The blood oxygen saturation (SpO2) detection is of great importance in medical science due to its relationship with cardiopulmonary function. Determination of SpO2 by infrared spectroscopy is a commonly used method. In this paper, a novel non-invasive blood oxygen saturation detection method with video image is proposed. Firstly, the index fingertip is illuminated by LEDs with four wavelengths. Then, the reflected light is collected by an image sensor. Meanwhile, a finger clip pulse oximeter is adopted to monitor SpO2 changes. Finally, a color regression model is established with the obtained RGB values and the corresponding SpO2. Furthermore, the influence of quantization noise and other factors is analyzed. Experiments with multiple samples are carried out using the proposed method. The results show that the relative errors between the predicted and reference values are within 5%. Compared with traditional methods, the proposed method can effectively detect the SpO2 in a specific area instead of a single point. In addition, it provides an alternative approach that guides an SpO2 detection device for daily use.
Coherent imaging is a well-established technique in the THz range, in this paper we explore the coherent continuous-wave (CW) THz imaging by recording the complex-valued spatial Fourier spectrum in the focal plane of the imaging system, and by utilizing the Fast Fourier Transform (FFT) technique to numerically retrieve both the intensity and the phase information of the object. System is built up based on the heterodyne detection consisting of two electric multiplier chain locked to each other with a slightly frequency off-set and a narrow-band CMOS TeraFET detector, aiming at the recording and reconstruction of 2D and 3D scenes. With a detection area of 80×70mm<sup>2</sup> and a sampling rate of 1pixel/mm<sup>2</sup> , both 7.6-cm-diameter 2D intensity image and 3D tomography extracted from the phase information of the object are reconstructed, which also reveals the system a capability of covering a large field of view (FOV).