Multipurpose system and method for optical assembly

Abstract

The disclosure provides a system for adjusting or evaluating an assembly for aerial or space applications, the system comprising; a supporting element configured to keep / position at least one element of the assembly with a longitudinal axis perpendicular to a direction of gravity; and a positioning structure configured to be coupled to the supporting element, and to rotate the at least one element about the longitudinal axis. The disclosure further provides a method, being at least partially a computer-implemented method, of adjusting or calibrating an assembly for aerial or space applications, the method comprising the steps of; performing a first measurement on light that has passed through an optical instrument included in the assembly, when the optical instrument is placed at a first position with a longitudinal axis being perpendicular to a direction of gravity; evaluating whether a maximum number of rotations about the longitudinal axis has been reached; rotating, by a positioning structure, the optical instrument about the longitudinal axis to place the optical instrument at a second position, if the maximum number of rotations has not been reached; and performing a second measurement at the second position.

Description

MULTIPURPOSE SYSTEM AND METHOD FOR OPTICAL ASSEMBLYCROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to European patent Application No. EP23383166.8, filed November 15, 2023, entitled “MULTIPURPOSE SYSTEM AND METHOD FOR OPTICAL ASSEMBLY”, and to the European Patent Application No. EP23383229.4, filed November 29, 2023, entitled “MULTIPURPOSE SYSTEM AND METHOD FOR OPTICAL ASSEMBLY”, the entire contents of which are incorporated herein in their entirety by reference.TECHNICAL FIELD

[0002] The present disclosure relates to systems and methods for assembling, adjusting, calibrating and / or evaluating optical assemblies. More particularly, the present disclosure provides systems and methods for adapting an optical assembly for space or aerial applications, by assembling, adjusting, calibrating and / or evaluating the components of the optical assembly.BACKGROUND

[0003] The components and instruments on board manned or unmanned aerial or space vehicles, such as aircrafts, satellites or spacecraft, that are to operate in the air or in orbit in space, have to be adjusted and tested beforehand on the ground. Normally, they have to go through exhaustive adjustment, calibration and testing (evaluation) to ensure that they will not be negatively affected by the launch conditions and the conditions of the upper atmosphere or space, or by landing or taking off movements and motions during flight. Such adjustment, calibration and testing should be done taking into account the effect of forces or perturbations that may affect the components or instruments. An example is the effect of gravity’ to which the components are subjected on the ground, when assembling and testing, and to which they will not be subjected once in orbit, since this effect of gravity, which is not present in space, may cause deformation in the structural parts of the components once they are put into orbit in space. Such adjustment, calibration and testing is normally performed with complex, heavy and bulky equipment, requiring a lot of human intervention, which for large satellites or spacecraft designed and manufactured individually may be convenient. However, for smaller satellites, aircraft or spacecraft, such complex and expensive setups may not be suitable, or may be unnecessary .SUMMARY

[0004] Considerable advantages can be achieved with embodiments of the present disclosure, which provide systems and methods for assembling, adjusting, calibrating and / or evaluating components of an optical assembly for use in a manned or unmanned aerial or space vehicle, such as an aircraft, satellite or spacecraft, with a simple setup that allows for robust, accurate and fast measurements.

[0005] According to certain embodiments of the present disclosure, an optimal position can be found for a light detecting device, correcting the effects of gravity and / or unexpected forces acting directly or indirectly on the components of the optical assembly, including the light detecting device, with a simple setup.

[0006] According to certain embodiments of the present disclosure, the quality and robustness of an optical instrument can be determined, with a simple setup. According to certain embodiments of the present disclosure, the quality and robustness of an optical instrument can be determined, correcting the effects of gravity and / or unexpected forces acting directly or indirectly on the components of the optical instrument, with a simple setup.

[0007] With certain systems and methods of the present disclosure, it is possible to have a single setup which can be used for performing several steps during manufacturing, assembling, adjusting, testing, calibrating and / or evaluating an optical assembly, because the single setup can be used for at least several steps: acceptance of an optical instrument, optimal placement of a light detecting device with respect to the optical instrument, and verification of the quality of the optical assembly before and after ambient tests are performed on the integrated mamied or unmanned aerial or space vehicle. The single setup for performing different steps while evaluating, reducing or correcting the effects of gravity and / or unexpected forces, provides significant versatility, simplifies the procedures, and allows to reduce the errors since the processes are simplified and the potential sources of errors are consequently reduced.

[0008] According to at least some embodiments of the present disclosure, the systems and methods are configured to evaluate the effects of gravity in an optical assembly by positioning at least some components / elements / instruments of the optical assembly with a longitudinal axis being substantially perpendicular to the direction of gravity, and rotating the optical assembly and / or at least some components / elements / instruments of the optical assembly about an axis aligned or parallel with respect to the longitudinal axis of the at least some components / elements / instruments, so as to perform measurements in multiple positions and obtain information about the overall effect of gravity taking into account the measurements in all the multiple positions. For example, the measurements in the multiple positions may be averaged. According to at least some embodiments, at least one component / element / instrument that the optical assembly comprises, includes an optical instrument configured to receive and redirect light, such as a telescope.

[0009] In an example according to embodiments of the present disclosure, it is possible to determine or evaluate whether an optical instrument (for example a telescope) to be placed on board a manned or unmanned aerial or space vehicle has an acceptable quality. When an optical instrument is manufactured or assembled, it is crucial to ensure that its optical components are precisely aligned to achieve optimal performance. This can be achieved by coupling a measuring unit to the optical instrument, moving together the optical instrument and the measuring rmit, and performing measurements at different positions. Having the measuring unit coupled to the optical instrument removes inaccuracies which may otherwise arise if they move independently from each other, and therefore allows to achieve more accurate results.

[0010] In an example according to embodiments of the present disclosure, it is possible to determine or evaluate whether an optical instrument to be placed on board a maimed or unmanned space vehicle has an acceptable quality which is robust against the effect of gravity. This can be achieved by placing the optical instrument with a longitudinal axis oriented perpendicularly to the direction of gravity, coupling a measuring unit to the optical instrument, rotating together the optical instrument and the measuring unit about the longitudinal axis of the optical instrument, and performing measurements with the measuring unit at different rotation positions.

[0011] According to at least some embodiments, the optical assembly comprises an optical instrument configured to receive and redirect light, such as a telescope, and a light detecting device configured to receive light redirected by the optical instrument and having at least one active surface including a plurality of pixel sensors. The pixel sensors may be light-absorbing diodes, arranged in a two-dimensional or a three-dimensional space. The light detecting device may be of various types, such as for example a charge coupled device (CCD), complementary metal oxide semiconductor (CMOS) sensor, or other suitable architecture. In an exampleaccording to embodiments of the present disclosure, it is possible to adjust a position of a light detecting device to an optimal location (e.g. within a threshold focus error tolerance) to receive the light coming from the optical instrument, because of the setup provided by the systems and methods of the present disclosure which are used to design, align and / or calibrate the optical assembly.

[0012] According to at least some embodiments of the present disclosure, the systems and methods are configured to find an optimal position of a light detecting device with respect to an optical instrument. In at least some embodiments, this is achieved by positioning at least the optical instrument with a longitudinal axis being substantially perpendicular to the direction of gravity, placing the light detecting device coupled to the optical instrument, and rotating them about the longitudinal axis of the optical instrument so as to perform measurements in multiple positions and obtain information about the overall effect of gravity taking into account the measurements in all the multiple positions. The optimal location is optimal in the sense that it allows to correct, reduce or eliminate the effects of gravity and / or unexpected forces acting on the light detecting device.

[0013] The present disclosure provides a system for adjusting or evaluating an assembly for aerial or space applications, the system comprising: a supporting element configured to keep / position at least one element of the assembly with a longitudinal axis perpendicular to a direction of gravity; and a positioning structure configured to be coupled to the supporting element, and to rotate the at least one element of the assembly about the longitudinal axis. This allows to adjust or evaluate at least some components / elements / instruments of the assembly with respect to the effects of gravity and / or unexpected forces acting on the assembly. According to embodiments, the at least one element of the assembly is an optical instrument. According to embodiments, the system further comprises a measuring unit configured to perform measurements of quality at each of multiple positions when rotating the at least one element of the assembly. According to embodiments, the positioning structure is configured to be coupled to the measuring unit and to move the measuring unit. According to embodiments, the measuring unit is configured to measure aberrations of an optical wavefront. According to embodiments, the measuring unit comprises at least one of an interferometer, a Shack Hartmann wavefront sensor, wavefront curvature sensor or a Ronchi tester. According to embodiments, the positioning structure is configured to detachably couple the measuring unit to the at least one element of the assembly, so as to move together the measuring unit with the at least one element of the assembly. According to embodiments, the system further comprises a light directing element configured to receive a light beam from a light source and reflect the light beam towards the at least one element of the assembly, which may be an optical element. According to embodiments, the system further comprises an air moving system in at least part of a column of air between the light source or the light directing element and the measuring unit. According to embodiments, the positioning structure is configured to be coupled to a light detecting device configured to detect light coming from the optical instrument, and wherein the positioning structure is configured to move the light detecting device. According to embodiments, the positioning structure is configured to detachably couple the light detecting device to the at least one element of the assembly, so as to move together the light detecting device with the at least one element of the assembly. According to embodiments, the system further comprises a projection system configured to generate an image to be detected by the light detecting device. According to embodiments, the light detecting device is an image capturing device, such as an area imaging device, AID, having a plurality of pixel sensors. According to embodiments, the supporting element is a first supporting element, wherein the system furthercomprises a second supporting element, and wherein the positioning structure comprises a first positioning structure configured to be coupled to the first supporting element and a second positioning structure configured to be coupled to the second supporting element. According to embodiments, the first positioning structure and the second positioning structure are configured to move together or independently from each other. According to embodiments, die second supporting element is configured to be coupled to the measuring unit. According to embodiments, the second supporting element is configured to be coupled to the light detecting device. According to embodiments, the system further comprises a control unit configured to control the positioning structure. According to embodiments, the positioning structure comprises at least one of an hexapod or a system of linear and / or rotational motors.

[0014] The present disclosure provides a method of adjusting or calibrating an assembly for aerial or space applications, the method comprising the steps of: performing a first measurement on light that has passed through an optical instrument included in the assembly, when the optical instrument is placed at a first position with a longitudinal axis being perpendicular to a direction of gravity; evaluating whether a maximum number of rotations about the longitudinal axis has been reached; rotating, by a positioning structure, the optical instrument about the longitudinal axis to place the optical instrument at a second position, if the maximum number of rotations has not been reached; and performing a second measurement at the second position.

[0015] According to embodiments, the method is at least partially a computer-implemented method, and further comprising instructing, by a control unit, a measuring element to perform the first measurement and the second measurement, and controlling the positioning structure to rotate the optical instrument. According to embodiments, the method further comprises placing a light detecting element detachably coupled to the optical instrument, and wherein rotating the optical instrument comprises rotating the optical instrument and the light detecting element. According to embodiments, the fest measurement and the second measurement include at least one of image sharpness, a measurement of how out-of-focus an image is, or a measurement of a size or shape of elements on an image. According to embodiments, the method further comprises determining a definitive position of the light detecting device based at least in part on the first measurement and the second measurement. According to embodiments, the first position is a first position along an axis following a direction of the longitudinal axis of the optical instrument and with a first orientation, and wherein the method further comprises: evaluating whether a maximum number of measurements at the first orientation has been reached; moving the light detecting device along the axis following the direction of the longitudinal axis of the optical instrument, to a third position with the first orientation, if the maximum number of measurements at tire first orientation has not been reached; and performing a third measurement at the third position. According to embodiments, the method further comprises determining a focus position for the light detecting device based at least in part on the first measurement and the third measurement. According to embodiments, the method further comprises evaluating whether a maximum number of orientations has been reached; moving the optical instrument and the light detecting device to a second orientation, if the maximum number of orientations has not been reached; and performing a fourth measurement at the second orientation. According to embodiments, the method further comprises determining a plane for positioning the light detecting device based at least in part on the first measurement and the fourth measurement. According to embodiments, the method further comprises having a measuring unit detachably coupled to the optical instrument, and wherein rotating the optical instrumentcomprises rotating the optical instrument and the measuring emit. According to embodiments, the first position is a first position along an axis following a direction of the longitudinal axis of the optical instrument and with a first orientation, and wherein the method further comprises: evaluating whether a maximum number of measurements at the first orientation has been reached; moving the measuring unit along the axis following the direction of the longitudinal axis of the optical instrument, to a third position with the first orientation, if the maximum number of measurements at the first orientation has not been reached; and performing a third measurement at the third position. According to embodiments, the method further comprises evaluating whether a maximum number of orientations has been reached; moving the optical instrument and the measuring unit to a second orientation, and moving the measuring unit within the second orientation, if the maximinn number of orientations has not been reached; and performing a fourth measurement at the second orientation. According to embodiments, the first measurement and the second measurement include measurements of aberrations of an optical wavefront. According to embodiments, the method further comprises determining whether a quality of the optical instrument is above a predetermined threshold based at least in part on the first measurement and the second measurement.

[0016] Further features and advantages, as well as the structure and operation of various embodiments are described in detail below, with reference to the accompanying drawings. It is noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s), based on the teachings contained herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The Detailed Description is set forth with reference to the accompanying figures. In the figures, the leftmost digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.

[0018] FIG. la shows a block diagram of components of a system according to embodiments of the present disclosure.

[0019] FIG. lb shows a block diagram of components of a system according to embodiments of the present disclosure.

[0020] FIG. 2 shows a method of operation of a system according to embodiments of the present disclosure.

[0021] FIG. 3 shows a method of operation of a system according to embodiments of tire present disclosure.

[0022] FIG. 4 shows a method of operation of a system according to embodiments of the present disclosure.DETAILED DESCRIPTION OF EMBODIMENTS

[0023] Embodiments include multi-purpose systems and methods for assembling, adjusting, calibrating and / or evaluating the components of an optical assembly to make it robust against effects of gravity or undesired forces or perturbations while providing a simple setup, the optical assembly intended to be used on board a manned or unmanned aerial or space vehicle.

[0024] In many known systems employed for calibrating optical assemblies for use onboard space vehicles, the optical instrument is placed vertically, and a projection system configured to generate an image is placed also vertically, above the optical instrument so as to project the image towards the optical instrument. These systems may be used to find a position for a light detecting device coupled to an optical instrument in an optical assemblywherein the light detecting device is placed after an optical instrument. However, projection systems are large and heavy, and using this configuration requires a complex infrastructure to place the projection system above the optical instrument. Furthermore, this kind of setup is not robust against the effect of gravity since vertical forces are applied to the optical components of the optical instrument, deforming them. Hence, if the optical instrument, after calibrating it vertically, is moved to another position, the optical components of the optical instrument are deformed due to the effect of gravity. Other known systems place the projection system horizontally while keeping the optical instrument in a vertical position, thereby requiring a less complex infrastructure for the projection system, but they require a system of mirrors to be able to cause the generated image to reach the optical instrument placed in vertical direction. In addition, this alternative setup is also not free of gravity effects. The present disclosure overcomes the drawbacks of these known systems, because at least some embodiments provide systems configured to operate on the optical assembly having the optical assembly placed with its longitudinal axis perpendicular to a direction of gravity. Throughout the present disclosure, the longitudinal axis of an optical assembly and the longitudinal axis of at least some components / elements / instruments of the optical assembly may be used interchangeably. Furthermore, embodiments allow placing a projection system horizontally, that is, with its longitudinal axis oriented perpendicular to the direction of gravity, while also allowing to place the optical assembly horizontally. The possibility of placing the optical instrument of the optical assembly as well as the projection system horizontally, with their longitudinal axis perpendicular to a direction of gravity, allows to streamline and facilitate the production.

[0025] Embodiments further include systems comprising a first supporting element coupled to a first positioning structure, and a second supporting element coupled to a second positioning structure, the systems configured to operate on an optical assembly which may be used onboard manned or unmanned aerial or space vehicles. The optical assembly may comprise at least one of an optical instrument, a light detecting device, an area imaging sensor, an optical filter, and a positioning structure or mechanism. For example, the optical assembly may comprise an optical instrument, such as a telescope, and a light detecting device, such as an imaging device or system.

[0026] The light detecting device may comprise at least one active surface including a plurality of pixel sensors, such as an area imaging sensor. In a non-limiting example, at least part of the light detecting device may be fixedly coupled to the optical instrument and at least part of the light detecting device may be configured to move with respect to the optical instrument. The movement with respect to the optical instrument may include any type of movement in at least one plane. For example, the light detecting device may be configured to move with respect to the optical instrument for motion compensation, for instance to image scenes in apparent motion. In some embodiments, the light detecting device may be coupled to a positioning mechanism for movement. The positioning mechanism may be a stabilizing positioning mechanism. Additionally or alternatively, the light detecting device may be configmed to align at least one active surface with a direction of apparent motion of a scene to be imaged by the light detecting device and / or move with a speed of apparent motion of the scene. Additionally or alternatively, the light detecting device may be configured to move irregularly or regularly, intermittently or periodically, for example in cycles or at predefined periods of time. At least one active surface of the light detecting device may be further coupled to an optical filter having one or more filter bands or filterarrays, and the light detecting device may be configured to move the at least one active surface coupled to the optical filter with respect to the optical instrument for selecting a spectral band or a portion of the optical filter. Additionally or alternatively, the light detecting device may be configured to move a non-integer pixel distance or a multiple thereof, in order to generate slightly offset exposures that are used to generate an increased resolution image.

[0027] FIG. la shows a block diagram of components of a system 100 according to embodiments of the present disclosure. In the embodiment of FIG. la, the system 100 comprises a first supporting element 102 connected or otherwise coupled to a first positioning structure 104 and a second supporting element 106 connected or otherwise coupled to a second positioning structure 108. The system 100 is configured to perform operations on an optical assembly comprising a light detecting device 110 and an optical instrument 112, such as a telescope, so as to make it robust against the effects of gravity or undesired forces, rotations or perturbations of the optical assembly when on board a manned or unmanned aerial or space vehicle.

[0028] The system 100 is configmed to find an optimal location for the light detecting device 110 coupled to the optical instrument 112, both of which may be placed on board a manned or unmanned aerial or space vehicle (not shown). The optimal location or position may be determined based on at least one of a focus or focus field error tolerance, alignment or alignment error tolerance, parallelism or parallelism error tolerance, and / or robustness against the effects of gravity or undesired forces, rotations or perturbations. The light detecting device 110 is connected or coupled to the optical instrument 112 through the second supporting element 106. When the light detecting device 110 is directly or indirectly connected or coupled to the optical instrument 112, the effect of gravity may make elements of the optical assembly, such as the optical instrument 112. fall or be attracted towards the ground 114. If the light detecting device is placed and no account is taken of this effect, when the optical assembly is on board a manned or unmanned space vehicle, or if the assembly is rotated and used in another position on board a manned or unmanned aerial or space vehicle, the light detecting device will be in a suboptimal position not properly aligned to detect a desired or intended image. In order to avoid this, an optimal position for the light detecting device is searched with the embodiment of FIG. la.

[0029] Additionally or alternatively, the system 100 is configured to calibrate an optical assembly that is to be placed on board a manned or unmanned aerial or space vehicle, allowing a projection sy stem 116 to be placed horizontally, that is, with its longitudinal axis oriented perpendicular to the direction of gravity 118, while also allowing to place the optical instrument 112 horizontally.

[0030] In the embodiment of FIG. la, the optical instrument 112 (such as a telescope), a light detecting device 110, a projection system 116 (such as a collimator, such as an auto-collimator), and a positioning structure are shown.

[0031] The light detecting device 110 is configured to detect the light 119 that passed through the optical instrument 112, and it is placed after the optical instrument 112 (considering that the light 119 enters the system from the left side as represented in FIG. la), so as to be adjusted and placed within the system 100 at an optimal position. The light detecting device 110 may be an image capturing device, such as an area imaging device (AID) having a plurality of pixel sensors, such as light-absorbing diodes, arranged in a two-dimensional or a three- dimensional space. The AID may be of various types, such as for example a charge coupled device (CCD), complementary metal oxide semiconductor (CMOS) sensor, or other suitable architecture. According toembodiments of the present disclosure, the light detecting device 110 may be fixed, connected or coupled, such as detachably coupled, with respect to the optical instrument 112. In some applications, the light detecting device may comprise more than one AID, distributed in many different arrangements known to a skilled person.

[0032] hi a non-limiting example, the optical assembly may be configured to image scenes in apparent motion relative to the optical assembly. For example, the optical assembly may be configured to be used on board a mamied or unmanned aerial or space vehicle as an aerial or satellite-based imaging system, and may be configured to image scenes in apparent motion relative to the vehicle where the optical assembly is mounted, while preventing motion blur and other visual artifacts. According to embodiments of the present disclosure, the light detecting device 110 may be fixed, connected or coupled, to a stabilizing positioning mechanism configured to stabilize and / or compensate for a movement of apparent motion between the optical assembly on board the mamied or unmanned aerial or space vehicle and the scene, so that the combination of the light detecting device 110 and the stabilizing positioning mechanism may be fixed, connected or coupled, such as detachably coupled, with respect to the optical instrument 112. Hence, an optical assembly, optionally placed on board a manned or unmanned aerial or space vehicle, which may be configured to image scenes in apparent motion, apart from comprising a light detecting device 110 and an optical instrument 112, may further comprise a stabilizing positioning mechanism. In some instances, the stabilizing positioning mechanism may be at least part of the second positioning structure 108. The system 100 is further configured to find an optimal location for the light detecting device 1 10 fixed, connected or coupled, to the stabilizing positioning mechanism, and coupled to the optical instrument 112, all of which may be placed on board a manned or unmanned aerial or space vehicle.

[0033] The projection system 116 is configured to change diverging light from a point source into a collimated beam, so as to generate an image as if it was coming from a large distance. The projection system 116 is configured to direct the generated image towards the optical instrument 112. The generated image is then detected by the light detecting device 110. Although not shown in Fig. la, a light source is present before the projection system so as to generate light that will enter the projection system, thereby allowing the projection system to generate an image that will be detected by the light detecting device 110 after passing through the optical instrument 112.

[0034] The positioning structure in the setup represented in FIG. la comprises a first supporting element 102, a first positioning structure 104, a second supporting element 106 and a second positioning structure 108. The optical instrument 112 is coupled to the first supporting element 102, which may be a platform, such as a moveable platform, and which in turn is connected or otherwise coupled to the first positioning structure 104, so the optical instrument is moved by the first positioning structure 104. The light detecting device 110 is coupled to the second supporting element 106, which in turn is connected or otherwise coupled to the second positioning structure 108, so the light detecting device is moved by the second positioning structure 106. It should however be noted that the first supporting element 102 may not be present, and the optical instrument 112 may be directly coupled to the first positioning structure 104, and / or the second supporting element 106 may not be present and the light detecting device 110 may be directly coupled to the second positioning structure 108. Other embodiments encompassed by the present disclosure include a single positioning structure configured to move both the light detecting device and the optical instrument.

[0035] The positioning structure may be configured to move the optical instrument 112 and / or the light detecting device 110 coupled thereto so as to align the light detecting device 110, in order to be positioned so as to be robust against effects of gravity, in at least one of orientation (tip and tilt angle, moving to x-y’ planes by rotating the x-y plane about the x axis, the z axis, or the y axis, as represented in FIG. la), in focus (moving to x-y’ planes by moving the x-y plane along the z axis, as represented in FIG. la), or radial position within the focal plane. In certain embodiments, the adjustment in the radial position is not required as it may be done based on specifications. The light detecting device 110 may be fixed to the optical instrument 112 in different ways, such as with a system of adjustable bolts or screws, clamps, grips, or any mechanism useful to (detachably) secure, couple or fasten the light detecting device 110 to the optical instrument 112 to prevent, minimize or control any relative movement between them. The light detecting device should be coupled and fixed to the optical instrument to avoid misalignments in the movements performed by the optical instrument and the light detecting device, but at the same time it should have enough degrees of freedom to explore in a controlled manner the behavior of the optical assembly.

[0036] In the embodiment of FIG. la, the light detecting device 110 is connected or otherwise coupled to the second supporting element 106, and thereby the second positioning structure 108 is configured to move the light detecting device 110 independently from the movement of the optical instrument 112. and in various directions, such as in linear movements and / or in tip and / or tilt rotations, to adjust its position with respect to the optical instrument 1 12 and / or, in embodiments comprising a stabilizing positioning mechanism, with respect to the stabilizing positioning mechanism. The light detecting device 110 may also be connected to the same or a different positioning structure, so as to move with respect to the optical instrument 112 and / or the stabilizing positioning mechanism when a certain position and / or orientation is determined for the light detecting device 110.

[0037] The certain position and / or orientation determined for the light detecting device 110 may include determining an aligmnent between the light detecting device 110 and the optical instrument 112, or, in addition or alternatively, in embodiments in which the light detecting device 110 is coupled to a stabilizing positioning mechanism, an aligmnent betw een the light detecting device 110 and the stabilizing positioning mechanism. For example, the aligmnent between the light detecting device 110 and the stabilizing positioning mechanism may comprise determining an initial field or initial plane, so that, when the light detecting device is placed in said initial plane (or in any plane parallel to said initial plane), the active surface of the light detecting device 110 is parallel to an area of the stabilizing positioning mechanism. The area of the stabilizing positioning mechanism may correspond to a plane of movement of the stabilizing positioning mechanism configured to compensate for the apparent motion. If the light detecting device 110 is not coupled to a stabilizing positioning mechanism, the initial field or initial plane may correspond to the plane of an active surface of the light detecting device 110. The alignment between the light detecting device 110 (with or without being coupled to the stabilization positioning mechanism) and the optical instrument 112 may comprise placing the initial field or initial plane parallel to a focal plane of tire optical instrument 112. In some embodiments, the alignment procedure to search for the initial field or initial plane between the light detecting device 110 and the stabilizing positioning mechanism may be performed before coupling the light detecting device 110 and the stabilizing positioning mechanism to the optical instrument 112.

[0038] Additionally or alternatively, the certain position and / or orientation determined for the light detecting device 110 may include determining specific fields or x-y ' planes having an optimal focus position for the initial plane / initial field or for the active surface area of the light detecting device 110, by detecting an image in focus (within a predetermined focus error tolerance) projected by the projection system 116, passing through the optical instrument 112 and detected by the light detecting device 110, as explained elsewhere within the Detailed Description.

[0039] According to embodiments, the positioning structure may move the optical instrument 112 and the light detecting device 110 together or independently (in this case by the first positioning structure and the second positioning structure, respectively) in different directions and / or orientations, the light detecting device 110 with or without being coupled to the stabilizing positioning mechanism. The positioning structure may be any structure that allows to change the position of the optical instrument and / or the light detecting device (with or without being coupled to the stabilizing positioning mechanism), in various directions and / or orientations. For example, the positioning structure may comprise a positioning structure with n degrees of freedom, where n is an integer number, such as a tetrapod, an hexapod, or an octopod, which provide high precision movements, rolling elements including or not roller bearings or ball bearings, or a system of motors or actuators including linear and / or rotary motors, which may be piezoelectric or stepper motors, or other suitable actuators, rolling elements, or positioning mechanisms combining any of these.

[0040] According to embodiments, the positioning structure may be configured to adjust the parallelism betw een a plane of movement of the stabilization positioning mechanism and the focal plane of the optical instrument 112, and make it coincide with the plane of the active surface of the light detecting device 110 having the plurality of pixel sensors. The plane of movement refers to the plane on which the stabilization positioning mechanism is moved to compensate for the apparent motion (e.g. direction and / or speed of apparent motion) between the optical assembly and the scene being imaged by the optical assembly.

[0041] According to embodiments, the positioning structure may be configured to move the light detecting device 110 (with or without being coupled to the stabilization positioning mechanism) with respect to the optical instrument 112 along at least one degree of freedom to determine the optimal focus position for specific fields (or x-y’ planes), of the light detecting device 110 with respect to the image projected by the projection system 116 and detected by the light detecting device 110. The x-y’ planes are the result of rotating the x-y plane about the x axis, the z axis, or the y axis, as represented in FIG. la, and an x-y’ plane may coincide with the x-y plane. According to embodiments, the positioning structure may be configured to move the optical instrument 112 and the light detecting device 110 together to change the field or x-y’ plane. For example, a first x-y’ plane may be selected to start the measurements, where the first x-y’ plane may correspond to the initial plane or initial field determined beforehand to be parallel to an area of the stabilizing positioning mechanism, in case such stabilizing positioning mechanism is present as part of the optical assembly. Alternatively, the first x-y’ plane may correspond to the initial plane or initial field determined beforehand to be parallel to an active surface of the light detecting device 110. A plurality of measurements at different fields and at different focus positions are performed to determine the optimal position to place the light detecting device. For example, the positioning structure may move the light detecting device along the z axis (as represented in FIG. la) so as to be placed at different z positions or focus positions. At a certain focus position, the optical instrument and the light detectingdevice may be moved together into at least one field or x-y’ plane, in a direction such that the projection of the image by the projection system, instead of reaching the center of the light detecting device, reaches a comer. In each field, at least one measurement is taken and optionally at least one image may be captured. After that, the light detecting device may be moved along the z axis, but keeping the field (x-y’ plane), and one or more measurements may be done and optionally images may be captured in the different focus positions (z positions). This is done so as to find the optimal focus position for the specific field of the light detecting device with respect to the detected image. This operation may be repeated for other fields of the light detecting device with respect to the detected image, for which the projection of the image by the projection system, instead of reaching the center of the light detecting device, reaches another comer, or another position of the light detecting device, and several measurements may be taken and images may be captured at different focus positions (z positions). The measurements may comprise any type of measurement aimed at maximizing a certain metric or parameter of interest depending on the application or the type of light detecting element. For example, the measurements may comprise a measurement of image sharpness (for example measuring the Spatial Frequency Response (SFR)), a measurement of how out-of-focus an image is, a measurement of the size or shape of the elements on an image, or any other suitable type of measurement. Based, at least in part, on a plurality of measurements at different fields and at different focus positions, it will be possible to determine the optimal position along the focus axis and the optimal field to place the light detecting device.

[0042] Therefore, what is done according to certain embodiments of the present disclosure is to measure a series of points on the light detecting device. The points may correspond to different fields or orientations. On each one of those points, one or more measurements are performed to search for a focus position. In some instances, the coordinates for the position where the image is best focused may be stored in a memory . With the coordinates of the measurements, it is possible to find the best plane possible in which the light detecting element is to be oriented. Once this plane is found, the light detecting device may be placed in said plane. This can be done either manually or automatically, and it can be done in many different ways, for example by adjusting one or more bolts that couple the light detecting device to the optical instrument. After adjusting to a new plane, new measurements can be done as explained above, in order to further fine tunc the orientation of the light detecting device, in an interactive process.

[0043] After all these measurements are performed, in the embodiment of FIG. la, the optical instrument 112 and the light detecting device 110 are rotated along the longitudinal axis of the optical instrument (z axis in FIG. la), and at different rotation positions, the same measurements described above are performed. By performing these rotations, and performing afterw ards an averaging operation, an optimal position of the light detecting device, which is robust against the effects of gravity, may be found.

[0044] In the embodiment of FIG. la, the actual light detecting device 110 that is to be placed on board the mamied or unmanned aerial or space vehicle may be used, or a different test light detecting device may be used. In this way, the test light detecting device may be used to find a position for the actual light detecting device, and later on, the actual light detecting device may be placed in the appropriate position. It may be advantageous to use a test light detecting device different from the actual one in situations in which, for example, the test light detecting device is more sensitive, has smaller pixels, or has another property thereby allowing to perform a more accurate aligning. In order to maintain the position to place the actual light detecting device, a system ofreference mirrors can be used. For example, a first mirror parallel to the test light detecting device may be placed, and a second mirror may be placed fixed to the optical instrument. After that, the alignment of the test light detecting device is performed as explained above, and the first and second mirror may be used to maintain the position of the test light detecting device.

[0045] FIG. lb shows a block diagram of components of a system according to embodiments of the present disclosure. FIG. lb shows a setup configured to adjust and / or calibrate and / or determine the quality of components of a satellite, aircraft or spacecraft.

[0046] In the setup represented in FIG. lb, an acceptance test can be performed on an optical instrument 112, to evaluate its quality. In the setup of FIG. lb, an optical instrument 112, a light directing element 111, a measuring unit 113 and a positioning structure are shown.

[0047] In the embodiment of FIG. lb, the optical instrument 112 is to be accepted, in other words, its characteristics and performance are to be evaluated and tested to satisfy predetermined functional parameters related to, for example, orientation of the optical axis or the image quality, such as the type of predominant wavelength detected or the value of the modulation transfer function (MTF) commonly used to evaluate the performance of a lens. The measuring unit 113 and the light directing element 111 are configmed to allow to accept the optical instrument 112, in other words, to inspect and validate the optical alignment and quality of the optical instrument in autocollimation. The light directing element 111 is configured to direct light towards the optical instrument 1 12, since the light directing element 1 1 1 may receive a collimated beam from a light source, which may be part of the measuring unit or it may be a separate element, and reflect it back (arrow 119) towards the optical instrument's primary’ mirror or objective lens. If the beam is generated by the measuring unit, as it passes through the optical instrument, it is collimated at the optical instrument before reaching the light directing element. The measuring unit 113 is configured to measure any deviations in the reflected light's path that indicate misalignment or collimation errors in the optical instrument's optics. In an alternative configuration, not shown in FIG. lb, the light directing element 111 may not be present, and a projection system, which may be a collimator, a lens, or any other suitable projection system, such as the projection sy stem 116 of FIG. la, may be present instead. In such configuration, the projection system is the light source that generates a light beam that enters the optical instrument 112.

[0048] The measuring unit 113 is configured to perform measurements to obtain information about the optical quality of the optical instrument 112. The measurements may include wavefront error (WFE) measurements. The measuring unit 113 may be an interferometer, a Shack Hartmann instrument, both of them so as to combine their measurements and make them more accurate, or any other suitable instrument that measures WFE, such as a wavefront curvature sensor or a Ronchi tester. An interferometer may be suitable when more precise measurements are required, as it is more sensitive in general, but it may also be more sensitive to noise, so the decision of which measuring unit to use may be based on at least one of the setup conditions, environmental conditions, precision requirements, or any other suitable requirement. The measuring unit 113 may be configured to be (detachably) coupled to the optical instrument 112, such as attached or affixed or otherwise fixedly connected to the optical instrument 112, so as to move with the optical instrument 112 and perform measurements associated with the light that has passed through the optical instrument 112. The measuring unit 113 may be fixed to the optical instrument 112 in different ways, such as with a system of adjustable bolts or screws, clamps,grips, or any mechanism useful to (detachably) secure, couple or fasten the measuring unit to the optical instrument 112 to prevent, minimize or control any relative movement betw een them. An advantage of having the measuring unit and the optical instrument coupled, fixed, fixedly comiected, or fixedly attached to each other, is that the calculations needed to process the measurements are simplified, because it avoids the presence of inaccuracies caused by the relative movement of the optical instrument with respect to the measuring unit, and the whole process may be hastened.

[0049] In certain embodiments, the measuring unit 113 may in addition or alternatively be configured to be moved independently from the optical instrument 112 in various directions, such as in linear movements, to adjust its position with respect to the optical instrument 112. This may be done to place the measuring unit at different positions within the focal plane, or the x-y plane (as seen in FIG. lb) so as to explore and perform the measurements at each of those different positions. This may be required when the measuring unit has a receiving surface smaller than an active surface of a light detecting device to be placed after the optical instrument, or when an image is formed in portions of the receiving surface. For example, in the setup of FIG. lb, the positioning structure comprises a first supporting element 102, a first positioning structure 104, a second supporting element 106 and a second positioning structure 108. The optical instrument 112 of the setup of FIG. lb is coupled to the first supporting element 102. which may be a platform such as a moveable platform, and which in turn is connected or otherwise coupled to the first positioning structure 104. so the optical instrument is moved by the first positioning structure 104. The measuring unit 113 is coupled to the second supporting element 106, which in turn is connected or otherwise coupled to the second positioning structure 108. so the measuring unit 113 is moved by the second positioning structure 108. It should however be noted that the first supporting element 102 may not be present, and the optical instrument 112 may be directly coupled to the first positioning structure 104, and / or the second supporting element 106 may not be present and the measuring unit 113 may be directly coupled to the second positioning structure 108. Alternatively, according to certain embodiments, the measuring unit 113 may be connected to the same positioning structure as the optical instrument 112, so as to move and perform measurements from different positions, for example in different positions within the focal plane.

[0050] The positioning structure is provided so as to change a position of the optical instrument 112. The positioning structure may allow different degrees of movement of the optical instrument 112, including a rotation about its longitudinal axis and displacements or rotations in other directions. For example, the positioning structure may allow to move the optical instrument 112 so as to be aligned with the light directing element 111.

[0051] In order to evaluate the performance of the optical instrument 112, the positioning structure, such as the first positioning structure 104, may be configured to rotate the optical instrument 112 and the measuring unit 113 (coupled, fixed, fixedly connected, or fixedly attached to the optical instrument 112) about the longitudinal axis of the optical instrument 112, and perform measurements at different rotation positions. These rotations may also be done manually. In order to evaluate the quality of the optical instrument 112 with respect to the effects of gravity, the optical instrument 112 is preferably placed with its longitudinal axis perpendicular to the direction of gravity 112. For example, the optical instrument 112 and the measuring unit 113 may be rotated in steps of 90 degrees about the z axis, and measurements may be performed after each rotation, so a total of 4 measurements are performed for a complete 360 degree rotation. However, rotations of less or more degrees may be performed,depending on the required accuracy for the measurements, for example rotations of 180 degrees or 45 degrees or any other suitable angle. A smaller rotation angle requires more measurements within a 360 degree complete rotation. This will lead to more measurements and therefore more accurate quality information, but it will require more time, so a tradeoff needs to be found.

[0052] The positioning structure may be any structure that allows to change the position of the optical instrument 112 and the measuring unit 113 coupled, fixed, fixedly coimected, or fixedly attached to the optical instrument 112, in various directions and / or orientations. For example, the positioning structure may comprise a positioning structure with n degrees of freedom, where n is an integer number, such as an w-axis positioning structure like a tetrapod, an hexapod, or an octopod, which provide high precision movements, or a system of motors or actuators including linear and / or rotary motors, which may be piezoelectric or stepper motors, or other suitable actuators or positioning mechanisms.

[0053] In some instances, some of the components of the setup of FIG. lb, such as the optical instrument 112 and the positioning structure, including the first supporting element 102, the first positioning structure 104, the second supporting element 106 and / or the second positioning structure 108, may be left in place after evaluating the quality of the optical instrument 112, so as to be used in the setup of FIG. la. For example, the light directing element 111 may be removed, and behind it the projection system 116 may be placed, and the measuring unit 113 may be detached from the optical instrument 112, and the light detecting device 110 of FIG. la may be fixed to the optical instrument 112. This allows for a system and method that can, with one simple setup, perform several steps of the manufacturing, testing, calibrating and / or adjusting of an optical assembly, and facilitates the process of chain manufacturing, while at the same time correcting or reducing the effect of gravity, undesired forces or perturbations on the optical assembly for use on board a manned or unmanned aerial or space vehicle.

[0054] The setup of FIG. lb can also be used during manufacturing and / or assembling of the optical instrument 112, in order to determine an optimal position of the elements comprising the optical instrument (mirror(s), connecting structures, etc.). That is, the setup of FIG. lb may be part of a manufacturing operation for the optical assembly / instrument, to determine where to place certain elements, or may be a subsequent testing step where after manufacturing the optical instrument, its quality is checked. The optimal position as well as the quality arc determined based, at least hi part, on the effects of gravity, undesired forces or perturbations.

[0055] The acceptance of optical instruments in the art is generally known to be performed in vacuum chambers, which requires a complex and expensive setup. An additional aspect of die system of FIG. lb is that it does not require vacuum conditions. Air is present between the light directing element 111 and the optical instrument 112 and between the optical instrument and the measuring unit 113. According to some embodiments, in order to avoid a static column of air to be generated, which can negatively affect the measurements, an air moving system may be put in place, in at least some sections or parts of the column of air between the light generating system and the detection system, so as to generate turbulence and keep the air moving, for example in at least part of the column of air between the light source or the light directing element and the measuring unit.

[0056] The system according to FIG. la and / or FIG. lb may be configured to move the optical instrument and the measuring unit, and / or the optical instrument and the light detecting device (with or without being coupled to the stabilizing positioning mechanism), manually or automatically. A control unit may additionally be present (not shown in the figures), configured to control the positioning structure to move the optical instrument and themeasuring unit, and / or the optical instrument and the light detecting device. The control unit may be configured to control an overall operation of the system. The control unit may be executable by one or more processors to control, such as through one or more input / output interfaces, the positioning structure, including controlling actuators included in the positioning structure, through one or more electronic controls (such as controllers, which may in turn operate actuators through one or more limit switches, checks, closed loop actuator controls, and so forth) to move, position, or otherw ise manipulate various mechanical aspects of the positioning structure. The actuators include for example linear actuator(s), rotary actuator(s), sub-pixel transverse actuator(s), and other actuators and variations thereof according to various embodiments of the present disclosure. The same or a different control unit may be used to control the stabilizing positioning mechanism, so as to move the light detecting device to compensate for the apparent motion of the scene being imaged.

[0057] A memory may also be present, configured to store overall information, and program instructions and program modules that are loadable and executable on one or more processor(s) of the control unit, as well as data generated during execution of, and / or usable in conjunction with, these programs.

[0058] Embodiments of the present disclosure also allow to perform tests on an already assembled manned or unmanned aerial or space vehicle, such as a satellite, after the optical assembly and all other components have been put together, to evaluate a quality of the vehicle’s camera before and after other tests such as ambiental tests. This can be done with a similar setup as the one of FIG. la. by placing the assembled vehicle on the positioning structure, in such a way that the optical instrument 1 12 is placed with its longitudinal axis perpendicular to the direction of gravity 118. The assembled vehicle can then be rotated along said longitudinal axis, manually or by the positioning structure, so that an effect of gravity on the quality of the camera after the vehicle is assembled can also be evaluated and a final test can be performed. FIGs la and lb illustrate how the system 100 is configured to provide a simple and versatile setup so that several operations can be performed on the optical assembly and / or the optical instrument, while making it robust against the effects of gravity or undesired forces, rotations or perturbations. This simple setup also allows to simplify calculations that are performed based on the measurements obtained using this setup.

[0059] FIG. 2 shows a method of operation of a system according to embodiments of the present disclosure. The method of FIG. 2 is performed with the setup of FIG. la. Step 201 comprises performing a measurement on light detected by the light detecting device 110, when the light detecting device and the optical instrument 112 are located at a certain first position along the z axis (z position, focus position) as represented in FIG. la, and at a certain first field (first x-y’ plane). As explained elsewhere within the Detailed Description, this first x-y’ plane may coincide with an initial plane or initial field, which has been determined beforehand to be parallel to an area of a stabilizing positioning mechanism, in case such stabilizing positioning mechanism is present as part of the optical assembly. Alternatively, the first x-y’ plane may correspond to the initial plane or initial field determined beforehand to be parallel to an active surface of the light detecting device 110. As explained elsewhere within the Detailed Description, the measurements may comprise any type of measurement aimed at maximizing a certain metric or parameter of interest depending on the application or the type of light detecting element. Step 202 comprises checking or evaluating whether the maximum number of measurements on the current field (x-y’ plane) of the light detecting device has been reached. The measurements may be performed on any x-y’ position within the x-y’ plane, given that the image is formed on the different x-y’ positions withinthe x-y’ plane. The x-y’ plane generally corresponds to the active surface of the light detecting device. This maximum number of measurements may be determined in advance. For example, a maximum number of measurements may be set as N measurements of image sharpness, wherein N is an integer number. Alternatively, the number of measurements may be determined based on a threshold level reached by the measurement on any x-y’ position on the current x-y’ plane. For example, the number of measurements may be considered maximum based on an image sharpness threshold, so that the maximum number of measurements is reached when the image sharpness is above or below a predetermined image sharpness threshold. If the answer is NO, the method moves to step 203, which comprises moving the light detecting device along the z axis or focus axis to a second focus position different from the first focus position. This is done so as to find the optimal focus position for any x-y’ position on a specific field (x-y’ plane) of the light detecting device with respect to the detected image. After step 203, the method goes back to step 201 in which a measurement is performed, and then step 202 is performed again to check whether the maximum number of measurements on any x-y’ position on the current field has now been reached. If the answer is YES, the method moves to step 204, which comprises checking whether a maximum number of fields or x-y’ planes has been reached. This maximum number may be determined in advance, or may be determined based on a threshold level. If the answer is NO, it means that the previous operations are to be repeated, in this case in a different field or x-y’ plane. The method moves thereafter to step 205, which comprises moving (displacing and / or rotating) the optical instrument and the light detecting device to a different x-y’ plane, and from there, the method goes back to step 201 as seen above. By moving (displacing and / or rotating) the optical instrument and the light detecting device, the x-y’ plane is moved to a different x-y’ plane. Due to the movement, a projection of the image by the projection system is changed, and instead of reaching the center of the light detecting device (corresponding to a field), it reaches a comer thereof (corresponding a different field). If the answer in step 204 is YES, it means that the maximum number of x-y’ planes has been reached, and the step moves then to step 206. Therefore, what is done according to certain embodiments of the present disclosure is to measure a series of points on the light detecting device. On each one of those points, one or more measurements are performed to search for a focus position. In some instances, the position information, such as die coordinates for the position where the image is best focused (c.g x, y and z coordinates), may be stored in a memory. With the stored position information of all the measurements, it is possible to find the best plane possible in which the light detecting device is to be oriented. Once this plane is found, the light detecting device may be placed in said plane.

[0060] In step 206, the method comprises checking whether a maximum number of rotations about the longitudinal axis of the optical instrument (z axis, focus axis) has been reached. If the answer is NO, the method moves to step 207, which comprises rotating the optical instrument and the light detecting device about the longitudinal axis of the optical instrument a certain predetermined angle, which may for example be 45 degrees, 90 degrees, 180 degrees or any other suitable angle. After the rotation, the method goes back to step 201 and the whole sequence is performed again. If the answer at step 206 is YES, that is, if the maximum number of rotations about the z axis has been reached, for example because a 360 degree rotation has already been performed, the method goes to step 208 and finishes. By performing these rotations, and performing afterwards a combining operation, such as an averaging operation, an optimal position of the light detecting device, which is robust against the effects of gravity, may be found. In the method of FIG. 2, steps 202 to 205 may or may not beperformed, in other words, the method may comprise performing in 201 the measurement and checking in 206 whether the maximum number of rotations has been reached, and in such case, move to step 207 to rotate the optical instrument and the light detecting device about the z axis and return back to step 201.

[0061] FIG. 3 shows a method of operation of a system according to embodiments of the present disclosure. The method of FIG. 3 is performed with die setup of FIG. lb. Step 301 comprises performing a measurement on light detected by the measuring unit 113, when the measuring unit 113 and the optical instrument 112 are located at a certain first position along the z axis (z position, focus position) as represented in FIG. lb, and at a certain x-y’ position within the x-y’ plane (field). As explained elsewhere within the Detailed Description, the measurements may comprise any type of measurement aimed at obtaining information about the optical quality of the optical instrument, such as wavefront error (WFE) measurements. Step 302 comprises checking or evaluating whether the maximum number of measurements on the current x-y’ plane of the measuring unit 113 has been reached. The measurements may be performed on an x-y’ position within the x-y’ plane on which an image is formed. This maximum number may be determined in advance or based on threshold levels. If the answer is NO, the method moves to step 303, which comprises moving the measuring unit 113 along the z axis to a second focus position different from the first focus position. This is done so as to find the optimal focus position to perform the measurement, for the x-y’ position on a specific x-y’ plane (field) of the measuring unit 113 with respect to the detected image. After step 303, the method goes back to step 301 in which a measurement is performed, and then step 302 is performed again to check whether the maximum number of measurements on an x-y’ position on the current x-y’ plane has now been reached. If the answer is YES. the method moves to step 304, which comprises checking whether a maximum number of x-y’ planes has been reached. This maximum number may be determined in advance, or may be determined based on a threshold level. If the answer is NO, it means that the previous operations are to be repeated, in this case in a different x-y’ plane. The method moves thereafter to step 305, which comprises moving (displacing and / or rotating) the optical instrument and the measuring unit 113, and from there, the method goes back to step 301 as seen above. The movement in step 305 may comprise a rotation of the optical instrument and the measuring unit together, and / or a displacement of the measuring unit with respect to the optical instrument. By rotating the optical instrument 112 and the measuring unit 113 together in step 305, the x-y’ plane is moved to a different x-y’ plane, and by displacing the measuring unit 113 with respect to the optical instrument 112, an x-y’ position different from the previous x-y’ position may be explored. Generally, the light directing element 111 forms an image at focused x-y’ positions within the x-y’ plane of the measuring unit 113, and for this reason it is necessary to make measurements along the focus position as well as at different x-y’ positions within the x-y' plane so as to measure the focus position where the image is formed. If the answer in step 304 is YES, it means that the maximum number of x-y’ planes has been reached, and the step moves then to step 306. Therefore, what is done according to certain embodiments of the present disclosure is to measure a series of points on the measuring unit. On each one of those points, one or more measurements may be performed at different focus positions, x-y’ planes, and / or x-y’ positions within x- y’ planes where the image is formed. By operating in this manner, the focus positions as well as x-y’ positions within different x-y’ planes may be explored. The image is formed in different fields or positions of the focal plane. With an extense sensor (like a light detecting device of a camera on board a satellite) what can be done is to take one image in various fields, in any x-y’ position. On the contrary, in the case of using a Shack Hartmanndevice and / or an interferometer, it is necessary to move to a different x-y’ position to reach a predetermined field, because the detection is generally highly focused in the field.

[0062] In step 306, the method comprises checking whether a maximum number of rotations about the longitudinal axis of the optical instrument (z axis, focus axis) has been reached. If the answer is NO, the method moves to step 307, which comprises rotating the assembly of the optical instrument and the measuring unit about the longitudinal axis of tire optical instrument a certain predetennined angle, which may for example be 45 degrees, 90 degrees, 180 degrees or any other suitable angle. After the rotation, the method goes back to step 301 and the whole sequence is performed again. If the answer at step 306 is YES, that is, if the maximum number of rotations about the z axis has been reached, for example because a 360 degree rotation has already been performed, the method goes to step 308 and finishes. By performing these rotations, and performing afterwards a combining operation, such as an averaging operation, measurement of the quality of the optical instrument may be found.

[0063] In some embodiments, the loop comprising the steps 304 and 305 may be performed before the loop comprising the steps 302 and 303, so that for an x-y’ position within the x-y’ plane, different focus positions (e.g.along the z axis) may be explored, and so forth exploring different z positions for different x-y’ positions for the same x-y’ plane. In the method of FIG. 3, steps 302 to 305 may or may not be performed, in other words, the method may comprise performing in 301 the measurement and checking in 306 whether the maximum number of rotations has been reached, and in such case, move to step 307 to rotate the optical instrument and the light detecting device about the z axis and return back to step 301.

[0064] FIG. 4 shows a method of operation of a system according to embodiments of the present disclosure. The method of FIG. 4 is performed with the setup of FIGs. la and lb. Step 402 comprises determining if the measuring unit 113 is attached to the optical instrument 112. As explained elsewhere within the Detailed Description, the measuring unit 113 can be coupled, fixed, fixedly connected, fixedly attached, or detachably coupled to the optical instrument 112, and this attachment may be performed using, for example, a supporting element like the second supporting element 106 or may be directly attached to a positioning structure, for example, the second positioning structure 108. If the answer is YES, the method moves to step 404, which comprises determining if die sharpness position is optimal by evaluating if the measuring unit is in optimal sharpness position. If the answer is NO, the method moves to step 406, which comprises moving the measuring unit with respect to the optical instrument along an axis following a direction of the longitudinal axis of the optical instrument until the sharpness position is optimal. When die answer is YES, the method moves to step 408, which comprises performing a measurement on light detected by the measuring unit 113, when the light directing element 111 is placed horizontally and aligned with the optical axis of the optical instrument 112, and directs light towards the optical instrument 112. As explained elsewhere within the Detailed Description, the measurements may comprise any type of measurement aimed at obtaining information about the optical quality of the optical instrument, such as wavefront error (WFE) measurements. Step 410 comprises determining whether a maximum number of fields or x-y’ planes has been reached. This maximum number may be determined in advance, or may be determined based on a threshold level. If the answer is NO, it means that the previous operations are to be repeated, in this case in a different field or x-y’ plane. The method moves thereafter to step 412, which comprises moving (displacing and / or rotating) the optical instrument and the measuring unitwith respect to the light directing element 111 to a different x-y ’ plane, with the light directing element 111 being in a fixed position. From there, the method goes back to step 404 as seen above. By moving (displacing and / or rotating) die optical instrument and the measuring unit with respect to light directing element 111, the x-y’ plane is moved to a different x-y’ plane. Due to the movement, light passes through the optical instrument and reaches the measuring unit, and instead of reaching for example the center of the measuring unit (corresponding to a field), it reaches a comer thereof (corresponding to a different field). If the answer in step 410 is YES, it means that the maximum number of x-y' planes has been reached, and the step moves then to step 414.

[0065] Step 414 comprises checking whether a maximum number of rotations about the longitudinal axis of the optical instrument (z axis, focus axis) has been reached. If the answer is NO, the method moves to step 416, which comprises rotating the optical assembly, which comprises the optical instrument and the measuring unit, about the longitudinal axis of the optical instrument a certain predetermined angle, which may for example be 45 degrees, 90 degrees, 180 degrees or any other suitable angle. After the rotation, the method goes back to step 402 and, if the measuring unit is attached to the optical instrument and the answer at step 414 is NO, the whole sequence (from step 404 to 416) is performed again. If the answer at step 414 is YES, that is, if the maximum number of rotations about the z axis has been reached, for example because a 360 degree rotation has already been performed, the method goes to step 418 and finishes. By performing these rotations, and performing afterwards a combining operation, such as an averaging operation based on the measurements obtained at step 408, measurement of the quality of the optical instrument may be found, which is robust against the effects of gravity' or rmdesired forces, rotations or perturbations. Furthermore, calculations are further simplified due to the fact that the measuring unit is (detachably) attached to the optical instrument.

[0066] If the answer at step 402 is NO, the method moves to step 420, which comprises determining if the light detecting device 110 is fixed to the optical instrument 112. As explained elsewhere within the Detailed Description, the light detecting device 110 may be fixed or detachably fixed to the optical instrument 112 in different ways. If the answer at step 420 is YES. the method moves to step 422, which comprises moving the light detecting device along the z axis or focus axis to a second focus position different from the first focus position. This is done so as to find the optimal focus position for any x-y’ position on a specific field (x-y’ plane) of the light detecting device with respect to the detected image. Step 424, comprises performing a measurement on light detected by the light detecting device 110, when the projection system 116 is placed horizontally and aligned with the optical axis of the optical instrument 112, and projects an image detected by the light detecting device 110 after passing through the optical instrument 112. The image is detected by the light detecting device 110 at a certain first position along the z axis (z position, focus position), and at a certain first field (first x-y’ plane). As explained elsewhere within the Detailed Description, this first x-y’ plane may coincide with an initial plane or initial field, which has been determined beforehand to be parallel to an area of a stabilizing positioning mechanism, in case such stabilizing positioning mechanism is present as part of the optical assembly. Alternatively, the first x-y’ plane may correspond to the initial plane or initial field determined beforehand to be parallel to an active surface of the light detecting device 110. As explained elsewhere within the Detailed Description, the measurements may comprise any type of measurement aimed at maximizing a certain metric or parameter of interest depending on the application or the type of light detecting element. Step 426 comprises checking or evaluating whether the maximum number of measurements on the current field (x-y’ plane) of thelight detecting device has been reached. The measurements may be performed on any x-y ' position within the x- y’ plane, given that the image is formed on the different x-y’ positions within the x-y’ plane. The x-y’ plane generally corresponds to the active surface of the light detecting device. This maximum number of measurements may be determined in advance. As explained in relation to FIG. 2, the maximum number of measurements may be set as N measurements of image sharpness or based on a threshold level reached by the measurement on any x-y’ position on the current x-y’ plane. In step 426, if the answer is NO, the method moves to step 422, and steps 424 and 426 are performed until the answer is YES in step 426. If the answer is YES in step 426, the method moves to step 428, which comprises checking whether a maximum number of fields or x-y’ planes has been reached. This maximum number may be determined in advance, or may be determined based on a threshold level. If the answer is NO, it means that the previous operations are to be repeated, in this case in a different field or x-y’ plane. The method moves thereafter to step 430, which comprises moving (displacing and / or rotating) the optical instrument and the light detecting device with respect to the projection system 116 to a different x-y’ plane with respect to the projection system 116 which does not move. From there, the method goes back to step 424 as seen above. By moving (displacing and / or rotating) the optical instrument and the light detecting device with respect to the projection system 116, the x-y’ plane is moved to a different x-y’ plane. Due to the movement, a projection of the image by the projection system is changed, and instead of reaching the center of the light detecting device (corresponding to a field), it reaches a corner thereof (corresponding to a different field). If the answer in step 428 is YES, it means that the maximum number of x-y’ planes has been reached, and the step moves then to step 414 as explained above. If the answer is NO in step 414. the light detecting device is (detachably) fixed to the optical instrument 112, hence the method moves to step 416 which comprises rotating the optical assembly, which now comprises the optical instrument and the light detecting device, about the longitudinal axis of the optical instrument a certain predetermined angle, which may be the same or different that the predetermined angle used for rotating the optical assembly comprising the optical instrument and the measuring unit. And given that the light detecting device is (detachably) fixed to the optical instrument 112, the steps included in the dash-line box are repeated again as explained above. If the answer is YES in step 414, ,By performing these rotations, and performing afterwards a combining operation, such as an averaging operation based on the measurements obtained at step 424 (stored focus position information of all the measurements) for the different number of rotations at predetermined angles (step 416), it is possible to find the best plane possible in which the light detecting device is to be oriented with respect to the optical instrument 112, which is robust against the effects of gravity or undesired forces, rotations or perturbations. Furthermore, calculations are further simplified due to the fact that the light detecting device is (detachably) fixed to the optical instrument.

[0067] Finally, if at step 420 the answer is NO, the method moves to step 432, which comprises attaching a measuring unit or light detecting device (with or without stabilizing mechanism) to the optical instrument to assembly, adjust, calibrate and / or evaluate the components of the optical assembly, which is robust against the effects of gravity, or undesired forces, rotations or perturbations.

[0068] Therefore, what is done according to certain embodiments of the present disclosure is to measure the quality of the optical instrument by performing a series of measurements by attaching the measuring unit to the optical instrument and rotating the optical assembly at different predetermined angles about the z axis of the optical instrument, to finally combine the series measurements by averaging the measurements to determine thequality of the optical instrument taking into account the effect of gravity , or undcsircd forces, rotations or perturbations, in a simple manner. And by replacing the measuring unit with the light detecting device (with or without being coupled to a stabilizing positioning mechanism) and fixing or attaching it to the optical instrument, what is also done with this setup is to determine the optimal field for the light detecting device which is robust against the effects of gravity or undesired forces, rotations or perturbations, by performing a first series of measurements at different x-y’ positions and x-y’ fields at a first predetermined angle about the z axis of the optical instrument to determine a first optimal field, and performing a second series of measurements at different x-y’ positions and x-y’ fields at a second predetermined angle about the z axis of the optical instrument, different from the first predetermined angle, to determine a second optimal field, to finally combine the information of the first and second optimal fields by averaging the positions of first and second optimal fields determined for the different predetermined angles, to obtain die optimal field which is robust against the effects of gravity or undesired forces, rotations or perturbations. Furthermore, the methods, systems and devices of these embodiments provide a simple setup that allows to perform several operations on an optical assembly by simply replacing the measuring unit by the light detecting device and the light directing element by the projection system, performing the measurements horizontally, and only moving the optical assembly without requiring to move complex and heavy optical components like the light directing element by the projection system.

[0069] It should be understood that other steps explained in FIGs. 2 and 3 may be also performed in FIG. 4, such as checking or evaluating whether the maximum number of measurements on the current x-y’ plane of the measuring unit 113 has been reached, moving the measuring unit 113 along the z axis to different focus positions, checking whether a maximum number of x-y’ planes has been reached, and / or exploring different x-y’ positions, given that generally, the light directing element 111 forms an image at focused x-y’ positions within the x-y’ plane of the measuring unit 113, and for this reason it is necessary' to make measurements along the focus position as well as at different x-y’ positions within the x-y’ plane so as to measure the focus position where the image is formed. As explained elsewhere within the Detailed Description, in the case of using a Shack Hartmann device and / or an interferometer, it can be necessary to move to a different x-y’ position to reach a predetermined field, because the detection is generally highly focused in tire field.

[0100] According to embodiments, after determining the optimal field or plane for the light detecting device or finding the optimal position of the light detecting device, as explained for example in FIGs. la, 2 and 4, which may be found with a test light detecting device with properties that may allow to perform a more accurate aligning than the actual light detecting device, a system of reference can be used to preserve or mark the optimal position in the optical assembly, so that the optical assembly can be stored with one or more marking elements of the system of reference, the marking elements configured to reserve or mark the optimal position in the optical assembly. The system of reference comprises one or more marking elements, the marking element preferably having at least one light reflecting surface, such as a mirror, polished metal, or any surface configured to reflect (partially or completely) light. For example, the system of reference can comprise one or more mirrors, and a method of adjusting or calibrating the one or more mirrors in an optical assembly for aerial or space applications to reserve or mark an optimal field for a definitive (or actual) light detecting device, comprises the steps of placing a first mirror parallel to the test light detecting device, wherein the field of the reflecting surface of the first mirror coincides with the optimal field of the test light detecting device; placing a second mirror parallel tothe first mirror and parallel to a lens of the optical instrument, wherein the field of the reflecting surface of the second mirror is parallel to the field of the reflecting surface of the first mirror and coincides with the field of the lens of the optical instrument. The lens of the optical instrument is generally an objective lens. As used herein, parallel refers to an element at a predetermined distance apart from another element, wherein the predetermined distance is the same distance along their whole length. The method may further comprise the step of removing the test light detecting device, so that the optical assembly may be stored with the mirrors of the system of reference for later use. The method may further comprise the step of placing the definitive light detecting device in the place of the test light detecting device so that the definitive light detecting device is parallel to the first mirror and the field of the definite light detecting device coincides with the field of the reflecting surface of the first mirror. The method may further comprise the step of removing the first and second mirrors, so that the definite light detecting device is placed in the optimal position of the light detecting device, which is the optimal position determined as explained elsewhere within the Detailed Description. In this manner, the optical assemblies for equipping manned or unmanned aerial or space vehicles may be stored during production with the marking element in the optimal position, until the definite or actual light detecting device is received and placed in the optimal position, which is robust against the effects of gravity or undesired forces, rotations or perturbations.

[0101] Embodiments provide a system for performing operations on an optical assembly for aerial or space applications, the system comprising a supporting element configured to couple an optical instrument with a first element or a second element; and a positioning structure configured to place the optical instrument with a longitudinal axis perpendicular to a direction of gravity and rotate the optical assembly about the longitudinal axis at one or more predetermined angles; wherein the optical assembly comprises the first element and the optical instrument, or the second element and the optical instrument. According to embodiments, the positioning structure is further configured to, at least one of: move the optical assembly with respect to a light directing element, move the optical assembly with respect to a projection system, move the first element with respect to the optical instrument, and move the second element with respect to the optical instrument; wherein the light directing element is configured to receive a light beam from a light source and reflect the light beam towards the optical assembly, and the projection system is configmed to generate an image to be detected by the second element after passing through the optical instrument. According to embodiments, the system further comprises an air moving system in at least part of a column of air between the light source or die light directing element and the first element. According to embodiments, the positioning structure is further configured to direct the positioning structure to move the first element or the second element along an axis following a direction of the longitudinal axis of the optical instrument. According to embodiments, the supporting element comprises a first supporting element and a second supporting element, and wherein the positioning structure comprises a first positioning structure configmed to be coupled to the first supporting element and a second positioning structure configured to be coupled to the second supporting element. According to embodiments, the first positioning structure and the second positioning structure are configured to move together or independently from each other. According to embodiments, the positioning structure comprises at least one of an hexapod or a system of linear and / or rotational motors. According to embodiments, the system further comprises a control unit configmed to control the positioning structure. According to embodiments, the optical instrument comprises a telescope.According to embodiments, the first element is a measuring unit configured to perform measurements of quality at each of the one or more predetermined angles. According to embodiments, the measuring unit is configured to measure aberrations of an optical wavefront; and optionally wherein the measuring unit comprises at least one of an interferometer, a Shack Hartmann wavefront sensor, wavefront curvature sensor or a Ronchi tester. According to embodiments, the second supporting element is configmed to be coupled to the measuring unit. According to embodiments, the second element is a light detecting device comprising a plurality of pixel sensors and is configmed to detect light coming from the optical instrument. According to embodiments, the light detecting device is an area imaging device, AID. According to embodiments, the second supporting element is configured to be coupled to the light detecting device. According to embodiments, the second supporting element is further configmed to move the light detecting device to compensate for the apparent motion of a scene and the optical assembly is configmed to capture one or more exposmes of the scene when the optical assembly is on board an aerial or space vehicle. According to embodiments, the second supporting element is further configured to move the light detecting device in one or more cycles compensating for the apparent motion of the scene.

[0102] Embodiments provide a device for performing operations on an optical assembly for aerial or space applications, the device comprising: a supporting element configmed to couple an optical instrument with a first element or a second element, wherein the optical assembly comprises the first element and the optical instrument, or the second element and the optical instrument; and a positioning structure configmed to, at least one of, move at least one of the first element or the second element with respect to the optical instrument, to place the optical instrument with a longitudinal axis perpendicular to a direction of gravity, and rotate the optical assembly about the longitudinal axis at one or more predetermined angles. According to embodiments, the positioning structure is further configured to move the second element to compensate for the apparent motion of a scene and the optical assembly is configured to capture one or more exposmes of the scene when the optical assembly is on board an aerial or space vehicle. According to embodiments, the positioning structure is further configmed to move together the optical assembly with respect to a projection system or a light directing element. According to embodiments, the first element is a measuring unit, the second element is a light detecting device, and the optical instrument comprises a telescope.

[0103] Embodiments provide a method for performing operations on an optical assembly for aerial or space applications, wherein die method comprises the steps of: rotating, by a positioning structure, an optical assembly at one or more predetermined angles about a longitudinal axis of an optical instrument included in the optical assembly, the longitudinal axis being perpendicular to a direction of gravity; performing one or more measurements on light that has passed through the optical assembly at the one or more predetermined angles, until a maximum number of rotations has been reached; wherein the optical assembly comprises a first element coupled with the optical instrument or a second element coupled with the optical instrument. According to embodiments, the first element is a measuring unit and wherein the measurement includes measurements of aberrations of an optical wavefront. According to embodiments, performing one or more measurements on light comprises: at the one or more predetermined angles: moving the optical assembly, at one or more predetermined orientations with respect to a light directing element, until a maximum number of predetermined orientations has been reached; at the one or more predetermined orientations: determine if the sharpness position is optimal; moving the measuring unit with respect to the optical instrument along an axis following a direction of thelongitudinal axis of the optical instrument until the sharpness position is optimal; performing one or more measurements at the optimal sharpness position. According to embodiments, the method further comprises determining, based on the one or more measurements at the one or more predetermined angles, whether a quality of the optical instrument is above a predetermined threshold. According to embodiments, the second element is a light detecting device, with or without being coupled to a stabilization system, and wherein the measurement includes at least one of image sharpness, a measurement of how out-of-focus an image is, or a measurement of a size or shape of elements on an image. According to embodiments, performing one or more measurements on light comprises: at the one or more predetermined angles: moving the optical assembly, at one or more predetermined orientations with respect to a projection system, until a maximum number of predetermined orientations has been reached; at the one or more predetermined orientations: moving the light detecting device with respect to the optical instrument along an axis following a direction of the longitudinal axis of the optical instrument; and performing one or more focus measurements, until a maximum number of focus measurements at the one or more predetermined orientations has been reached. According to embodiments, the method further comprises determining, based on the one or more measurements at the one or more predetermined angles, an optimal focus field for positioning the light detecting device with respect to the optical instrument. According to embodiments, the light detecting device is a test light detecting device, and wherein the method further comprises: placing a first marking element parallel to the test light detecting device; and placing a second marking element parallel to the first marking element and parallel to a lens of the optical instrument, wherein a field of the reflecting surface of the first marking element coincides with the optimal focus field of the test light detecting device; and wherein a field of the reflecting surface of the second marking element is parallel to the field of the reflecting surface of the first marking element and coincides with a field of the lens of the optical instrument. According to embodiments, the method further comprises removing the test light detecting device and storing the optical assembly with the first and second marking element for later use. According to embodiments, the method further comprises placing a definitive light detecting device parallel to the first marking element and the second marking element, so that the field of the definite light detecting device coincides with the field of the reflecting surface of the first marking element. According to embodiments, the method according is at least partially a computer-implemented method, and further comprising instructing, by a control unit, the positioning structure to rotate the optical assembly at the one or more predetermined angles.

[0104] It is to be appreciated that embodiments of the methods and apparatuses discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The methods and apparatuses are capable of implementation in other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. In particular, acts, elements and features discussed in connection with any one or more embodiments are not intended to be excluded from a similar role in any other embodiment.

[0105] Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Any references to embodiments or elements or acts of the systems and methods herein referred to in the singular may also embrace embodiments including a plurality of these elements, and any references in plural to any embodiment or element or act herein may also embrace embodiments including onlya single element. The use herein of “including,” “comprising.” “having,” “containing,” “involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of die described terms.

[0106] hi the descriptions above and in the claims, phrases such as “at least one of or “one or more of' may occur followed by a conjunctive list of elements or features. The term “and / or” may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases “at least one of A and B:”, “at least one of A or B:”,“one or more of A and B:”, and “A and / or B' are each intended to mean "A alone, B alone, or A and B together.” A similar interpretation is also intended for lists including three or more items. For example, the phrases “at least one of A, B, and C:”, “at least one of A, B, or C:”, "one or more of A, B, and C:” and "A, B, and / or C” are each intended to mean "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.” In addition, use of the term “based on” above and in the claims is intended to mean “based at least in part on”, such that an unrecited feature or element is also permissible.Conclusion

[0107] The subject matter described herein can be embodied in systems, apparatus, methods, and / or articles depending on the desired configuration. Although the disclosure uses language that is specific to structural features and / or methodological acts, the invention is not limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the subject matter described herein. The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and / or variations can be provided in addition to those set forth herein. For example, the implementations described above can be directed to various combinations and sub combinations of tire disclosed features and / or combinations and sub combinations of several further features disclosed above. In addition, the logic flows depicted in the accompanying figures and / or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims.

Claims

CLAIMSWhat is claimed is:

1. A system for performing operations on an optical assembly for aerial or space applications, the system comprising: a supporting element configured to couple an optical instrument with a first element or a second element; and a positioning structure configured to place the optical instrument with a longitudinal axis perpendicular to a direction of gravity and rotate the optical assembly about the longitudinal axis at one or more predetermined angles; wherein the optical assembly comprises the first element and the optical instrument, or the second element and the optical instrument.

2. The system according to claim 1, wherein the positioning structure is further configured to. at least one of: move the optical assembly with respect to a light directing element, move the optical assembly with respect to a projection system, move the first element with respect to the optical instrument, and move the second element with respect to the optical instrument; wherein the light directing element is configured to receive a light beam from a light source and reflect the light beam towards the optical assembly, and the projection system is configured to generate an image to be detected by the second element after passing through the optical instrument.

3. The system according to claim 2, further comprising an air moving system in at least part of a column of air between the light source or the light directing element and the first element.

4. The system according to any one of the preceding claims, wherein the positioning structure is further configured to direct the positioning structure to move the first element or the second element along an axis following a direction of the longitudinal axis of the optical instrument.

5. The system according to any one of die preceding claims, wherein the supporting element comprises a first supporting element and a second supporting element, and wherein the positioning structure comprises a first positioning structure configured to be coupled to the first supporting element and a second positioning structure configured to be coupled to the second supporting element.

6. The system according to claim 5, wherein the first positioning structure and the second positioning structure are configured to move together or independently from each other.

7. The system according to any one of the preceding claims, wherein the positioning structure comprises at least one of an hexapod or a system of linear and / or rotational motors.

8. The system according to any one of the preceding claims, further comprising a control unit configured to control the positioning structure.

9. The system according to any one of the preceding claims, wherein the optical instrument comprises a telescope.

10. The system according to any one of the preceding claims, wherein the first element is a measuring unit configured to perform measurements of quality at each of the one or more predetermined angles.1 1 . The system according to claim 10, wherein the measuring unit is configured to measure aberrations of an optical wavefront; and optionally wherein the measuring unit comprises at least one of an interferometer, a Shack Hartmann wavefront sensor, wavefront curvature sensor or a Ronchi tester.

12. The system according to claims 5 or 6, when dependent on claim 10, wherein the second supporting element is configured to be coupled to the measuring unit.

13. The sy stem according to any one of claims 1 to 9, wherein the second element is a light detecting device comprising a plurality of pixel sensors and is configured to detect light coming from the optical instrument.

14. The system according to claim 13, wherein the light detecting device is an area imaging device, AID.

15. The system according to claims 5 or 6, when dependent on claim 13, wherein the second supporting element is configured to be coupled to the light detecting device.

16. The system according to claim 15, wherein the second supporting element is further configured to move the light detecting device to compensate for the apparent motion of a scene and theoptical assembly is configured to capture one or more exposures of the scene when the optical assembly is on board an aerial or space vehicle.

17. The system according to claim 16, wherein the second supporting element is further configured to move the light detecting device in one or more cycles compensating for the apparent motion of the scene.

18. A device for performing operations on an optical assembly for aerial or space applications, the device comprising: a supporting element configured to couple an optical instrument with a first element or a second element, wherein the optical assembly comprises the first element and the optical instrument, or the second element and the optical instrument; and a positioning structure configured to, at least one of, move at least one of the first element or the second element with respect to the optical instrument, to place the optical instrument with a longitudinal axis perpendicular to a direction of gravity, and rotate the optical assembly about the longitudinal axis at one or more predetermined angles.

19. The device according to claim 18, wherein the positioning structure is further configured to move the second element to compensate for the apparent motion of a scene and the optical assembly is configured to capture one or more exposures of the scene when the optical assembly is on board an aerial or space vehicle.

20. The device according to any claim 18 or 19, wherein the positioning structure is further configured to move together the optical assembly with respect to a projection system or a light directing element.

21. The device according to any one of claims 18-20, wherein the first element is a measuring unit, the second element is a light detecting device, and the optical instrument comprises a telescope.

22. A method for performing operations on an optical assembly for aerial or space applications, wherein the method comprises the steps of: rotating, by a positioning structure, an optical assembly at one or more predetermined angles about a longitudinal axis of an optical instrument included in the optical assembly, the longitudinal axis being perpendicular to a direction of gravity; performing one or more measurements on light that has passed through the optical assembly at the one or more predetermined angles, until a maximum number of rotations has been reached:wherein the optical assembly comprises a first element coupled with the optical instrument or a second element coupled with the optical instrument.

23. The method according to claim 22, wherein the first element is a measuring unit and wherein the measurement includes measurements of aberrations of an optical wavefront.

24. The method according to claim 23, wherein performing one or more measurements on light comprises: at the one or more predetermined angles: moving the optical assembly, at one or more predetermined orientations with respect to a light directing element, until a maximum number of predetermined orientations has been reached: at the one or more predetermined orientations: determine if the sharpness position is optimal; moving the measuring unit with respect to the optical instrument along an axis following a direction of the longitudinal axis of the optical instrument until the sharpness position is optimal; performing one or more measurements at the optimal sharpness position.

25. The method according to claim 24, wherein the method further comprises determining, based on the one or more measurements at the one or more predetermined angles, whether a quality of the optical instrument is above a predetermined threshold.

26. The method according to claim 22. wherein the second element is a light detecting device, with or without being coupled to a stabilization system, and wherein the measurement includes at least one of image sharpness, a measurement of how out-of-focus an image is, or a measurement of a size or shape of elements on an image.

27. The method according to claim 26, wherein performing one or more measurements on light comprises: at the one or more predetermined angles: moving the optical assembly, at one or more predetermined orientations with respect to a projection system, until a maximum number of predetermined orientations has been reached; at the one or more predetermined orientations: moving the light detecting device with respect to the optical instrument along an axis following a direction of the longitudinal axis of the optical instrument; andperforming one or more focus measurements, until a maximum number of focus measurements at the one or more predetermined orientations has been reached.

28. The method according to clahn 27 , wherein the method further comprises determining, based on the one or more measurements at the one or more predetermined angles, an optimal focus field for positioning the light detecting device with respect to the optical instrument.

29. The method according to claim 28, wherein the light detecting device is a test light detecting device, and wherein the method further comprises: placing a first marking element parallel to the test light detecting device; and placing a second marking element parallel to the first marking element and parallel to a lens of the optical instrument, wherein a field of the reflecting surface of the first marking element coincides with the optimal focus field of the test light detecting device; and wherein a field of the reflecting surface of the second marking element is parallel to the field of the reflecting surface of the first marking element and coincides with a field of the lens of the optical instalment.

30. The method according to claim 29, wherein the method further comprises removing the test light detecting device and storing the optical assembly with the first and second marking element for later use.

31. The method according to claim 30, wherein the method further comprises placing a definitive light detecting device parallel to the first marking element and the second marking element, so that the field of the definite light detecting device coincides with the field of the reflecting surface of the first marking element.

32. The method according to any one of claims 22 to 31, being at least partially a computer- implemented method, and further comprising instructing, by a control unit, the positioning structure to rotate the optical assembly at the one or more predetermined angles.

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