Potassium dihydrogen phosphate (KDP) crystals are widely used in high-power laser systems and inertial confinement fusion applications. However, machining KDP crystals using ultra-precision fly-cutting technology poses challenges due to the combined elastic, plastic, and brittle deformation mechanisms, making it difficult to analyze the material removal process. This investigation aims to observe and analyze the elastoplastic behavior of KDP crystals in the ductile region, which has received limited attention in previous studies. Nanoindentation experiments were conducted to analyze the elasto-plastic transition in KDP crystals, employing an approach instead of the traditional Oliver–Pharr method. Additionally, a cutting experimental method was developed to observe the reverse behavior during manufacturing by introducing a process with a 0 nm depth of cut. The results reveal significant rebound deformation and anelastic behavior, providing a comprehensive understanding of the deformation mechanism in KDP crystals at the nano- and micro-scale cutting levels. This knowledge contributes to modifying the diamond turning process and optimizing the fabrication procedure of KDP crystals.
A novel subaperture stitching method based on monoscopic deflectometry in single point diamond turning is introduced in this study for measuring large-aperture optical surfaces. This method not only solves the phase position deviation between subapertures, but also eliminates the system calibration error. The objective optimization is achieved by utilizing the gradient deviation and form deviation at the overlapped areas of adjacent subapertures. To achieve full-aperture measurement of the SUT, the global gradient is integrated to reconstruct the SUT. Experimental validation confirms the feasibility of the method.
Phase measuring deflectometry (PMD) is a high-precision and low-cost measurement method for specular surface. The simple system configuration and nanoscale measurement accuracy make it possible to integrate the fabrication and testing systems of ultra-precision components, which is of great significance to the improvement of manufacturing efficiency and reliability. In machining, workpiece clamping is a key step before turning. However, repeated the clamping error of the workpieces will reduce the accuracy of manufacturing. Therefore, an alignment method is needed to obtain the actual position of the remounted workpiece to ensure machining quality. A method is proposed to realize non-contact workpiece self-positioning using PMD. A positioning method is proposed with strong anti-noise ability based on PMD in this paper. By adding different centroid positioning errors to the camera target surface, it is verified that the positioning accuracy of the model can achieve a micron level and strong noise immunity. The method solves the problem of workpiece positioning using PMD without increasing the complexity of the system.
Weak-rigid components have a wide range of applications in the fields of aerospace, vehicle and ship power. They have the characteristics of high accuracy, poor rigidity, and easy deformation. The uncertainty of their deformation has an important impact on the overall performance and subsequent use of the equipment. Weak-rigid plates are one of the most common types of weak-rigid components. At present, the research on weak-rigid plates mainly focuses on the deformation control of the workpiece during processing, and there are relatively few studies on the measurement of comprehensive parameters. The surface profile parameters of the weak-rigid plate will reflect the performance and processing quality of the weak-rigid plate. In this paper, a comprehensive index measuring device for weak-rigid components based on dispersion confocal sensor and a stress change test system for weak-rigid components based on dynamic interferometer are used to accurately measure the surface profile of weak-rigid plates, which provides a basis for its process parameters and subsequent assembly use. It provides a reference for the subsequent measurement of the surface profile and thickness of weak-rigid curved components.
With vigorous development of modern optical manufacturing in the direction of intelligence and precision, coupled with the continuous increase in the diameter of optical components and continuous improvement of precision requirements, industrial robot polishing technology has a wide range of application scenarios and broad development space in the field of optical manufacturing. The integration of processing and measurement is a key technology to improve the reliability and intelligence of precision manufacturing. Therefore, the research and development of in-situ measurement technology has become an important trend in the field of optical manufacturing. A measurement method based on deflectometry is a type of surface gradient measurement method that has been proposed and developed in recent years. Due to the advantages of superior simplicity, stability, and high dynamic range, it is promising for the in-situ measurement of optical surfaces. Based on monoscopic deflectometry, this paper develops an in-situ measurement device for industrial robot polishing system. The key problems of phase decoupling and optical path correction of transparent components are being researched, and high-precision double-surface measurement of transparent optical elements is realized, which is of great significance to the intelligent manufacturing of key optical elements.
Stereo deflectometry can specify the position of a workpiece and reduce the difficulty of geometrical calibration. But the measurement scope is limited, and this issue is especially severe for the measurement of complex surfaces. A method is proposed to extend the measuring scope of stereo deflectometry. The nominal model of the surface under test is aligned with the overlapped measurement area of the stereo vision system, and the other areas outside overlapped region are measured using the monoscopic SCOTS approach with each camera, respectively. This method effectively combines the advantages of stereo and monoscopic deflectometry, and the measuring accuracy and flexibility can be improved.
The dual wavelength interferometry in digital holography can eliminate 2π ambiguities with a large synthetic wavelength, but the measurement error tends to be amplified. In this paper, a new numerical algorithm is proposed to reduce the amplification error, and further expand the measurement range. The wrapped phase map associated with one wavelength is used to assist unwrapping the phase map associated with the other wavelength. Since these two phase maps correspond to the same step height, an exhaustive searching method is applied. The measurement error will not be amplified linearly with the synthetic wavelength, but controlled at the same level with the single wavelength interferometry. In consideration of the measurement errors such as the environmental vibration, instability of wavelength and so on, a tolerance is set to guarantee the stability of the solution. The performance and feasibility of the proposed algorithm is verified by the numerical demonstration.
An IRB6620 industrial robot from ABB Co. Ltd. (Zurich, Switzerland) is used as a processing platform for optical processing, and computer-controlled optical surfacing is applied as a key technology. The function of each coordinate system of the robot in processing is reviewed, as well as the relationship of each coordinate system and coordinate transformation. An algorithm governing coordinate transformations is provided. In order to assess the functionality of the robot as a polishing instrument, experiments have been designed so that the removal rate and surface form error correction of the robot facility have been compared with those from established computer numerical control polishing. The importance for the application of industrial robot in optical processing is also presented.
As the development of modern optical technology, especially space optical science, more high precision mirrors with
large apertures are needed. But it is difficult to manufacture high precision large aperture optical components. The
method of optical polishing using an ultra-precise bonnet is based upon the technology of computer controlled optical
surfacing. A bonnet filled with air is applied as a precise polishing tool which is flexible and able to adapt itself well to
the shape of the part, which is superior to other polishing methods. A material removing model of bonnet precessed
polishing is established according to kinematic principle based on the Preston equation. The model is modified in terms
of Hertz contact theory using the physical characteristics of polishing bonnet tools. A satisfactory result was obtained for
one of the surfaces of a wedge mirror with a diameter of 570mm. The resulted PV and RMS parameters are 1/8 λ and
1/75 λ respectively.
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