This paper analyzes dot-line envelope grinding principle, which is applicable to mid-large- aperture square aspheric
optical element, determines the mathematical process control model based on X/Y/C three-axis aspheric grinding
machine, We develop the appropriate high-precision aspheric grinding manufacturing and measurement systems
software, using the plane grinding wheel to do the grinding experiments and the repeated compensation processing
experiment. The experiments show that: high-precision aspheric grinding manufacturing and measurement systems
software can be realized axisymmetric aspheric high-precision machining control and measurement; using compensation
processing of the X/Y/C three-axis aspheric grinding machine which can effectively improve the precision PV value,
surface error from the initial processing of the PV value :12 μm to the compensation processing of the PV value :3 μm .
In this study, uniform InAs QDs were grown on the GaAs (001) substrate by MBE by the S-K mode. The effects of strain reducing layer and rapid thermal anneling on the optical properties of InAs/(In)GaAs QDs were investigated by PL measurements. The annealing results in PL peak energy red-shift which strongly depends on In composition of InxGaAs strained reducing layer , QDs with lower density and/or capped by an InGaAs layer are very sensitive to the annealing. At given annealing conditions, PL peak energy blue-shift of low-density QDs is much larger than that of high density QDs.
The growth parameters affecting the deposition of InGaSb quantum dots (QDs) on
GaAs substrate by molecular beam epitaxy (MBE) were reported. The InGaSb were
achieved using lower growth temperature and optimized growth interruption, which is
important to obtain high-quality materials Photoluminescence (PL) measurements show
the good optical quality of InGaSb QDs. At room temperature, the wavelength of PL
spectrum and full-width at half-maximum (FWHM) are around 1.3 m and 106 meV,
High quality crack-free GaN layers were successfully grown and the InGaN/GaN based blue LEDs
fabricated on patterned Si (111) substrates. In addition to using the patterned growth technique, thin AlN and SiNx
interlayers grown at high temperatures were also employed to partially release the residual stress and to further
improve the crystalline quality. 300 µm square blue LEDs fabricated on the islands, without thinning and package,
exhibited a high output power of around 0.68 mW at a drive current of 20 mA.
The AlGaAs/GaAs double quantum well semiconductor lasers grown by molecular beam epitaxy show high
external quantum efficiency and high power conversion efficiency at continuous-wave power output using an
asymmetric structure. The threshold current density and slope efficiency of the device are 200A/cm2 and 1.25W/A,
respectively. The high external quantum efficiency and maximum conversion efficiency are 81% and 66%, respectively.
Semiconductor lasers at wavelengths around 1.3μm are widely used for optic communications. For GaInNAs, the
incorporation of nitrogen in the active layer can reduce the band-gap energy and allow emission wavelengths as long as
1.3μm. Ridge waveguide GaInNAs strain single-quantum-well lasers were fabricated with pulsed anodic oxidation
(PAO). Using the technology PAO, we prevented the damage from the ion bombardment in the procedure of sputtering
silicon dioxide used for building the insulating film. The output power of the laser with a wavelength of 1.31μm reached
14mW in CW mode at room temperature. The threshold-current was 18mA and its density was 360A/cm2. The
characteristic temperature of lasers was 135.1K and the quantum efficiency reached 76%.
Motion estimation plays an important role in video compression systems, and it's the most intensively computational and the most time-consuming part at the same time. So it could significantly affect the operation efficiency of whole video coding systems and the reconstructed quality of video sequence. The latest video coding standard, H.264, provides a significant coding efficiency than previous standards. But this coding gain comes at the cost of a very computationally-intensive motion estimation module. To realize the implementation of the H.264 video coding in-time, it's desirable to develop fast motion search algorithm. In order to reduce computation complexity of the motion search at sub-pixel accuracy, a fast and effective search algorithm for half-pixel motion estimation is proposed in this paper. Based on the single valley characteristic of half-pixel error matching function inside search grid, half-pixel candidate points needing checking are predicted with the help of comparison results of SAD values for four integer-pixel points around integer-pixel motion vector, so a great number of computations associated with search process are avoided. The experimental results reveal that, to all kinds of video sequences, the proposed algorithm can obtain almost the same video quality as that of the half-pixel full search algorithm with reduced average 72% computation cost.
The operation principle of laser rotary encoders is expounded and the optical quadruple frequency technology used in laser rotary encoders is explained, and the design idea of optical system in (phi) 66 mm laser rotary encoder is mainly introduced, as well as the choice of principal devices.
A new method of laser scribing on polycrystalline diamond film is proposed in the paper, the requirements of laser machine output, the calculation of technological parameters and the best combination of voltage, pulse duration and feed rate are discussed. Finally, the paper gives the laser scribing experimental results.
The paper introduces an auto measuring system of belt transmission parameters. In the paper, the auto measuring method and device of the torque, slip ratio and pulling force measurement are described in detail finally, the paper gives an agreeable measuring results of some parameters in belt transmission.
Appraise the properties of bullet synthetically, a fine instrument for measuring the equatorial rotational inertia and polar rotational inertia of various bullets and rifle grenades is precisely developed. In this measuring instrument, a double suspensions structure is adopted, and a reflecting photoelectric coupler is used to extract the signal of torsional-oscillation period of the measured bullet, the extracted signal is processed by computer, and the data concerned is output on the displayer, furthermore, the measuring precision of the instrument has been analyzed with theoretically, main factors affect the precision has been discussed. The maxima of radial deviation of the measured bullet to the ideal position and the maxima inclination of the axis of the bullet to the axis of steel wires are calculated, and measured to ensure measuring precision are proposed.
This paper introduces a novel method of non-contact dynamic measurement of liquid level position with an instance of the monitoring system of liquid-steel level position; presents an important aspect to improve the system sensitivity and stability, and explores the system measurement theory and the resolution speed.