WO2005125193A1

WO2005125193A1 - Method and system for preventing the photography of certain objects

Info

Publication number: WO2005125193A1
Application number: PCT/IL2005/000634
Authority: WO
Inventors: Sharon Ehrlich; Gilad Shenhar; Boaz Tadmor; Zipora Alster; Ehud Givon; Dror Pesso
Original assignee: Camjam Ltd.
Priority date: 2004-06-15
Filing date: 2005-06-15
Publication date: 2005-12-29
Also published as: IL162535A0

Abstract

A method and system are presented for preventing imaging of a region of interest (11). The method comprises: providing external electromagnetic radiation randomly varying in space and time in the vicinity of the region of interest. By this, a radiation pattern reaching a radiation sensitive element of an imaging device (13), while collecting radiation from the region of interest, is randomly affected.

Description

METHOD AND SYSTEM FOR PREVENTING THE PHOTOGRAPHY OF CERTAIN OBJECTS

FIELD OF THE INVENTION This invention is generally in the field of security/privacy techniques, and relates to an optical method and system for preventing the photography of certain objects.

BACKGROUND OF THE INVENTION The continuing miniaturization of cameras, together with improved performance, and the appearance of various systems incorporating such cameras (e.g., as mobile phones, mini-computers, button cameras, etc.), enable photographing practically in any place. This caused concern for photography in areas where it must be prevented (or is prohibited). Various techniques have been developed aimed at disrupting this type of photography. Japanese patent number 2004363838 discloses a mobile telephone set, sneak photography prevention system, photographic signal transmitting and receiving method used therefore. According to this technique, the mobile telephone set is capable of preventing sneak photography etc., by letting people around the mobile telephone set recognize camera photography to the circumference without being limited to a folding type. When a user indicates camera photography through an operation part, the camera photography indication is reported from the operation part to a control part and then reported from the control part to a camera part, which carries out photography. The photography by the camera part is reported from the control part to a weak radio part, which sends a photographic signal through an antenna. The weak radio part, once receiving a photographic signal sent from another mobile telephone set through the antenna, sends its information to the control part. The control part once informed of the photographic signal, drives a vibration part and a display part; and the vibration part vibrates and the display part makes a display showing that the different mobile telephone set is taking a photograph. Japanese patent No. 2004328475 discloses photography prevention system capable of preventing photography with a mobile terminal device with camera at a photography prohibited place. The photography prevention system performs control so that the mobile terminal device with camera cannot perform the photography by a camera part of the mobile terminal device with camera by allowing the mobile terminal device with camera to receive a signal of Bluetooth communication from a Bluetooth module provided in the vicinity of an object the photography of which is prohibited. The known techniques, however, provide only partial solutions for the photography disrupting problem. Indeed, the techniques utilizing blocking of the mobile phone activity in specific areas, while preventing transmission of data indicative of acquired images to an external source, do not prevent saving of this data (photographs) in the mobile phone memory. Moreover, this solution is irrelevant for other systems, such as micro digital cameras or micro computers, such as PDA and the like. The techniques based on the provision of instructions from remote to cancel the camera's activity in a mobile phone when located in defined areas, need co-operation from the equipment's manufacturer and mobile phones' service providers, in order to involuntarily implant the remote control. This is practically difficult to implement. In addition, this solution also does not address systems other than mobile phones, such as micro digital cameras or micro computers (such as IPAK and the like). Another approach is disclosed in U.S. 6,351,208 describing a device for preventing detection of a traffic violation. The device includes an ultraviolet laser emitter that interferes with the photographing of a traffic violation or the violating car by an automatic camera installed on a traffic signal. The automobile is provided with a plurality of ultraviolet laser emitter devices adjacent to the license plate that prevent the photographing of the violating automobile's license plates. The automobile may also include ultraviolet laser emitter devices on its planar surface to further prevent the automatic photographing of the automobile Yet another solution is disclosed in US 20040227634. Here, an apparatus and method for preventing a photographic image from being taken, utilizes a triggering mechanism which will generate a signal when detecting a light signal indicative of a camera flash. A flash unit is coupled to the triggering mechanism for generating a counteracting flash after receiving the signal generated by the triggering mechanism. By generating a counteracting flash, a very short time after detecting the flash, the apparatus saturates an area of the camera's image field during the camera's exposure period. Thus, the image in that area is obscured.

SUMMARY OF THE INVENTION There is a need in the art to facilitate protection of regions of interest from being imaged (photographed), by providing a novel method and system capable of disrupting the abilities of an imaging device, digital or analog, to receive meaningful images, from areas where this is to be prevented. The present invention provides a novel optical solution for the above problem. The invented technique allows for preventing the meaningful image capture by a camera (constituting an imaging device) from a region of interest without affecting the camera configuration and operation, and without a need to follow external instructions. This is achieved in the present invention by providing external radiation randomly varying in space and time, in the vicinity of a region of interest. By this, the intensity of a radiation pattern collected by a radiation sensitive element of an imaging device (while collecting radiation from the region of interest) is randomly affected, thereby impeding interpretation of the collected radiation. There is thus provided, according to one aspect of the invention, a method for preventing imaging of a region of interest, the method comprising: providing external electromagnetic randomly varying in space and time in the vicinity of the region of interest, thereby randomly affecting at least one of the intensity and wavelength of a radiation pattern reaching a radiation sensitive element of an imaging device while collecting radiation from the region of interest. The randomly varying radiation is provided by randomly varying deflection of the external radiation, and possibly also altering a rate of the radiation deflection. The randomly varying deflection consists of randomly varying a trajectory of propagation of the external radiation in a three- dimensional space. Preferably, the external radiation includes radiation of different wavelength ranges. The intensity and/or polarization of the external radiation may also be varied. The generation of the randomly varying external radiation may be initiated in response to an external identification signal. This may be implemented using one or more sensor devices accommodated in the vicinity of the region of interest and being responsive to a predetermined condition indicative of an external object approaching the region of interest. The system configuration may be such that the randomly varying external radiation is directed towards the imaging device, and/or towards the region of interest. Preferably, one or more control radiation sensor is used. Such a sensor is appropriately accommodated to collect light from the region of interest and therefore test the quality of the image disruption. Preferably, such a sensor is configured to generate a warning signal in case the disruption is not achieved or is not sufficiently effective. According to another broad aspect of the invention, there is provided a system for use in preventing imaging of a region of interest, the system comprising a source of external electromagnetic radiation and a radiation deflection unit, the system being configured and operable to provide the external radiation, randomly varying in space and time in the vicinity of the region of interest, thereby randomly affecting a radiation pattern reaching a radiation sensitive element of an imaging device while collecting radiation from the region of interest. Preferably, the radiation source unit includes several radiation sources generating radiation of different wavelengths. The system may include one or more spectral filter. The deflection unit may include a radiation scattering surface, and/or one or more reflector units. The reflector unit preferably includes an array of micro- mirrors controllably movable to provide the randomly varying deflection. The system includes at least one drive unit configured for displacing the radiation source unit and/or the deflection unit or at least part thereof. The deflection unit may include at least one movable light modulator. The light modulator may be driven for rotating and vibration during the rotation. The light modulator may include a plurality of randomly distributed spaced-apart spectral filters. The light modulator may be formed by a plurality of spaced- apart randomly shaped and distributed light transmitted regions spaced by relatively light blocking regions. According to another broad aspect of the invention, there is provided a device for projecting information on a plane in a region of interest, the projection device comprising the above-described system for preventing capturing an image of the projected information by any imaging device. According to yet another aspect of the invention, there is provided an object carrying the above-described system for preventing capturing an image of the object by any imaging device.

BRIEF DESCRIPTION OF THE DRAWINGS 5 In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non- limiting example only, with reference to the accompanying drawings, in which: Fig. 1 is a block diagram of a system of the present invention for preventing the photography of a region of interest by disrupting the image of the l o region of interest; Fig. 2 is a schematic illustration of an example of the implementation of the system of Fig. 1; Fig. 3 exemplifies various alternatives suitable for use in the invention for activating the system; 15 Fig. 4 shows another example of the implementation of the system of the present invention utilizing a deflection unit based on MEMS formed by digital micro mirror devices (DMD) and digital light processing (DLP); Fig. 5 illustrates a system formed by a point-like light source, a mirror, and a camera, for explaining the operational principles of the present invention; 0 Fig. 6 exemplifies a system of the present invention configured to direct randomly varying external radiation towards an imaging device; Figs. 7 and 8 show two examples, respectively, of a projection device utilizing the system of the present invention for preventing photography of a certain projected material or film; ^L 5 Fig. 9 exemplifies the system of the present invention carried by an object for preventing imaging or identification of the object by an imaging device (e.g., biometric imaging); and Fig. 10 illustrates schematically yet another example of an illumination system of the present invention. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Referring to Fig. 1, there is illustrated, by way of a block diagram, a system 1 of the present invention configured and operable for disrupting image data collected by a radiation sensitive element (not shown) of an imaging device 13 from a region of interest 11. System 1 is configured as an illumination system, and includes such main constructional parts as a light source unit 14 and a light deflector 16. System 1 is configured and operable such that electromagnetic radiation L produced by system 1 randomly varies in space and time. This can be achieved by appropriately (e.g., vibrating) moving the radiation source and/or the radiation deflector. Radiation deflector 16 may include a radiation scattering surface, and/or one or more reflectors, and/or one or more light modulators; or may be constituted by a drive unit randomly displacing the light source unit. The scattering and/or reflective surface may be constituted by walls surrounding the region of interest by providing an appropriate coating on the walls. System 1 is accommodated in the vicinity of region of interest 11, and is arranged such that randomly deflected light L is directed towards imaging device 13, when the latter is oriented to collect light from region of interest 11. It should be noted that the system of the present invention may be configured to directly propagate light onto the imaging device, rather than illuminating the region of interest (object) that is to be prevented from being photographed (imaged). This can, for example, be achieved by accommodating the radiation source (and/or deflector) around the region of interest, such that any imaging device, while targeted on the region of interest, would collect light produced by the system of the invention. This configuration will be described below with reference to Fig. 6. Alternatively, or additionally, the system of the present invention is arranged with respect to the region of interest such that the randomly deflected light illuminates the region of interest, as will be described below with reference to Fig. 2. Thus, the system of the present invention is configured for providing external electromagnetic radiation randomly varying in space (preferably along three axes) and time. As a result, the intensity of a radiation pattern received by the light sensitive element of an imaging device, when targeted to the region of interest, is randomly affected, thereby impending and practically making impossible the interpretation of this image data and thus the reconstruction of the image of an object in the region of interest. The random deflection of radiation consists of randomly varying the trajectory of the radiation propagation, and may also include random variation of a rate of the radiation deflection. Additionally, the intensity and/or wavelengths and/or polarization of the external radiation may be randomly altered. The following are various examples of the configuration and operation of a system of the present invention. To facilitate understanding, the same reference numbers are used for identifying components that are common in all the examples of the invention. Fig. 2 schematically illustrates an illumination system, generally at 10, appropriately oriented with respect to a region of interest 11 and configured and operable as the image disruption system, aimed at preventing an object 12 located within region of interest 11 from being photographed by an imaging device (camera) 13. The latter may be any independent digital camera, or digital camera integrated into a phone device, PDA, or a regular movie camera. System 10 includes a light source unit 14, and a light deflection unit 16. The light deflection unit is operable by a control unit 18 to randomly vary the trajectory of light propagating from light source unit 14 towards region of interest 11. As a result, light produced by system 10 randomly varies in space and time. Such light, when received by camera 13, distorts the original picture so that it becomes difficult, if not impossible to view. Light deflector unit 16 includes a light scattering surface 16A, which is oriented with respect to light source unit 14 so as to be in optical path of light 24 emanating from the light source unit. Scattering surface 16A is configured to randomly deflect light 24 impinging thereon in various directions. Such a scattering surface may be formed by a mirror with a granular coating. Light deflection unit 16 may also include one or more reflectors - one such reflector 16B being shown in the present example. Reflector 16B is appropriately accommodated with respect to surface 16A to reflect a part of deflected light 24' impinging thereon. Light source unit 14 may include a single light source, e.g., a broadband light source, or a plurality of light sources. In the present example of Fig. 2, an array of ten such light sources is shown. Preferably, light generated by light source unit 14 is of various wavelength ranges (from UV to far IR range), which is achieved by using either one or more broadband sources, or a plurality of light sources each operating in a different wavelength range (e.g., an array of LEDs). As indicated above, system 10 may be arranged such, that deflected light 24' is directed towards imaging device 13, when the latter is oriented to collect light from region of interest 11. Preferably, as shown in Fig. 2, system 10 is arranged with respect to region of interest 11 such that deflected light 24' illuminates the region of interest (illuminates object 12). In order to achieve the randomly variable light deflection, either one of scattering surface 16A (and/or reflector 16B as the case may be) and light source unit 14, or both of them, are mounted for movement, e.g., vibration. In the present example of Fig. 2, both the light source unit and the scattering surface are mounted for vibration. Accordingly, a drive assembly 19 is provided having a first drive unit 19A associated with light source unit 14 and a second drive unit 19B associated with deflection unit 16 (with scattering surface 16A). The drive assembly is operated by control unit 18. The drive unit may include a 3-axes mechanical displacement system for displacing the light source unit, and/or may include a light beam manipulator based on mirrors, lenses or fibers moved by galvanometers, piezo-electric actuators or micro electro mechanical systems (MEMS). Thus, random light response of the scattering surface 16A is achieved, in addition to the randomness of the actual movement of surface 16A. Preferably, control unit 18 operates to vary (randomly) a rate of the light deflection, namely the vibration rate of light source 14 and/or of deflection unit 16. Control unit 18 is a computer system including inter alia a data processing and analyzing utility 20 and a movement controller 22. In the present example, movement controller 22 includes a first controller utility 22A for controlling the operation of drive unit 19A to move light source unit 14, and a second control utility 22B for controlling the operation of drive unit 19B to move scattering surface 16A. As indicated above, the system of the present invention may be configured to provide radiation of various wavelengths and/or to vary the intensity of illuminating light. To this end, control unit 18 may include an additional utility 26 associated with light source unit 14 and preprogrammed for controlling the intensity of light generated by the light source unit, and/or for selectively operating different light sources. Thus, system 10 operates to produce light randomly varying in 3D space and time in the vicinity of region of interest 11. In the example of Fig. 2, system 10 operates to illuminate region of interest 11 with such randomly varying light. When someone takes a picture of object 12 located in region of interest 11 using camera 13, the camera operates in the conventional manner to collect light 28 reflected from object 12. This light 28 includes the directly projected light 24 (randomly deflected due to the vibration of light source unit 14) and the scattered/reflected light 24' (randomly deflected due to the scattering from surface 16A and also due to vibration of this surface). As a result, a light pattern incident onto a light sensitive surface (e.g., a pixel matrix) of camera 13 has a randomly varying intensity during the camera exposure time. The search rate of the reflecting/scattering surfaces and of the light source unit is very high, as is the intensity of the illumination, so that even a very brief exposure will not enable contending with the disruption. As indicated above, light source unit 14 is configured to generate light of long and short wavelengths (UV and IR) in case the cameras are fitted with spectral filters. As also shown in Fig. 2, system 10 preferably includes a feedback control assembly 32. Assembly 32 includes one or more light sensors, two such light sensors 34 being shown in the present example, appropriately accommodated with respect to region of interest 11. The output of light sensor 34 is connectable to the processor of control unit 18. Assembly 32 operates to test the quality of distortion of light source unit 14, and to provide a feedback signal to the processor utility, which tests the status of the distortion, and possibly operates light source unit 14 to intensify the illumination, and in case of particularly strong peripheral illumination, generates a warning signal. The randomness of deflection of light produced by system 10 makes it difficult for AGC Systems (Automatic Gain Control) to respond effectively, in the majority of imaging devices. In those imaging devices that are not equipped with such an AGC, it is difficult to adjust a shutter in time, due to the variance of light, and the changing optical distance of the light source (3-dimentional vibration). As indicated above, generation of the randomly varying illumination for image disruption, may also include the use of varying light polarization, and/or the use of a strong illumination lamp targeted (by the control unit) onto imaging device 13. It should be noted that the effectiveness of the image disruption can be improved due to reflectivity of surfaces within the outer space in the vicinity of region of interest 11, and/or the use of special external reflector(s) such as reflector 16B. In case of a specifically designed outer space, the permanent surfaces of the outer space could be painted (coated) by reflective/scattering materials to thereby significantly improve the image disruption efficiency. The configuration may be such that system 10 is intended for continuous operation to produce randomly varying radiation, at least during certain time periods. Alternatively, generation of the randomly varying external radiation is initiated in response to an external actuation signal, for example, being an identification signal generated by an external sensor system accommodated in the vicinity of the region of interest and responsive to a predetermined condition indicative of an external object approaching the region of interest. Reference is made to Fig. 3 exemplifying various alternatives suitable for use in the system of the present invention for activating the system operation, in case such operational mode of the system is considered. As shown, control unit 18 is provided with an additional activating processor utility 25. Processor 25 is configured to be responsive to an external actuation signal to generate output data for operating a light source operator utility (26 in Fig. 2) and a movement controller (22 in Fig. 2). Control unit 18 optionally includes a status display 27 whose input is connectable to the output of processor 25, and one or more communication port, generally at 29. As further shown in Fig. 3, control unit 18 may be provided with an appropriate data input utility 40 for manually inputting the external actuation signal by an operator. Alternatively, or additionally, the system may be equipped with one or more sensors generating an external identification signal to be received by activating processor 25. The following are some specific, but not limiting, examples of such sensors: A proximity sensor 41 may be used that enables examination of the approach of different objects. This sensor may be magnetic, acoustic (e.g., ultrasonic), etc. A motion sensor 42 may be used that enables identification of any motion in the vicinity of the region of interest. These sensors may include control cameras (imaging device), acoustic (ultra-sound) sensors and/or RF receivers 43, IR arrays 45, etc. The system may include heat sensors 46 which enable another supplementary detection of robotic instruments, humans, animals, etc. The use of one or more acoustic sensors 47 (microphones of varying wavelengths, in the sound, ultrasound and infrasound ranges) allows for locating other presences in the vicinity of the region of interest. Pressure sensors 48, and/or humidity sensors 49 and/or gas (smoke) sensors 50 may be used. Other options include the use of magnetic and electrical field sensors 51, 52, as well as light sensors 45, 53 (including also a regular camera). Such one or more sensors transmit its output to the control unit (to 5 activating processor 25). Control unit 18 is preferably configured as the so- called "expert system" capable of for carrying out a learning mode and decision making. The various systems situations are stored in memory utilities 54 and 56. Decisions that are made by control unit 18 are transmitted via communication ports 29 (using wires or wireless communication) to be presented to the system ιo operators. It should be noted that, when choosing appropriate wavelengths, as well as the light intensities, to be used in the system, the need to maintain suitable conditions for people to remain in the secure area, must be taken into consideration. For example, in an area containing people, while distortion

15 signals are being created, these signals may be in the infra-red range. This range does not disturb people while distorting the activities of photography systems. Another factor that might be considered is the rate of the variance of the intensity of illumination. Flickering infrequencies between 6-15Hz may cause various side-effects in people, such as epilepsy. Certain light intensities and

20 frequencies might cause damage to eyes, therefore this is to be avoided in an area where people are. The system may operate to alter the composition of light rays, in the presence of people, in order to reduce the above-indicated side effects. Reference is made to Fig. 4 exemplifying a system 100 of the present invention utilizing a MEMS based on digital micro mirror devices (DMD) and

25. digital light processing (DLP). System 100 is configured for preventing imaging of one or more certain objects 12 (disrupting image data) within a certain space 11 (region of interest). System 100 includes a light source unit 14 and a light deflection unit 16. Light source unit 14 includes one or more light source - an array of light

30 sources in the present example. These may be LEDs, lasers, a combination of LEDs and lasers, or any other light source(s) such as halogen or quarts lamp(s), etc. Light deflection unit 16 includes a multi-mirror unit 116A, and preferably also includes an optical system 116B. Optical system 116B includes focusing and/or polarization affecting and/or scattering and/or filtering optical elements. Multi-mirror unit 116 A includes an array of a very large number of micro- mirrors (e.g., about 10⁵-2-10⁶ or more mirrors each of about 15μmxl5μm size), associated with a drive unit (not shown here) operable by a control unit 18 to appropriately move the micro-mirrors. Deflection unit 116 is mounted on a 2-6 axes controlled stage 60 operable by control unit 18. Stage 60 provides for displacing deflection unit 116, and in the present example, also provides the movement of light source unit 14, to appropriate orientation so as to direct light towards region of interest 11. Control unit 18 includes a light source operator utility 26 that operates a power supply to light source unit 14. A feedback control assembly 32 is also preferably provided, including one or more imaging device (camera). Assembly 32 serves for the system calibration aimed at providing a desired orientation of the system (randomly deflected light) with respect to region of interest 11 (as described above). This is implemented by moving stage 60 in response to signals coming from camera 32. The operation of camera 32 may be controlled manually using a remote control panel, or by means of unique marking of region of interest 11 (object 12), allowing camera 32 to search for the marked target within the predefined space. Camera 32 also allows for real-time determination, by the system operator, whether the system provides effective image disruption, or not, namely whether an image data collectable by camera 32 during the system operation (i.e., after the system has been actuated to produce randomly varying light deflection) is desirably disrupted or not. The following is an example of measuring the amount of light collected by a light sensor (camera) from a "blocking" (image-disrupting) point-like light source (e.g., LED) as compared to a regular room illumination (ambient light). In this connection, reference is made to Fig. 6 exemplifying an illumination system 200 of the present invention mounted in a room typically illuminated by a lamp-based light source 70. System 200 includes a "blocking" light source unit 14 spaced a distance di from an imaging device 13 and located in the vicinity of an object 12 (imaging of which is to be prevented), which is mounted on a wall 72 and is spaced approximately the same distance d₂ from imaging device 13. Object 12 is illuminated by light source (lamp) 70, which in the present example, includes a day light neon lamp of a 40W operational power, a similar cool light lamp, and an incandescent bulb lamp of a 100W power. Blocking light source unit 14 includes a super bright LED at 621nm operating wavelength. The measurements at a distance of 0.3m between blocking light source 14 and imaging device 13 within a segment of 8° have shown the light from blocking light source 14 and from object 12 (i.e., reflection of light coming from light source 70) is, respectively, 320 foot candle and 80-100 foot candle. These measurements demonstrate that the amount of light producible by an array of LEDs will provide the light intensity allowing the desired effect of image disruption. Fig. 7 exemplifies a projection system 300 utilizing the present invention for preventing photography of a certain projected material or film. System 300 includes a light source system 314 that includes a "blocking" light source unit 14 aimed at preventing the photography of the projected data and a light source 80 used for the regular operation of the projection system. Further provided in system 300 is a light deflection unit 16. Light deflection unit 16 includes a single array of MEMS mirrors (DMD-DLP) 316A and also includes a spectral filter unit 316B mounted on a rotatable disk. Also preferably provided in system 300, is an optical system 82 including a first optical unit 82A accommodated in an optical path of light emanating from light source unit 314 upstream of filter disk 316B, and a second optical unit 82B downstream of the filter disk. Filter disk 316B is driven by a disk rotation operator utility 86 of a control unit 18) to thereby selectively allow propagation of a selected wavelength of the illuminated light towards the deflection unit. Filtered light is directed by second optical unit 82B onto mirrors 316A. The latter is controllably operated by a DMD control utility 87 of the control unit to define the spatial structure and the relative intensity of each point in a displayed region. The operation of utility 87 is in turn controlled by a signaling utility 88, namely, by an operating signal (used for information projection) and a blocking signal. A light signal reflected from mirror 316B is projected by a lens arrangement 90 on a screen or any other location. Reference is made to Fig. 8 showing another example of a projection system 400 utilizing the present invention for preventing photography of a certain projected material or film. System 400 is configured generally similar to the above-described system 300, but utilizes several MEMS mirror arrays (DMD-DLP). System 400 includes a light source system 414, a light deflection unit 16, and a control unit 18. It should be understood that in this figure as well as in the previous one, only those utilities of the control unit that are relevant to the understanding of the system operation are shown. Light source system 414 includes a "blocking" light source unit 14 operating for preventing the photography of the projected image, and a light source unit 92 formed by three light sources of wavelengths used for the regular projection system operation. Light deflection unit 16 includes a movable mirror unit formed by four arrays of MEMS mirrors, DMD-1, DMD-2, DMD-3 and DMD-4; and a spectral filter unit 416B formed by four spectral filters, each for directing a different wavelength range from the respective light source towards the respective mirrors' array. Thus, each light channel is directed onto its respective mirrors' array, which in turn defines the spatial structure and the relative intensity of each point in a displayed region. The movement of mirrors is controlled by a DMD control utility 87 of the control unit. The operation of utility 87 is controlled by a signaling utility 88, namely, by an operating signal (for the projection purposes) and a blocking signal. A light signal reflected from mirror's array is projected by a lens arrangement 90 on a screen or any other location. Referring to Fig. 9, there is exemplified a portable system 500 utilizing the present invention for disrupting undesired photography. System 500 is formed by photography disruption blocks 1 of the present invention (i.e., each configured to produce light randomly varying in time and space) associated with a power source 94. These elements are mounted on a movable object 12 (bone, person or any other subject) that is to be prevented from being photographed or identified by a biometric system, without creating a prominent and suspected camouflage. Reference is made to Fig. 10 showing one more examples of a system 600 of the present invention having a portable and non-expensive configuration. System 600 includes a light source unit 14, a light deflection unit 16 and a control unit 18. System 600 is configured to produce light of different wavelengths randomly varying in time and space. Light source unit 14 may be formed by an array of high intensity LEDs generating light of different wavelengths, or a one or more other type high- intensity light source allowing operation with a broader spectral range. The operation of light source unit 14 is controlled by control unit 18. Deflection unit 16 includes a light modulator 516A movable by an appropriate drive unit 19. Light modulator 516A is configured as a perforated disk 97 that carriers a plurality of spectral filters, generally at 98, mounted in said perforations. The perforations (i.e., spectral filters) are randomly distributed within the disk. Disk 97 is rotated with a variable speed, and is non-concentrically mounted on a shaft of drive unit 19, which operates to vibrate the disk during the disk rotation. Preferably, light deflection unit 516 includes one or more additional light modulator - two such light modulators 99 being shown in the figure, each in the form of a disk-like mask (e.g., randomly distributed perforations or light transmitting regions spaced by light blocking regions of the disk material). Each such additional modulator is randomly movable (rotatable and vibratable) by its own drive unit. By this, randomly scattered light (i.e., randomly varying in trajectory of propagation, and preferably also wavelength and intensity) is provided. Thus, the present invention provides for safety and effective means for preventing undesired imaging of an object. The system of the invention may be a stand-alone system accommodated in the vicinity of the object, so as to propagate randomly varying radiation to a region where an imaging device might be located, or may be arranged to direct such radiation to a region containing the object. Those skilled in the art will readily appreciate that various modification and changes can be applied to the embodiments of the invention as hereinbefore exemplified without departing from its scope defined in and by the appended claims.

Claims

CLAIMS:

1. A method for preventing imaging of a region of interest, the method comprising: providing external electromagnetic radiation randomly varying in space and time in the vicinity of the region of interest, thereby randomly affecting at least one of the intensity and wavelength of a radiation pattern reaching a radiation sensitive element of an imaging device while collecting radiation from the region of interest.

2. The method of Claim 1, wherein said providing of the randomly varying radiation includes randomly varying deflection of the external radiation.

3. The method of Claim 2, wherein said providing of the randomly varying deflection includes altering a rate of the radiation deflection.

4. The method of Claims 2 or 3, wherein said providing of the randomly varying deflection comprises randomly varying a trajectory of propagation of the external radiation in a three-dimensional space.

5. The method of any one of preceding Claims, wherein said providing of the randomly varying radiation, includes providing the external radiation of different wavelength ranges.

6. The method of any one of preceding Claims, wherein said providing of the randomly varying radiation includes varying intensity of the external radiation.

7. The method of any one of preceding Claims, wherein said providing of the randomly varying radiation includes providing the external radiation of various polarizations.

8. The method of Claim 7, comprising randomly varying the polarization of the external radiation.

9. The method of any one of preceding Claims, wherein generation of said randomly varying external radiation is initiated in response to an external identification signal.

10. The method of Claim 9, wherein said external identification signal is generated by at least one external sensor device accommodated in the vicinity of the region of interest and responsive to a predetermined condition indicative of an external object approaching the region of interest.

11. The method of any one of preceding Claims, wherein said randomly varying external radiation is directed towards the imaging device.

12. The method of any one of preceding Claims, wherein said randomly varying external radiation is directed towards the region of interest.

13. The method of any one of Claims 2 to 12, wherein the external radiation is deflected with a frequency substantially not less than 15Hz.

14. The method of any one of preceding Claims, comprising sensing radiation from the region of interest to detect whether an image of the region of interest is desirably disrupted.

15. A method for use in projecting certain information, the method comprising, while projecting the information onto a screen surface, carrying out the method of any one of Claims 1 to 14 thereby preventing undesirable photography of the projected information.

16. A system for use in preventing imaging of a region of interest, the system comprising a source of external electromagnetic radiation, and a radiation deflection unit, the system being configured and operable to provide the external radiation randomly varying in space and time in the vicinity of the region of interest, thereby randomly affecting a radiation pattern reaching a radiation sensitive element of an imaging device while collecting radiation from the region of interest.

17. The system of Claim 16 comprising a control unit connectable to the deflection unit and the radiation source unit to operate them.

18. The system of Claim 17, wherein control unit is configured to operate the deflection unit to vary a trajectory of propagation of the external radiation in a three-dimensional space.

19. The system of Claim 17 or 18, wherein the control unit is configured to operate the deflection unit to alter a rate of the radiation deflection.

20. The system of any one of Claims 16 to 19, configured and operable to provide the external radiation of different wavelength ranges.

21. The system of any one of Claims 17 to 20, wherein the control unit is configured to operate the radiation source unit to vary intensity of the external radiation.

22. The system of any one of Claims 16 to 21, configured and operable to provide the external radiation of various polarizations.

23. The system of any one of Claims 17 to 22, wherein the control unit is configured to operate the radiation source unit to randomly vary the polarization of the external radiation.

24. The system of any one of Claims 16 to 23, comprising at least one sensor device accommodated in the vicinity of the region of interest and responsive to a predetermined condition indicative of an external object approaching the region of interest.

25. The system of any one of Claims 16 to 24, configured to direct said randomly varying external radiation towards the imaging device.

26. The system of any one of Claims 16 to 25, configured to direct said randomly varying external radiation towards the region of interest.

27. The system of any one of Claims 17 to 26, wherein the control unit operates the deflection unit to provide the deflection of the external radiation with a frequency substantially not less than 15Hz.

28. The system of any one of Claim 16 to 27, wherein the radiation source unit comprises several radiation sources generating radiation of different wavelengths.

29. The system of any one of Claims 16 to 28, comprising a spectral filter unit.

30. The system of any one of Claims 16 to 29, wherein the deflection unit comprises a scattering surface oriented to receive radiation generated by said source of radiation.

31. The system of any one of Claims 16 to 30, wherein the deflection unit 5 comprises at least one reflector unit oriented to reflect said external radiation.

32. The system of Claim 31, wherein the reflector unit comprises an array of micro-mirrors controllably movable to provide said randomly varying deflection.

33. The system of any one of Claims 16 to 32, comprising a drive system configured and operated for displacing at least one of the radiation source unit

10 and the deflection unit.

34. The system of any one of Claims 16 to 32, comprising a drive system configured and operated for displacing at least one of the radiation source unit and the deflection unit along three axes.

35. The system of any one of Claims 16 to 34, comprising at least one 15 radiation sensitive device configured for collecting radiation from the region of interest and generating data indicative thereof, thereby enabling identification whether the image of the region of interest is^' desirably disrupted or not.

36. The system of any one of Claims 16 to 35 wherein the deflection unit comprises at least one movable light modulator.

20 37. The system of Claim 36, comprising at least one drive unit associated with said at least one light modulator, and configured for rotating the light modulator and vibrating it during the rotation.

38. The system of Claim 36 or 37 wherein said at least one light modulator includes a plurality of randomly distributed spaced-apart spectral filters.

25 39. The system of any one of Claims 36 to 38 wherein the light modulator is formed by a plurality of spaced-apart randomly shaped and distributed light transmitted regions spaced by relatively light blocking regions.

40. A device for projecting information on a plane in a region of interest, the projection device comprising the system of any one of Claims 16 to 39 for preventing capturing an image of the projected information by any imaging device.

41. An object carrying the system of any one of Claims 16 to 39 for preventing capturing an image of said object by any imaging device.