Hard and brittle materials are critical components of optical systems. Due to their unique mechanical properties, these materials' surfaces are highly susceptible to damage during the grinding process. Surface damage on optical components significantly reduces their mechanical strength, laser damage resistance, and impact resistance. Therefore, it is imperative to research grinding technologies that minimize surface damage in hard and brittle optical materials. This paper begins by examining the grinding mechanisms of hard and brittle optical materials, summarizing the mechanisms of surface damage, the transition between toughness and brittleness, and their applications. Additionally, the research progress of ultrasonic vibration-assisted grinding technology is reviewed. The influence of processing parameters, such as grinding force, grinding depth, and wheel morphology, on subsurface damage is investigated. The study also explores how parameter control in the grinding process can predict surface damage and analyzes the mechanisms, advantages, and disadvantages of ultrasonic vibration-assisted grinding technology in mitigating grinding damage.
Central to future optical device developments in diamond is the provision of smooth, low defect density substrate materials. Research progress of optical diamond material surface polishing technology were comprehensively reviewed, the polishing effect and the advantages and disadvantages of the current high-usage polishing methods were introduced, including mechanical polishing, thermal chemical polishing, chemical auxiliary mechanical polishing, laser polishing, plasma treatments etc. The generation of composite polishing technology helps to improve the deficiencies of the original polishing technology and obtain a smaller surface roughness, which is the main research direction at present. Super ultra-precision and high quality on optical diamond surface is the technical development trend in future. A new no contacting method of polishing optical diamond using ion beam was proposed in this paper, which has great application potential because of its advantage of super ultra-precision and no damage.
KEYWORDS: Ion beams, Optical components, Ions, Chemical species, Thermal effects, Optical surfaces, Monte Carlo methods, Glasses, Sputter deposition, Optical simulations
Ion beam has the advantages of high accuracy and little damage to components, which has been widely used in the figuring of optical components. However, in figuring, the collision between the ions with high-speed collides and the surface of the optical component will cause the temperature of the optical component to rise quickly. In order to investigate the thermal effect of the ion beam figuring, the thermal deposition model is established based on the Sigmund theory of sputtering, and the thermal power density function of the surface heat source is obtained. On this basis, taking BK7 glass as the research object, Monte Carlo method was used to obtain the total power of thermal deposition under the different incidence angle of ion beam. Then the finite element method was used to simulate the thermal effect of the ion beam figuring. The result shows that the deposition energy, maximum temperature and the maximum stress decrease with the increase of incidence angle, and the maximum stress appeared in the clamping position of fixture. The corresponding simulation result shows that comparing with the fixing fixture, the maximum stress in the optical component could be reduced more than 70% by using elastic fixture.
In order to the dwell time function can be solved quickly and accurately, the sampling step length of the dwell point in the solution process of ion beam polishing dwell time has been optimized. Taking the PV value for per unit of uniform material removal and dwell time as the analysis object, the fluctuation caused of uniform removal and the total dwell time under different dwell time sampling step length are analyzed. The optimal dwell time sampling step length of ion beam polishing is 1.5σ。Using the determined sampling step length, the optical element with a diameter of 50mm is simulated polishing, and the surface PV value of the element decreases from 110.81nm to 20.06 nm. The optical element was polished by ion beam according to the simulation results, the PV value of the element surface decreased from 110.81nm to 46.46nm. The experimental results verify the effectiveness of the simulation results. Using the determined dwell point sampling step length, the dwell time can be solved quickly, and the PV value of the optical elements converges well.
In order to study the lattice damage caused by low-energy argon ions on the single crystal silicon substrate and the influence of incident energy on the substrate damage during the ion beam polishing process, the molecular dynamics (MD) was used to simulate the incidence of a single argon ion on the single crystal silicon substrate. Compare the lattice defects produced by the bombardment of single crystal silicon by ions of different incident energy. Ion beams with different incident energy were used to polish the surface of single crystal silicon, and the surface roughness after polishing was compared. Experimental and simulation results show that ion bombardment will cause lattice damage to the surface of the substrate. As the energy increases, the range of lattice damage will expand and the resulting lattice defects will be more dispersed. The use of low-energy (200~600eV) ion beams can further reduce the surface roughness of the substrate on the basis of reducing lattice damage
Surface of fused silica optical components were polished by Ion Beam Figuring (IBF) ultra-precision process. Based on the analysis of the relationship between the ion beam current density distribution parameters obtained by faraday scan and the removal function, the removal function model for IBF was established. The IBF experiment for fused silica optical materials were carried out. The experimental results show that the IBF method based on faraday scan can achieve the same figure correcting ability as the traditional IBF method based on line scan experiment. But the offline calculation time of the removal function can be reduced from 2 hours to 5minutes, which improves the efficiency of IBF greatly. After several cycles the initial surface figure error of the optical element before processing, with a PV value from more than 500 nm to less than 15nm and an RMS value from more than 120nm to less than 1.5 nm. Ultra-precision surface of fused silica optical components with nanometer scale were obtained by IBF.
In order to solve the problems of no uniform coating, edge coating, and severe coating defects in the process when processing 430mm×430mm optical components, The basic requirements of surface roughness data acquisition are analyzed and the application of inductive sensor in surface roughness is introduced. Optical element flattening layer coating and flow direction mechanisms, flattening layer material selection, and research on material characteristics and optical element planarization layer deposition process, achieving uniform coating of optical elements, reducing coating defects, and meeting the requirements of the next process polishing
PS plate (presensitized plate) is a new type of plate used in the fast printing industry. Due to the "squeaking" caused the production process, it will seriously affect the printing quality. This kind of helium detection device is currently entirely monopolized by large foreign companies, the price is expensive, and it is also not suitable for the conditions of domestic enterprises. The development of this device will fill the gap in the domestic field. At present, most domestic companies adopt manual inspection methods for naked eye observation. Because of the subjective nature of human beings, it is impossible to quantitatively analyze. The PS version quality report provided by the device development provides data basis for later-stage sheet and stacking work which can realize Intelligent production.
In the ion beam figuring(IBF) process, a stable removal function is the premise of ion beam figuring, and the information of removal function is generally obtained by experimental methods. Based on the study of removal function model, the stability of the removal function is analyzed by line scan method. A line scan experiment was performed on a 50mm diameter optical component, within 1h, the removal function's peak removal rate varies in 0.74%, full width at half maximum (FWHM) varies in 0.41%, and volume removal rate varies in 2.62%. The removal function is stable and can be used for actual ion beam figuring. Using this method, the stability of the removal function can be verified to ensure that it satisfies the figuring requirements.
It is a critical technology to improve the optical film uniformity during the film deposition process. The ion beam sputtering and polishing system was used to prepare the film on the surface of large-aperture optical elements. A calculation method for controlling the dwell time ratio I of the ion beam working at the center and edge of optical component was proposed. The dwell time ratio I was calculated by the film thickness data obtained from the center and edge, and the dwell time ratio I was revised step by step. Then it was input in the program as one of the sputtering process parameters. The experimental results show that, when I was revised to -26.6%, uniform film can be achieved on optical elements with a diameter of 300mm-600mm. Taking a Si film on the surface of fused silica as an example, the experiment was carried out for 6 hours. The film thickness is about 212 nm, and the film uniformity could reach up to 0.42%, which meets film thickness uniformity requirements by ion beam sputtering deposition method.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.