Optical Coherence Microscopy (OCM) enables the acquisition of high resolution, en face images. Most current OCM systems are based on slow analog or high speed digital demodulation schemes. In this paper we demonstrate a low-cost, high speed analog fringe generation and demodulation method. A high power operational amplifier drives a mirrored piezoelectric stack mounted in the reference arm of the interferometer. The drive signal is synchronized with the demodulation frequency of two analog lock-in amplifiers, which extract the first and second harmonic power of the coherence fringes. Tenth order Bessel low-pass filters (LPFs) allow fast system response and reduce carrier frequency noise. Four outputs (X and Y components of first and second harmonic) are acquired with a low-cost data acquisition board and combined to eliminate the slow phase drift in the interferometer. C# software processes and displays the image, and performs automatic interferometer pathlength matching and adjustment. We present images of Arabidopsis leaf in situ, sections of carrot, and ex vivo rat ovary. Excellent image quality is achieved at acquisition speeds up to 40,000 samples/second.
Optical Coherence Tomography (OCT) and Laser Induced Fluorescence Spectroscopy (LIF) have separately been found to have clinical potential in identifying human gastrointestinal (GI) pathologies, yet their diagnostic capability in mouse models of human disease is unknown. We combine the two modalities to survey the GI tract of a variety of mouse strains and sample dysplasias and inflammatory bowel disease (IBD) of the small and large intestine. Segments of duodenum and lower colon 2.5 cm in length and the entire esophagus from 10 mice each of two colon cancer models (ApcMin and AOM treated A/J) and two IBD models (Il-2 and Il-10) and 5 mice each of their respective controls were excised. OCT images and LIF spectra were obtained simultaneously from each tissue sample within 1 hour of extraction. Histology was used to classify tissue regions as normal, Peyer’s patch, dysplasia, adenoma, or IBD. Features in corresponding regions of OCT images were analyzed. Spectra from each of these categories were averaged and compared via the student's t-test. Features in OCT images correlated to histology in both normal and diseased tissue samples. In the diseased samples, OCT was able to identify early stages of mild colitis and dysplasia. In the sample of IBD, the LIF spectra displayed unique peaks at 635nm and 670nm, which were attributed to increased porphyrin production in the proliferating bacteria of the disease. These peaks have the potential to act as a diagnostic for IBD. OCT and LIF appear to be useful and complementary modalities for imaging mouse models.