为实现太赫兹辐射特性精准认知, 开展太赫兹辐射功率密度测量研究.通过光学频率梳产生太赫兹频率梳, 利用太赫兹频率梳实现太赫兹辐射源空间辐射功率密度测量.本文利用电光采样和光电导探测两种方式, 实现了100 GHz辐射源空间辐射功率密度测量; 将100 GHz辐射总功率溯源到标准太赫兹功率计, 实现太赫兹辐射功率密度绝对测量.分析比较了利用800 nm空间光进行电光采样和利用1550 nm光纤激光进行光电导探测的测量结果.在不同距离下, 对太赫兹辐射源的空间辐射功率密度进行了测量和量值溯源, 实验揭示了太赫兹辐射传输的空间演化特性.

Optical coherence tomography (OCT) has been widely applied to the diagnosis of eye diseases during the past two decades. However, valid evaluation methods are still not available for the clinical OCT devices. In order to assess the axial resolution of the OCT system, standard model eyes with micro-scale multilayer structure have been designed and manufactured in this study. Mimicking a natural human eye, proper Titanium dioxide (TiO2) materials of particles with different concentrations were selected by testing the scattering coe±cient of PDMS phantoms. The artificial retinas with multilayer films were fabricated with the thicknesses from 9.5 to 30 micrometers using spin coating technology. Subsequently, standard OCT model eyes were accomplished by embedding the retina phantoms into the artificial frames of eyes. For ease of measurement processing, a series of model eyes were prepared, and each contained films with three kinds of thicknesses. Considering the traceability and accuracy of the key parameters of the standard model eyes, the thicknesses of multilayer structures were verified using Thickness Monitoring System. Through the experiment with three different OCT devices, it demonstrated the model eyes fabricated in this study can provide an effective evaluation method for the axial resolution of an ophthalmic OCT device.

太赫兹技术的重要应用急需准确的太赫兹辐射功率计量作为支撑和保障，国际计量局组织开展了国际首次太赫兹辐射功率测量比对。为实现太赫兹辐射功率准确测量，保障我国太赫兹功率计量取得国际等效互认，报导了全吸收型太赫兹辐射功率计，对太赫兹辐射功率计的计量性能和测量不确定度进行详细分析和实验测试。利用一种具有镜反射的太赫兹辐射计，对全吸收型太赫兹辐射计的计量性能进行实验验证，保障了太赫兹辐射功率计响应度量值的准确性和不确定度分析的合理性。利用自主研制的太赫兹辐射计参加国际首次太赫兹功率比对，取得了国际等效一致。

Alignment and testing of optical axis parallelism are the key problems in alignment of a multi-optical axis system. We propose a method which can adjust optical axis parallelism and single-channel wavefront aberration simultaneously in multi-axis imager. Firstly, the imager's installation base surface is adjusted to be perpendicular to the optical axis of the interferometer and remain motionless precisely by using theodolite. Then, according to the measurement principle of wave aberration with interferometer, each channel axis is adjusted to be parallel to the axis of the interferometer. While imaging quality in each channel is measured, alignment on each channel axis parallelism is accomplished. By this method, three-axis parallelism in annular three-channel imager is aligned. The accuracy of axis parallelism is up to 15″, and the imager requirement (30″) is satisfied. Feasibility and precision of this method are verified.

The integrated manufacturing technology is introduced to improve the imaging quality of an off-axis -three-mirror anastigmatic (TMA) system. With the integration of system design, manufacturing of highly -precise optical elements, simulation and evaluation capabilities of the manufactured system, and testing and -alignment with the same fiducial, we can efficiently and precisely achieve high quality of an optical system. In order to prove the efficiency of this technology, we design an off-axis TMA system with MTF invariance better than 0.50 (57 lp/mm), and manufacture the aspherical surfaces of this optical system with surface figure error better than l/50 (RMS, l = 632.8 nm). We develop an interface software named MetroMax to achieve the connection between the final surface figure and the optical design software. The MetorMax also forecasts the imaging quality of the system, and guide us in aligning the system with a same fiducial with the whole field of view approached l/14 and MTF invariance better than 0.95. To confirm the imaging system after integrated manufacturing, we test the system on the ground and orbit; the result proves effective improvement in the imaging quality of the optical system.

A wavefront reconstruction algorithm based on sub-aperture stitching is proposed to reconstruct a phase from its phase differences to improve calculation efficiency. The proposed algorithm is similar to the sub-aperture stitching interferometry. It divides large phase grids into several small sub-apertures, reconstructs the phase of each sub-aperture from the phase differences through the standard wavefront reconstruction algorithm, and then stitches the results of the sub-apertures together. The proposed algorithm can efficiently reconstruct the phase with much less computer memory and calculation time. Simulations and experiments are conducted to demonstrate the effectiveness of the proposed algorithm.