This paper presents a semirigid (SR) bonnet tool which has the advantages of high efficiency and determinacy for material removal on optical elements and also has the potential to be used on aspheric optics. It consists of three layers: a metal sheet, a rubber membrane, and a polishing pad, from inside to outside. It inherits the flexibility of a normal bonnet but has a higher stiffness. Finite element analysis was performed to determine that the stainless steel is the best-suited material for use as the metal sheet. An SR bonnet with a stainless-steel metal sheet was fabricated and tested. Its tool influence function (TIF) is Gaussian-like, and the TIF stability is more than 90%. The peak-to-valley of its uniform removal area is less than 0.1λ. Tool ripples are highly depressed and the surface profile is well preserved in the prepolishing test. In 12 min, ∼36 mm3 of material is removed.
The purpose of this paper is to study the effect of the inner pressure to the tool influence function (TIF) for polishing using a semi-rigid (SR) bonnet tool. The simulation model of a Semi-rigid (SR) bonnet polishing tool polishing BK7 is demonstrated and the pressure distribution data under different inflated-pressures in the contact area has been extracted. It’s observed that the inflated-pressure has few effects to the polishing pressure, and their shapes are also Gaussian-like. Hence, we made a hypothesis that the effect of inflated-pressure to the TIF is rather small. To verify this hypothesis, a group of experiments to generate TIFs under different inflated-pressure are conducted, and the hypothesis has been proved to be correct through comparing these TIFs.
For extremely high accuracy optical elements, the residual error induced by the superposition of the tool influence function cannot be ignored and leads to medium-high frequency errors. Even though the continuous computer-controlled optical surfacing process is better than the discrete one, which can decrease this error to a certain degree, the error still exists in scanning directions when adopting the raster path. The purpose of this paper is to optimize the parameters used in bonnet polishing to restrain this error. The formation of this error was theoretically demonstrated and will also be further experimentally presented using our newly designed prototype. Orthogonal simulation experiments were designed for the following five major operating parameters (some of them are normalized) at four levels: inner pressure, z offset, raster distance, H-axis speed, and precession angle. The minimum residual error method was used to evaluate the simulations. The results showed the impact of the evaluated parameters on the residual error. The parameters in descending order of impact are as follows: raster distance, z offset, inner pressure, H-axis speed, and precession angle. An optimal combination of these five parameters among the four levels considered, based on the minimum residual error method, was determined.
Bonnet polishing system is mostly used in rough polishing and fine polishing because of its own features. Due to
different aims of polishing stages, optimal ranges of key parameters are different in various polishing stages. Simulations
in ANSYS are present in order to get optimal ranges of key parameters including inner pressure P and compression of
bonnet H in different polishing stages, firstly, the reliability of simulation of bonnet polishing using ANSYS is verified
through a series of simulation about fine polishing stage, on the condition of using ranges of key parameters got by
former researchers from polishing experiment; secondly, simulations about rough polishing were carried out, and optimal
ranges of key parameters were found, which have reference value in future work.
The tool path generation based on iso-phote is a kind of feature based path generation method. Iso-phote curves represent
the characteristic curves on a parametric surface. Accordingly, iso-phote based tool paths has been proposed as an
important path pattern for parametric surface machining. An adaptive interpolation method for tool path generation based
on iso-phote interpolation for wedge/aspheric lens element grinding was proposed, which takes into account the
symmetry problem of wedge/aspheric process behavior. This paper presents an efficient interpolation method for tool
path generation approach based on iso-phote curves and bisection method. By the application of parallel grinding, the
approach can guarantee the feature of aspheric lens, maximize machining speed and smooth the machine operation for
high surface quality. The interpolation method guarantees that step length of the interpolated points always keep the
precision. The method can improve and automate large scale wedge/aspheric lens element grinding for 3-axis
CAD/CAM systems. As part of the validation process, the tool paths generated and interpolation error are analyzed and
compare with the traditional method.
To improve machining accuracy of non-axisymmetric lens, this paper presents the grinding mode with equal arc length feeding in parallel grinding, and analyses the relations between machining error and machining step in both equal length mode and equal arc length mode. For the same purpose, this paper also discusses the calculation of 2-axis machining path compared with 3-axis machining. Finally, the calculation and simulation of machining path are carried out to guide practical grinding.
Currently, many large-scale, resource-intensive applications and services such as Grids supported only by high-performance,
highly distributed infrastructures are being developed. These ultra-broadband services have put forward
high requirements of end-to-end Quality of Service (QoS) and of dynamic resource management, which makes end-to-end
optical resource provisioning necessary. For this reason an intelligent optical access network which combines
advantages of Generalized Multi-Protocol Label Switching (GMPLS) and Passive Optical Network (PON) proposed here.
In our scheme, GMPLS is in charge of providing control plane to manipulate PON communication and introduce traffic
engineering, while PON technology such as WDM-PON is employed as data plane following the control of GMPLS. We
describe the architecture of proposed network and illustrate the concept of common GMPLS control plane shared by
both core and access network. Then the functional module of intelligent Optical Line Terminal (OLT) and Optical
Network Unit (ONU) has been discussed. Finally, QoS model for access network and entire scheme for end-to-end
optical service provisioning have been introduced in detail.
To generate axisymmetric aspheric surface function rapidly, virtual quadratic curves are adopted. Mesne constant, peak to picked length L, half parietal angle α and inclination between section & axes Φ are adopted in the selection of suited curves. The relationship between L, α, Φ and idiocratic parameter p, eccentricity e is analyzed with Matlab. Then machining locus is generated and optimized. Research results showed that, with the mathematical model found on the basis of virtual quadratic curves, the axisymmetric aspheric function and its machining locus could be generated rapidly.
The key technology for aspheric machining offers exact machining path and machining aspheric lens with high accuracy and efficiency, in spite of the development of traditional manual manufacturing into nowadays numerical control (NC) machining. This paper presents a mathematical model between virtual cone and aspheric surface equations, and discusses the technology of uniform wear of grinding wheel and error compensation in aspheric machining. Finally, a software system for high precision aspheric surface manufacturing is designed and realized, based on the mentioned above. This software system can work out grinding wheel path according to input parameters and generate machining NC programs of aspheric surfaces.
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