WO2013155629A1

WO2013155629A1 - Low order shape control of primary and secondary mirror modules

Info

Publication number: WO2013155629A1
Application number: PCT/CA2013/050296
Authority: WO
Inventors: Caisey HARLINGTEN; Jeff KUHN
Original assignee: HARLINGTEN CENTER FOR INNOVATIVE OPTICS Ltd
Current assignee: HARLINGTEN CENTER FOR INNOVATIVE OPTICS Ltd
Priority date: 2012-04-17
Filing date: 2013-04-17
Publication date: 2013-10-24
Anticipated expiration: 2014-10-17

Description

LOW ORDER SHAPE CONTROL OF PRIMARY AND SECONDARY MIRROR MODULES

FIELD OF THE INVENTION

[0001] The present invention pertains to the field of astronomical optics, and in particular to optical interferometric imaging.

BACKGROUND

[0002] Previous attempts to build large optical interferometric telescopes have implemented a lattice of segmented mirror segments where the light of each segment is combined to form the optical image.

[0003] In previous implementations, such as the Thirty Meter Telescope (TMT), each segment is not corresponding to a specific independent secondary mirror. This nearly-filled aperture telescope requires each segment to be accurate within a fraction of a wavelength of light to every other segment on the telescope in order to avoid phase aberration and achieve high resolution and optical quality.

[0004] In such an arrangement, increased mechanical rigidity is required to ensure all segments are in alignment and have minimal deformation with respect to atmospheric defects (gravitational deformation, temperature, etc.). Mechanical rigidityin the support structure increases weight and therefore changes the scalability and physics of such a structure. Additionally, cost increases with increased materials and increased labor. Finally, manufacturing time is also increased with mechanical rigidity in order to assemble and account for additional mechanical supports.

[0005] Therefore, there is a need for an optical imaging system which allows for independent pairing of primary and secondary optical modules such that dependency of accuracy with respect to each segment relative to all other segments is eliminated as a factor which determines optical quality when relative optical phase of each primary-secondary pair is measured and corrected.

[0006] This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.

SUMMARY OF THE INVENTION

[0007] An object of the present invention is to provide a low order shape control of primary and secondary mirror modules. In accordance with an aspect of the present invention, there is provided a nearly filled aperture interferometric imaging system having: at least one primary mirror module, the primary mirror module having a primary mirror and means for manipulating the primary mirror;at least one secondary mirror module corresponding to the at least one primary mirror module, the secondary mirror module having a secondary mirror and means for manipulating the secondary mirror; and a controller having means to communicate with each of the primary mirror module and the secondary mirror module, the controller configured to receive optical data from at least one of the at least one primary mirror module and the at least one secondary mirror module, the controller configured to perform assessment of the optical data and generate corresponding adjustment data for at least one of the at least one primary mirror module and the at least one secondary mirror module based on the assessment, the controller sending the adjustment data to at least one of the at least one primary mirror module and the at least one secondary mirror module, such that each of the means for manipulating the primary mirror module and the means for manipulating the secondary mirror are operable based on the adjustment data such that the at least one primary mirror module is manipulable relative to the at least one secondary mirror module.

[0008] In accordance with another aspect of the present invention, there is provided a method of optical imaging a nearly filled aperture interferometric imaging system having the following steps: receiving optical data from at least one of an at least one primary mirror module and an at least one secondary mirror module, assessing the optical data to generate an assessment; generating adjustment data for at least one the at least one primary mirror module and the at least one secondary mirror module based on the assessment; sending the adjustment data to at least one of the at least one primary mirror module and the at least one secondary mirror module; and manipulating the at least one of the at least one primary mirror module and the at least one secondary mirror module based on the adjustment data. BRIEF DESCRIPTION OF THE FIGURES

[0009] Figure 1 illustrates an isometric view of a telescope apparatus;

[0010] Figure 2 illustrates the light path within the optical system;

[0011] Figure 3illustrates an example of primary mirror support structures;

[0012] Figure 4 illustrates an example of the optical system configuration;

DETAILED DESCRIPTION OF THE INVENTION

[0013] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0014] An implementation of the system can be seen in Figurelwhere an isometric view is shown of a telescope apparatus. An aggregate of primary mirror modules (101) can be seen to be comprised of individual primary mirror modules (103) to model a parabolic shape oriented towards a secondary cluster of smaller mirrors (110). The entire telescope system is oriented towards a bright object such that the entire system, including the alignment of the primary mirrors, is oriented to capture light with optimal positioning. The light captured by each primary mirror module is reflected to a corresponding paired smaller secondary mirror module.

[0015] The optical system can be seen in Figure 2 where the path of light is illustrated as it navigates through the system. As stated previously, the primary mirror modules (201) capture light from an area of the sky plane where a bright object is situated which is reflected to a prime focus (205), and further continues to the corresponding secondary mirror modules (203). The light is finally reflected by the secondary mirror modulesstraight through to combine the individual beams of light in the aft-optics module (207).

[0016] Each primary mirror module has a corresponding secondary mirror module constituting a pair.A large interferometric imaging system may consist of many pairs. The shape and positioning information between this pair ensures the elimination of wavefront aberration. In this way, multiple pairs are distinct from each other in the sense that the alignment of each large primary mirror to every other large primary mirror is not constantly required as the corresponding secondary mirrors allow for correction of any deformations occurring on the primary mirror to be corrected utilizing adjustments to the secondary mirrors. This ensures the image produced by the pair is free of wavefront aberrations. Additionally, a piston alignment of secondary mirror modules is conducted simultaneously to align the aggregate corresponding pairs relative to one another in order to resolve the relative pairwise phases of each of the pairs constituting respective primary and secondary mirror modules. This provides for an aggregate summation of synchronized images. In this way, it is the relative positioning of each respective primary and secondary mirror within each pair to each other, as well as the piston alignment of each pair to all other pairs that is of relevance. Therefore, the summation of each of the pairs in aggregate, where each pair has been corrected within itself to be co-phased that produces the final bright optical image of high resolution.

Primary Mirror Modules

[0017] The system includes a primary mirror module comprising the optical mirror surface and all required elements required to manipulate the optical mirror surface depending on application.

[0018] The one or more primary mirror modules receive light input from the sky plane and reflect the light to a dedicated corresponding secondary mirror module. For each primary mirror module, there is a corresponding secondary mirror module configured to receive light from the paired primary mirror module.

[0019] The primary mirror module must maintain the shape of the optical surface to allow for high resolution and optical quality. In some embodiments, to maintain shape of the optical surface, low order shape control may be used comprising positional based actuation, shape based actuation, or any combination thereof.

[0020] In some embodiments, the mirror module includes the optical mirror surface and mechanical support structure for the optical mirror surface. The mechanical support structure allows for the optical mirror surface to affix at various points to relieve the inherent tension and stress of the material. An example of one variant of mechanical support structure may be seen in Figure 3. An isometric bottom side view of the primary mirror mechanical support structure can be seen in (310) and an exploded side view of the same structure can be seen in (320). [0021] In some embodiments, a single primary mirror module is implemented. In other embodiments, more than one primary mirror module is implemented. These multiple primary mirror modules may be combined, as the summation of inputs from the one or more mirrors is utilized as a close-packed interferometer. The formation of multiple mirrors resembles one large curved surface as seen in Figure 1.

[0022] In some embodiments, the mirrors used are fairly large in scale and may be implemented to include 8 meter large optical surfaces. In some embodiments, the mirrors have a thin profile, even at scale (8 meters), to allow for lighter optical surfaces. The thinner mirrors may include mechanical support structures to sustain the required rigidity to maintain a desired shape. In some embodiments, the mirrors used are deformable mirrors requiring mechanical support structures.

[0023] The primary mirror module also comprises means for measuring shape and positioning of the optical surface. In some embodiments the means for measuring shape and positioning are by way of interferometric positioning devices. In some embodiments, the interferometric positioning device stores positional and shape information within an integrated storage unit within the interferometric positioning device. In other embodiments, the interferometric positioning device measures and stores information within a discrete embedded storage unit in the primary mirror module. In other embodiments, measurements taken from the interferometric positioning device are sent straight to the controller module by one or more communication means.

[0024] In some embodiments, a Shack-Hartmann sensor is placed at the prime focus of the primary mirror modules such that the sensor may be used to calibrate the shape of each of the one or more primary mirror modules. An example of the optical configuration may be seen in Figure4.The primary mirror modules (401) reflect light to the prime focus (403) where the Shack- Hartmann sensor is placed. This is a temporary configuration for calibration and removed once the calibration is set. Communication from the primary mirror module is made to the controller to calculate the corresponding required adjustment. This adjustment is calculated by the controller and communicated back to the primary mirror module for implementation.

[0025] The optical surface of the primary mirror module can be constructed from any substrate material provided the weight and rigidity characteristics meet the desired threshold across varied temperature ranges. Potential mirror substrates include, but are not limited to, glass, epoxy-glass composites, SCHOTT Zerodur, Astro-Sital, Fused Silica, ULE, Silicon Carbide(SiC), Aluminum, Beryllium, SiliconizedSiC, and SiC CVD. [0026] The mirrors may utilize any shape conducive to telescopic optics. In some embodiments the mirrors are circular. In other embodiments the mirrors are hexagonal. In yet other embodiments, the mirrors are octagonal.

[0027] The primary mirror module also comprises means for communicating with system modules. In some embodiments, the primary mirror module communicates with a controller module allowing for instructions to be sent and received coordinating adjustments to the shape of the mirror and the positional orientation of the mirror with respect to six-degrees of freedom. In some embodiments, the primary mirror module communicates with the secondary mirror module or aft- optics module. In some embodiments, the means for communicating include wired communication and wireless communication protocols including but not limited to, TCP/IP, IEEE 802.15.1 (Bluetooth), 802. llx (WLAN), wireless metropolitan area networks (WMAN), infrared, radio, cellular communication (2G, EDGE), cellular data communication (3G, HSPDA, LTE), and mobile satellite communications.

[0028] The means for communication in the primary mirror module allows for sending of information with respect to positioning, orientation, atmospheric conditions, and other relevant information with respect to positioning to system modules. In some embodiments, the primary mirror module sends information to the controller module. In some embodiments, the primary mirror module sends information to the secondary mirror module. In some embodiments, the primary mirror module sends information to the aft-optics module.

[0029] Additionally, the means for communication also allows the primary mirror module to receive adjustment data from system modules. In some embodiments, data from the primary mirror module and all other modules (e.g., secondary mirror modules) are analyzed and processed to generate the corresponding adjustment data, which is sent by the controller module to the primary mirror module. In some embodiments, the secondary mirror module sends adjustment data to the primary mirror module. In some embodiments, the aft-optics module sends adjustment data to the primary mirror module.

Secondary Mirror Modules

[0030] The system includes a secondary mirror module comprising the optical mirror surface and all required elements required to manipulate the mirror surface depending on application. [0031] The one or more secondary mirror modules receive light input from the corresponding one or more primary mirror modules. For each secondary mirror module, there is a corresponding primary mirror module configured to reflect light to the paired secondary mirror module.

[0032] The secondary mirror module must maintain the shape of the optical surface to allow for high resolution and optical quality. Furthermore, the secondary mirror module is utilized to adjust for wave-front imperfections of the reflected light received from the primary mirror module. In some embodiments, to maintain shape of the optical surface, the required adjustments may be implemented by low order shape control comprising positional based actuation, shape based actuation, or any combination thereof.

[0033] In some embodiments, the mirror module includes the optical mirror surface and mechanical support structure for the optical mirror surface. The mechanical support structure allows for the optical mirror surface to affix at various points to relieve the inherent tension and stress of the material. An example of one variant of mechanical support structure may be seen in Figure 3. An isometric bottom side view of the primary mirror mechanical support structure can be seen in (310) and an exploded side view of the same structure can be seen in (320).

[0034] In some embodiments, a single secondary mirror module is implemented. In other embodiments, more than one secondary mirror module is implemented. These multiple secondary mirror modules may be combined as the summation of inputs from the one or more mirrors is utilized as a close-packed interferometer. The formation of multiple mirrors resembles one aggregated curved surface.

[0035] In some embodiments, the mirrors used are fairly small in scale relative to the primary mirrors, namely less than 300 millimeters. In some embodiments, the mirrors have a thin profile to allow for lighter optical surfaces. The thinner mirrors may include mechanical support structures to sustain the required rigidity to maintain a desired shape. In some embodiments, the mirrors used are deformable mirrors requiring mechanical support surfaces.

[0036] Similar to the primary mirror module, the secondary mirror module also comprises means for measuring shape and positioning of the optical surface. In some embodiments the means for measuring shape and positioning are by way of interferometric positioning devices. In some embodiments, the interferometric positioning device stores positional and shape information within an integrated storage unit within the interferometric positioning device. In other embodiments, the interferometric positioning device measures and stores information within a discrete embedded storage unit in the secondary mirror module. In other embodiments, measurements taken from the interferometric positioning device are sent straight to the controller module by one or more communication means.

[0037] The secondary mirror module is configured with various optical sensory mechanisms to evaluate the optical quality of the wavefront received from the primary mirror module. In some embodiments, the sensory mechanism includes Shack-Hartmann wavefront sensors to measure the phase aberration.

[0038] The one or more optical surfaces of the secondary mirror module can be constructed from any substrate material provided the weight and rigidity characteristics meet the desired threshold across varied temperature ranges. Potential mirror substrates include, but are not limited to, glass, epoxy-glass composites, SCHOTT Zerodur, Astro-Sital, Fused Silica, ULE, Silicon Carbide(SiC), Aluminum, Beryllium, SiliconizedSiC and SiC CVD.

[0039] The mirrors may utilize any shape conducive to telescopic optics. In some embodiments the mirrors are circular. In other embodiments the mirrors are hexagonal. In yet other embodiments, the mirrors are octagonal.

[0040] Similar to the primary mirror modules, the secondary mirror module also comprises means for communicating with system modules. In some embodiments, the secondary mirror modules comprises means for communicating with a controller module allowing for instructions to be sent and received coordinating adjustments to the shape of the mirror and the positional orientation of the mirror with respect to six-degrees of freedom. In some embodiments, the secondary mirror module communicates with the primary mirror module or aft-optics module. In some embodiments, the means for communicating include wired communication and wireless communication protocols including but not limited to, TCP/IP, IEEE 802.15.1 (Bluetooth), 802.11x (WLAN), wireless metropolitan area networks (WMAN), infrared, radio, cellular communication (2G, EDGE), cellular data communication (3G, HSPDA, LTE), and mobile satellite communications.

[0041] The means for communication in the secondary mirror module allows for sending of information with respect to positioning, orientation, atmospheric conditions, and other relevant information with respect to positioning, to system modules. In some embodiments, the secondary mirror module sends information to the controller module. In some embodiments, the secondary mirror module sends information to the primary mirror module. In some embodiments, the secondary mirror module sends information to the aft-optics module. [0042] Additionally, the means for communication also allows the secondary mirror module to receive adjustment data from system modules. In some embodiments, data from the secondary mirror module and all other modules (e.g., primary mirror modules) are analyzed and processed to generate the corresponding adjustment data, which is sent by the controller module to the secondary mirror module. In some embodiments, the primary mirror module sends adjustment data to the secondary mirror module. In some embodiments, the aft-optics module sends adjustment data to the secondary mirror module.

Aft Optics Module

[0043] As illustrated in Figure 2, the section denoted (207) illustrates the position where the aft- optics module lies. The aft-optics module receives reflected light from the one or more secondary mirror modules.

[0044] The function of the aft optics module allows for the combining of light beams and the performance of the interferometry to generate a single optical image from the one or more primary and secondary mirror modules. At this stage each light beam reflected from the secondary mirror module is phase corrected to ensure the elimination of all atmospheric defects and phase aberration.

[0045] The aft optics apparatus is configured with various optical sensory mechanisms to evaluate the optical quality of the wavefront. In some embodiments, the sensory mechanism includes Shack- Hartmannwavefront sensors to measure the phase aberration. As illustrated in Figure 4, the Shack- Hartmann sensor is placed in the aft-optics module (404) behind the primary mirror modules (401). In some embodiments, the aft-optics sensory mechanism includes interferometric positioning devices.The aft-optics is further configured with a phase detector mechanism to detect the relative pairwise phase offsets of the corresponding pairs (constituting primary mirror modules and secondary mirror modules) relative to all other pairs.

[0046] This information feedback loop between the aft-optics module and the primary and secondary mirror modules ensures dynamic correction of shape and positioning to ensure the elimination of all atmospheric defects and phase aberration.

[0047] The aft-optics module also comprises means for communicating with system modules. In some embodiments, the aft-optics module communicates with a controller module allowing for instructions to be received coordinating adjustments to the primary and secondary mirrors with respect to wavefront aberrations measured by optical sensory mechanisms (e.g., Shack-Hartmann wavefront sensors, phase detection mechanisms). In some embodiments, the aft-optics module communicates with the primary mirror module or secondary mirror module. In some embodiments, the means for communicating include wired communication and wireless communication protocols including but not limited to, TCP/IP, IEEE 802.15.1 (Bluetooth), 802. llx (WLAN), wireless metropolitan area networks (WMAN), infrared, radio, cellular communication (2G, EDGE), cellular data communication (3G, HSPDA, LTE), and mobile satellite communications.

Controller

[0048] The controller module comprises a computing engine configured to receive positional, atmospheric, and optical data from the primary and secondary mirror modules,the aft-optics module, and other system modules through the communication means.

[0049] The computing engine may be comprised of any conventional computing hardware and software means sufficient to computing fast high level calculations from multiple inputs. In some embodiments, the controller is on site with the large interferometric imaging system. In some embodiments, the controller may be off-site receiving information from each of the system modules and computing them accordingly. In some embodiments, the hardware utilized may be of conventional computing resources such as personal computers, wherein the specific implementation is captured in a computer program product. In other embodiments, the controller may be a discrete hardware and software bundle which integrates with conventional computing systems.

[0050] In some embodiments, the means for communicating include wired communication and wireless communication protocols including but not limited to, TCP/IP, IEEE 802.15.1 (Bluetooth), 802. llx (WLAN), wireless metropolitan area networks (WMAN), infrared, radio, cellular communication (2G, EDGE), cellular data communication (3G, HSPDA, LTE), and mobile satellite communications.

[0051] The controller allows for the manipulation of real-time collected information of the system, assessing said information, and sending adjustment data to various modules of the system in order to correct for atmospheric, system related, or other defects. Defects may be caused by, but are not limited to, gravitational forces, temperature fluctuation, environmental strain, wind gusts, and dynamic terrain defects. [0052] The controller receives information from each primary mirror and corresponding secondary mirror pair. Each pair has a separate data-set with respect to the positional information of each of the mirror modules and the wavefront aberration of the pair measured by the aft-optics module. This information for the pair is sent to the controller by communication means.

[0053] The analysis of the pair information comprises various checks. With respect to the primary mirror module positioning and shaping, the controller verifies the position and shape of the mirror with respect to a pre-defined model to compare any deformation. The controller receives information in real-time regarding the shape and positioning and assesses against the model to compute adjustment data. In some embodiments the information is relayed by the primary mirror's means for measuring shape and positioning (e.g., ainterferometric positioning device). In some embodiments, the information is relayed by a discrete information storage unit within the primary mirror module.

[0054] Once the information is received, the adjustment data is generated by the computing engine after comparing to pre-defined models and previous information to calculate for any deformation. The adjustment data is sent to the primary mirror module for implementation.

[0055] In some embodiments, the frequency of monitoring the primary mirror module is constant. In some embodiments, the frequency of monitoring the primary mirror module is specified to be at a defined interval.

[0056] With respect to the secondary mirror module positioning and shaping, the controller verifies the position and shape of the secondary mirror with respect to the primary mirror module. The controller receives information in real-time regarding the shape and positioning of both the primary and secondary mirror modules and wavefront aberration, and assesses this information against a pre-defined model to compute adjustment data. In some embodiments, the information is relayed by the primary mirror's and secondary mirror's means for measuring shape and positioning (e.g., ainterferometric positioning device). In some embodiments, the information is relayed by a discrete information storage unit within the primary and secondary mirror modules.

[0057] With respect to the aft-optics module, the controller receives information regarding the wavefront aberration from the optical sensory mechanism (e.g., Shack Hartmann wave-front sensor). In some embodiments, the information from the aft-optics module is combined with positional and shape information from the primary and secondary mirrors in order to compute the required adjustments to the primary and secondary mirror modules. [0058] The aft-optics module also provides the controller with relative pairwise phase difference calculated by a phase detector mechanism within the aft-optics unit. The controller receives this information and calculates the necessary phase adjustments for relative pairwise phase offset utilizing phase resolution methods involving mathematical optical models. This information is sent to the secondary mirror modules to effect piston-alignment corrections. This piston alignment correction does not affect the quality of the image produced by the corrected corresponding pair, but rather aligns the phase of pair to all other pairs. This piston alignment for the secondary mirror module is conducted simultaneously with the low order shape control correction for the primary and secondary mirror modules.

[0059] In some embodiments, the adjustments of the primary mirror module may be based on information solely from the secondary mirror module. In some embodiments, the adjustments of the primary mirror module may be based on the information solely from the aft-optics module. In some embodiments, the adjustments to the primary or secondary mirror modules are based on any combination of system modules.

[0060] In some embodiments, the adjustments of the secondary mirror module may be based on information solely from the primary mirror module. In some embodiments, the adjustments of the secondary mirror module may be based on the information solely from the aft-optics module.

Low Order Shape Control

[0061] With each primary mirror module having a corresponding secondary mirror module constituting a pair,a large interferometric imaging system may consist of many pairs. The shape and positioning information between this pair ensures the elimination of wavefront aberration. In this way, multiple pairs are distinct from each other in the sense that the alignment of each large primary mirror to every other large primary mirror is not constantly required as the corresponding secondary mirrors allow for correction of any deformations occurring on the primary mirror to be corrected utilizing adjustments to the secondary mirrors. This ensures the image produced by the pair is free of wavefront aberrations. Additionally, a piston alignment of secondary mirror modules is conducted simultaneously to align the aggregate corresponding pairs relative to one another in order to resolve the relative pairwise phases of each of the pairs constituting respective primary and secondary mirror modules. This provides for an aggregate summation of synchronized images. In this way, it is the relative positioning of each respective primary and secondary mirror within each pair to each other, as well as the piston alignment of each pair to all other pairs that is of relevance. Therefore, the summation of each of the pairs in aggregate, where each pair has been corrected within itself to be co-phased that produces the final bright optical image of high resolution.

[0062] The adjustments of the primary and secondary mirror modules allow for positional transformation and shape transformation to achieve a desired orientation, shape, or any combination thereof.

[0063] Positional transformation may be implemented to the mirror modules by various means to transform the mirror module with respect to six degrees of freedom. In some embodiments the means to transform include actuators. In some embodiments, the actuators may be affixed to the optical surface itself. In some embodiments, the actuators may be attached to the optical surface mechanical support structure. The mirror module may receive instruction from the controller with adjustment data to transform the position of the module by a specified amount. The module would implement said positional change through the actuators to implement the instructions from the controller module.

[0064] In some embodiments, positional transformation, known as is used solely by the secondary mirror module in order to rapidly correct for low order and high order wavefront aberrations caused by the reflected wavefront from the primary mirror module for alignment. These positional transformations to correct for alignment are known as "tip-tilt". The secondary mirror module may be configured, due to its small size relative to the primary mirror module, to make adjustments in the range of 100-500 per second. Phase aberrations up to frequencies of a few hundred hertz may be corrected solely by positional transformation of the secondary mirror module.

[0065] Positional transformation of the secondary mirror module, with respect to piston- alignment, is performed solely on the z-axis which aligns each pair (constituting a primary and a secondary) to all other pairs to resolve the relative pairwise phasing errors. The z-axis may be defined as being perpendicular to the prime focus of the primary mirror modules. This concept is illustrated in Figure 4. The actuator applies fast piston control (405) of the secondary mirror modules (406) in order to correct the pairwise relative phasing.

[0066] In some embodiments, calibration of the primary mirrors modules in aggregate may be accomplished by positional transformation where the angular diameter of the bright object in the sky is used to match a pre-determined value or model.

[0067] Shape transformation may be implemented to the mirror modules by various means to transform the shape of the optical surface. In some embodiments, means for shape transformation include the affixing of actuators to the optical surface itself to apply force such that the inherent surface shape may be modified based on instructions from the controller module.

[0068] In some embodiments, shape transformation is used solely by the primary mirror module in order to maintain a pre-set model. For example, the primary mirror may be a large 8 meter off- axis parabolic shaped optical surface. The theoretical ideal shape for reflecting light from the sky plane may be simulated in mathematical computer models to achieve ideal brightness and optical resolution. If any imperfections are caused in the shape of the primary mirror due to atmospheric conditions, the means to detect the shape imperfection may notify the controller which notifies the primary mirror module to effect shape correction.

[0069] In some embodiments, the primary optical surfaces of the primary mirror modules are large in the order of 8 meters, which allows for relatively slower corrections compare to the secondary mirror modules. Typically adjustments, shape or positional, may be in the order of 1 adjustment per second.

[0070] The system may implement different types of transformation techniques for the various mirror modules. In some embodiments, the primary and secondary mirror modules utilize shape transformation, positional transformation, or any combination thereof.

[0071] The invention will now be described with reference to specific examples. It will be understood that the following examples are intended to describe embodiments of the invention and are not intended to limit the invention in any way.

EXAMPLES

EXAMPLE 1: Operation of Large Interferometric Imaging System

[0072] This example illustrates the operation of a large interferometric imaging system.

[0073] The system is comprised of ten primary mirror modules and ten corresponding secondary mirror modules. This constitutes ten pairs of each primary to a corresponding secondary mirror module. Each module in the system is equipped with WLAN communication means for communication between the controller and all other system modules. [0074] Initially the interferometric imaging system at large is orientated towards a bright object in a section of the sky plane. The primary mirror modules are calibrated in reference to this bright object to aim to match a theoretical angular diameter.

[0075] The primary mirror modules and secondary mirror modules are set to an averaged positional correction based on an average of atmospheric conditions.

[0076] The light from the sky plane is received by each of the primary mirror modules and reflected to each of the secondary mirror modules. Aninterferometric positioning device is implemented to verify the overall pairwise image co-phasing. Other averaged optical wavefront measurement modules (e.g. Shack-Hartmannwavefront sensor) establish that the shape and position of each of the primary mirror modules match the theoretical idealized shape to maximize the reflected beams with maximum brightness. This information is recorded in the module and forwarded to the controller module via WLAN communication means.

[0077] The secondary mirror modules implement interferometric positioning devices and Shack- Hartmann sensors in order to verify the shape of the secondary mirror modules.The interferometric positioning devices initializeinterferometric positioning measurements to establish that the positioning is correct in reference to the ideal primary mirror modules positioning. Once the feedback loop has completed one iteration of analysis in the controller, the position is compared to the last known position of the corresponding primary mirror module sent by the controller to the secondary mirror modules through WLAN.

[0078] The secondary mirror modules reflect the incoming light to the aft-optics module.The aft- optics module collects the light from the ten secondary mirror modules and analyzes the wavefront aberration from the secondary mirror modules and communicates said information to the controller through WLAN.

[0079] The controller module receives input from all modules, including the primary mirror module and aft-optics module sending information received from interferometric positioning devicesand Shack Hartmann sensors regarding the shape and position of each of the primary mirror modules by WLAN. The controller also receives information sent by the secondary mirror module sending information regarding the positioning and shape of the secondary mirror modules.

[0080] The controller additionally receives input from a phase detector mechanism in the aft- optics unit measuring the pairwise phase offset of each pair in the system. This information is interpreted and processed to provide the corresponding correction to each pair such that all pairs are co-phased to ensure a synchronized wavefront. The corresponding correction adjusts each pair by sending transformation information to each of the secondary mirror modulesallowing for the actuators to effect the corresponding adjustments along the z-axis.

[0081] The controller utilizes all the information given to assess the current information against previous information and theoretical desired models. The assessment is divided between the different modules. The secondary mirror module analysis occurs 300 times per second, compare to primary mirror module which only occurs once per second. After the assessment of information, adjustment data is prepared based on the comparisons to previous information and desired models, and this adjustment information is sent to each respective module with corresponding adjustment data for each module.

[0082] Each module receives the information by WLAN from the controller and implements the adjustment data in order to alter the shape, positioning, or both to achieve high optical resolution. Implementation of the adjustment data by the primary and secondary mirror modules is done by positional and shape actuation, where actuators mounted to the back of the mirror modules perform the required adjustments.

[0083] This process is conducted, as mentioned hundreds of times per second for the secondary mirror modules and once a second for the primary mirror modules.

[0084] It is obvious that the foregoing embodiments of the invention are examples and can be varied in many ways. Such present or future variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

WE CLAIM:

1. A nearly filled aperture interferometric imaging system comprising:

at least one primary mirror module, said primary mirror module having a primary mirror and means for manipulating said primary mirror;

at least one secondary mirror module corresponding to said at least one primary mirror module, said secondary mirror module having a secondary mirror and means for manipulating said secondary mirror; and

a controller having means to communicate with each of said primary mirror module and said secondary mirror module, said controller configured to receive optical data from at least one of said at least one primary mirror module and said at least one secondary mirror module, said controller configured to perform assessment of said optical data and generate corresponding adjustment data for at least one said at least one primary mirror module and said at least one secondary mirror module based on said assessment, said controller sending said adjustment data to at least one of said at least one primary mirror module and said at least one secondary mirror module, wherein each of said means for manipulating said primary mirror module and said means for manipulating said secondary mirror module are operable based on said adjustment data such that said at least one primary mirror module is manipulable relative to said at least one secondary mirror module.

2. A system of claim 1, wherein means for manipulating said primary and secondary mirror modules comprise position actuation of the one or more primary and secondary mirror modules comprising angular adjustment or planer adjustment of said primary and secondary mirror modules

3. A system of claim 1, wherein means for manipulating said primary and secondary mirror modules comprise force actuation of the one or more primary and secondary mirror modules comprising shape adjustment of said primary and secondary mirror modules.

4. A system of claim 1, wherein the optical data comprises relative positioning and phase difference of the said at least one primary mirror module and said at least one secondary mirror module.

5. A system of claim 4, wherein aninterferometric positioning device is implemented to measure the relative positioning of the said at least one primary mirror module and said at least one secondary mirror module.

6. A system of claim 1, wherein the controller is configured to communicate with an aft-optics module, wherein said aft-optics module sends information related to wavefront aberration to said controller.

7. A method of optical imaging a nearly filled aperture interferometric imaging system comprising the following steps: receiving optical data from at least one of an at least one primary mirror module and an at least one secondary mirror module,

assessing said optical data to generate an assessment;

generating adjustment data for at least one said at least one primary mirror module and said at least one secondary mirror module based on said assessment;

sending said adjustment data to at least one of said at least one primary mirror module and said at least one secondary mirror module; and

manipulating said at least one of said at least one primary mirror module and said at least one secondary mirror module based on said adjustment data.

8. A method of claim 7, wherein means for manipulating said primary and secondary mirror modules comprise position actuation of the one or more primary and secondary mirror modules comprising angular adjustment or planer adjustment of said primary and secondary mirror modules

9. A method of claim 7, wherein means for manipulating said primary and secondary mirror modules comprise force actuation of the one or more primary and secondary mirror modules comprising shape adjustment of said primary and secondary mirror modules.

10. A method of claim 7, wherein the optical data comprises relative positioning and phase difference of the said at least one primary mirror module and said at least one secondary mirror module.

11. A method of claim 10, wherein aninterferometric positioning device is implemented to measure the relative positioning of the said at least one primary mirror module and said at least one secondary mirror module.