The manufacturing procedure of a 500 mm in diameter, f/2 hyperbolic primary mirror based on Computer-Controlled Polishing is introduced in detail. The mirror was finally polished to the shape accuracy of 13 nm rms and the surface roughness of 2 nm Ra. Testing methods and data analysis for different stages ranging from grinding to polishing are discussed. Some critical factors affecting the efficiency and accuracy of the grinding/polishing procedure are summarized. In addition, the preliminary work to make large off-axis asphere mirrors is presented. The difficulties in polishing and testing for both circular aperture and rectangular aperture mirrors are previewed, and a possible solution is given. To control the geometrical parameters such as radius of curvature and conic constant, a new profiler has been built, and it has proven very useful to improve the grinding efficiency. Finally, the manufacturing of small aspheres using deterministic grinding tool is also introduced. The fine grinding procedure of LOH's asphere grinding machine is presented.

We describe the silver coating of 1.3-m secondary nirror being used for infrared observations at Subaru Telescope. This was the first successful in-house runof silve coating on thelarge moern astronimical mirror. Silver was desposited over the chromium bondange layer, using a 1.6-m vacuum coating chamber at the Advanced technology Center of the National Astronomical Obervatoryof Japan in March 1998. The reflectnc eand scatter performnce are measured by micrScan at 670 nm and 1300 nm. Monitor over 17 month shows the silve coated mirror continues to maintain high refleciton.

In wide linear-field of view, large relative aperture mirror system, it is unavoidable to use high order aspheric surfaces. In this paper the design of the compensators for testing the secondary and the tertiary mirror of a 3 mirror system is described. The surfaces under testing have high order up to r¹⁶. The diameter of the secondary is 112 mm, radius of curvature is 211.462 mm, and the conic constant is 0.07744075. The diameter of the tertiary is 272 mm, radius of curvature is 197.722 mm, and the conic constant is 0.2623604. Three elements and four elements compensators have been designed. The residual aspherical aberration has been minimized to about λ/20.

Three-dimensional or x-y-z profilometer is a well-established method for measuring non-symmetric aspherical surface. In this paper, the design of three-dimensional, x-θ -z profilometer called dual gauge profilometer (DGP), which uses a granite straight edge with high precision linearity as reference to reduce the linearity error of ball slide, is presented. The benefits of using this reference structure, data processing and error surface reconstruction are also discussed. Through the use of the novel profilometer, a non- symmetric off-axis mirror with 600 millimeter in diameter can be measured with accuracy of 4 microns Peak to Valley (PV) within 40 minutes, including data processing time.

The increase of the primary mirror diameter for the modern telescopes brings to the necessity to search for the universal high-productive technology of optical mirror manufacture, that would allow loss of the optical quality. Such a technology has been developed by the authors. The main principle, taken as a basis, includes the fact, that the optical elements have a rigid light structure that is connected with the facial (operating) and rear plates in a non-detachable manner. The parameters of such a structure are chosen from the conditions to provide for the demands to the optical element rigidity, both in the exploitation and in the manufacture process as well. The optical elements (mirrors) produced by the given technology, surpass the known ones by their physical and mechanical characteristics, that allows to reach the ultimate optical characteristics, using in this case the traditional approaches and means for the optical surface processing. The given technology, in combination with bearing frame of the same construction and precision actuators (for example, magnetorheological ones), allows to create not only large mirrors but also segmented mirrors in large range of sizes.

Removal function models play an important role in the computer simulation and the practical Computer Controlled Optical Surfacing. This paper presents a novel general model, which can simulate the removal function of a grinding (polishing) tool with any configuration, as long as the tool runs in dual rotation mode. The removal functions of a dual rotation tool with a single pad or with two pads were calculated by this general model and by the existing single pad and two-pad removal function models, respectively and the simulation results coincide with each other. The grinding & polishing experiments also verify this general model. A set of optimized seven-pad flexible grinding (polishing) tool was developed according to this model. A template function model, which simplified the two-dimension parallel circles tracks programming problem into a one-dimension problem was derived from this model. A Φ300 mm, F5.9 focus lens, with 46 μm aspheric degree was successfully fabricated according to the programming results after 8 hours 43 minutes fine grinding & 15 hours polishing.

The advantages of common path interferometers for reducing effects of vibrations are well known. A scatterplate interferometer is one common-path interferometer that is well suited for the testing of large concave mirrors, however due to the common path characteristics it is difficult to perform phase-shifting. This paper describes a phase-shifting scatterplate interferometer where the phase-shifting is achieved by making use of the polarization characteristics of a birefringent scatterplate. The major advantage of this design is that it does not require any optical components to be placed near the surface under test. The theory of the interferometer is presented and experimental results are shown.

Complex optical system, especially the all-reflecting off-axis spherical system is developed and used in the remote sensing camera and the UVX lithophotography. The alignment becomes more important to such system. In this paper, a computer-aided alignment method is described. The wavefront errors are obtained by using the autocollimating interferometric test at some field of views. A serial of aberrations explained by the coefficients of Zernike polynomials is gotten. They are the object values and will be corrected. The least square method is used to determine the misalignments. This method is demonstrated by the results of numerical simulation. The practical experiments are also given.

A computer-aided alignment method is put forward in this paper. It combines laser shearing interferometry and computer- aided optimization, accurately measures the alignment of the optical elements of the system being aligned and gives the adjustment project to control the wavefront quality. The theoretical analysis and experiments demonstrate the ability and effectiveness of this computer-aided alignment method and it especially suits for the on-site alignment of large and complex optical system.

Cryogenic optical system undergoes wide temperature change; therefore it must be athermal. That means when the system is cooled down to very low temperature, its imaging property should be kept as good as at room temperature. One way to achieve athermal optical system requires that all optical and mechanical parts in the system be made from same material. An all-reflective cryogenic optical system was thus developed in IOECAS, in which aluminum alloy was utilized to make such a system. This paper describes the key techniques for manufacturing this cryogenic optical system: material selection, forging process of the aluminum alloy blanks, initial machining, heat treatments, and final figuring. The cryogenic test of the developed system proved the validity of the manufacturing process.

The control system of adaptive optic of a large astronomical segmentated telescope was designed and tested. The dynamic model and the amplitude-frequency analysis of the new magnetic rheology (MR) drive are presented. The loop controlled drive consists of hydrostatic carrier, MR hydraulic loop controlling system, elastic thin wall seal, stainless seal which are united in a single three coordinate manipulator. This combination ensures short positioning error δφ⪅50 nm and small time of response. The main feature of a large astronomical telescope (diameter 25 m) is the large number (in our case 512) of primary mirror segments usage, which are united in one reflecting system. This design makes easier the problem of the primary mirror manufacturing but brings another problem to ensure precise movement of every mirror segment movement and to provides a perfect coincidence of the mirror segments constantly. Suggested parameters of the drive, based on magnetic rheology (MR) liquid are: precision δφ⪅50 nm, time of response T≤0.2 s. Error of positioning of loop-controlled MR drive may be expressed: δφ = δ_r + δ_db + δ_f + δ_i, where δ_r -- 'reproduction' error (depends on drive structure and controlling system, and in our case the drive ensures δ_r = 0); δ_db -- 'disturbance' error (δ_db = 5...10 nm); δ_f -- error, because of static friction forces action (δ_f equals k_t x F_st = 2 x I_s/k_i = 30 nm, where k_t -- transformation coefficient of the drive; F_st -- static force in the drive; I_s -- 'starting' current in the drive; k_i -- transformation coefficient of the measuring system); δ_i -- 'instrumental' error. In case of a laser interferometer usage δ_i = 10 nm and the summarized error is δφ≤50 nm. Time of response T of the drive depends mainly on the combination of time constants of the next elements: MR-valve T_m, elastic elements (pipes, thin-wall tubes, bellows) T_el, moved object (mirror segments) T_s. Experiments show what the MR drive ensures: T_m = 20 ms, T_cl = 20 ms, T_s = 100 ms. Analysis of the amplitude-frequency graphs shows, that the MR-drive ensures summarized time of response till T≤110 ms.

Balloon-borne Solar Telescope is an optical telescope with effective aperture of 80 cm. To reduce polarization effect to measuring of solar magnetic field, the optical system is specially designed and the collimating lens is special and difficult to calibrate. To reduce the gross weight of telescope, the primary mirror is lightweight with thickness- to-diameter ratio of 1/10. But the system must reach to its imaging quality of diffraction limit. So some special techniques are introduced to guarantee the optical imaging quality. First, lateral shearing interferometer is used to test every optical component after they are assembled in barrels or cells; then two visible points that can be seen through alignment telescope form the optical axis of every component. After system optical axis is established also by alignment telescope, those optical components can be calibrated precisely on it. Since lacking standard mirror that is the same size as primary mirror, some ground-base trial observations without vacuum tube were taken to test the imaging quality. According to astronomer's conclusion, the system can get high resolution solar image when in operation.

A kind of super larger, aperture combined, reflective plane wavefront is recommended in this paper. Structure principle and the method of forming accurate plane wavefront are described. Accuracy is analyzed, and several results of local experiments for arguments are discussed. All these prove that the SLAPW with accuracy higher than λ/20(λ-wavelength) can be constructed, which will be used in testing astronomic instruments with any super large aperture.

The development of a lightweight space optics remote sensor with wide field and high resolution is one of the key projects of the researchers. As the traditional approaches couldn't meet the requirements of the project, some modern strategies and methods should be adopted. A high precision, long shaped meniscus mirror is studied in this paper, and its material selection, shape, lightweight strategies, machining method, multi-point support pattern and structure are described. Fused silica or Zerodur is selected as material of the mirror in connection with specific stiffness, dimension stability, machining and cost. An aspherical long shaped meniscus mirror is designed for the optical system. There are rarities of lightweight patterns, i.e. triangular, rectangular, circular and hexagon, and the open hexagon (honeycomb) lightweight pattern is selected with regard to the mechanical and thermal property of the mirror. The mirror should be supported at the edge. With the computer simulation, 6-point flexural support pattern is employed, and the conflict problem between multi- point constraint and freeing the degrees of freedom (DOF) is solved. While the mirror is under the loads (0 gravity at different directions, temperature level exchanging and specified temperature gradient, etc.), the deformation of its surface profile is also acceptable. Finally, the machining method of the mirror is introduced and the allowable assembly error of the mirror set is presented.

The surface of K9 glass substrate whose size is 220x220x40mm³ is polished by bowl-feed polish with polishing agent of ultra pure water combined with cerium dioxide (CeO₂). The super smooth surface with standard rms surface roughness less than 1 nm and reflective wavefront 0.127 λ(p-v) (λ=632.8 nm) was got. The high reflective thin film, whose reflectivity measured by Lambda 19 photometer is more than 99.5% at wavelength 1054 nm for incidence angle 0°, and whose laser induced damage threshold is 26 J/cm² (1054 nm, 1 ns), was coated on this super smooth surface of K9 glass substrate by electronic beam evaporation deposition in the APS1504 coating machine. After alternately coating hafnia (HfO₂) and silicon dioxide (SiO₂) multilayer on the K9 glass substrate surface, this mirror's reflective wavefront is 0.17 λ(p-v) (λ=632.8 nm). The high quality cavity mirror was got.

This paper introduces our research on design and manufacture of space remote sensor's big lightened scan mirrors in brief. And we also look forward to the development.

In the investigation of Inertial Confinement Fusion (ICF), the high power laser beam must be focused on the target (focus plane) given. In the ICF indirect drivers, the target fixed in a cavity is cylinderal, there are the Deuterium and the Tritium in the target, the experiment result relatives with the temperature radiated in the cavity, and the temperature relatives with the laser energy power incided. Thus, it is key that there must be enough of energy incided, and the energy runs out barely. So, to increase the laser energy incided, the focus spot should be very small. Base on the design of focus optical systems of the SHENGUANG serial facilities and the theory analyses, as the diffraction of the light, the laser beam passing through the optical systems gets a spot on the focus plane. In order to reduce the edge of the main spot or the focus spot size, we advance a method of dividing aperture of the focusing optical system, the diffraction theory of light shows that the diffraction main spot is reduced, it indicates that the method of dividing the aperture may be recommended.

The largest astronomical telescope in China with 2 (DOT) 16 m aperture had been installed in 1989 at Xinglong station of Beijing Astronomical Observatory (BAO). From observations of many years including international cooperation programs, a lot of valuable astronomical data and some influential achievement had been obtained. This equipment had been appraised in December 1996. The optics of the telescope has some distinctive features. It has the Ritchey-Chretien Cassegrain system of focal ratiof/9, and the Coud'e system of focal ratiof/45. In this paper, the principle and procedure of alignment of Cassegrain and Coud'e optical systems are described. In the process of adjusting we used two sets of micro-alignment telescope (MAT) and its accessories, designed and manufactured an especially cube prism and its mechanical device. We also used a telescope tube of a 6' theodolite and some adjustable reticles to finish the alignment. With a star as the light source, Foucault's knife-edge test photograph of the optical system at the Cassegrain focus is given. After assembling the fused quartz field corrector on Cassegrain focus, a star cluster photograph, with a whole field of view (30 X 30 cm) also performed. Finally, in the whole field of view from center to edge and corner, the images are round. A member of the appraisement committee measured the linear size. The diameters of dim stars are 0 (DOT) 18 - 0 (DOT) 20 mm. These show that the alignment of the optical system, the design of the fused quartz field corrector, the select of the fused quartz material and its fabricate method are successful.

An ellipsoid mirror with Φ500 mm aperture has been successfully manufactured by NAIRC. The parameters of the mirror are as follows: diameter is Φ500 mm, radius of curvature is 1996 mm, conic constant k=-0.9545, requirements of surface accuracy are λ/10 (P-V) and λ/40 (RMS), (λ=632.8 nm). Based on the surface type, three kinds of test optics are designed. The errors of the elements in the testing optical path are analyzed. The small tools are used to figure the asphericity of the mirror. Finally surface accuracy of λ/10 (P-V) and λ/50 (RMS) are reached.

In this paper, according to the structural features of large reflecting mirror positioning system and the fitting requirement and professional standard of 'Matched Fit,' we explained in detail for the design principle if machining tolerance of the reflecting mirror fitting hole and positioning central shaft. The design procedure and computing method of the tolerance and the technological design process and the guaranteeing measurement when the 'Matched Fit' mode of production is adopted.

The potassium dihydrogen phosphate (KDP) crystal elements served as switcher and frequency converter are the key components in large laser system for inertial confinement fusion (ICF). Such kinds of crystal components, which can be treated as thin plates, are usually fixed on a vacuum chucker connected to the worktable and fabricated by the single point diamond turning machine. The bend due to the vacuum chucking is one of the most important contributors aggravating the distortion of the crystal plate. In this paper, we analyze the influence of vacuum chucking on the distortion of the crystal plate by using finite element analysis method. The calculating results show that the parameters of the chucker, such as the size of the chucking hole, the distribution of the holes, the vacuum pressure and the status of holding the crystal plate, are closely related to the distortion. Another interesting result is that the chucking force from the holes would have effect on the waviness of the surface.

Varied line-space (VLS) plane grating is the great achievement in the history of gratings. But its fabrication is so difficult that only few countries can make it with a grating ruling engine. This paper firstly studies the focusing property of the VLS plane grating. Then a VLS plane grating is designed. The ray-tracing result shows that the grating has a good self-convergence feature. A VLS grating sample was ruled using the improved equi-space, intermittent grating ruling engine in Changchun Institute of Optics and Fine Mechanics (CIOM). The groove spacings of the grating sample were measured by using Talystep. The results show that the groove spacing is varied continuously, which gives the conclusion that the design method and the VLS control method in this paper are effective.

Numerical simulation of temporal evolution and spatial distribution of directors in a liquid crystal (LC) microlens is presented. We show that splay deformation and twist deformation obtained for the LC microlenses with a pre-tilt angle and without one are quite different. Details of director orientation in both types of LC microlenses are discussed.

It is known that for the converged laser beam, the axial intensity distribution corresponds to a Gaussian curve, that is, the intensity on the focal plane is the peak intensity. When it defocuses, the intensity would decrease rapidly. In some cases, optical data storage, for instance, we expect the intensity within a certain distance to be almost equal. In this paper, we propose to use a pure phase superresolution apodizer to optimize the axial intensity distribution of the converged laser beam and at the same time attain superresolution. The intensity point spread function remains almost identical within certain region and the depth of focus is extended.

Composite recording material was synthesized by hydrolysis and polycondensation of tetraethoxyorthosilicate and silane with photoinitiator added. With infrared spectral, the mechanism of response to light of the material was investigated. Vibrational spectroscopy is used to provide insight into the structure changes that occur when films are exposed with UV light. The decrease of absorption intensity in v(C = O) 1698 cm^-1 and v(C = C) 1636 cm^-1 bands reveal the polymerization in material after irradiation. Comparative experiments between two systems with mixed initiation and sole initiation are exported. UV spectra show that the transmittance of the sol-gel thin films drops down in a wavelength range of UV with addition of photoinitiator and irradiation. Developed in dilute base solution, micro-optical elements, such as gratings, were fabricated by contact copy with UV-exposure.

To realize a well defined binary grating (for grating originals as well as grating masks), it is helpful to use a rectangular resist profile because of the importance of the fill factor. This can be achieved easier by e-beam writing than by holography. On the opposite, well-known handicaps of e-beam writing are large writing times and grating ghosts (caused e.g. by stitching errors). We fabricated chromium grating masks (period 500 nm, size 100 mm x 100 mm) by an extremely fast and specialized e-beam direct writing process. The typical and critical parameters, like fill factor and wave front, were locally measured in the whole grating area. The paper will show the method of e-beam writing and the results of lateral grating quality. The remaining errors are separated in problems caused by the writing process and in problems related to resist technology and etching process.

The high frequency compensation of the array micro-optical elements (MOE) is presented in this paper. The authors analyzed the spatial frequency loss of the profiles of the elements by Fourier series at first, and give the compensation scheme in the mask moving (M2) project exposing system. The blazed grating is discussed as an example with the smart mask design and element fabrication. As a result, the transitions of the 5 micrometer blazed gratings were cut down from 1.58 μm to 1.29 μm.

Optical subwavelength gratings are of growing interest for the realization of special optical effects such as artificial birefringence or antireflection layers, for example. The optical properties of such elements strongly depend on the accuracy of the fabrication technology and tools. Although e- beam lithography is known to be a high-accuracy fabrication method, even with this technology systematic grating errors may occur which affect the optical function. One example is the existence of grating ghosts (i.e. undesired propagating diffraction orders) which may occur even in the case of subwavelength grating periods. In this paper we describe how this effect is related to the address grid of the e-beam writer. Measurements of the diffraction spectrum of subwavelength gratings indicate the importance of this effect. The adaptation of grating period and address grid allows the fabrication of ghost-free subwavelength gratings.

We designed and fabricated a diffractive optical element (DOE) applied to improve the characteristics of the divergent angles of the high power infrared semiconductor laser. The fabrication of the DOE and the test of the infrared illuminating system integrated with the DOE are studied in this paper. In order to reduce the difficulty of the micro- fabrication, we proposed a method of quantizing the continuous profile partly with different level while the DOE was designed. The diffraction efficiency of the DOE and the ellipticity of the illuminating system were tested and the results of the experiment illustrated that the DOE with variable-level step phase achieved the design requirement very well.

An interesting scope in micro optics is the transformation of an arbitrary incoming wave front into another arbitrary intensity distribution. This task includes simple focusing as well as the sophisticated control of the propagation properties of the illumination wave. For the reasons of wave length independence and high efficiency, it is necessary to use refractive elements. The design of these beam shaping elements is made by well-known numerical methods based on wave optics. One technology for the fabrication of refractive micro optical elements is gray tone lithography which is capable of the realization of continuous surface profiles with a total height of up to 65 μm. With the use of gray tone lithography on a preform, even higher profiles are capable of being produced. We fabricated high quality lens arrays and different beam shaping elements. The generation of top-hat intensity distributions with different (non separable) shapes or a line of constant intensity are examples of application. We used a single mode fiber as well as a laser diode and a multi mode fiber as light sources. The illumination waves are Gaussian or Gaussian-like beams.

Performances of diffractive and refractive microlens array have been studied and compared. Besides the diffractive microlens array which can be fabricated by means of the microfabrication technologies, method for manufacturing continuous profile refractive microlens array with larger sag depth has been developed for solving the unique problems like diode laser alignment. Both diffractive and refractive microlens array with different numerical aperture and other parameters are fabricated according to the application requirements, experimental results are given.

A uniform period fiber Bragg grating can be chirped by applying an axially strain gradient. We have demonstrated a novel technique for making the chirped fiber Bragg gratings (CFBG), which involves bonding an unchirped fiber grating to the surface of a tapered stainless steel plate which is strained by loading. Three kinds of tapered profiles (convex, gradient and concave) of plates and two kinds of loading procedures (bending and dilating) were used as the means of an in situ absolute center wavelength shifting and reflection bandwidth broadening of a CFBG. By this method, the center wavelength of a CFBG could be tuned from 1548.92 nm to 1550.99 nm, and a maximum adjustable chirp bandwidth of 2.00 nm was obtained for a fiber Bragg grating in 50 mm length. An application in the accelerometer was introduced.

The transmission characteristics of phase-shifted long-period gratings (LPGs) are simulated theoretically by a combination of coupled-mode theory and fundamental-matrix method. It is suggested that a phase-shifted LPG device cascaded with another normal LPG can be used to flatten the gain spectrum of an erbium-doped fiber amplifier (EDFA) with all three gain peaks. The results of simulations have shown that a broadband amplifier with peak-to-peak 0.7 dB gain variation over 36 nm can be practically realized. It proves that such a gain- flattening fiber filter is indeed plausible, and has a potential application in gain-flattening in dense wavelength- division multiplexed (DWDM) telecommunication systems.

In this paper, the process of fabrication of binary optical elements by thin film deposition has been introduced. An eight-level phase microlens array has been fabricated with 20 X 20 rectangularly shaped microlenses, focal length of 100 mm and lens size of 0.8 mm for the wavelength of 0.6328 μm. Our measurements show that all the step heights are nearly identical and the controlled precision of step heights was better than 1 nm.

In this paper we give a brief review of the fundamental acousto-optic interaction theory. Design and fabrication considerations for Multichannel Bragg Cell are studied. We designed and fabricated a four-channel LN/ZF-6 modulator which has 75 MHz center frequency, 15 MHz bandwidth and more than 10% diffraction efficiency.

Concave gratings are now being widely developed for applications of spectrometers, imaging spectrometers and homochrometers. But for the holographic manufacture of concave gratings, it's hard to design the recording parameters because of the nonlinear equations set. We have developed an interactive program, which can be used to auto-design the position parameters of the two recording spherical wave, and evaluate the results by using a ray-trace procedure. The performance is satisfactory.

The principle, method and technical characteristics of high- precision centering and undeformed cementing technique for optical lens are presented in the paper. The method has been used in achromatic lens of 5X and 10X projection photolithographic objective in IOECAS'. The decentration error is within 1" and surface accuracy maintains in original ± λ/20 approximately ± λ/40. The method has the advantages of high precision, fast speed and undeformation.

In this paper, we have discussed the development trend of modern ultra-precision machining technology, described the new structural and control technologies recently used, especially the characteristics of Linear Motors and their applications in ultra-precision machining system. We have also presented our own conception on the future development of ultra-precision machining technology.

The requirements to the design of the optical components, the surfaces of which are machined by diamond turning, are systematized. It is demonstrated that the requirements to the design are determined by the type and parameters of the machine on which processing is realized as well as by the optical component application taking into consideration the possibilities of the technology control of component geometry and optic parameters and the technology of the assembling of the whole device. The examples of the design of the low cooled off-axis, W shaped, scanning and other types of optical components. There are presented design of the some components that may be manufactured only by means of diamond turning (polygon mirrors with different tilt angles, mirrors with concentric and shifted optical surfaces). Recommendations and design solutions that are suggested may be used for the designers of the optical devices.

A quantitative expression for mid-spatial frequency error of the large planar mirror fabricated by computer controlled polishing is employed in terms of wavefront's power spectral density (PSD). The PSD information is calculated from wavefront measured by large phase shifted interferometer. The optimized process parameters are investigated to reduce the mid-spatial frequency error with adequate efficiency to meet the conventional requirements such as P-V and RMS wavefront errors. Based on the criteria of efficiency and PSD, the optimized parameters have been obtained for fabricating precision planar mirror. As an application, a 270 mm x 270 mm x 30 mm mirror has been finished after 10 polishing hours. The P-V value of the reflective wavefront is 0.19 λ (λ= 0.6328μm), and the PSD distribution has also met the requirements.

Though Optical lens with free-form lens (FFL) can be significantly used in optical rectification, it is very difficult to manufacture it. Computer-controlled optical surfacing technology is used to fabricate it efficiently. In the stage of figuring FFL, the component is fixed with vacuum flat sucking disk, then ground by the progressive mode while the abrasion wheel is trimmed on-line. A lapping and polishing tool that conforms to the shape of FFL is used to finish the optical mirror. Because FFL has no any constraints, general interferogram technique can not be applied to its measurement and the accuracy of three-coordinate measuring machine is too low. So a high-precision measurement method based on image conversion is developed to measure the surface. Generally speaking, the precision after forming is under tens of micron. Then the error correction technology is employed to improve surface precision. Getting input controlled variables from error dot matrix involves deconvolution. Least-square filtration is used to solve deconvolution and wavelet analysis is used to filter fringe and tip. Then the surface after error correction is measured again. So a closed loop is formed. The accuracy of optical mirror in our experiment is under 4 micrometers while Ra is under 5 nm.

To test the small aspherical mold surface with large NA, we develop a kind of null lens system which is made up of four thin lenses, the first two thin lenses form a system with small NA which is mainly used to produce positive spherical aberration; the other two thin lens form a large NA system which offers negative spherical aberration; the latter together with that of the front two elements meets the null testing need. The wavefront variation of testing system due to the manufacture & test & assembly and adjustments error is analyzed, by this analyses, we know that we are capable of measuring the aspherical surface to the accuracy of 0.05λ, it is enough to satisfy the testing of mold surface of compact disc object lenses.

People usually take the machining of elements with super- smooth surfaces just as a polishing process. But occasionally super-smooth polishing cannot be accomplished even conducted under a succeeded polishing procedure, resulting in the failure of obtaining super-smooth surfaces repeatedly. A concept of super-smooth surfaces machining 'process technology' is proposed which takes super-smooth surfaces machining as a system in general, not merely a polishing process. We take the machining of super-smooth surfaces as a chain consisted of some key nodes. The failure at any node will result in the failure of the final surfaces. The nodes in the process technology system refer to a series of key sub- items, such as sample material selection, pre-machining, and super-smooth surface evaluation, et al. With the aid of polishing experiments, the effects of some key sub-items are discussed.

In this paper, based on the indentation under different loads, the influence factors for brittle-ductile transition of optical glasses has been investigated theoretically through the simulation of a single grain grinding with the diamond indenter. By the surface and fracture features, the grinding rules and the critical load conditions for the brittle-ductile transition of different optical glasses, the critical grinding depth of the single grain and its influence factors are obtained for the brittle-ductile transition in ultra-precision grinding process. The experimental results show that brittle- ductile transition of optical glasses is controlled by cutting depth of a single grain. When the cutting depth is less than the critical depth, optical glasses are ground in ductile mode. When mean grain size is less than 20 μm, ductile mode grinding of optical glasses can be realized with the relatively larger tangential speed and smaller feed. Otherwise, lubricants is the important factor influence critical cutting depth. Finally, the experimental results of BK7 and FCD1 optical glasses grinding are given.

According to Preston equation, mathematics model of magnetorheological finishing (MRF) is established in this paper. We analyze the pressure acting on workpiece of this model, and find out that the pressure consists of hydrodynamic pressure and magnetization pressure. At same time, the magnetic field used in magnetorheological finishing is introduced, and the expression of intensity of this magnetic field is given. A MRF example for convex spherical surface workpiece in this magnetic field is presented, the mathematical expression of the pressure is deduced, and the rationality of the mathematical expression of the pressure and the reliability of the mathematics model is verified by experiment. Based on mathematics model of magnetorheological finishing and experiment, the curves and the laws of the effect on magnetorheological finishing by several parameters are given.

In order to ensure surface shape accuracy of ground optical parts produced by locus forming, factors of precision grinding machine that affects surface shape accuracy of the part are theoretically analyzed. Formulas used to calculate the error that can be canceled through the machine fine-adjusting device are deduced. Using calculated error values to adjust the fine- adjusting device is able to reduce the surface shape error, and then surface shape accuracy of parts is ensured.

This paper combines nonabrasive polishing with cryogenic polishing and proposes a new method to get super-smooth surface with angstrom dimension -- cryogenic polishing without abrasive. We describe its process and give some experiments to show how to keep stabilization in polishing and how to reduce effects of water quality of ice disk on surface roughness. Experiment results show that modifying ice disk before polishing for eliminating vibration and water quality of ice disk have a vital effect on surface roughness. Experiments of polishing K9(Chinese type) glass with ice disk of tape water, pure water and de-ionized water show that workpiece surface roughness polished by ice disk of de-ionized water is the lowest, up to about Ra 0.5 nanometer (nm). This is a new process to gain super-smooth surface with angstrom level on optical material.

In this paper, the authors present a new technique which through electrolytic truing, could use metal bonded supermicro diamond wheel to machine optical glasses and obtain optical surfaces with best-quality finish. Using this technique to machine K9, F4 and zerodur, the surface roughness Ra could reach a value less than 10 nanometer and a planeness less than 1 μm. In addition, the authors have also studied some phenomena occurred in the grinding process.

Sagittal focusing double-crystal monochromator, which has the double functions that are dynamically monochromating synchrotron light and focusing the monochromatic light, is the kernel instrument of hard x-ray beam line in synchrotron radiation, and sagittal focusing crystal is the key part in the monochromator. The sagittal focusing monochromator, which is being manufactured, has energy range, 5 to approximately 20 KeV, focusing radius, 0.8 to approximately 5 m, focusing precision ΔR/R, better than 0.75%, and at 10 KeV, meridional anticlastic deformation, less than 1.8 arcsec, sagittal focusing slope error, less than or equal to 2 arcsec. This paper discusses the design, manufacturing and testing about the sagittal focusing crystal in the sagittal focusing monochromator.

The newest achievement of super smooth processing technology of optical element bowl-feed polishing (BFP) is described. The need background and developing tendency of super-smooth optical elements are analyzed. The key problems of BFP have been found, the process parameters have been determined, and the basic method of BFP has been worked out by the study of process factors and processing principle. Φ50 mm k9 glass sample with 0.5 nm surface roughness and better than λ/8 surface shape has been processed.

ELID (Electrolytic In-process Dressing) grinding is a new ultra-precision machining technique which employs in-process electrolysis to dress the metal bond diamond wheel in grinding process. In this paper, the principle of ELID grinding is introduced. An optical glass sample is ground by using cast iron bond diamond wheel and ELID technique. Tested by WYKO RST Plus, the grinding surface roughness Ra is 2.48 nm. A conclusion can be drawn that using ELID technique can realize the ultra-precision grinding of optical glass.

Experiment methods such as X-ray diffraction, ICP-AES, TEM are adopted to study the relationship between optical properties and inside defects of CVDZnS samples which deposit at different experiment conditions. Through our studies, we draw the conclusion that there inside the material exists a kind of Zn-H associated particle which functioned as optical scatter centers. These scatter centers will lower the transmittance of CVDZnS both in the visible and the IR spectral regions. However, these Zn-H associated particles can be diminished through Hot Isostatic Pressing processing, and after the processing the transmittance of ZnS will substantially improved, especially in the visible spectral region.

Based on the anisotropy of granular structure, the reasonable criterion was given to understand the generation of the prior cleavage or slip for each cleavage system or slip system. The phenomenon that the roughness of the diamond turned single crystal materials's surface distributes in scallop is explained, and a turning method is presented to eliminate the scallop distribution. Beside this, the AFM was used to observe the micro-topography of the light and shade area of brittle single crystal material's diamond turned surface. The criterion is in good agreement with the observed results.

A scheme of tunable optical orthogonal encoder/decoder for all optical code division multiple access communication is proposed in this paper. It consists of a fiber splitter, a fiber combiner, N of 2 x 2 electro-optic switches and N of optical delay lines. It overcomes the poor correlation, small capacities and narrow tunable range of prime-code and 2ⁿ code tunable optical encoder/decoder found in the literature. The configuration of the proposed tunable encoder/decoder is simple and it is flexible for application. In addition, it has low optical power loss and easy in practical uses.

In this paper a practical optical CDMA (Code-Division Multiplexing Access) encoder/decoder based on optical fiber delay lines (OFDL) for OOCs (optical orthogonal codes) is proposed, its performance is analyzed in three aspects, (1) The probability of bit error versus chip pulse width, (2) Stability versus temperature, pressure and strain, (3) The relationship between length error and bit error rate in NRZ format and RZ format.