The Image Converter for Middle Infrared Radiation
The Creation of Demonstrative Model of Image Converter for Middle Infrared Radiation
Tech Area / Field
- INF-SIG/Sensors and Signal Processing/Information and Communications
- PHY-OPL/Optics and Lasers/Physics
3 Approved without Funding
National Academy of Sciences of the Republic of Belarus / Institute of Technical Acoustics, Belarus, Vitebsk
- Instituto Maspec/CNR, Italy, Parma\nThomson CSF Laboratoire Central de Recherches, France, Orsay\nCentro Ricerche FIAT / Optics Department, Italy, Torino\nSiemens AG, Germany, Munich\nFraunhofer Institute Zerstörungsfreie Prüfverfahren, Germany, Saarbrücken
Project summaryThe objective of the project is the investigation of the sensitometric characteristics of pyroelectric (PE) – liquid crystal (LC) structure and the creation on its base of the demonstrative model of image converter (IC) for middle infrared radiation (10 m).
The state of the art in the field. Among the different types of IC the converters have got the widest distribution nowadays, in which LC is electric-optical medium. First of all this circumstance is determined by the unique properties of liquid crystals: their extremely high sensibility for controlling actions, high steepness of modulate characteristic; simplicity of producing on their base of multi elements devices. These ICs are compact, simple in exploitation and can work at low feeding voltages. Nowadays liquid ctystal ICs are used with the great success both in the information representation systems and information processing systems (SID Symposium - May 1999, San-Jose, USA). The great attention is paid to devices converting the image of infrared radiation into visible one. This is connected with the fact that the majority of objects, surrounding us, have the temperature close to 300K that corresponds to the spectral range of radiation 2-100 m with the maximum about 10 m.
By the present time ICs are developed on the base of the metal-dielectric-LC structure and photosemiconductor –LC structure. These devices are effective in the area of visible and near IR-radiation (1 m) only (R.D.Sterling, W.P.Bleha, ILA projectors for advanced application, Proc. Of 4th Int. Display Workshop, Nov.1997, Nagoya, Japan, pp.809-814). The movement into the longwave area is prevented by the absence of suitable materials having good sensitivity in this range of spectrum. In particular, the narrow-zone semiconductors of CdxHg1-xTe type are difficult to be subjected to processing. These semiconductors require deep cooling for their work. And this fact excludes the possibility of LC application. Taking into account the quick development of IR-range techniques, the expanding of a spectral range of IC sensibility right up to the tens of microns has become the very actual task. One of the ways of solving this problem could be the application of pyroelectrics as a photosensitive layer in IC. Pyroelectric materials convert heat radiation into the corresponding space distribution of connected charges on their surface. The pyroelectric materials can be used for detecting the radiation in the wave’s length range from 10-5 up to 104 m (M.E. Lines, A.M. Glass, Principles and Application of Ferroelectrics and Related Materials). The evidence of the prospective of such approach is in successes achieved at the creation of devices for visualization of images of heat objects with a help of the method of scanning the pyroelectric plate by the electron beam (pyroelectric vidicon).
The image converters on the base of PE-LC structure will allow to carry out image conversion without using of rather complex electronic systems of scanning and cooling. Created on the base of pyroelectric materials, IC for the middle IR -radiation (10 m) will be compact and not expensive. These devices will be able to find the wide range of application for visualization of invisible images in medicine, in technique of non-destructive control, etc. The special interest is caused by the creation of simple and reliable devices for the diagnostics of mode structure of IR-lasers (Applying Beam Profiling to Indastrial Lasers, Laser Application in Metalloworking, August, 1996. CCD Camera Baseline Calibration and its Effects on Imaging Processing and Laser Beam Analysis, 10TH Meeting on Optical Engineering – 4 March 1997, Israel). IC on the base of PE-LC structure can be used without the essential constructive changes also for the purpose of image’s visualization in the part of spectrum with longer waves – in submillimetre range (300-400 m and more). On the other hand the stability of pyroelectrics to action of a penetrating radiation makes the application of such systems perspective in nuclear engineering. That is why the research in this area is perspective.
The impact of the proposed project on the progress in this field. This project is pointed to solve the problem connected with converting the image of infrared radiation into visible one. The realization of this project will give opportunity of producing the simple reliable compact image converters for middle and far infrared radiation (> 10 m). There are no cheap devices of such type for abovementioned range of radiation nowadays. And necessity of such equipment is extremely high. The research of the converters will make positive influence on development of laser technologies, power engineering and medicine.
Project members. Members of research group are qualified to carry out this project. The base of research group consists of «weapon» specialists. Development of tracking systems behind the air targets and guidance elements for weapon carriage systems resisting attacks of penetrating radiation had been the main task of this research group till the mid of 90s.. Since military orders had been decreased, members of this project began to use their experience and knowledge for peace purposes. There are four candidates of physical – mathematical sciences in this group who received their degrees for above mentioned researches (obtaining and investigation of pyroelectric materials, development of LC displays). These specialists have already accumulated the great experience in development of different IR systems. The members of this group published more than 20 articles devoted to this topic in well-known journals. The investigations were carried out on different aspects of the general task.
Expected Results. While carrying out the project, four interconnected tasks will be solved and the following results will be obtained:
1. Methods of obtaining of pyroelectric films (thickness 1-5 m) and pyroelectric layers from bulk materials (thickness 50-200 m) with high characteristic will be developed.
2. Homogeneous on thickness PE and LC layers of 20 cm2 square will be obtained. The regimes of coating the orienting, absorbing layers and transparent electrodes will be developed. The sensitometric characteristics of optic-electric pare PE-LC will be studied.
3. The construction of the converter will be worked out, the necessary optic elements for IR-range will be produced. The main result of the project will be the creation of the demonstrative model of the image converter for middle IR-radiation on the base of the structure PE-LC. The sensitometric characteristics of the device will be studied.
4. The particularities of operation of the image converter at action of the power radiation on it will be studied. Images of heat objects and mode structure of IR-lasers will be obtained.
The creation of the experimental samples of IC and the carrying out of their testing for potential users is possible on the base of conducted investigations. These works will not require the essential material expenses and can be conducted in short time (4-6months). It is supposed to present the claim for patent to the device under development.
The application of the project results. The project results can be used at designing and producing of different modifications of cheap image converters for different fields of science and technology:
1. In power engineering and techniques of non-destructive control – for non-contact control of heat regimes of work of electric transmission lines, force machines, etc. Due to resistance of pyroelectrics to action of penetrating radiation such devices are perspective for nuclear engineering.
2. In laser techniques – for diagnostics of mode structures and profiles of laser beams.
3. In medicine – for diagnostics of inflammations in a man’s organism.
Meeting ISTC Goals and Objectives. The project meets the ISTC goals and objectives:
1. The support of this project by the ISTC will assist the use of the experience and knowledge of weapon specialists for the development of technologies for peace purposes and solutions of important scientific tasks.
2. The carrying out of the project will give a possibility to authors to set close contacts with the abroad specialists and will assist their integration into the scientific community.
3. The support of the given project will assist the solution of important scientific-technical task – the visualization of heat fields and objects. Project results can be applied in the area of power engineering (including nuclear engineering), in medicine, in laser physics, techniques of non-destructive control.
4. The development of any military technologies is not the purpose of the project.
Scope of Activities. The project will be carried out in two years and a half (30 months) by the group of ten executors in the Institute of Technical Acoustics NAS of Belarus.
The total efforts will be 264 man*months. The efforts of “weapon” specialists will be 209 man*months. Four interconnecting tasks will be solved during carrying out the project sequentially:
- Investigation of the characteristics and optimization of the parameters of pyroelectric layers obtained by thin-film technology and from bulk materials;
- Development of production technology of the functional layers of converter and studying of the influence of their characteristics on the sensitivity and space resolution of the whole structure;
- Creation of the demonstrative model of IC for the middle IR-radiation;
- Obtaining of the images of heat objects and mode structure of IR-lasers.
Role of Foreign Collaborators. The project implementation will be carried out in a close contact with the foreign collaborators:
- Information exchange in the course of project implementation
- Conduction of joint workshops
- Possibly testing of image converters connected with diagnostics of mode structure of IR-lasers
- Participation in technical monitoring of project activities performed by ISTC staff
- Assistance for project participants to join international meetings
It is also possible to continue cooperation with Collaborators for creation of the experimental samples of IC and carrying out of their testing for potential users after the project will be finished.
Technical Approach and Methodology. To solve the project tasks the Institute has the suitable methods and the main equipment, which need insignificant modernization.
Task 1. The participants of the project have developed original methods for obtaining of unipolar mono-crystal and glass-ceramic ferroelectric materials, which are suitable for production of pyroelectric cascade with high characteristics. These methods are based on creation of non-homogeneous distribution of dopants in the samples. The authors of the project have priority in this field of investigation that are confirmed by inventor’s certificates and publications in well-known journals.
Task 2. The vacuum technologies (including RF-magnetron sputtering) will be used for obtaining of converter’s functional layers (the orienting and absorbing coatings, transparent electrodes, pyroelectric thin films).
Task 3-4. The participants of the project have made the theoretical analysis of image converter operation by solving the appropriate heat conduction and electrical equations. The result of this analysis will be used for the optimization of the parameters of converter’s functional layers.
In particular, the original methods of obtaining the uni-polar mono-crystal and glass-ceramic ferroelectric materials based on creation in the samples of non-homogeneous distribution of dopant were developed. The vacuum technologies of converter’s functional layers coating (the orienting and absorbing coatings, transparent electrodes, pyroelectric thin films) with the use of RF-magnetron sputtering were developed. The optical testing bench was created in the Institute. It allows to investigate the sensitometric characteristics of pyroelectric-LC structures, to control the basic parameters of converters (sensitivity, space resolution, time of switching over) and to obtain images of heat objects.
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