Spectral analysis is an important method for noninvasive blood glucose measurement. Presently, Fourier-transform spectroscopy is a well-established technique that provides highly resolved spectral measurements in the infrared, visible and ultraviolet ranges. In this study, we proposed a novel method for obtaining linear spectra based on regular Spatial Heterodyne Spectrometers. In particular, we wanted to use a fluorescent dye-coated screen and a Fourier lens to directly obtain uniform K-space spectra. In the system, the up-conversion luminescent material on the screen is hoped to absorb coherent incident light and emit light of a specific wavelength that maintains the coherence. According to our calculation, the photodetector array receives the Fourier image pattern on the screen and can directly obtain the spectrum of the measured substance, therefore the scientists can directly observe the spectrum of the test sample. Furthermore, we replace the fluorescent dye-coated screen by an infrared laser detector card, which is commonly used in laboratories, to primary verify the feasibility of the method. Up-conversion luminescent materials that are widely used in the fields of analytical chemistry, biomedicine, and life sciences, have very good application prospects in biological imaging, photodynamic therapy, solar cells, flexible fluorescent films and sensing.
In this study, we describe a simple method to produce signals which can reveal the cross-sectional information of samples in an optical coherence tomography (OCT) system. Instead of using the spectrometer and the Fourier transformation calculation in the conventional spectrum domain (SD) OCT system, we use a Mach-Zehnder interferometer structure of the spatial heterodyne spectrometer. In a spatial heterodyne spectrometer, because each position on the photodetector array could be mapped to a specific optical path difference, the spectral density distribution could be retrieved with Fourier transformation. And in an SD-OCT system, cross-section signals are obtained by conducting Fourier transformation to the spectrum signals. Therefore, in our OCT system, the spatial signals captured by the photodetector array is related to the cross-sectional signals obtained in an SD-OCT system. The theoretical study and the numerical simulation demonstrate that by applying our method in an OCT system, the heterodyne spectrometer structure could generate a symmetrical pattern composed of fringes with high spatial frequency. Then the photodetector array captures the pattern to generate a spatial signal. The spatial ordinate of this signal is linearly related to the optical depth in sample, while the amplitude of the signal intensity variation is linearly related to the intensity of coherent backscattered light in the sample. The imaging depth is theoretically unlimited. Also, because of the high spatial frequency of the signal, we further adjust the inclination angle in the heterodyne spectrometer structure to visualize the signal.
We present an automatic classification algorithm for retinal optical coherence tomography (OCT) images based on convolution neural network (CNN). This algorithm inherently contains feature extraction and classification, thus avoiding the design feature extractor manually. Firstly, we processed the OCT images to focus on and determine the pathological area of the retinal OCT images, and to speed up the training of the network. Then we input the original images to crop them, which can effectively prevent the noise introduced in the processes of image processing and changing the pixels in the original image. Secondly, we augmented the OCT images in the source data set to obtain sufficient images, and to alleviate the impact of a relatively small number of target classification images on the model accuracy and generalization ability. Our method was introduced the random translation in image cropping and horizontal flipped to augment the OCT images. Then we applied two methods to build two data sets used to train the network, and we divided each of the data sets into a training set and a validation set. Next, we designed an efficient classification network and trained it with the two training sets respectively, to acquire the two models that can classify OCT images. The results indicate that the network trained by the augmented data can classify images more effectively. In our classification algorithm, the accuracy, the sensitivity and the specificity are 93.43%, 91.38%, and 95.88%, respectively.
Diabetes has been a serious problem that poses threat to people's health all around the world. It is still a challenge for us to detect blood glucose concentration continuously and non-invasively. In this research, we developed a free-space spectrum domain optical coherence tomography (SD-OCT) system for non-invasive blood glucose detection which possessed advantages of easy construction, analyzation and control. In this system, a laser with center wavelength of 980nm was applied because of its low absorption in both glucose and water, which was suitable for OCT imaging. However, the laser with wavelength of 980nm was not used in the OCT with optic fiber type which was commercially designed for wavelengths of 830nm, 1310nm and 1550nm. By applying a dispersing prism, we could obtain higher resolution spectrum to acquire better OCT images and more accurate glucose concentration. The tomography function of this free-space SD-OCT system was proved to work by scanning onion sample. Pristella maxillaris is a kind of fish with transparent body structure and suitable size, thus we consider it to be an ideal animal for blood glucose measurement by optical methods. We cultivated pristella maxillaris, an ideal fish for this experiment, in glucose solutions with five different concentrations as samples to study glucose monitoring. The OCT signals of the five groups correlated respectively to the glucose concentrations. Therefore, our method provided the potential for measuring blood glucose concentration non-invasively.
Binary optics has been interested widely in recent years, where the optical element can be fabricated on a thin glass plate with micro-ion-etching film layer. A novel optical scanning system for gene disease diagnostics is developed in this paper, where four kinds optical devices are used, such as beam arrays splitter, arrays lens, filter arrays element and detection arrays. A soft for binary device designing with iterative method is programmed. Two beam arrays splitters are designed and fabricated, where one devices can divide a beam into the 9x9 arrays , the other will divide a beam into the 13x13 arrays. The beam arrays splitter has a good diffraction efficiency >70%, and an even energy distribution. The gene disease diagnostics system is portable by biochip and binary optics technology.
Laboratory-on-a-chip has been interested widely in recent years, where the sample preparation, bio-chemical reaction, separation, detection and analysis, are performed in a small biochip which is only a fingernall dimension. In order to obtain a high detection sensitivity 1 fluors/micrometers 2 (one fluorescence molecular per square micrometer) in biochip scanning system, it is required that the scanning objective lens is a big numerical aperture (> 0.5), very small focal spot (< 5 micrometers ) and long back focal length (> 3 mm). In this paper, a combined lens is designed for the scanning objective lens, which is with big numerical aperture NA > 0.7, very small focal spot (< 2 micrometers ) and long back focal length (> 3 mm). The phase aberrations of combined lens, including the aspherical aberration and the chromatic aberration corresponding to wavelength 532 nm, 570 nm, 635 nm, 670 nm, are corrected very well. The encircled energy diagram of the lens is good to the diffraction limit. The focal spot diagram, the optical path difference diagram, the transverse ray fan plot and the modulation transfer function, are studied also. A novel confocal scanning system of biochip with the designed combined lens as the objective lens is developed, some experiment results in a multi-channel biochip are obtained.
A multichannel joint transform correlator, using a Dammann grating as a beam-splitter to split one incident beam up into 2D array of equal intensity beams to form multichannel for correlation, is presented and investigated. Mathematical analysis and optical experimental results are presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.