Objective and accurate lesion assessment is one of the key factors for the optimal photodynamic therapy (PDT) of Port Wine Stains (PWS). The evaluation method based on 3D point cloud can effectively solve the problems. Comparing to the traditional point cloud registration algorithms such as ICP which tend to global registration, the feature description method is more suitable for facial point clouds fusion since each clouds is obtained from different angle and just overlap in certain area. In this paper, the method of fusion of multiple point clouds is applied, in which point cloud fusion is achieved by characterizing randomly selected sampling points. The point cloud fusion result is obtained by matching the public area between the two point clouds. Several fusion experiments are designed and conducted using the facial point cloud acquired by Artec Eva three-dimensional scanner. The experimental results show that it can accomplish the point cloud fusion of patient facial point cloud (including all the information on the skin lesions of PWS), which could be an efficient support for effective 3D lesion assessment.
The monochromators, which are able to separate a specific wavelength light from a complex spectrum and a continuous spectrum light source, have been widely used in optical measurements. As one crucial specification, wavelength accuracy has always been a research theme for monochromator users around the world. When the monochromator is utilized for calibrating the wavelength in the ultraviolet, visible, and near-infrared regions, low-pressure discharged lamps, such as mercury lamps, are usually employed to obtain wavelength deviations at certain wavelength points of atomic emission lines of lamps,which are well-known recognized. For the requirement of monochromator wavelength calibration, a light path based on the low-pressure discharged lamp method was constructed. Three strong radiation flux lines of the mercury lamps were selected and tested,whose wavelength values were 365.015 nm, 435.833 nm, and 546.075 nm. Meanwhile a new method based on continuous spectrum light source and Fourier transform spectrometer was proposed and light path was also built. Near the wavelength value points of the selected atomic emission lines of mercury lamp, a measurement experiment was performed both on the same monochromator and the same experimental conditions, and the wavelength deviation values of the monochromator was obtained. The consistency of the two methods was good, and the best repeatability error was better than 0.005nm. The work of this article is of positive for those measurement laboratories to select suitable approach to perform their monochromators wavelength calibrations.
The monochromator has been widely used in the field of optical precision measurement. It can effectively separate the monochromatic light of the specific wavelength required for the experiment from a complex spectrum and a continuous spectrum light source. The wavelength accuracy of a monochromator is an important indicator of its performance，and the research of wavelength accuracy calibration methods to improve measurement accuracy is a hot theme for researchers around the world.When the monochromator is utilized for calibrating the wavelength in the ultraviolet, visible, and near-infrared region, low-pressure discharged lamps, such as mercury lamps and neon lamps, are usually used to calibrate on the well-known limited atomic emission lines of lamp to obtain the wavelength deviation value at the wavelength points of these lines.For some high-precision requirements, for example, when measuring the spectral responsivity of a reference solar cell using a tunable laser as light source, it is difficult for these discrete and finite lines to fully satisfy the demand.To solve this problem, a new method based on combination of continuous spectrum light source and fourier transform spectroradiometer was used. A calibrated experimental optical path was successfully built, and the wavelength deviation values of 322 wavelength points from 400 nm to 2000 nm were obtained. The optimal measurement repeatability reached 0.3 pm, which met the need for high-precision measurement requirement. As a comparison, a low-pressure discharged lamp method was also used. Using a mercury lamp and a neon lamp, a wavelength calibration experiment was performed on the same monochromator in the same wavelength range, and only 20 wavelength deviation values were obtained at its atomic emission lines wavelength point. The number of wavelength deviation values is less than 6.5% of that of the new method.The new method proposed in this paper,which not only can significantly improve the quality of the monochromator calibration wavelength deviation values, but in which the obtained values are able to establish traceability to the international SI unit system, is an ideal wavelength accuracy calibration method.