Extended range imaging
An imager that can provide separated images corresponding to differing depths in a sample is presented. In accordance with some embodiments of the invention, an imager can include a light source; a sample arm that receives light from the light source, directs the light to a sample, and captures light returning from the sample; a modulation source that provides different modulations corresponding to differing imaging depths in the sample; a detector system to receive the captured light from the sample with the different modulations; and a processor that receives signals from the detector system and separates a plurality of images corresponding with the differing image depths in the sample.
1. An imager, comprising:
a light source;
a sample arm that receives light from the light source, directs the light to a sample, and captures light returning from the sample;
a reference arm that provides different modulations corresponding to differing imaging depths in the sample, the reference arm comprising:
a plurality of reference paths being modulated to have different carrier frequencies corresponding to the differing imaging depths in the sample;
a first splitter/coupler forming the plurality of reference paths, wherein at least one reference path comprises optics coupled to a mirror and a modulator;
a detector system to receive the captured light from the sample and the different modulations provided by the reference arm; and
a processor that receives signals from the detector system and executes instructions to:
simultaneously obtain a plurality of overlapping images from the plurality of reference paths, the plurality of overlapping images corresponding to the differing imaging depths in the sample;
combine the simultaneously obtained plurality of overlapping images into a combined dataset, the combined dataset having a spatial frequency dimension and a transverse dimension;
perform a transform on the combined dataset along the transverse dimension for each value in the spatial frequency dimension to form a plurality of distributions along a carrier frequency dimension in the transformed dataset;
spectrally separate the plurality of distributions into a plurality of separated data based on a carrier frequency of each of the plurality of separated data; and
perform mathematical operations on each of the plurality of separated data to form a plurality of images corresponding with differing reference paths.
2. The imager of claim 1 , wherein a path length of the reference path correlates with an image depth of one of the plurality of images.
3. The imager of claim 1 , further comprising a second splitter/coupler coupled to the light source, the sample arm, the reference arm, and the detection system, wherein the splitter/coupler provides light to the sample arm and the reference arm, receives light from the sample arm and the reference arm, and provides combined light from the sample arm and the reference arm to the detector system.
4. The imager of claim 1 , wherein the processor provides control signals to the reference arm and the sample arm.
5. The imager of claim 1 , wherein the light source includes a broad band source and the detection system can include a spectrometer.
6. The imager of claim 1 , wherein the light source includes a swept laser source and the detection system can include a photodiode detector system.
7. The imager of claim 1 , wherein the reference arm further comprises a polarizer.
8. A method of separating simultaneously obtained images in an OCT imager, comprising:
simultaneously obtaining a plurality of overlapping images using the OCT imager from a plurality of reference paths that each provide different modulations to induce different carrier frequencies corresponding to differing imaging depths in a sample;
combining the simultaneously obtained plurality of overlapping images into a combined dataset, the combined dataset having a spatial frequency dimension and a transverse dimension;
performing a transform on the combined dataset along the transverse dimension for each value in the spatial frequency dimension to form a plurality of distributions along a carrier frequency dimension in the transformed dataset;
spectrally separating the plurality of distributions into a plurality of separated data based on a carrier frequency of each of the plurality of separated data; and
performing mathematical operations on each of the plurality of separated data to generate separate images from the plurality of overlapping images.
9. The method of claim 8 , wherein the transform is a Fourier transform.
10. The method of claim 8 , wherein performing mathematical operations includes performing an inverse Fourier transform in a transverse direction on the separated data; and
performing the inverse Fourier transform in a frequency direction on the separated data.