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Measurement of the OTF/MTF of lens systems
Published in Tom L. Williams, The Optical Transfer Function of Imaging Systems, 2018
Like collimators and decollimators, relay lenses must be well corrected since there is no direct method of compensating for the effect any residual aberrations may have on the measured OTF. Most commonly, in the visible wavelength range, standard microscope objectives are used as relay lenses.
Asymmetric Abel inversion in imaging spectroscopy for tilted TIG arc plasma
Published in Welding International, 2022
Yuto Yamashita, Masaya Shigeta, Hisaya Komen, Manabu Tanaka
Table 1 shows experimental conditions. In this study, the static TIG arc on a water-cooled copper plate was used as the measurement target. Pure argon was used as the shielding gas, and a tungsten electrode with thoria (electrode diameter 3.2 mm, tip angle 60°) was used as the cathode, and the welding current was 150 A and the arc length was 5 mm. Figure 5(a) shows the experimental setup used in this study, and Figure 5(b) shows a schematic diagram of the TIG torch and arc plasma viewed from the high-speed camera with spectrometer. The black dashed line in Figure 5(a) shows the light path. In this experiment, the radiation from the arc plasma on the base metal was focused by an objective lens and formed an image by a relay lens. The imaged radiation was split into two light paths by a half-mirror. Each of the bifurcated imaged radiations was spectrally split into the wavelengths of interest inside the spectrometer. A high-resolution image was obtained by capturing the light at the spectral wavelengths of the line spectrum with a 12-bit (4096-levels) high-speed camera.
A four-channel ICCD framing camera with nanosecond temporal resolution and high spatial resolution
Published in Journal of Modern Optics, 2021
Yuman Fang, Minrui Zhang, Junfeng Wang, Lehui Guo, Xueling Liu, Yu Lu, Jinshou Tian
Multiple-frame operation is achieved by using multiple gated intensifier tubes. This requires that the optical system provide a separate image to each GOI channel. The splitter assembly consists of an objective lens, a relay lens, a mirror-based beamsplitter, and four reflecting mirrors. Figure 3 shows a scale drawing of the splitter assembly. The medial axis of the beamsplitter is aligned with the optical axis of the lens, therefore, each rectangle face of the beamsplitter deflects only a portion of the total incoming beam. The image splitting is done by splitting the aperture into four parts and directing the light exiting from each in a different direction. Finally, mirrors M1 through M4, which are arranged in a square grid, are used to direct each beam out of the plane of the assembly. The output optical axis is parallel with the original input optical axis and has been offset a distance from the splitter assembly. The beams emerge to the mounting plate where the four ICCD cameras are attached (Figure 4).
Optical design of a simultaneous polarization and multispectral imaging system with a common aperture
Published in Journal of Modern Optics, 2020
Xin Liu, Jun Chang, Yue Zhong, Shuai Feng, Dalin Song, Yaoyao Hu
We choose F DoAP architecture to build an MWIR polarization imaging system with a cooled infrared FPA, as illustrated in Figure 3. Light entering the system passes through four identical divided aperture systems first, generating four identical intermediate images. Then, considering cold stop matching into consideration, these four intermediate images are focused onto four quadrants of the focal plane through the relay lens. The focal length fM of the whole MWIR system is given by where fMO is the focal length of every objective lens, and βM is the reduction ratio of the relay lens.