Abstract:
A service providing system comprising a server device, a terminal device, and a service providing device in combination with an optical wireless tag device to achieve transmitting of ID, password, or other service information stored in the service providing device in a non-contact and non-broadcasting manner, thus enabling highly secured and reliable services.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a non-contact service providing system comprising of a terminal, a server device, and a service providing device enclosed with an optical wireless ID tag, and. In particular, the invention relates to a technique of delivering a secured electronic transaction service or a secured and reliable identification service to a terminal from a service providing device by using an optical wireless ID tag. 
       BACKGROUND OF THE INVENTION 
       [0002]    Radio Frequency Identification (RFID) based wireless tag devices and services have been successfully used in various applications in various tag forms such as label, card, coin, and stick types. More recently, attentions have been paid to the electronic transaction functions by implementing RFID tag devices into portable hand held devices. In particular, one important class of such service providing devices—cell phones, is integrated with RFID tags to enable services such as credit card payments and ticketing pass card services. 
         [0003]    However, using RFID based communication for wireless financial services could lead to fatal risks of card security and privacy because of the inherent broadcasting nature of the RF communication. For a credit card enabled cell phone device, failures of card security result in not only great direct financial loss but also customer dissatisfaction and possible nagging legal hassling. Though the security of the RFID communication can be improved with chip encryption, it remains technically breakable for professionals. A miniature RF recorder can be stealthily tapped in close proximity to a Point of Sale (POS) terminal to record thousands of cards and transaction data easily. The recorded data can be stored or relayed to a remote site where installed are equipments for breaking card encryption. The cost of equipments for breaking card encryption is marginal by comparison with the potential gains for professional identity theft providing enough incentive for organized professional crimes. Furthermore, being eavesdropped or tapped is not the only sensitive concern that may arise due to the uses of RFID based method for wireless financial services, signal cross talk and contamination between adjacent devices in a close proximity may disturb the operation reliability of the entire service providing platform. 
         [0004]    Thus, there is a need for equipping a cell phone with a new wireless ID device capable of transmitting data in a non-broadcasting manner. There is a need for equipping a service providing device (e.g. a cell phone) with a new wireless ID device that offers immunizations not only from eavesdropping or tapping, from being relayed and/or amplified, but also from signal cross talk and contaminations. There is also a need for uses of such non-broadcasting identification devices with other service devices and apparatus systems to enable highly secured ID authentications. 
       SUMMARY OF THE INVENTION 
       [0005]    It is therefore an object of this invention to enhance card security of an service providing device (e.g. cell phone) by using a non-broadcasting optical wireless ID tag in replacement of an RFID tag. 
         [0006]    It is a further object of this invention to provide a service providing device (e.g. a cell phone) with an integrated non-broadcasting wireless optical ID tag to enhance the data transmission reliability of a service providing system. 
         [0007]    The service providing devices include cell phones, smart phones, media players, portable digital assistants (PDAs), digital cameras, game playing systems, view-finders, e-books, wristwatches, pagers, rings, necklaces, key chains, keys, and other portable hand held devices. The service providing devices may provide services including credit card/debit payment, road pass, ticketing, and other ID sensitive services. The service providing devices may also be used as switching devices to authorize the turning on and off conditions of ID sensitive equipments (e.g. an automobile), instruments, and apparatuses, thus minimizing the number of “keys” or identification “cards” one needs to maintain. Accordingly, the service providing device described herein provides a housing for the optical ID tag. Accordingly, the system for fulfilling the needs of various applications includes in general a terminal device for reading the tag, a server device, and a service providing device (e.g. cell phone) in integration with an optical ID tag device. Alternatively, the service providing system may not include a separate server device if the same functionalities in certain cases can be provided by either the terminal device or the service providing device. 
         [0008]    In one aspect, such a terminal device includes a controller, a memory unit, a power source, and a mean for transmitting/receiving optical signals; 
         [0009]    In another aspect, such a terminal device includes a controller, a memory unit, a power source, a light source, and a means for transmitting/receiving optical signals. 
         [0010]    In one aspect, such an optical ID tag device includes a controller, a memory unit, a power source, a light modulator, and a mean for transmitting/receiving optical signals. 
         [0011]    In another aspect, such an optical ID tag includes a controller, a memory unit, a power source, a light source, and a means for modulating and transmitting optical signals. 
         [0012]    This invention results from the realization that an improved ID service device which eliminate the numerous problems with prior art RFID based service devices, including broadcasting communication, signal contamination, and being lack of security and privacy, is achieved by establishing a non-broadcasting optical wireless link by integrating the device with an optical ID tag. 
         [0013]    In a preferred embodiment, the present invention provides a service providing device being integrated with a passive optical ID tag device wherein no light source is required, and wherein the optical ID tag device comprises of a Micro-Electro-Mechanical Systems (MEMS) light modulator attached to a corner cube retro-reflector, capable of modulating and retro-reflecting an interrogating incident light beam, thus enabling a non-broadcasting optical communication link while still maintaining insensitivity to incident angles. 
         [0014]    In some embodiments, the MEMS light modulator is a rotational rigid micro-mirror installed onto one of the corner cube facets. 
         [0015]    In some embodiments, the MEMS light modulator is an array of rotational rigid micro-mirrors installed onto one of the corner cube facets. 
         [0016]    In some embodiments, the MEMS light modulator is a deformable membrane micro-mirror installed on one of the corner cube facets. 
         [0017]    In some embodiments, the MEMS light modulator is an array of deformable membrane micro-mirrors installed on one of the corner cube facets. 
         [0018]    In all embodiments, the corner cube retro-reflector can be either a hollow or a solid corner cube. 
         [0019]    In another preferred embodiment, the present invention provides a service providing device being integrated with an active optical ID tag device wherein a light source is included to modulate and transmit ID and other service data to a service terminal device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The above and other objects, advantages and features of the present invention will occur to those skilled in the art from the following description of the preferred embodiments and the accompanying drawings, in which: 
           [0021]      FIG. 1A  is a schematic diagram of a service providing system composed of a service providing device, a terminal device, an optical ID tag device housed in the service providing device, and a server device, according to an preferred embodiment of the present invention; 
           [0022]      FIG. 1B  is a schematic diagram of a service providing system composed of a service providing device, a terminal device, an optical ID tag device housed in the service providing device, and a server device, according to another preferred embodiment of the present invention by incorporating in RF wireless communication capability into the system; 
           [0023]      FIG. 1C  is a schematic block diagram of the service providing device in accordance with the preferred embodiment of  FIG. 1A  illustrating the function elements of the service providing device and the optical ID tag device; 
           [0024]      FIG. 1D  is a schematic block diagram of the terminal device and the server device in accordance with the preferred embodiment of  FIG. 1A  illustrating the function elements of the terminal device and the server device; 
           [0025]      FIG. 2  is a schematic block diagram of a terminal device in optical communication with an optical ID tag device that is built by attaching a MEMS light modulator to a corner cube retro-reflector according to a preferred embodiment of the present invention; 
           [0026]      FIG. 3A  is a block diagram showing the primary optics components of a terminal device in accordance with the preferred embodiment of the present invention showing  FIG. 2 ; 
           [0027]      FIG. 3B  is a block diagram showing the primary components of a terminal device incorporating a fiber coupled infrared laser source, a collimator, a beam splitter (or a beam shifter), a beam expander, and a photo detector (receiver) in accordance with the embodiment of the present invention showing in  FIG. 2 ; 
           [0028]      FIGS. 4A-C  are magnified perspective views of three preferred embodiments of the MEMS modulating corner cube retro-reflector in accordance with the present invention as shown in  FIG. 2 ; 
           [0029]      FIG. 5A  is a perspective view of the optical ID tag device with a MEMS light modulator according to the embodiment showing in  FIG. 2  wherein the MEMS light modulator is a rotational rigid micro-mirror; 
           [0030]      FIG. 5B  is a perspective view of the optical ID tag device with a MEMS light modulator according to the embodiment showing in  FIG. 2  wherein the MEMS light modulator is an array of rotational rigid micro-mirrors; 
           [0031]      FIG. 5C  is a perspective view of the optical ID tag device with a MEMS light modulator according to the embodiment showing in  FIG. 2  wherein the MEMS light modulator is a deformable membrane micro-mirror; 
           [0032]      FIG. 5D  is a perspective view of the optical ID tag device with a MEMS light modulator according to the embodiment showing in  FIG. 2  wherein the MEMS light modulator is an array of deformable membrane micro-mirrors; 
           [0033]      FIGS. 6A-B  are magnified views of the MEMS modulating corner cube retro-reflector composed of a plural of rotational rigid micro-mirror in an arrayed arrangement according to the preferred embodiment showing in  FIG. 5B ; 
           [0034]      FIGS. 6C-D  are a magnified views of the MEMS modulating corner cube retro-reflector composed of an array of deformable membrane micro-mirrors, functioning effectively as a diffractive grating according to the preferred embodiment showing in  FIG. 5D ; 
           [0035]      FIG. 7A  is a perspective views of an omni-directional corner cube embodiment comprising four MEMS modulating corner cube retro-reflectors arranged respectively on four quadrants of a support substrate; 
           [0036]      FIG. 7B  is a perspective view of a hollow corner cube retro-reflector being installed with three MEMS light modulators on three facets, respectively, each modulating light independently, capable of representing multiple or multiplexed data channels; 
           [0037]      FIG. 8A  is a schematic cross sectional view showing the primary components of the diffractive grating light modulator associated with the array of the deformable membrane micro-mirrors as shown in  FIG. 5D  embodiment of the present invention; 
           [0038]      FIG. 8B  is a schematic cross sectional view showing the primary components of the arrayed deformable membrane micro-mirrors being deflected under electrostatic actuation, functioning as a diffractive grating light modulator, in accordance with the  FIG. 5D  embodiment of the present invention; 
           [0039]      FIGS. 9A-F  are partial isometric cross-sectional views of the deformable membrane micro-mirrors at various stages of fabrication, according to one preferred fabrication process of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    To provide an overall understanding of the invention certain illustrative embodiments will now be described, including the server device, the service providing device, the optical ID tag device, and the terminal device. More particularly, the devices and methods described herein include, among other things the preferred embodiments of the service providing devices with the built-in optical ID tag device and the methods for making the same suitable for integration into the service providing device. Those skilled in the art will recognize that many alternative embodiments can be accomplished using the teachings of the present invention and that the systems and methods described herein may be adapted, modified, and employed for other suitable applications, and that such other additions and modifications will not depart from the scope hereof. 
         [0041]      FIG. 1A  is a conceptual schematic diagram of a service providing system  100  composed of a cell phone  1  as a service providing device, a terminal device  3  (as ID reader), an optical ID tag device  2  housed in the service providing device  1 , and a server device  4 , according to an preferred embodiment of the present invention. The service providing system  100  can alternatively be formed by incorporating an optical ID tag device into other forms of service providing device other than the cell phones such as smart phones, media players, portable digital assistants (PDAs), digital cameras, wristwatches, rings, keys and necklaces. The optical ID tag device  2  is incorporated in or attached to the cell phone  1  which provides a housing for the optical ID tag device  2 . The cell phone  1  transmits/receives data to/from the terminal device  3  by using the optical communication link  6  that is enabled by the optical ID tag  2 . The terminal device  3  transmits/receives data to/from the server device  4  through a network line  5 . The terminal device  3  receives an ID of the optical ID tag  2  and relays the received ID to the server device  4  for authentication. The server device  4  authenticates the received ID and service request information, and generate a notification to allow or not allow the provision of the requested service, or provides information data contents to be sent to the terminal device  3 , or relayed to the cell phone  1 . 
         [0042]    Alternatively, as shown in  FIG. 1B , data generated by the server device  4  can be directly transmitted to the cell phone  1  by using a RF wireless communication channel such as a commercial mobile phone service. Alternatively, the cell phone  1  may use the RF communication channel  7  to directly transmit data to the server device  4  for confirmation of the transaction contents. Alternatively, the optical ID tag device  2  may be used as an optical receiver for receiving data from the terminal device  3 . 
         [0043]    Referring to  FIG. 1C , a schematic block diagram of the service providing device in accordance with the preferred embodiment of  FIG. 1A  is used to illustrates the function elements of the service providing device that includes the enclosed optical ID tag device. 
         [0044]    As shown in  FIG. 1C , the cell phone  1  includes an optical ID tag device  2 , a display  11 , a memory  13  as a storage unit, a key board  15  as an input unit, and a controller  17  as a control unit. These components are connected through a control bus  12 . The optical ID tag device  2  includes a light modulator  20  as a data-modulating unit, a transmitting/receiving optics  22  as a optical path control unit, a memory  24  as a storage unit, and a controller  26  as a control unit. Among them, the electronic components  24  and  26  and the electronic portions of components  20  and  26  are connected through a control bus  28 . Under the control of the controller  26 , the light modulator unit  20  reads information (ID and other information necessary for fulfilling the requested service) stored in the memory unit  24 . Electrical signal data is transformed to optical signal data by the light modulator  20 , and the optical signal is then transmitted to the terminal device  3  through the transmitting/receiving optics  22 . The optical ID tag device  2  and other components of the cell phone  1  are supplied with electrical power through a shared power source  16  which may be a built-in battery unit or an external power supply. The optical ID tag device  2  and other components of the cell phone  1  are capable of interfacing through an interface circuit  18 . Under the control of the interface circuit  18 , the controller unit  17  of the cell phone  1  and the controller unit  24  of the optical ID tag  2  are able to exchange instructions. As a result, the user interfaces of the cell phone  1  (i.e. the display  11  and the key board  15 ) enable users to control the progress for the requested service and confirm the data contents of the provided service thereafter. 
         [0045]    Referring to  FIG. 1D , the server device  4  may include a memory unit  50  as data storage unit, and a transmitting/receiving circuit  52 , a controller  54  as control unit, and a control bus  56  for connecting these elements. The server device  4  fulfills the communication with the terminal device  3  through the service network line  60 . Optionally, the server device  4  communicates with the cell phone  1  through a RF communication channel. 
         [0046]    The terminal device  3  includes a transmitting/receiving optics  32  to enable data acquisition from the transmitting/receiving optics  22  of the optical ID tag device  2 , as shown in  FIG. 1D . The terminal device  3  includes a power source  34 , a controller  36  as a control unit, a memory  38  as a storage unit, and optionally, a display unit  40  and a key board unit  42  as user interfaces, and a light source  44  for either actively sending data to the optical ID tag device  2  or passively interrogating data from the optical ID tag device  2 . Among them, the electronic components  34 ,  36 ,  38 ,  40 ,  42 , and the electronic portions of the components  44  and  32  are connected through a control bus  46 . Under the control of the controller  46 , the transmitting/receiving optics  32  reads ID and other data from the optical ID tag device  2 . 
         [0047]    When light source  44  is present, a highly preferred embodiment will be to use the light source  44  for data interrogating. An optical communication link can be established between the terminal device  3  and the optical ID tag device  2  in an optically passive manner. The term “optical passive” used herein is understood as such that no light source is required to install in the service providing device (i.e. the cell phone  1 . Therefore, under this passive communication circumstance, the optical ID tag device  2  is utilized as an optical passive transmitter  80  wherein no light source is necessarily required but instead a light modulating retro-reflector device  90  is incorporated in the optical ID tag device for data modulating. The modulated data is then loaded onto the retro-reflected beam, returning to the terminal device  3 , as shown in  FIG. 2 . 
         [0048]    Referring to  FIG. 2 , the optical ID tag device  2  is now designated as a passive optical transmitter  80  comprising of a memory unit  24  as data storage unit, a controller  26  as control unit, a power source  82 , a high speed switch circuit  84 , a data pulse generator  86 , and a MEMS modulating corner cube retro-reflector device  90  according to a preferred embodiment of the present invention. In the preferred embodiments, data can be stored either in the memory unit  24  or externally input through a service data interface  83  and a signal processor  85 . Data can be digitized to feed the high speed switch circuit  84  through the pulse generator  86 . The power source  82  converts the power supply of the cell phone  1  to a preset DC voltage level (e.g. optical extinction voltage for the light modulator), the data pulse generator  86  feeds the data pulse train signals (from the memory  24  or from the signal processor unit  85 ) for controlling the high speed switch circuit  84 , and the switch circuit  84  then hammers the DC voltage and outputs the pulsed preset voltage signals to the MEMS modulating corner cube retro-reflector device  90 . Alternatively, the power source  82  can be designed to convert the power supply provided by the cell phone  1  to a preset current level. The MEMS modulating corner cube retro-reflector device  90  is formed by attaching a MEMS light modulator  94  with a corner cube retro-reflector component  92 . The MEMS light modulator  94  may be attached to one inner facet of a hollow corner cube, or to one back facet of a solid corner cube. 
         [0049]      FIG. 2  schematically shows an optical link system  200  established between a terminal device  3  and a MEMS-modulated optical ID tag  80  that is formed by attaching a MEMS light modulator  94  with a corner cube retro-reflector component  92  according to the preferred embodiment of the present invention. 
         [0050]    Referring to  FIG. 2 , the terminal device  3  herein is schematically simplified to show two function elements: the light source  44  (i.e. the interrogating laser) and the transmitting/receiving optics  32 . In optical operation, the interrogating laser (i.e. the light source  44 ) sends interrogating light beam  96  to the passive optical transmitter  80 , the MEMS modulating corner cube retro-reflector  90  retro-reflects the incident light beam  96  back to the terminal device  3 . The retro-reflected light beam  98  is directed to the transmitting/receiving optics  32 . Electrically, data is provided to the MEMS light modulator  94  through the pulse generator  86  and the switch circuit  84 . The data sequence  91  is first expressed as pulsed train signals  93  at a preset voltage level. The pulsed train signals  93  actuate the mechanical motion of the MEMS light modulator  94  to modulate the retro-reflected light intensity of the incident light beam  96 . The electrical data signal is represented as the modulated data  99  carried by the retro-reflected light beam  98 . As such, an optical link is established between the terminal device  3  and the optical ID tag  2 . The link physically is composed of two types of light beams: the incident light beam  96  serving for data interrogating, the retro-reflected light beam  98  serving as a data carrier. 
         [0051]    Referring to  FIG. 3A  and  FIG. 3B , the optical link system  200  showing in  FIG. 2  is described with more details in optics. 
         [0052]      FIG. 3A  is a block diagram showing the primary optics components of an optical interrogator terminal  3  in accordance with a preferred embodiment of the present invention. The primary optics of the interrogating terminal  3  includes a light source  301 , an illumination assembly  303 , a beam splitter  309 , a collimating lens  311 , a spatial filter  313 , and a light detector  315 . The light source  301  can be either broadband (e.g. commercial white light sources) or narrowband (e.g. lasers). The illumination assembly  303  is used to adjust the size and collimation of the light beam  310 , and to direct the light beam  310  onto a beam splitter  309 . The beam splitter  309  directs a portion of the light beam  310  onto a collimation lens  311 . The collimation lens  311  directs a light beam  320  out of the interrogating terminal  3 , serving as the incident beam to interrogate the service providing device  1 . A portion of the light beam  320 , —the light beam  302 , i.e. the light portion incident onto the region where the optical ID tag device  2  is located, is retro-reflected. This portion of light then transmits through the beam splitter  311 , through the spatial filter  313 , to reach a light detector  315  to be detected into electrical data signals. The presence of the corner cube retro-reflector ensures certain portion of the incident beam be retro-reflected according to the relative angular positions of the optical ID tag device with respect to the interrogating light beam. As the light modulator is capable of transmitting data at much higher bit rate than the possible shaking or waving frequency of a human hand, the ID and other service information can be reliably delivered to the terminal device without disturbance. The communication is non-broadcasting because (1) a tiny portion of the interrogating light beam is effectively in use for data communication, and (2) the retro-reflected light portion can be restricted to return to the output window of the terminal device. 
         [0053]    Now referring to  FIG. 3B , a block diagram showing the primary optics of a terminal device  3  incorporating a fiber coupled infrared laser source  351 , fiber link  353 , a collimator  355 , a beam splitter  357 , a beam expander assembly  358 , a focusing lens  364 , a spatial filter  366 , and a light detector  368  in accordance with another illustrative embodiment of the present invention. The collimator  355  directs the light beam  370  onto a beam splitter  357 . Beam splitter  357  directs the light beam  370  to a beam collimation and expanding assembly  358 . Beam collimation and expanding assembly  358  directs the light beam  360  out of the terminal device  3  to the service providing device. A portion of the light beam  360 , i.e. the light beam  362 , as shown in  FIG. 3B , is retro-reflected by the optical ID tag device  2 , transmitted through the beam splitter  357 , the focusing lens  364 , and the spatial filter  366 , finally reaches the a light detector  368 . 
         [0054]    In summary, as shown in  FIG. 3A  and  FIG. 3B , the optical ID tag device  2  resides in the cell phone  1 , functioning to retro-reflect a portion of the incident interrogating light beam. As at least one facet of the corner cube is attached with a light modulator, the portion being retro-reflected becomes capable of carrying modulated data. As such, non-broadcasting optical wireless communication is achieved. 
         [0055]    To attach a light modulator to a corner cube retro-reflector, there exists in general three configurations as follows: (1) attaching the light modulator to in inner facet of a hollow corner cube, (2) attaching the light modulator to an back facet of a solid corner cub, and (3) attaching the light modulator in front of the three facets of a corner cube, as shown in  FIG. 4A ,  FIG. 4B , and  FIG. 4C , respectively. 
         [0056]    Referring now to the  FIGS. 4A-C , the three basic configurations are illustrated for attaching a light modulator  494  to a corner cube retro-reflector  492  in order to build a modulating corner cube retro-reflector  490 . In  FIG. 4A  the light modulator  494  is attached to one inner facet of a hollow corner cube  492 . In  FIG. 4B  the light modulator  494  is attached to one back facet of a solid hollow corner cube  492 . In both configurations, the light modulator  494  can optionally be attached to any of the three facets of the corner cube  492 . In both configurations, the light modulator  494  is preferred to be a MEMS light modulator wherein light modulation is usually achieved by moving a micron-sized tiny mechanical mirror part. However, in  FIG. 4C  a light modulator  454  is placed in front of the three facets of a corner cube  452  by which the light modulator  454  is used in transmission mode to modulate light. The preferred light modulator for use in the  FIG. 4C  configuration is liquid crystal light modulator, multi quantum well light modulator, phase conjugate light modulator, or electro-optic crystal based light modulator. In enabling a modulating corner cube retro-reflector, these refractive light modulators are disadvantageous in their angular sensitivity because the optical path in the propagation media has angular dependence. In contrast, MEMS light modulators are preferred to be used in reflective mode. Shown in  FIG. 5A ,  FIG. 5B ,  FIG. 5C  and  FIG. 5D  are four typical types of MEMS light modulators in attachment with a hollow corner cube, respectively. 
         [0057]      FIG. 5A  shows a perspective view of a MEMS light modulating corner cube retro-reflector according to the preferred embodiment of the present invention showing in  FIG. 2 . Herein the MEMS light modulator is a rotational rigid micro-mirror  514  installed to one facet (X-Y plane) of a hollow corner cube retro-reflector  512 . The tilting mirror  514  is suspended by a set of torsional springs  516 , capable of rotate around the axis  518  under an actuation force. The actuation force can be generated by electrostatic, electromagnetism, thermal, and piezoelectric mechanisms, etc.  FIG. 5B  shows a perspective view of a MEMS light modulating corner cube retro-reflector according to the preferred embodiment of the present invention showing in  FIG. 2 . Herein the MEMS light modulator is a 4×4 array of rotational rigid micro-mirrors  524  installed onto one facet (X-Y plane) of a hollow corner cube retro-reflector  522 . Similar to the mirror  514  in the  FIG. 5A , each of the mirrors in the array  524  is also suspended by a set of springs  526 , thus capable of rotation under actuated conditions.  FIG. 6A  shows a magnified view of the MEMS light modulator comprising of a 4×4 array of the micro-mirrors  524  suspended by springs  526  in the fixed frame of  601  according to the embodiment showing in  FIG. 5B . According,  FIG. 6B  shows the magnified top view of the micro-mirror array  524 . 
         [0058]    Alternatively, the MEMS light modulator, as used in the preferred embodiment of the present invention showing in  FIG. 2 , may also be constructed of flexible membrane whose deformation alters the retro-reflected intensity of an incident light. Shown in  FIG. 5C  is a perspective view of this type of MEMS modulating corner cube retro-reflector according to the preferred embodiment wherein the MEMS light modulator includes a deformable membrane  534  and a frame  536 . The edge portion of membrane  534  is disposed onto the frame  536 . The light modulator is installed to one facet (X-Y plane) of the hollow corner cube retro-reflector  532 . 
         [0059]    Alternatively, the MEMS light modulator, as used in the preferred embodiment of the present invention showing in  FIG. 2 , can also be constructed of an array of membrane micro-mirrors.  FIG. 5D  is a perspective view of this type of MEMS light modulator built on a support substrate  546  illustrating the array of deformable membrane micro-mirrors is formed by stretching a flexible membrane  544  over an array of posts  548 , thus dividing the membrane  544  into a plural of small deformable membrane micro-mirrors. In optics, the array of the micro-mirrors functions as a reflecting diffractive grating capable of diffracting an incident light beam into multiple far field orders of light beams following the principle of diffractive optics.  FIG. 6C  shows a magnified view of the MEMS light modulator. Accordingly,  FIG. 6D  is the magnified top view of the posts  548 , illustrating the way the deformable membrane  544  is divided into multiple membrane micro-mirrors. 
         [0060]    Referring to  FIG. 7A , a perspective view of an omni-directional corner cube embodiment  751  comprising four MEMS-modulating corner cube retro-reflectors  753  arranged on four quadrants of a common support substrate plate  752 , is used to illustrate an preferred embodiment of an optical ID tag device  2 . In theory, such an optical ID tag device is capable of building optical communications with interrogating lights incident from all directions from above the plane of the support substrate  752 .  FIG. 7B  further shows one quadrant portion  753  of the preferred corner cube embodiment  751  in attachment with three MEMS light modulators  754 ,  756 , and  758  on each of three facets, respectively, each representing an independent optical communication channel, providing an increased bandwidth for the service providing device  1 . Each of the three MEMS light modulators may operate at different frequency or data rate, and the three channels can be configured to operate in time sequence or in a multiplexed manner. 
         [0061]    In a preferred embodiment of the present invention, the three communication channels enabled in each of the four quadrants of the omni-directional corner cube retro-reflector  751  can be designed to modulate and transmit data in a time sequential manner and operate to code data in varied bit rates. Thus, each channel is capable of representing one unique ID and communication channel. These unique IDs with channels may be used for different type of identities for communication of various application or service data. For example, in one preferred embodiment, the omni-directional modulating retro-reflector, when in attachment with a service providing device, can be used to determine the relative position and angular positions of the device with respect to an interrogating terminal. 
         [0062]    Referring to  FIG. 8A , a schematic cross sectional view of a diffractive light modulator  810  shows the layered components  544 ,  546 , and  548  of the diffractive light modulator  810  associated with the  FIG. 5D  embodiment of the present invention. The membrane  544  herein is a composite membrane comprising a supporting layer  804  and a reflective layer  802 . Either of the two layers can be electrical conductive and the supporting substrate  546  has a pre-deposited electrode layer  550 . The two electrodes may form an electrostatic capacitor device. When actuated at a voltage V the membrane  544  will deform to show surface depth distribution, which effectively in optics is a diffractive grating light modulator  810 . The surface depth distribution relies on the shape geometry, dimensions and the arrayed distribution of the posts  548 . The preferred post shape designs in accordance with the present invention are square, rectangular bar, triangle, circle and hexagon. The preferred post shape designs also include those curved features by modifying the above fundamental shapes. Another important design consideration for the posts  548  is the arrayed distribution manner. In real practice, the preferred post distributions include linear or line (for long bar posts) distribution, triangular, square and hexagonal distributions. 
         [0063]    Referring now to  FIG. 8B , a schematic cross sectional view of an actuated diffractive light modulator  810 ′ is shown to illustrate the deformed membrane  544 ′ under electrostatic voltage V. An incident light beam  820  is reflectively diffracted at the surface of the membrane  544 ′, generating not only the zero order diffractive beam  822  but also multiple higher order diffractive beams at varied angles. Shown in  FIG. 8B  are the zero order diffractive beam  822 , a +1 order diffractive beam  824  and a −1 order diffractive beam  826 . As the zero order diffractive beam  822  has the same direction as that of a normal reflected beam, the beam is used as the retro-reflected signal. 
         [0064]    Manufacturing a suspended deformable membrane, however, is usually troublesome and controlling such a membrane for quality optical surface (e.g. flatness and roughness), thickness uniformity, and for repeatability in the actuated deflection, is also problematic. There are in general three basic types of methods for fabricating a suspended membrane onto a micromachined semiconductor substrate: direct membrane disposing method, wafer-level membrane transfer method, and the method of using sacrificial materials, each has its unique advantages and disadvantages. Shown in  FIGS. 9A-F  are partial isometric cross-sectional views of a deformable membrane diffractive grating at various stages of fabrication, according to one preferred embodiment of the present invention showing in  FIG. 5D  and  FIG. 8B , wherein the disclosed fabrication process flow is a improved wafer-level membrane transfer process that is preferred to be used in producing high quality MEMS membrane light modulators. 
         [0065]    Shown in  FIG. 9A  is a semiconductor substrate  901  coated with a spacer material layer  903 . In  FIG. 8B , the posts  548  are produced on the substrate  901  by using micromachining techniques. A wafer-level bonding technique is then used to merge the spacer layer  903  of the first substrate  901  with a first membrane material layer  905  of a second a substrate  910 , as shown in  FIG. 9C , followed by a wafer thickness reducing process showing in  FIG. 9D . 
         [0066]    As shown in  FIG. 9D , a wafer thickness reducing process is applied to the bonded wafer pair to reduce the thickness of the second substrate  910 . In a preferred embodiment, the second substrate  910  is silicon material, and the thickness reducing methods are preferred to be grinding, lapping, and/or polishing methods. Wet chemical etching may not recommended at this step because of the technical concerns on thickness uniformity, surface roughness, and generating of pits and waviness on the surface. After grinding, lapping and/or polishing operation, the target substrate  910  could be reduced to a thickness less than 100 microns, sufficient thin now for a time-saving chemical etching for removal of the silicon layer in full. 
         [0067]    As shown in  FIG. 9E , a chemical wet etching process, a dry etching process, or a reactive ion etching process, may be applied to remove the left-over thickness of the substrate  910  in full, exposing the suspended membrane  905 . The entire fabrication for deformable membrane may be concluded with a reflective material coating process to add an optical reflective layer  920  as shown in  FIG. 9F . 
         [0068]    Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments.