Frontier disciplines. The planar relief binary optical device based on computer-aided design and micron-scale processing technology has the advantages of light weight, easy replication and manufacturing.
Low cost, etc., and can realize new functions such as miniaturization, array, integration and arbitrary wavefront transformation that are difficult to be completed by traditional optics, thus making optical engineering and technology
It is used in many fields of modern national defense science and technology and industry, such as space technology, laser processing, computing technology and information processing, optical fiber communication and biomedicine.
It shows an unprecedented important role and broad application prospects. In the early 1990s, the study of binary optics rose internationally, and at the same time,
It has aroused great interest and favor from academia and industry.
With the rapid development of modern optics and photoelectric technology, profound and great changes have taken place in photoelectric instruments and their components. The optical component not only has
Only refractive lenses, prisms and mirrors. New optical elements such as microlens array, holographic lens, diffractive optical element and gradient index lens.
It is also increasingly used in various photoelectric instruments, making photoelectric instruments and their components more miniaturized, arrayed and integrated. Micro-optical element
It is a key component for manufacturing small photoelectric subsystem. It has the advantages of small size, light weight and low cost, which is difficult for ordinary optical elements to achieve.
New functions such as miniaturization, array, integration, imaging and wavefront conversion have been realized.
Optics is an ancient science. Since Galileo invented the telescope, optics has gone through a long way for hundreds of years. The appearance of laser in 1960s promoted the development of laser technology.
With the rapid development of optical technology, traditional optical elements (devices) based on catadioptric principle, such as lenses and prisms, are all mechanically milled, ground and polished.
Lights, etc. Not only the manufacturing process is complicated, but also the parts are large in size and heavy in weight. Under the current trend of optical, mechanical and electrical integration, instruments
The child becomes bloated and heavy, which is extremely mismatched. It is an urgent task for the optical community to develop small, efficient and arrayed optical elements. In the mid-1980s, America
The research team led by Veldkamp of Lincoln Laboratory of Massachusetts Institute of Technology in China took the lead in proposing the concept of "binary optics" to design a new sensing system.
Reading, he described it like this at that time: "Now there is a branch of optics, which is almost completely different from the traditional production method. This is diffractive optics and its optical elements. "
The surface of the sheet has a relief structure; Because the original manufacturing method is used to manufacture integrated circuits, the mask used is binary, and the mask is also binary.
The code form is layered, so the concept of binary optics is introduced. "Then binary optics has developed rapidly not only as a technology, but also as a discipline.
For the favor of academia and industry, there is an upsurge of studying binary optics in the world. Binary optical elements (devices) are widely used in light wave conversion.
It has many outstanding functions that traditional optics do not have, which is conducive to promoting the miniaturization, array, integration and opening up of optical systems.
A new vision in the field of optics. Up to now, there is no unified view on the exact definition of binary optics, but it is generally believed that binary optics
Based on the diffraction theory of light wave, using computer-aided design and VLSI manufacturing technology, the thin film substrate (or traditional light)
The surface of a chemical device) is etched to produce a relief structure with two or more step depths, forming a diffraction with pure phase, coaxial reproduction and high diffraction efficiency.
Optical element. It is a frontier subject of mutual penetration and intersection between optics and microelectronics. Binary optics is transforming not only conventional optical elements, but also traditional optics.
It is technically innovative and can achieve many goals and functions that traditional optics can't, so it is known as "optics in the 1990s". it
Its appearance will bring a revolution to the traditional optical design theory and processing technology. Binary optical elements are derived from holographic optical elements (HOE), especially computational holograms.
Information element. It can be considered that the phase diagram is an early binary optical element. However, holographic elements are inefficient and reproduce off-axis; mutually
Although the infographic is reproduced coaxially. But the process has not been solved for a long time, so the progress is slow and the application is limited. Binary optics technology solves the problem of diffraction element at the same time.
Speed and handling problems. It approximates the continuous relief structure of information graph with multi-order phase structure. Binary optics is an important branch of micro optics. Microscopic optics
It studies the design and manufacturing technology of micron and nano-sized optical elements, and uses this element to realize the emission, transmission, conversion and connection of light waves.
A new theoretical and technical discipline. The two main branches of micro-optics development are: (1) gradient index optics based on refraction principle, and (2) diffraction principle.
Binary optics of science. Both of them have their own characteristics in device performance and process manufacturing. Binary optics is the most dynamic and promising micro-optics field.
A forward branch of the army. The development of optics and electronics is based on two key technologies of micromachining: submicron lithography and anisotropic etching.
Microelectronics promotes the development of binary optics, and the progress of microelectronics industry benefits from the improvement of lithography level. In addition, binary optical technology
The scalar diffraction theory and Fourier optics are analyzed. The mathematical expression between diffraction efficiency and phase order of binary optical elements is also scalar diffraction.
The result of projective theory. In this range, the design of binary optical elements can be regarded as an inverse diffraction problem, that is, given the incident light field and the required
The transmittance function of the diffraction screen is obtained from the outgoing light field. There are roughly five optimization design methods based on this idea: Gershberg-Saxton.
(Gerchberg-Saxton) algorithm (GS) or error subtraction (ER) and its correction algorithm, direct method of bisection method (DBS is also called hill climbing method (HC)), simulated regression.
Fire fighting algorithm (SA) and genetic algorithm (GA). Among them, simulated annealing algorithm is a method suitable for solving large-scale combinatorial optimization problems and has the advantage of simple description.
And has the advantages of flexible use, wide application, high operation efficiency, less restriction by initial conditions and the like; Genetic algorithm is a kind of learning of natural selection and self in biology.
The high parallelism, randomness and adaptive search algorithm of genetic mechanism combine the principle of survival of the fittest with gene exchange mechanism to form a genetic algorithm.
Search technology has a unique optimization mechanism, especially suitable for parallel operation, and has been applied in many fields. At home, Institute of Physics, Chinese Academy of Sciences
He Gu put forward the general theory of amplitude and phase recovery of arbitrary linear transformation system and Yang-Gu (Y-G) algorithm, and successfully applied them to the solution.
Solve various practical problems and transform the system. In many applications, the feature size of binary optical elements is on the order of wavelength or sub-wavelength, and etching
The depth is also very large (up to several wavelengths), and the assumptions and approximations in scalar diffraction theory are no longer valid. At this time, the polarization properties and polarization of light waves are different.
The interaction between light plays an important role in the diffraction results of light, so it is necessary to develop strict vector diffraction theory and its design method. Vector diffraction theory
Based on the electromagnetic field theory, Maxwell equations must be solved strictly under appropriate boundary conditions, and several related design theories such as integration have been developed.
Methods, differential method, modal method and coupled wave method. Although the first two methods can get accurate results, they are difficult to understand and implement and need to be complicated.
Numerical calculation; Comparatively speaking, the mathematical processes of modal method and coupled wave method are relatively simple and easy to realize. Both methods are phase modulation.
Mode method expands electromagnetic field according to mode, and coupled wave method expands electromagnetic field according to diffraction order.
The second expansion. Therefore, the mathematical theory involved in coupled wave method is relatively simple, and the observation coefficient of diffraction order is given, not electromagnetic field.
Mode coefficient. But generally speaking, designing binary optical elements with these theoretical methods requires complex and time-consuming computer operations, and it is only suitable for
Periodic diffractive element structure. Therefore, when the transverse feature size of the diffraction structure is larger than the wavelength of light waves, the polarization characteristics of light waves become less important.
The traditional scalar diffraction theory can still get some reasonable results. For more complex diffraction structures, it is necessary to develop practical and effective designs.
Design theory. Two. Progress in fabrication technology The basic fabrication technology of binary optical elements is microelectronics processing technology in VLSI. but
Microelectronics processing belongs to thin film graphics processing, which mainly controls two-dimensional thin film graphics; Binary optical elements are three-dimensional relief knots on the surface.
Structure, it is more difficult to control the fine size and longitudinal depth of plane graphics at the same time. In recent years, in VLSI processing technology, electronics, separation
Driven by the development of sub-etching technology, the progress of binary optical fabrication technology focuses on: from binary phase elements to multi-order phase elements.
Or even the development of continuously distributed phase elements; From mask superposition technology to maskless direct writing technology. The earliest binary optical manufacturing process was to make hair with graphics.
Fabrication of second-order phase diffractive optical elements by generator and VLSI technology. By the late 1980s, with the development of high-resolution mask manufacturing technology (such as electron beam)
The plate-making resolution can reach 0. 1μm), which improves the alignment accuracy of mask overlay and film deposition for many times, and can make multi-stage phase binary optical elements with large size.
And the diffraction efficiency is greatly improved. However, the discrete phase and alignment errors of the mask still affect the manufacturing accuracy and diffraction efficiency of binary optical elements.
Tall man. Therefore, in the early 1990s, the direct writing technology was studied, the mask manufacturing process was omitted, and the required materials were directly written on the substrate by laser and electron beam.
Two-dimensional or three-dimensional relief pattern. Using this direct writing technology, by controlling the exposure of electron beam at different positions or modulating the intensity of laser beam, you can
The surface relief structure with multi-stage phase and even continuous distribution is etched. Maskless direct writing technology is more suitable for making a single binary or multi-order phase element, or simple.
By using laser mask and covering, continuous contour is more suitable for complex contour and mass production. In the etching technology of mask pattern, at present, it mainly
High resolution reactive ion etching and thin film deposition technology are adopted. The resolution of ion beam etching is as high as 0. 1μm, and the edge of the pattern is steep and accurate.
It is an ideal treatment method. One of the advantages of binary optical elements is that they are easy to copy. Commonly used replication techniques are: casting method.
(casting), embossing and injection molding. Among them, electroforming and molding replication will be large-scale production in the future.
The main technology of production. According to the characteristics of binary optical elements, new technologies such as LIGA, sol-gel, hot melt and ion are introduced.
Diffusion and other technologies have also been applied to the processing of binary optical elements, and continuous-phase devices can also be made by using gray-scale masks and PMMA ultraviolet-sensitive glue. Third, it should be
With the development of binary optical technology, binary optical elements have been widely used in optical sensing, optical communication, optical computing, data storage and laser.
Special systems such as optical medical treatment and entertainment consumption. Perhaps it can be said that its development has experienced three generations. In the first generation, people used binary light.
Science and technology improve traditional refractive optical elements to improve their conventional performance and realize special functions that ordinary optical elements cannot achieve. such
Components are mainly used for phase difference correction and achromatic. Usually, the diffraction pattern is etched on one surface of the spherical refractive lens to realize the refraction/diffraction compound aberration elimination and comparison.
Achromatic color in broadband. For example, Perkin-Elmer Company in the United States has successfully used Schmidt telescope to eliminate spherical aberration.
; In the far infrared system, the American company Honey-well has achieved apochromatic, and they also use binary optical technology to produce small light.
Disk read/write head. In addition, binary optical elements can generate arbitrary wave front to realize many special functions, which has important application value. Such as material processing and
Beam shaping elements in surface heat treatment, He-Ne laser focusing corrector in medical instruments, and optical interconnection elements in optical parallel processing system (Isooptics).
Strong beam splitting Dammann grating) and radiation focusing device. The first generation application technology of binary optical components has matured, and there are more than 50 companies around the world.
A new optical system is being designed by using mixed special functional elements. The second generation is mainly used for micro-optical elements and micro-optical arrays. In the late 1980 s, two
Meta-optics has entered the field of micro-optics, developing towards miniaturization and array, and the element size ranges from a dozen microns to1mm. The high density produced by binary optics method.
Degree microlens array has high diffraction efficiency and can realize diffraction-limited imaging. In addition, when the etching depth exceeds several wavelengths, the behavior of microlens array
It shows the characteristics of ordinary refractive elements and has unique advantages: the array structure is flexible and can be arranged in matrix, circle or closely packed hexagon; Capable of production
Lens surfaces with various contour shapes, such as paraboloid, ellipse and synthetic surface. The "dead zone" of the array lens can be reduced to zero (i.e., the fill factor reaches.
100%)。 This high-quality diffractive or refractive microlens array is widely used in optical communication, optical information processing, optical storage and laser beam scanning.
It has important applications. For example, binary micro-optical elements can be used as telescopic hybrid optical systems, intelligent beam control and multi-channel micro-sensing systems.
Trajectory processing, detector array and adaptive optical interconnection. In the third generation, binary optics aims at multi-layer or three-dimensional integrated low light.
Beam transformation and control in science, imaging and complex optical interconnection. Multilayer micro-optics can integrate the conversion, detection and processing of light.
As a multifunctional integrated photoelectric processor, this research will make an adaptive adjustment according to different light intensity, detect the movement of the target and adjust itself.
The image sensor can be moved to determine the position of the target in the background. Veldkamp combines this new binary optical technology with quantum well laser array or
The concept of "integrated circuit" is put forward by combining SEED device with CMOS analog electronic technology.
The focal plane structure is coupled with the local processing unit, which simulates the short-distance detection of nerve cells on the retina without long-term processing. The system has edge enhancement,
Dynamic range compression and neural network. The typical application of this generation of micro-optics technology is multilayer photoelectric network processor. This is the focal plane preparation.
Principle technology, using binary optical elements to provide flexible feedback and nonlinear preprocessing ability. The microlens array on the silicon substrate of the detector focuses the incident signal light.
Focusing on the active area of the array detector, the integrated circuit of the substrate excites the gallium arsenide indium diode to emit light by focusing light, and emits the second plane of light waves.
The diffractive elements on both sides of the substrate are guided to the array detector on the third silicon substrate, and the diodes are excited to emit light after being processed by the integrated circuit ... and vice versa.
Press to get the processed signal. Each layer of this multi-layer focal plane preprocessor is interconnected and coupled by a micro-optical array, which is a sensor.
The miniaturization, integration and intelligence of. The development trend of binary optics is based on diffraction theory, computer aided design and micro-addition
Based on engineering technology, one of the frontier sciences in the field of optics, the design and processing of ultra-fine structure diffraction elements is the key technology to develop binary optics. two
The development of meta-optics not only makes profound changes in the design and processing technology of optical systems, but also the overall development trend in the future is micro-optics and microelectronics.
Integrated technology of chemistry and micromechanics and high performance integrated system. In the future, the research of binary optical elements may develop in the following aspects. First, there are waves.
Research on long-structure binary optical elements (including design theory and fabrication technology) The characteristic size of such elements is smaller than wavelength, and their reflectivity and transmittance.
Refractive index, polarization characteristics and spectral characteristics all show completely different characteristics from traditional binary optical elements, so it has many unique application potentials, such as
It can be used as anti-reflection element, polarization element, narrow-band filter and phase plate. The research focuses include: establishing correct and effective theoretical model and ultra-precision design.
Fine structure diffraction element; Research on the algorithm of special wavefront transformation: develop wavefront engineering to make micro-components close to critical size and develop sub-wavelength.
The application of structured diffractive elements promotes the development of micro-optics. 2. Up to now, it has not been found that the development of CAD software package for binary optics is suitable for different relief structures.
The simple and effective theoretical model of projection structure and the design of binary optical elements are still lacking. Like the ordinary optical design program, any surface shape can be found.
Transfer function and system distortion, user-friendly universal software package. However, with the development of universal design tools, binary optical elements may become universal.
The standard optical elements have been widely used and combined with conventional optics to form a new generation of optical systems.
3. Low-light-level electromechanical system is the general trend of binary optics research. Micro-electro-mechanical integration system Micro-electro-mechanical micro-electromechanical 199 1 year, USA.
The National Key Technology Committee submitted the report "National Key Technologies of the United States" to the President of the United States, of which the eighth item was "Micro-scale and Nano-scale Manufacturing", namely
Micro-engineering technology mainly includes microelectronics, micromechanics and micro-optics, in order to develop a new generation of computers.
Advanced robots and intelligent systems are the core technologies to promote the integration and miniaturization of machinery, electronics and instrumentation industries. Binary optical technology
It is an important pillar of the development of micro-optics. Binary optical elements can be directly etched on integrated circuit chips, and micro-optical arrays can be arranged on one chip.
Column, or even fully integrated photoelectric processing unit, which will lead to the emergence of all kinds of brand-new ultra-dense sensing systems.
Micro-optoelectronics Micro-optical microelectronics diagram describes the intersection of three disciplines of micro-engineering technology. Obtained in micro-optics
While making remarkable progress, another frontier science-MEMS combined with three-dimensional integrated circuits has also made rapid development.
Micro-machining technology has been successfully used to improve the performance of sensors and actuators and reduce the cost. Micro-sensor designed based on this new technology.
However, micro-mechanical actuators, at least one dimension has reached micron level, and the other dimensions are less than a few millimeters, which is very important for military, industry and consumption.
All products have potential application markets. MEM and micro-optics technology have a common feature, both of which are based on VLSI technology, and the combination of them can produce one.
In laser scanning, optical switch, dynamic microlens and integrated electromechanical devices, a new and wider MEMS has been shown.
It shows attractive prospect and product market, and will be further developed into the fields of differential optical instruments, micro interferometers and small on-line mechanical detection systems. In a microcomputer
Micro-optical systems supported by machinery and microelectronics are also easier to be commercialized, thus forming a binary optical industry. Achromatic focal plane pretreatment of multilayer structure
Processor is a typical application of micro-optics, micro-electronics and micro-mechanical integrated system, which reduces the speed and frequency band of electronic processing through parallel optical processing.
Wide requirements, enhance the processing capacity and flexibility of the integrated system. The further development of multilayer micro-electromechanical devices can even imitate biological vision elements.
Science, the research results in this direction will have immeasurable significance to mankind. It is foreseeable that optical engineers can be like electronic engineers today.
Sample, sitting in front of the computer terminal, by pressing the mouse or tapping the keyboard to design the binary optical component combination and various optical, mechanical and electrical combination systems, this day.
It won't be long before ... will come.
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