spectral width,
• wherein the spectral width of each of the spectral distributions is determined by a minimum of a difference between two wavelengths, between which 90% of an intensity of the respective spectral distribution is located;
• wherein in each of the first and the second measurement, a difference between the peak wavelength of the first measuring light and the peak wavelength of the second measuring light represents a sweeping range of the respective measurement;
• wherein the sweeping range of the first measurement is at least 2 times greater or 5 times greater than in the second measurement;
• and
• wherein an average of the spectral widths during the first measurement is at least 2 times greater than an average of the spectral widths during the second measurement.

A Swept source domain optical coherence tomography (SSOCT) system, the system comprising:

• an illumination system for illuminating an object region with measuring light having a spectral distribution having a peak wavelength and a spectral width, wherein the peak wavelength is sweepable and the spectral width is adjustable;
• wherein the spectral width of the spectral distribution is determined by a minimum of a difference between two wavelengths, between which 90% of an intensity of the spectral distribution is located;
• an interferometer for interferometrically superimposing measuring light returned from the object region with reference light;
• and
• a detector for detecting the superimposed light;
• a controller which is configured to switch between a first and a second operation mode of the system by adjusting the spectral width and controlling a sweeping of the peak wavelength over a sweeping range;
• wherein an average of the spectral width in the first operation mode is at least 2 times greater than an average of the spectral width in the second operation mode;
• and
• wherein the sweeping range of the first measurement is at least 2 times greater, or is 5 times greater than in the second measurement.