Focal Length Optical System Research Articles

Functional Surfaces via Laser Processing in Nickel Acetate Solution.

This study presents a novel laser processing technique in a liquid media to enhance the surface mechanical properties of a material, by thermal impact and micro-alloying at the subsurface level. An aqueous solution of nickel acetate (15% wt.) was used as liquid media for laser processing of C45E steel. A pulsed laser TRUMPH Truepulse 556 coupled to a PRECITEC 200 mm focal length optical system, manipulated by a robotic arm, was employed for the under-liquid micro-processing. The study's novelty lies in the diffusion of nickel in the C45E steel samples, resulting from the addition of nickel acetate to the liquid media. Micro-alloying and phase transformation were achieved up to a 30 µm depth from the surface. The laser micro-processed surface morphology was analysed using optical and scanning electron microscopy. Energy dispersive spectroscopy and X-ray diffraction were used to determine the chemical composition and structural development, respectively. The microstructure refinement was observed, along with the development of nickel-rich compounds at the subsurface level, contributing to an improvement of the micro and nanoscale hardness and elastic modulus (230 GPa). The laser-treated surface exhibited an enhancement of microhardness from 250 to 660 HV0.03 and an improvement of more than 50% in corrosion rate.

Performance evaluation of super resolution algorithms in generating high resolution images using MSE and PSNR

In recent days, requirement of high spatial resolution remote sensing data in various fields has increased tremendously. High resolution satellite remote sensing data is obtained with long focal length optical systems and low altitude. As fabrication of high-resolution optical system and accommodating on the satellite is a challenging task, various alternate methods are being explored to get high resolution imageries. Alternately the high-resolution data can be obtained from super resolution techniques. The super resolution technique uses single or multiple low-resolution mis-registered data sets to generate high resolution data set. Various algorithms are employed in super resolution technique to derive high spatial resolution. In this paper we have compared two methods namely overlapping and interleaving methods and their capability in generating high resolution data are presented.

Design and Alignment of Airborne Compact Long Focal Length Optical System

Design and Alignment of Airborne Compact Long Focal Length Optical System

Analysis and Test of Line-of-sight Error of Large-aperture Long Focal Length Optical Imaging System under Reaction wheel Disturbance

Analysis and Test of Line-of-sight Error of Large-aperture Long Focal Length Optical Imaging System under Reaction wheel Disturbance

长焦分档变倍光学系统的设计

Based on the R-C system a cooled infrared swith-zoom optical system with long effective focal length is designed.The initial parameters are calculated and the components' focal power is deduced.Secondary imaging structure is adopted,and relay lens is used to match the cold stop.Zoom is realized by switching the relay lens of the short focal length system and the long focal length system.The optimized design of optical system aberration is made.The optimized imaging results of the long effective focal length optical system and the short effective focal length optical system at different field of view are presented,and the modulation transfer functions within 0.8 field of view at 17 lp / mm of spatial frequency are greater than 0.4.Finally,corresponding precision analysis of the main structure is made and the results show that the structure is rational and the imaging quality is good.The optical system can meet actual requirement.

P单传感器全景与长焦组合光学系统设计

p单传感器全景与长焦组合光学系统设计

Bernhard Schmidt and the Schmidt Telescope for Mapping the Sky

Abstract Bernhard Voldemar Schmidt (1879-1935) was born in Estonia. He ran an optical workshop in Mittweida, Saxonia, between 1901 and 1927. Astronomers appreciated the quality of his telescopes. Starting in 1925, working freelance in Hamburg Observatory, he developed a short focal length optical system with a large field of view. He succeeded in inventing the “Schmidt Telescope” in 1930, which allows the imaging a large field of the sky without any distortions. Shortly after Schmidt’s death, the director of the observatory published details on the invention and production of the Schmidt Telescope. After World War II, Schmidt telescopes have been widely used. The first large Schmidt telescope was built in 1948, the “Big Schmidt” (126 cm), Mount Palomar, USA. Schmidt telescopes are also important tools for cosmology. The result of the Palomar Observatory Sky Surveys (1949-1958, 1985-1999) is a data base of about 20 million galaxies and over 100 million stars, supplemented in 1971 by the ESO Schmidt for the southern sky. Also high resolution spectrometers can be fitted to the Schmidt telescope. The 80 cm Schmidt telescope of Hamburg Observatory, planned since 1936, finished 1955, is on Calar Alto, Spain, since 1975. Combined with two objective prisms, it was used for a Quasar survey project.

The development of the Schmidt telescope

AbstractBernhard Schmidt (1879–1935) was born in Estonia. After a few years of studying engineering he ran an optical workshop in Mittweida, Saxonia, between 1901 and 1927. Astronomers appreciated the quality of his telescopes. Starting in 1925, on behalf of the Hamburg Observatory, he developed a short focal length optical system with a large field of view. For this purpose, Schmidt moved his workshop to the observatory. He succeeded in inventing the “Schmidt telescope” which allows the imaging of a large field of the sky without any distortions. Schmidt's first telescope (spherical mirror diameter 0.44 m, correction plate 0.36 m diameter, aperture ratio 1:1.75, and focal length 0.625 m) has been used since 1962 at the Boyden Observatory in Bloemfontein/South Africa. Apart from his 0.36m telescope, Schmidt produced a second larger one of 0.60m aperture. Shortly after Schmidt's death, the director of the observatory published details on the invention and production of the Schmidt telescope. After World War II, Schmidt telescopes have been widely used. The first large Schmidt telescope, the “Big Schmidt” (1.26 m), Mount Palomar, USA, was completed in 1948. The 0.80 m Schmidt telescope of Hamburg Observatory, planned since 1936, finished in 1954, is now on Calar Alto/Spain (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The Research of Screw Thread Parameter Measurement Based on Position Sensitive Detector and Laser

A technique and system of measuring screw thread parameter based on the theory of laser measurement is presented in this paper, which can be carried out the automated measurement of screw thread parameter. An inspection instrument was designed and produced, which included exterior imaging system of optical path, transverse displacement measurement system, axial displacement measurement system, and a module to deal with, control and assess the data in the upper system. The inspection and estimate of the screw thread contour curve were completed by using position sensitive device (PSD) as photoelectric detector to measure the coordinate data of the screw thread contour curve in the transverse section, and using precise raster to measure the axial displacement of the precision worktable under the screw thread test criterion., computer can gives a measured result according to coordinate data of the screw thread obtained by PSD. The relation between measured spot and image is established, and optimum design of the system organization are introduced, including the image length of receiving lens focal length optical system and the choice of PSD , and some main factor affected measuring precision are analyzed. The experimental results show that the measurement uncertainty of screw thread minor diameter can reach 0. 5μm, which can meet most requests for the measurement of screw thread parameter.

Effect of a laser prepulse on a narrow-cone ejection of MeV electrons from a gas jet irradiated by an ultrashort laser pulse.

Spatial and energy distributions of energetic electrons produced by an ultrashort, intense laser pulse with a short focal length optical system (Ti:sapphire, 12 TW, 50 fs, lambda=790 nm, f/3.5) in a He gas jet are measured. They are shown to depend strongly on the contrast ratio and shape of the laser prepulse. The wave breaking of the plasma waves at the front of the shock wave formed by a proper laser prepulse is found to make a narrow-cone (0.1pi mm mrad) electron injection. These electrons are further accelerated by the plasma wake field generated by the laser pulse up to tens of MeV forming a Maxwell-like energy distribution. In the case of nonmonotonic prepulse, hydrodynamic instability at the shock front leads to a broader, spotted spatial distribution. The numerical analysis based on a two-dimensional (2D) hydrodynamic (for the laser prepulse) and 2D particle-in-cell (PIC) simulation justifies the mechanism of electron acceleration. The PIC calculation predicts that electrons with energy from 10 to 40 MeV form a bunch with a pulse duration of about 40 fs.

Vibration isolation and damping for long focal length synchrotron radiation instruments

Vibrations of the optical elements in long focal length, high resolution monochromators and other long focal length optical systems used at synchrotron radiation facilities can lead to serious degradation of the performance of these systems. As higher resolution instruments with state-of-the-art spherical and plane elements come on line, vibration will become an increasingly serious problem. The vibrations excited in beamline elements can be at least as serious as position variations of the synchrotron radiation source. Vibrations of beamline and monochromator components may be driven by acoustic waves, ground motion, scanning system vibrations, or vibrations coupled in from experimental equipment such as pumps, fans, motors, etc. This paper will include a discussion of isolation and damping of vibrations in monochromators and beamlines. Various diagnostic methods are described, and a case study of vibration-caused loss of resolution in a 4 m normal incidence monochromator will be presented.

ON THE IMAGE QUALITY OF PLANE GRATING SPECTROMETER

In this paper various factors influencing the image quality of plane grating spectrometer are discussed in detail. By means of vector elgebra a general formula is given for the form of the spectral lines in relation to the form of the entrance slit. A formula describing the angular dispersion of the spectral line resulting from a circular slit is also given. Investigation on the optical performance of the Ebert-Fastie grating spectrometer shows that among various residual optical aberrations, due to unsymmetrical disposition of the incident and diffracting beams with respect to the grating surface, coma is the most serious image defect. This can however be corrected by changing the focal length of one of its reflecting mirrors and placing it at a definite distance from the other mirror. It is also shown that residual aberrations can be well eliminated by placing an aspherical correcting plate near the grating surface. By the latter means there is the potentiality of greatly improving the performance of the instrument; either the volume of the instrument may be greatly reduced where shorter focal length optical systems can be used, or much better light gathering capacity can be achieved without sacrificing its monochrometicity when the spectrometer is used as a monochrometor.