Calibration apparatus and method for tunable filters for hyperspectral microelectromechanical systems

Abstract

According to one aspect of the presently disclosed subject matter, there is provided an apparatus configured to allow light to be shone onto a tunable filter, each time onto a different portion thereof, and to detect an optical response (e.g., transmission or reflection of the portion shone by the light). By detecting the optical response of the different portions of the tunable filter, each time isolated from the illumination, the state of the tunable filter at the illuminated portion (e.g., an optical gap between a movable component and a fixed component of the tunable filter) can be determined. By monitoring different portions of the tunable filter, a general state of the tunable filter can be determined. For example, the general state of the tunable filter can be determined based on the optical gap of the different portions of the tunable filter, while the driving parameters remain unchanged.

Description

Technical Field

[0001] This disclosure belongs to the field of inspection technology for calibrating optical devices, and in particular to tunable filters based on microelectromechanical systems (MEMS). Background Technology

[0002] The manufacturing process of relatively small devices often results in minute variations between different devices. For some devices, identifying these minute variations can be crucial. For example, in the fabrication of tunable filters based on microelectromechanical systems (MEMS), manufacturing variations can lead to substantial differences in the performance of these devices. Therefore, developing tools to monitor and identify the precise state of such devices is essential. By understanding the exact state of the device under different conditions, manufacturing variations and other defects that may occur throughout the entire lifecycle of such devices can be overcome. Summary of the Invention

[0003] The currently disclosed subject matter includes a device for monitoring the state of a tunable filter (e.g., a MEMS-based tunable filter). An example of a tunable spectral filter is an etalon (also known as a Fabry-Perot filter), which can be used, for example, in sequential imaging. The etalon comprises two parallel mirrors, wherein the spectral transmission distribution of the filter is determined by a corresponding "filter state" defined by a specific gap between the mirrors (which provides a so-called "optical cavity" or "optical gap").

[0004] To bring a tunable filter to a desired state, multiple driving parameters are applied. For example, a tunable filter can be driven by applying a voltage difference between a movable part and a fixed part, which causes an electrostatic force between the parts. The magnitude of this force between different parts of the tunable filter determines the state reached by the filter during driving. Each desired filter state needs to be mapped to a corresponding driving parameter used to obtain that state. In other words, driving parameters are needed to achieve each desired filter state (gap) for the correct operation of the tunable filter.

[0005] According to some examples, the apparatus of this disclosure is configured to direct light to a tunable filter, each time to a different portion thereof, and detect the optical response, i.e., the transmission (transmission) or reflection of the illuminated portion. By detecting the optical response of the isolated illumination to different portions of the tunable filter each time, the state of the tunable filter at the illuminated portion (e.g., the optical gap between a movable part and a fixed part of the tunable filter) can be determined. By monitoring different portions of the tunable filter, the general state of the tunable filter is determined. For example, the general state of the tunable filter can be determined based on the optical gap between different portions of the tunable filter, while the driving parameters remain constant.

[0006] One aspect of this disclosure relates to an apparatus configured to determine the state of a tunable filter and optionally calibrate the apparatus. The apparatus according to this aspect may include, for example, a light selection unit. The light selection unit is located between a light source and a tunable filter, placed at a designated location within the apparatus, and configured to selectively transmit light emitted from the light source to one or more different spatial portions of the tunable filter. That is, light from the light source propagates through the light selection unit to reach the tunable filter. It should be noted that, depending on the state of the light selection unit, some light may be filtered out before reaching the tunable filter. The light source is characterized by a given / known illumination distribution (e.g., a light source with a known illumination spectrum).

[0007] In some examples, the device includes a tunable filter holder for holding the tunable filter. It should be noted that the tunable filter holder can be a position relative to the device suitable for placing the tunable filter to operate with the device, for example, a surface on which the tunable filter is placed. In some other embodiments, the tunable filter holder can be a physical element that attaches the tunable filter to the device during device operation.

[0008] In some examples of the device, the adjustable filter holder includes an adjustable filter housing for receiving and holding the adjustable filter in place during a monitoring process. It should be noted that the adjustable filter housing can be configured according to various suitable configurations and designs.

[0009] In some examples, the device is configured for on-device calibration and includes a camera mount or clamp for holding a camera including an adjustable filter. It should be noted that the camera mount may refer to a position relative to the device suitable for placing a camera that will operate with the device, for example, a surface on which the camera is placed. In some other embodiments, the camera mount may be a physical element that attaches the camera to the device during operation.

[0010] In some examples, the device includes guiding optics for directing light from the light source toward the light selection unit and the tunable filter.

[0011] In some examples, the device further includes an optical component holder configured to hold an optical component including a light source. The light source is held such that it illuminates in the direction of the tunable filter housing when in place and when operated. When the tunable filter housing receives a tunable filter, the light source held by the optical component holder is configured to illuminate the tunable filter or a portion thereof.

[0012] In some examples, the light selection unit is located between the optical component fixture and the tunable filter housing, and includes one or more surfaces configured to selectively transmit light from the light source to different spatial portions of the tunable filter when the light source illuminates along the direction of the tunable filter. The light selection unit is capable of transmitting light to a single portion of the tunable filter at a time. Different states of the light selection unit are designed to transmit light to different portions of the tunable filter when light is received in the tunable filter housing.

[0013] In some examples, the light selection unit is configured to simultaneously transmit light to multiple parts of the tunable filter.

[0014] The optical response of a tunable filter to light irradiated by a light source within a portion of the tunable filter indicates the state of the tunable filter at a location associated with one or more of those portions. In other words, the optical response of illumination at a portion of the tunable filter indicates the gap between the two optical components of the tunable filter at that portion. The set of optical responses from each respective portion of the tunable filter indicates the gap and tilt value of the tunable filter (considering the geometry of the filter, such as an arcuate shape).

[0015] It should be noted that the term "optical response" includes both the transmission and reflection of light.

[0016] In some examples of the device, the tunable filter receiver includes a recess sized to receive the tunable filter. In some examples, the recess is sized to tightly receive the tunable filter.

[0017] In some examples, the tunable filter housing includes a holding mechanism for holding the tunable filter in place. For example, the holding mechanism may include a plurality of protrusions configured to be received by the tunable filter or a frame for holding the tunable filter in place.

[0018] In some examples, the device is configured for on-device calibration, and the camera mount includes a holding mechanism for holding the camera in place. For example, the holding mechanism may include a frame for holding the camera in place, the frame being adaptable to the size of the camera.

[0019] In some examples, the tunable filter housing is configured to form an electrical coupling with a tunable filter in which it is received to allow control over its operation, such as applying multiple drive parameters.

[0020] In some examples of the device, the optical component clamping unit is configured to hold a light source such that its optical axis is aligned with the optical axis of the tunable filter when the tunable filter is housed in the tunable filter housing. In this configuration, the center of the light beam is directed toward the optical components of the tunable filter. In some embodiments, the optical component clamping unit is configured to hold a light source such that its optical axis passes through a portion of the light selection unit and / or the tunable filter housing. In other words, the optical component clamping unit is configured to hold a light source such that its light spot overlaps with a portion of the light selection unit and / or the tunable filter housing.

[0021] In some examples, the light selection unit is configured to allow light to be transmitted to a single portion of the tunable filter at a time, i.e., the state of the light selection unit (here referred to as the "light selection state") provides a single illumination at a portion of the tunable filter.

[0022] A single section should be understood as a single location of the tunable filter that is illuminated / colored by the light source. In other words, a single section is an area (e.g., the area of ​​the tunable filter) covered by a spot of light illuminated by the light source.

[0023] In some examples, when the device is configured for on-device calibration, the optical component clamping unit is configured to hold a light source such that its optical axis is aligned with the optical axis of the camera, for example, when the camera is held by a camera mount. In this configuration, the center of the light beam is oriented towards the optical axis of the camera, with a lens barrel and an adjustable filter aligned along the optical axis. In some examples, the optical component clamping unit is configured to hold a light source such that its optical axis passes through a portion of the light selection unit and / or the adjustable filter housing. In other words, the optical component clamping unit is configured to hold a light source such that its light spot overlaps with a portion of the light selection unit and / or the adjustable filter.

[0024] In some examples of the device, the light selection unit is configured to filter a desired optical bandwidth to illuminate different portions of a tunable filter. In some embodiments, the light selection unit is configured to filter only one of red, green, blue, or infrared light to reach and interact with one or more portions of the tunable filter. A specific bandwidth of filtering can be applied such that different portions of the tunable filter are illuminated with the desired filtered bandwidth, and each state of the light selection unit results in a filtered illumination of a different portion of the tunable filter. In yet another embodiment, the light selection unit is configured to filter two different bandwidths of light such that at least two portions of the tunable filter are illuminated simultaneously, each portion having a different filtered light.

[0025] In some examples, the light selection unit is configured to apply one or more filters to filter one or more desired bandwidths to obtain filtered light that interacts with different portions of the tunable filter.

[0026] In some examples, in addition to the optical selection unit, or when the optical selection unit is not used, a specified optical filter is used to filter the desired optical bandwidth to illuminate different parts of the tunable filter.

[0027] The optical response distribution of a tunable filter for a desired wavelength is predetermined, for example, measured or calculated in previous experiments. Therefore, by analyzing the optical response detected using the device and identifying a matching distribution within the detected response that matches the predetermined distribution, the gaps between the optical components of the tunable filter can be inferred. In some examples, the light selection unit includes a fixed surface having a plurality of fixed pinholes. Illumination from a light source through each of the fixed pinholes illuminates a portion of the tunable filter at a time. In some other embodiments, illumination from a light source guided through each of the fixed pinholes illuminates one or more portions of the tunable filter at a time. It should be noted that, in order to obtain accurate and focused light concentration on the tunable filter, in some examples, the fixed pinholes are characterized by a relatively large aspect ratio; that is, the pinholes are elongated, thus being long and narrow.

[0028] In some examples of the device, each of the one or more fixed pinholes is configured to be switched between a transmission mode and a blocking mode and / or a bandwidth filter mode, i.e., filtering light of a certain bandwidth. In other words, each fixed pinhole is configured to block light transmission in one state and allow transmission of a selected wavelength range and / or intensity in its different states.

[0029] In some examples of the device, the one or more fixed pinholes are extended such that their depth along a vertical axis is much greater than their maximum horizontal dimension, for example, their diameter when they are cylindrical. This produces an accurate and focused spot of light on the tunable filter, primarily derived from collimated light.

[0030] In some examples of the device, the light selection unit includes a movable surface located above or below the fixed surface and the light source (e.g., between the fixed surface and the light source), and the movable surface has one or more movable pinholes. Movement of the movable surface causes switching between different states, wherein in each state, different movable pinholes are aligned with different fixed pinholes, thereby allowing different portions of the tunable filter to be illuminated in each state.

[0031] It should be noted that in some examples, the light selection unit may consist of only a movable surface configured to switch between different light selection states, each state being configured to expose (i) different portions of the tunable filter for illumination and / or (ii) apply different filters to expose tunable filters with different light bandwidths.

[0032] In some examples, the light selection unit includes a fixed surface, wherein a specific area of ​​the fixed surface blocks light emitted by the light source (creating a "light-blocking region"), while other areas of the surface are transparent to light emitted by the light source. Illumination from a light source directed at the light selection unit illuminates a portion of the tunable filter at a time, i.e., the portion corresponding to the transparent region. According to one example, half of the light selection unit is configured as a light-blocking region, and the other half is transparent to light emitted by the light source. According to another example, the light selection unit is divided into quarters, with two-quarters configured as light-blocking regions and two-quarters transparent to light emitted by the light source.

[0033] In some examples of the device, rotational motion may be applied to a light selection unit around its center, wherein the rotational motion of the light selection unit causes the unit to switch between different light selection states, wherein in each light selection state, a different portion (e.g., a different half) of the tunable filter is illuminated by the light source. It is worth noting that the rotational motion can be angular motion, planar motion, or any other type of motion besides angular motion. In some examples, each light selection state results in the transmission of light on a single portion of the tunable filter.

[0034] In some examples, the device includes a drive unit configured to switch the light selection unit between light selection states. For example, a servo motor or stepper motor may be used to rotate the light selection unit and switch between different light selection states.

[0035] In some examples, the light selection unit can be configured to electronically shield the emitted light. For example, the light selection unit can be an LCD screen, wherein different areas of the screen are driven to block or transmit the light emitted by the light source in different light selection states.

[0036] In some examples of the device, the movable pinhole is larger than the fixed pinhole, i.e., has a larger diameter. This allows for a looser placement tolerance of the movable surface relative to the fixed surface, allowing light to be properly transmitted through the pinhole array, including both fixed and movable pinholes.

[0037] In some examples of the device, the optical component fixture includes a longitudinal aperture with guiding optics for guiding light through it, wherein the light is emitted from the light source and is received in the optical component fixture.

[0038] According to another aspect of the subject matter of this disclosure, a system is provided that includes the apparatus described in any of the foregoing examples. The system also includes a light source for providing the known illumination spectrum. In some examples of the system, the light source is held in the optical component fixture and configured to illuminate the tunable filter.

[0039] In some examples, the system also includes an adjustable filter.

[0040] In some examples, the system includes a photodetector for detecting the optical response from the illumination portion of the tunable filter.

[0041] In some examples of the system, the photodetector is a spectrometer or an image sensor (e.g., RGB, IR-RGB, or monochromatic). The spectrometer is capable of detecting and analyzing light across a relatively broad spectrum, such as the entire visible and infrared spectrum. The spectrometer can provide data on the detected intensities, encompassing a wide wavelength range.

[0042] In some examples of the system, the photodetector is held in the optical component fixture and configured to detect the reflection of the illumination from the light source onto different portions of the tunable filter.

[0043] In some examples of the system, the light source and the photodetector are formed in a single optical unit, i.e., sharing some optical components and having a common optical axis. For example, the single optical unit including the light source and the detector may include an optical fiber, such as a Y-bundle for reflective and backscattered spectroscopy / reflection probe types.

[0044] In some examples, the system includes a processing circuit (or more) configured to control the execution of one or more of the following:

[0045] (a) Applying driving parameters, such as applying different voltages to each of the plurality of electrodes of the tunable filter, to control the state of the tunable filter (e.g., the state of the movable component), namely, a gap with a fixed element of the tunable filter and an angular position relative to the fixed element, such as roll or pitch. The state of the movable component defines the optical response of the tunable filter;

[0046] (b) Controlling the light selection unit to determine the portion of the tunable filter illuminated by the light source. This is performed by switching between states of the light selection unit, for example by driving (e.g., rotating) the moving surface from one state to another. Furthermore, the processing circuitry can be configured to control the filtering of light transmitted to the portion of the tunable filter;

[0047] (c) Controlling the spectral transmission of the light selection unit, i.e., controlling the light selection unit to transmit a selected illumination wavelength range to the tunable filter; (d) Analyzing the optical response from one or more portions of the tunable filter, determining the state of the tunable filter based on this, and determining whether the state of the tunable filter satisfies a predetermined condition. The predetermined condition is satisfied if the different optical gaps of different portions of the tunable filter are within a predetermined tolerance and / or if the angular angle of the movable component relative to the fixed component is within the predetermined angular tolerance.

[0048] (e) Adjust the illumination spectrum of the light source.

[0049] In some examples of the system, where the state of the tunable filter does not meet the predetermined condition, the processing circuitry is further configured to iteratively apply multiple new driving parameters to bring the state of the tunable filter to the desired condition. After obtaining the desired predetermined condition, the processing circuitry is configured to store the driving parameters in a computer data storage device (e.g., a NAND flash memory device) to be executed to bring the tunable filter into the corresponding state, i.e., the desired optical gap.

[0050] In some examples of the system, the light source is configured to illuminate a wide bandwidth, which includes visible light and infrared light.

[0051] In some examples of the system, the processing circuitry operatively connected to the device is configured to match the optical response of the known illumination spectrum in the tunable filter with reference data for identifying a predetermined optical response distribution of an identifiable pattern (e.g., intensity peak) indicating the state of the tunable filter, such as a specific optical gap. The optical response may be transmission of illumination through the tunable filter or reflection of illumination from the tunable filter. In other words, reference data of optical response distributions across various wavelength ranges (e.g., transmission detected by an image sensor at a specific wavelength of the tunable filter) are predetermined and stored in memory. This reference data is associated with the intensity distribution of the optical response of the tunable filter being calibrated, such as the intensity distribution detected in an image sensor transmitting a specific wavelength through the tunable filter. The state of the tunable filter being calibrated is determined by identifying a matching distribution between the predetermined reference data and the detected intensity distribution.

[0052] In some examples of the system, the reference data, i.e., the identifiable pattern indicating the state of the tunable filter, includes one or more predetermined intensity distributions of the optical response for one or more wavelength ranges or specific wavelengths (e.g., red, green, blue, or IR).

[0053] Another aspect of this disclosure provides a method for monitoring the state of a tunable filter and / or calibrating the tunable filter. The method includes applying multiple driving parameters to the tunable filter, for example, tuning the tunable filter to an estimated optical gap between movable and fixed parts of the tunable filter. The estimated optical gap is characterized by a specific light transmission or light reflection distribution.

[0054] The method further includes illuminating one or more portions of the tunable filter and detecting an optical response, i.e., transmission or reflection, from the one or more portions. The optical response from the illuminated portions of the tunable filter is then analyzed, and based on this, the state of the tunable filter is identified, and it is determined whether the state of the tunable filter satisfies a predetermined condition. The predetermined condition is satisfied if the different optical gaps between different portions of the tunable filter are within a predetermined tolerance and / or if the angular angle between the movable component and the fixed component is within a predetermined angular tolerance.

[0055] In some examples of the method, where the state of the tunable filter does not satisfy the predetermined condition, the method includes iteratively applying a plurality of new driving parameters to bring the state of the tunable filter to the desired condition. After obtaining the desired condition, the driving parameters are stored in a memory.

[0056] In some examples of the method, applying multiple new driving parameters involves applying different driving parameters to different parts of the tunable filter. That is, applying a new set of electrostatic / piezoelectric / magnetic / mechanical forces between the driving electrodes / devices of the tunable filter results in a new state of the tunable filter.

[0057] In some examples, the method includes filtering the illumination to illuminate the one or more portions with a desired wavelength bandwidth or a specific wavelength (e.g., red, green, blue, or infrared light).

[0058] In some examples of the method, detecting the optical response includes detecting a spectral distribution of the optical response. This includes detecting the intensity at various wavelengths.

[0059] In some examples of the method, the analysis includes identifying a predetermined distribution of the optical response to determine the state of the tunable filter. In some examples of the method, the predetermined distribution is characterized by a rate of change of the transmission or reflection distribution through or from the tunable filter at a specific wavelength, such as a local minimum or maximum, a known differential function, etc.

[0060] In some examples, the method includes matching the optical response to a reference data of a predetermined illumination distribution. The optical response may be the transmission of illumination through a tunable filter or the reflection of illumination from a tunable filter.

[0061] In some examples of the method, the reference data includes one or more intensity distributions of the optical response over one or more wavelength ranges or at one or more specific wavelengths.

[0062] Another aspect of this disclosure provides a computer-readable non-transitory program storage device, specifically embodying a computer-executable computer-readable instruction for performing a computerized method of any of the above examples of the methods according to the various examples of the foregoing aspects.

[0063] According to another aspect of the subject matter of this disclosure, an apparatus is provided comprising: a processing circuit operatively connected to a detector (e.g., an image sensor or a spectrometer); wherein the apparatus is configured to interact with a tunable filter (e.g., a Fabry-Perot etalon) and enable a light source to illuminate the tunable filter with a beam; the processing circuit is configured to: determine, based on different optical responses, whether the state of the filter meets a desired condition for each optical response received at the detector from a corresponding illumination of a light source in a specific spatial portion of the tunable filter; if not, apply a plurality of updated driving parameters to bring the state of the tunable filter to the desired condition.

[0064] In some examples of the device, the processing circuitry is configured to iteratively apply multiple updated driving parameters and compare different optical responses until the state of the tunable filter is determined to be under a desired condition.

[0065] In some examples of the device, it further includes a light selection unit located between the tunable filter and the light source, the light selection unit being configured to selectively transmit light illuminated by the light source during a corresponding illumination period to a specific spatial portion of the tunable filter, thereby producing a corresponding optical response; the light selection unit is configured to switch between different light selection states, wherein a different spatial portion of the tunable filter is illuminated in each light selection state, and wherein when the light selection unit is in a corresponding light selection state, the different optical responses compared by the processing circuitry are all obtained.

[0066] In some examples of the device, the processing circuitry is configured to automatically switch the light selection unit between the different light selection states.

[0067] In some examples of the device, the processing circuitry is also configured to store the driving parameters in a computer data storage device operatively connected to the device when the desired conditions are obtained.

[0068] In another aspect of the currently disclosed subject matter, a method for adjusting a tunable filter is provided, the tunable filter including a movable part and a stationary part, and a plurality of at least three drivers, the plurality of at least three drivers being adapted to control the state of the tunable filter by driving a relative position of the movable part relative to the stationary part; the method comprising: detecting a plurality of optical responses, each optical response being obtained in response to illumination of a plurality of different spatial portions of the tunable filter; the detected optical responses indicating the state of the tunable filter, the tunable filter being associated with a plurality of geometric parameters of a gap between the movable part and the stationary part; and, based on the plurality of optical responses, determining a plurality of updated driving parameters to operate the plurality of drivers to adjust the state of the tunable filter to a desired state.

[0069] In some examples, the method includes illuminating the filter in multiple (at least three) different spatial portions;

[0070] In some examples of the method, the plurality of at least three drivers includes at least four drivers.

[0071] In some examples of the method, the initial driver includes:

[0072] In response to driving the plurality of drivers of the general filter of the type with corresponding driving parameter sets, a model is provided that indicates an estimation result state of a general filter of a type of tunable filter;

[0073] Using the model, perform at least one of the following:

[0074] I. Prior to the detection, an initial drive is set for the filter, wherein the setting includes determining an initial drive parameter set for the initial operation of the tunable filter based on the desired state; and

[0075] II. The plurality of updated driving parameters are determined by performing the following operations:

[0076] a. Using the model [e.g., its derivative] to determine an incremental correction to a specific driving parameter of the tunable filter, thereby obtaining the plurality of optical responses; and

[0077] b. Determine the plurality of updated driving parameters based on the specific driving parameters having the incremental correction.

[0078] In some examples of the method, the model includes a compliance function of the tunable filter, wherein the compliance function [F1] is independent of the plurality of driving parameters.

[0079] In some examples of the method, the plurality of drive parameters includes at least three drive parameters [V1, V2,...V] respectively associated with the at least three drivers. N A number N; and wherein the state of the tunable filter is characterized by at least the following geometric parameters of the gap: the size w of the gap is a nominal distance between the movable part and the fixed part, and the relative lateral orientation angles θ and Ф between the movable part and the fixed part.

[0080] In some examples of the method, determining the plurality of updated driving parameters includes performing the following operations:

[0081] (a) Provides three drive parameters [V] θ V Ф V w The diagonalized group of the three driving parameters [V] θ V Ф V w The diagonalized group of ] is formed as the at least three driving parameters [V1, V2, ... V N A predetermined linear combination of the plurality of diagonalized driving parameters [V], characterized in that... w V θ V Ф A change in each of the geometric parameters w, θ, and Ф affects a corresponding change in one of them, while substantially not affecting the changes in the other geometric parameters; and

[0082] (b) Process the plurality of optical responses to determine a current state of the tunable filter based on the geometric parameters;

[0083] (c) Determine a desired incremental correction of the plurality of diagonalization driving parameters based on a difference between the current state and the desired state of the tunable filter, thereby generating a set of corrected diagonalization driving parameters;

[0084] (d) Determine the at least three driving parameters [V1, V2, ... V] based on the set of corrected diagonalized driving parameters. N The correction of ].

[0085] The currently disclosed subject further considers a system comprising a processing circuit operatively connected to an tunable filter and configured to perform a computerized method according to any of the above examples of the methods according to the foregoing aspects.

[0086] The currently disclosed subject further envisions a computer-readable, non-transitory program storage device, specifically embodying a computer-executable computer-readable instruction to perform a computerized method of any of the above examples of the method according to the foregoing aspects.

[0087] As used herein, the term "processing circuit" should be interpreted broadly to include any type of electronic device with data processing capabilities, including at least one computer processing device configured and operable to execute a plurality of computer instructions stored, for example, in a computer memory operatively connected thereto. Examples of such devices include: digital signal processors (DSPs), microcontrollers, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), etc. Attached Figure Description

[0088] To better understand the subject matter disclosed herein, and to illustrate how it can be implemented in practice, implementation schemes will now be described with reference to the accompanying drawings, using only non-limiting examples, wherein:

[0089] Figure 1A-1E These are schematic diagrams of different views of an apparatus based on some examples of currently publicly available topics; Figure 1A This is a perspective view of the top of the device; Figure 1B It is a top view; Figure 1C It is a side view; Figure 1D This is a perspective view of the bottom of the device; Figure 1E This is a bottom view of the device;

[0090] Figure 2 This is a schematic cross-sectional view of a component of an adjustable filter calibrated by the apparatus of this disclosure, based on some examples of currently disclosed subjects.

[0091] Figure 3 This is an exploded schematic diagram of the components of a device with an adjustable filter, based on some examples of currently disclosed topics;

[0092] Figures 3A-3B This is a block diagram schematically illustrating some examples of a calibration system based on currently disclosed topics;

[0093] Figure 3C-3D These are schematic diagrams of calibration systems based on some examples of currently publicly available topics;

[0094] Figure 3EThis is a schematic diagram of a calibration system based on another example of the currently disclosed subject matter;

[0095] Figure 4 This is a schematic perspective view of a portion of a Fabry-Perot filter, including movable parts and their associated electrodes. According to some examples of the currently disclosed subject matter, such a Fabry-Perot filter can be received by an adjustable filter housing of the device of this disclosure for calibration;

[0096] Figures 5A-5D This is an example based on some examples of the currently disclosed subject matter, based on the state of the tunable filter, i.e., the optical gap between optical components, a curve of the expected reflection intensity distribution from the tunable filter;

[0097] Figures 6A-6B These are some examples of currently disclosed subjects, and are non-limiting examples of different calibration stages presented in a user interface of software for calibrating an adjustable filter using the apparatus of this disclosure;

[0098] Figures 7A-7B This is a flowchart illustrating a non-limiting example of a method for calibrating an tunable filter, based on some examples of currently disclosed topics; and

[0099] Figures 8A-8B It is an image of a Fabry-Perot tunable filter, taken during illumination of the filter from a top-down view, in both calibrated and uncalibrated states. Detailed Implementation

[0100] The following figures are provided to illustrate various embodiments and implementations of the invention described in this disclosure.

[0101] First refer to Figure 1A-1E , Figure 1A-1E Different views of an apparatus are shown, illustrating some examples of currently disclosed topics. See below for reference. Figures 3A-3E An additional example of a calibration apparatus is described. The apparatus 100 includes an optical component clamp 102 mounted on a support structure 104 extending upwards 106 from a base 107 of the apparatus 100. It should be noted that related terms throughout the specification, such as upwards and downwards, are used for ease of description and do not restrict any direction or orientation. Figure 1CAs shown, the optical component clamp is cylindrical in shape and has a longitudinal hole 108 extending along the axis Y of the component, and is configured to receive an optical component (not shown), which includes optical elements, such as a light source and / or a photodetector. The optical component may be formed of an optical fiber configured to emit light (e.g., light in the visible and / or infrared spectra) and to detect light of similar spectra (i.e., visible and / or infrared spectra). It should be noted that the spectrum of illumination from the light source and the spectrum detected by the detector may be different.

[0102] An adjustable filter housing 110 is formed on a downward surface 111 of the base 107 of the device 100, such as Figure 1D-1E As shown in the diagram. The adjustable filter housing 110 includes a housing, such as a recess 112 in the base 107, in which the adjustable filter is mounted. Therefore, the recess 112 is configured to receive the adjustable filter, and attachment elements 114 (e.g., locating pins for positioning the adjustable filter and bolts for securing it) are configured to attach and hold the adjustable filter or a frame holding the adjustable filter to the device 100 during calibration. In some examples, the housing is configured to receive an adjustable filter integrated into a device such as a camera (“on-device calibration”).

[0103] A portion of the recess is formed by a plurality of fixed pinholes 116 to allow light to be transmitted from the other side of the base 107 (i.e., from the light source), thereby interacting with different parts of the tunable filter. The transmission of light through the different fixed pinholes results in the interaction of light with different parts of the optical elements of the tunable filter, such as transmission and / or reflection. Figure 2 This is a schematic cross-section of element / component 215 of the tunable filter, showing an example of an illuminated portion through which light is transmitted via different fixed pinholes 116. In this example, the central fixed pinhole transmits light to the center 217 of the active optical component 215, and each of the peripheral fixed pinholes allows light to be transmitted toward different areas of the optical component (i), (ii), (iii), and (iv).

[0104] A movable surface 118, formed by movable pinholes 120, is arranged between fixed pinholes 116 and the optical component fixture 102. A drive unit 122 is configured to move the movable surface in a rotational motion, switching between different filtering states of the movable surface (also referred to herein as "light selection states"), wherein, in each filtering state, one or more movable pinholes 120 are aligned with one or more fixed pinholes 116 to allow light to travel from one side of the base 107 to the other, toward a selected portion of the optical element of the tunable filter. For example, when an optical component is received and held in the optical component fixture 102, light emitted from it is transmitted through a pair of aligned movable and fixed pinholes, interacts with a specific portion of the optical element of the tunable filter, and is reflected back to the optical component. The detection of the reflection of the illumination is analyzed to determine the state of the tunable filter, i.e., the gap between the fixed and movable optical elements.

[0105] Therefore, the longitudinal aperture 108 of the optical component holder 102 is configured such that the optical component received and held therein is positioned to provide illumination to the tunable filter, when a portion of it is exposed due to the alignment of the paired pinholes. In this example, the longitudinal axis Y is aligned with the optical axis of the optical component, i.e., the emitted and reflected light diffuses around this axis.

[0106] It is understood that the movable surface 118 is formed by a plurality of pinhole groups 124A, 124B, and 124C. Each group is designed to filter different wavelengths and expose a portion of the tunable filter to filter illumination of the light source of the optical component at one time. For example, one group includes three movable pinholes, one of which aligns with different fixed pinholes as the rotational state / position of the movable surface changes, so that in each rotational state, only a single portion of the tunable filter is illuminated as a single point of light. It should be noted that in some embodiments, a single movable pinhole may align with two or more different fixed pinholes in different rotational states. Furthermore, each group of movable pinholes may include a specific bandpass filter for filtering light of a desired bandwidth or wavelength. For example, the first group may include a red filter, the second a green filter, the third a blue filter, and the fourth an infrared filter.

[0107] In some examples, the movable pinhole 120 is designed to be larger than the fixed pinhole 116, for example, having a larger diameter, to allow for relatively wide placement and assembly tolerances. Therefore, the fixed and movable pinholes are designed to form a filtering device for filtering the illumination from the optical component light source, such that only the desired portion of the tunable filter is illuminated at a time. Figure 3This is a schematic exploded view of the elements of a device having a tunable filter, illustrating an example according to this disclosure. According to this example, the illumination light from a light source is filtered by a bandpass filter. For example, the filter may only allow red, green, blue, or specific infrared wavelengths. The filtered light is diffused to a pinhole mask (light selection unit) configured to guide the filtered light to a desired portion of the tunable filter, such as a miniature Fabry-Perot filter. As described above, in some examples, filtering is accomplished by a filter formed as part of a light selection unit. In some examples, the light transmitted through the tunable filter is directed by a lens to an image sensor (e.g., RGB, RGB-IR, monochrome, etc.), the image sensor being configured to sense the spectral response received from the tunable filter, i.e., the intensity of the filtered light transmitted through the tunable filter.

[0108] The calibrated tunable filter, such as a Fabry-Perot filter, in some examples has a fixed optical component and a movable component, such that the gap between the fixed and movable components defines the spectral transmission of the illumination, i.e., the transmitted wavelength and its intensity. Typically, the two components are not perfectly parallel, and due to manufacturing tolerances, the plurality of specific driving parameters that bring the gap to a certain value differ from those of a single tunable filter. Therefore, the apparatus of this disclosure is for identifying the plurality of driving parameters, such as the electrostatic force applied by electrodes, that bring the tunable filter to any desired gap, and that the two components are parallel to each other according to a certain threshold, i.e., allowing a degree of non-parallelism tolerance. The illumination of a single portion of the tunable filter allows the gap between the two components to be determined based on the transmitted spectrum, such as the reflected or transmitted intensity distribution of red, green, blue, or infrared light.

[0109] Figure 3A This is a block diagram of a non-limiting example of a calibration system 300a. The calibration system 300a includes a calibration device 320a, as referenced above. Figure 1A-1E The system also includes a light source 321 (e.g., a collimating light source) and a detector 323 (e.g., an image sensor, a spectrometer, etc.), received by the optical component fixture 325 and a processing circuit 330 of the calibration device 300a. In some examples, the system also includes an adjustable filter housing for holding the adjustable filter or a camera bracket for holding the camera (324).

[0110] The processing circuit 330 is configured to control the execution of various operations, including one or more of the following:

[0111] (a) Apply driving parameters, such as applying different voltages to each electrode, to control the state of the tunable filter (e.g., by controlling a movable component). The state of the tunable filter defines at least one of the gap between the tunable filter and a fixed component, an angular state relative to the fixed component (e.g., roll or pitch), and defines the optical response of the tunable filter;

[0112] (b) Controlling the sampling process of each part of the tunable filter during the iterative process of the calibration process, i.e. switching between states of the light selection unit and driving the moving surface to switch from one state to another.

[0113] (c) Analyze the optical response of one or more components, determine the state of the tunable filter based on this, and determine whether the state of the tunable filter satisfies a predetermined condition; and

[0114] (d) Adjust the illumination spectrum of the light source.

[0115] These operations can determine whether the transmitted central wavelength (CWL) and full-width half-maximum (FWHM) are within acceptable tolerances. Alternatively, these operations can determine whether the tunable filter is within acceptable tolerances for the gaps between different parts of the tunable filter and / or within acceptable angular tolerances.

[0116] Once the tunable filter reaches a state within acceptable tolerances, the plurality of driving parameters AP that bring the tunable filter to the desired state are transmitted to computer data repository 329, for example, operatively connected to the tunable filter.

[0117] Figure 3BThis is another block diagram of a non-limiting example of a calibration system according to one aspect of the present disclosure. In the diagram, calibration system 300b includes a calibration device 320b. The calibration device has guiding optics 327 for guiding light from an external light source 321 to a photodetector 323 (e.g., an image sensor, a spectrometer). The guiding optics may be configured as a light selection unit or as a light collimator. The processing circuitry 330 is configured to control the execution of one or more of the following: (a) applying driving parameters, such as applying different voltages in each electrode, to control the state of a movable component of the tunable filter. The state of the tunable filter defines at least one of the gap between the fixed component of the tunable filter and the angular state relative to the fixed component (e.g., roll or pitch), and defines the optical response of the tunable filter; (b) during the iteration of the calibration process, controlling the sampling process of each part of the tunable filter, i.e., switching from one state to another between states of the driving moving surface; (c) analyzing the optical response of one or more parts, determining the state of the tunable filter based on it, and determining whether the state of the tunable filter satisfies a predetermined condition; and (d) adjusting the illumination spectrum of the light source. In other words, determining whether the tunable filter is within an acceptable tolerance range for the gap between different parts of the tunable filter and / or an acceptable angular tolerance range. Once the tunable filter reaches a state within the acceptable tolerance range, the plurality of driving parameters AP that bring the tunable filter to the desired state are transmitted to the computer data repository 329 associated with the tunable filter.

[0118] Figure 3C-3E Different implementations of a tunable filter calibration system based on examples of the currently disclosed subject matter are schematically illustrated. According to one method, a tunable filter (e.g., a MEMS-based Fabry-Perot filter) is assembled in a dedicated device (e.g., such as...) Figure 3C As illustrated in the diagram, after being fixed to the lens barrel, it is calibrated (here also referred to as "on-device" calibration). According to the second method, as... Figure 3D As shown, an adjustable filter is calibrated as a separate device (hereinafter also referred to as "non-device calibration") before it is installed or integrated into other devices (such as cameras).

[0119] Figure 3C This is a schematic diagram of a calibration system 300C on a device based on some examples of currently disclosed topics. Figure 3CA calibrator 320c connected to camera assembly 310 is schematically shown. Camera assembly 310 can be an actual integrated camera device or a camera model integrated as part of a calibration system, including specific camera elements capable of calibrating the tunable filter as if integrated into an actual camera. According to the latter, a tunable filter is calibrated using camera assembly 310 and can then be installed in an actual camera after calibration. It should be noted that the method on the device is not limited to multiple tunable filters integrated into a camera, but can also be applied to other devices integrating a tunable filter.

[0120] The camera assembly 310 includes a series of elements positioned along the optical axis, extending from the object side to the image size, including an adjustable filter 311, a lens barrel 313 including one or more lens elements, and an image sensor 323.

[0121] The calibrator 320c includes a light selection unit 331 and a light source 321, or is otherwise operated and connected to a light source. The light source 321 is configured to direct light to the camera assembly 310, and in some examples, is characterized by a given / known illumination distribution (a light source with a known illumination spectrum). According to some examples, the light source 321 is a collimated light source. A collimated light source is advantageous because it helps to counteract the effect of the transmission angle of light incidence on the tunable filter, which could affect sensor readings.

[0122] In some examples, the calibration system 300C also includes a camera bracket configured to hold the camera 310 and / or an optical component clamp unit (not shown) configured to hold the light source 321, for example, with its optical axis aligned with the camera's optical axis when the camera is fixed by the camera bracket. In this configuration, the center of the light source beam faces the camera's optical axis, and the tunable filter and lens barrel are aligned along the same optical axis. In some examples, the light selection unit 331 is also positioned along the same optical axis such that light illuminated by the light source passes through the light selection unit, and a spot of light illuminates a portion of the surface area of ​​the tunable filter.

[0123] According to the reference Figure 3C In the example shown, the light selection unit 331 does not include a surface with pinholes, but instead includes a light shield configured to block light from passing through the entire tunable filter area. Figure 3CAs shown, the light selection unit 331 can be configured as a disk mounted on the optical aperture of the tunable filter 311, wherein a region of its surface (here, the "light-blocking region") has an opaque color or other coating, particularly for light irradiated by the light source 321. According to one example, half of the surface area of ​​the light selection unit is configured to block illumination light, while the other half is transparent to light irradiated by the light source. According to another example, the light selection unit is divided into quarters, where two non-adjacent quarters are configured as light-blocking regions, and the other two quarters are transparent to light emitted by the light source.

[0124] According to some examples, the light selection unit 331 is further configured as a bandpass filter that allows light to pass through one or more specific wavelengths (e.g., the filter may only allow red, green, blue, or specific infrared wavelengths). According to another example, light illuminated by a light source is filtered by a designated bandpass filter separate from the light selection unit. The light illuminated by the light source diffuses toward the light selection unit, which blocks a portion (e.g., half) of the beam and allows the other half to pass through and enter the lens barrel. The light passing through the lens barrel is focused into a spot by the lens, which illuminates a portion of the image sensor. The image sensor (e.g., RGB, RGB-IR image, monochrome, etc.) is configured to sense the spectral response received from the tunable filter, i.e., the intensity of the light transmitted through the tunable filter.

[0125] The light selection unit 331 is configured to rotate relative to the tunable filter (e.g., in planar motion around its center), wherein each rotation results in a respective state of the light selection unit (referred to herein as a "light selection state"), and in each state, the light selection unit 331 blocks light from passing through different regions of the tunable filter. For example, with half the surface area of ​​the light selection unit blocked from light, each state can be defined by rotating the light selection unit by 45 degrees or 180 degrees (resulting in four light selection states or two light selection states, respectively).

[0126] According to examples of the currently disclosed subject matter, when the tunable filter 311 is illuminated by a light source, the light selection unit is rotated to present different light selection states, wherein in each state the optical response of the image sensor is detected, i.e., transmission or reflection from the illuminated area (e.g., half).

[0127] The calibrator 320c may further include or otherwise operate connected to a processing circuit 330, which is configured to perform the above-described reference... Figure 3A and 3BThe operation described above. For example, the processing circuitry can be configured to compare the received optical responses under different light selection states. If the variation between the optical responses exceeds an acceptable tolerance, multiple updated drive parameters are applied to adapt the optical gap and tilt angle, and the state of the tunable filter is placed under desired conditions (e.g., the desired state). Specifically, by comparing, variation can be reduced, a more uniform optical response can be obtained across the entire region of the tunable filter, and a narrow FWHM and accurate CWL can be obtained in the transmission spectrum of the tunable filter. The comparison and updating of the multiple drive parameters can be repeated until the variation between the optical responses under different light selection states is within an acceptable range. Once the tunable filter reaches a state within acceptable tolerance, the multiple drive parameters AP that bring the tunable filter to the desired state are transmitted to a computer data repository 329, for example, operationally connected to the tunable filter. (See below for reference.) Figure 7A and 7B A more detailed description of an example of the calibration process performed by the processing circuit 330.

[0128] Figure 3D This is a schematic diagram of a non-device calibration system 300D, based on some examples of currently published topics. Figure 3D A classifier 320d is shown, which includes features similar to those in the reference above. Figure 3C The light source is light source 321. The classifier is operatively connected to one of the processing circuits 330 and a computer data repository, as referenced above. Figure 3C The classifier is also operatively connected to a filter assembly 340 including a detector 323 (e.g., an image sensor) and is configured to receive and hold an adjustable filter 311 (e.g., a MEMS Fabry-Perot filter) during calibration.

[0129] The light source is configured to illuminate the tunable filter device, and the image sensor (e.g., RGB, RGB-IR, monochrome, etc.) is configured to sense the spectral response received from the tunable filter, i.e., the intensity of the filtered light transmitted through the tunable filter.

[0130] According to one example of the non-device method, no light selection unit is used. Instead, the surface area of ​​the image sensor 323 is divided into sub-regions, and the spectral response received by each sub-region is integrated to obtain a corresponding value. As previously described, the system includes, or is otherwise connected to, a processing circuit 330 configured to compare between a set of values, each integrated across a respective sub-region of the sensor, and if the variation between the values ​​is determined to be greater than a certain threshold, apply multiple updated driving parameters to accommodate the optical gap and bring the state of the tunable filter to the desired condition, as described above regarding... Figure 3CThe partitioning of the image sensor surface region can be repeatedly applied, with the partitioning applied to different dimensions of the image sensor in each iteration. In the case of partitioning by dividing the surface region in half, in one example, two partitions can be obtained, one spanning a first dimension and the other spanning another dimension. In some examples, other partitions can also be applied, such as dividing the sensor along its diagonal. The comparison and updating of the plurality of driving parameters can be performed iteratively until the variation between the optical responses under different light selection states is within acceptable limits. Once the tunable filter reaches a state within acceptable tolerances, the plurality of driving parameters AP that bring the tunable filter to the desired state are transferred to a computer data repository 329, for example, operatively connected to the tunable filter.

[0131] Figure 3E Another example of a calibration system 300E is shown. The calibration system 300E includes a tunable filter sensor assembly (e.g., a MEMS Fabry-Perot) configured to receive and hold a tunable filter 311. The assembly also includes, or otherwise operates, connected to, similar to the reference above. Figure 3A The light source is light source 321. According to some examples, the tunable filter is integrated into the device, such as a camera, during calibration.

[0132] The light source is configured to illuminate the component, and in some of the examples described above, the light illuminated by the light source is filtered by a bandpass filter, allowing light to pass through at one or more specific wavelengths. The filter diffuses light to an image sensor, which is configured to sense the spectral response received from the tunable filter, i.e., the intensity of the filtered light transmitted through the tunable filter.

[0133] The system 300E according to the example also includes a camera 335 facing the tunable filter, the camera 335 being configured to capture an image of the surface of the tunable filter while the tunable filter is illuminated by a light source. The captured image is processed by a processing circuit configured to identify interference fringes caused by interference from the tunable filter. When the two mirrors of the tunable filter are parallel, the resulting interference fringes are observed as symmetrical circles around the center of the tunable filter. On the other hand, if the mirrors are not parallel, the observed interference fringes are off-center. Figure 8A and 8B It is a photograph of a Fabry-Perot tunable filter, taken during a top-down view of the filter, i.e., with the image sensor oriented at an angle substantially perpendicular to the filter surface.

[0134] Figure 8A An image of an uncalibrated Fabry-Perot tunable filter is shown, in which interference fringe 10 is clearly visible. Figure 8BAn image of a calibrated Fabry-Perot tunable filter is shown, in which interference fringes are aligned with the edge of the tunable filter's optical aperture, and are therefore not visible in the image, or are perceived as a complete loop around the aperture concentric with its edge.

[0135] The processing circuitry 330 is configured to process images captured by the camera, and if interference fringes are detected, apply multiple updated driving parameters to adapt to the optical gap and adjust the state of the tunable filter to the desired state. After updating the optical gap, the camera captures and processes one or more additional images to determine whether the multiple newly applied driving parameters provide the desired result. These operations can be repeated until the interference fringes are symmetrically aligned around the center of the tunable sensor. Notably, in some examples, machine learning algorithms can be applied during image processing to identify images representing the desired optical state. Once the driving parameters used to obtain the desired optical state are determined, they can be stored in a computer storage device for future reference.

[0136] Figure 4 This is a schematic diagram of an example perspective view of a portion of a Fabry-Perot tunable filter, including a movable component and its associated actuators (e.g., electrodes), suitable for receiving by a tunable filter housing of the present disclosure for calibration. The number of actuators can be three or more. The movable component 450 includes an optical component 452 formed therein in its intermediate portion. The optical component 452 is in the form of a mirror with an optical coating, and the gap between the optical component 452 of the movable component 450 and another optical component (e.g., stationary; not shown) defines the transmission / reflection spectrum. The movable component 450 is configured to move a flexible suspension beam 453 due to suspension thereon. Movement is fabricated in the movable component 450 (e.g., silicon-doped regions) and its respective electrodes 454 according to electrostatic forces applied between the driving regions. The presence of four electrodes allows the movable component to move along the vertical axis Y by a vertical amount w and about the axes X and Z, i.e., to rotate by angles 0 and f, respectively. It should be noted that these movements can only be achieved by three electrodes. The linear combination of electrostatic forces applied by each pair of electrodes, i.e., the voltage difference between the electrodes on the movable component and their respective electrodes, can result in any desired motion, whether it is a combination of vertical and rotational motion, or isolated vertical or rotational motion.

[0137] Figures 5A-5D An example illustrates the relationship between the expected quantum efficiency (QE) distribution in an image sensor and the state of the tunable filter, namely the optical gap between optical elements. Figures 5A-5DThe transfer function of the tunable filter at specific wavelengths is shown for red 610 nm (5A), green 510 nm (5B), blue 485 nm (5C), and IR 800 nm (5D), with values ​​given in the form of QE detected by a given image sensor. It should be noted that these values ​​can be adjusted depending on the selected image sensor. According to an example of this disclosure, when using a transfer-based calibration technique, the light transmitted through the tunable filter is detected by an image sensor, and it is expected that a respective transfer function / intensity distribution of the transmission will be displayed for each wavelength. Based on the expected distribution, the measured intensity may indicate the desired state of the tunable filter. For example, by using red light at a wavelength of 610 nm (nanometers), when the optical gap is between state 5 and 10 (e.g., ... Figure 5A As shown, when the intensity peak is expected, each state represents a specific optical gap. The multiple estimated driving parameters used to obtain the gap are applied to each selective unit state, and an iterative process is initiated to determine the precise driving parameters that bring all parts of the tunable filter to the desired gap (within acceptable tolerances), i.e., to the peak of the transmission intensity. Once the precise driving parameters are determined, they are stored in a (computer data repository device) for future use in driving the desired gap. The technique essentially uses a known transfer function for a specific wavelength, and the system's processing circuitry operates the tunable filter to achieve a state where the transmission at the corresponding wavelength matches a known transmission distribution, such as the maximum / minimum point of transmission or any identifiable distribution within the transfer function. It should be noted that... Figures 5A-5D Any identifiable distribution in the diagram shown can be used to identify the optical gap between two optical elements using the apparatus of this disclosure.

[0138] Figures 6A-6B This is a non-limiting example of a software user interface for calibrating an adjustable filter using the apparatus disclosed herein. Figure 6AThe transition phase of the calibration process is shown. In this example, the drive parameters required for a 540 nm optical gap are the required voltages applied by four different electrodes of the device to achieve a relatively equal 540 nm gap between the movable and fixed optical components of the tunable filter. Multiple initial drive parameters are used to bring five measurement sections (one at the center of the filter, four at the periphery) to the desired optical gap in each section, which is essentially the desired optical gap along the vertical axis and tilted relative to the horizontal axis perpendicular to the vertical axis defining the optical gap. Iterations to achieve the desired optical gap stop when an acceptable tolerance is reached, for example, a difference of up to 1 nm from the desired gap (540 ± 1 nm) and a tilt angle of up to 3 microradians. It should be noted that the process can be configured such that a specific section (e.g., the center section) needs to be at a specific desired optical gap, and the tolerance applies only to the other peripheral sections. In other words, these iterations will bring the tunable filter to acceptable tolerances for angles θ and Ф, i.e., tilts relative to X and Z, and the desired tolerance relative to the gap along the Y axis, as shown. Figure 4 As shown. Figure 6A The top right corner of the image shows the last sample of the five different parts of the tunable filter, the bottom left corner shows the applied voltage of each electrode in each iteration, and the bottom right corner shows the error in each parameter—center gap, θ, and Ф. Figure 6B The final stage of the calibration process is shown, in which the final iteration brings the device to a state below acceptable tolerance. The voltage applied to each electrode to achieve the desired state is stored in memory for use when the device needs to be driven to this state.

[0139] Figures 7A-7B This is a flowchart of a non-limiting example of a method for calibrating / adjusting a tunable filter. For example, according to... Figure 7A and 7B The method can be used as described above. Figures 3A-3D Various calibration systems can be used for any of these applications. As described above, the calibration system disclosed according to the above figure includes or otherwise operates connected to a processing circuit, which is configured to perform and control the calibration process. According to some examples, the processing circuit is configured to perform reference... Figure 7A and 7BVarious operations are described. As described above, the filter includes movable parts and additional parts (movable or stationary), and multiple actuators (e.g., three or more actuators, which can be implemented as electrostatic actuators) adapted to control the state of the tunable filter by driving the relative position of the movable parts with respect to another / stationary part. Typically, in some examples, the driving parameters of the tunable filter include at least three driving parameters [V1, V2, ... V...]. N (e.g., voltage), respectively associated with or applied to at least three drivers of the filter. In response to their actuation, the state of the tunable filter can be characterized by at least the following geometric parameters of the gap between the movable parts and other / stationary parts: (i) the size ω of the gap is the nominal distance between the filter parts (e.g., the average distance between them or the distance between their centers); (ii) the relative lateral orientation angle θ; and (iii) the relative lateral orientation angle Ф orthogonal to the orientation angle θ. Typically, the method includes: illuminating the filter at multiple different spatial portions of the filter (e.g., at least three positions / angles, capable of evaluating the respective distances between the movable parts and other parts at the positions based on the filter responses from the positions); accordingly detecting multiple at least three optical responses obtained from the different spatial portions of the tunable filter; determining multiple updated driving parameters for operating the multiple drivers to adjust the state of the tunable filter to a desired state (wherein the determination is based on features indicating the state of the tunable filter based on the detected optical responses (e.g., geometric parameters indicating the gaps).

[0140] It should be noted that the tunable filter does not necessarily include four drivers, but may include at least three drivers through which angles θ and Ф, as well as gap w, can be independently controlled. Therefore, the drivers may be coupled with three or more respective drive voltages V1 to V3, and, as will be readily understood by those skilled in the art, the following equation can be similarly implemented for the three drive voltages. It should also be understood that the tunable filter can be implemented using more than four drivers; therefore, the state of the tunable filter will be set using / calibrating more than four corresponding drive voltages.

[0141] Figure 7A A method is described, which optionally includes applying a plurality of driving parameters 701 to a tunable filter to set it to a desired state. Since the exact driving parameters for achieving the desired state of the tunable filter are unknown prior to the calibration process, estimated parameters for achieving the desired state of the tunable filter are applied. Then, portions of the tunable filter are individually illuminated 703 by a light source (e.g., a central portion and several peripheral portions) (as described above regarding...). Figure 2As shown in the diagram, the optical responses of the illumination interacting with the portions (i.e., transmission or reflection) are detected at 705, thereby generating a set of optical responses. Each optical response in the set is obtained from the illumination of the respective portion and represents a geometric parameter characterizing the gap between the components of the tunable filter (e.g., the tilt of a movable component relative to a fixed component). The optical responses in the set at 707 are analyzed to determine whether the tunable filter meets predetermined conditions, such as an acceptable tolerance for variations in optical responses between different portions. As described above, in some examples, when using a light selection unit, the processing unit can be configured during the illumination phase to drive the light selection unit to switch between light selection states, wherein in each state, different portions of the tunable filter are illuminated by the light source.

[0142] Note that in some examples, multiple portions can be illuminated simultaneously. This can be accomplished, for example, by illuminating different portions with different wavelengths and normalizing the optical response of the different wavelengths. For this purpose, the light source can be illuminated with white light, and a light selection unit configured to illuminate multiple portions of the tunable filter at once (e.g., the light selection unit can be used to illuminate the tunable filter simultaneously with multiple pinholes) can be used. The light selection unit is configured to filter the white light using different filters applied to different portions of the tunable filter, thereby providing different beams of different wavelengths, each beam being guided by the light selection unit to a different portion of the tunable filter.

[0143] Figure 7B Showing about Figure 7A Additional features of the method. The analysis according to block 707 includes comparing the optical responses in the group obtained through different illumination portions of the tunable filter and determining whether the tunable filter meets a predetermined condition. If the difference between the optical responses in the group is greater than an acceptable threshold (tolerance) 709, the plurality of driving parameters are updated, and the process returns to block 701, producing a new set of optical responses identical to those previously obtained from illumination of each of the group's respective portions. The loop is repeated until the plurality of driving parameters provide an optical response that meets the predetermined condition, i.e., an optical response within acceptable tolerances. Once the predetermined condition is met, the driving parameters (e.g., the applied voltage in each electrode of the tunable filter) are stored in a computer data repository 710.

[0144] It is important to note that the desired driving parameters refer to the desired conditions (e.g., desired states) providing the tunable filter, i.e., a uniform optical response across the entire tunable filter. However, the optical responses received by illuminating different portions of the tunable filter depend on parameters including the expected geometry of the tunable filter in a calibrated state and the relative positions (e.g., relative to the center) of the individual illumination portions on the tunable filter. For the expected geometry of a tunable filter in a calibrated state, the ratio of the desired optical responses measured in different illumination portions (different light selection states) can be derived from the geometry. For an axisymmetric geometry (e.g., an arc shape), the ratio between the optical responses of illumination portions equidistant from the center is expected to be 1 (or close to 1, within acceptable tolerances), while the ratio between the optical responses of illumination portions at different distances from the center is proportional to the corresponding distance from the center. Therefore, it should be understood that the predefined conditions used to compare the optical responses obtained by individual isolated illuminations of specific portions of the tunable filter described herein take into account parameters including the expected geometry of the tunable filter in a calibrated state and the relative positions of the individual illumination portions on the tunable filter.

[0145] Figure 7B The method described also includes optional operation of filtering the desired bandwidth of illumination 704, such that narrowband light interacts with the tunable filter and provides an optical response. For example, the filtering may result in only red, green, or blue light reaching the tunable filter.

[0146] Comparisons between different optical responses can be made in several ways. As an example, actual optical responses are compared. This can be achieved by comparing illumination distributions (e.g., spectrometer readings) under different illumination conditions. According to other examples, some derivatives of the optical response can be compared. One example of a derivative of the optical response is the integral or average intensity value received under a specific light selection state. Another example is the physical gap that can be derived from the optical response. For example, a lookup table (e.g., stored on a storage device accessible to the processing circuitry) can be used to correlate the optical response / illumination distribution with their respective physical gaps. Alternatively, other functions of the optical response can be applied and used during the comparison.

[0147] Another example of the technique of the present invention for calibrating / adjusting a tunable filter includes a desired state Xset and the actual state of the tunable filter, wherein each state is derived from a function applied to a group (or subgroup) of optical responses, each response being obtained from the corresponding illumination of a portion of the tunable filter.

[0148] For example, as mentioned above, the state of a filter can be defined as a vector (denoted by x in Equation 1 below) containing a center gap ω and two tilt angles θ and Ф. Typically, in the desired state of the filter, the center gap ω is set to a value derived from the desired CWL, and the tilt angles are usually set to 0 (therefore, the filtering characteristics produced by different spatial portions of the filter will be similar).

[0149] Equation 1:

[0150]

[0151] Here, F2 is a vector of the plurality of driving parameters, which can take, for example, the following form:

[0152]

[0153] V1-V4 here illustrate the drive voltages under measurement conditions. Note that in some implementations, fewer than three or more than four drive voltages can be used to adjust the filter, and those skilled in the art will readily understand how to adjust the upper and lower equations to a specific number of drivers.

[0154] In Equation 1, the function (matrix function) F1 represents a model of a general filter of the type of tunable filter to be adjusted / calibrated. Model F1 represents the estimated state X of the filter of that type in response to the driving of the corresponding set of driving parameters, exemplified here as V1-V4. In practice, as will be readily understood, similar types of actual filters often deviate from the expected estimated state X provided by this model (e.g., this could be due to manufacturing variations and tolerances causing actual differences in the type of filter).

[0155] A. Using the model to set an initial pre-calibration state for the filter.

[0156] Nevertheless, this model provides a good estimate of the initial state for setting up filter calibration. Therefore, some implementations of filter calibration / adjustment according to the present invention include:

[0157] a) Provide this model F1 filter type (w, θ, Ф) (e.g., the model may be stored in system memory or remotely accessible); and before calibration, use the model carrying one of the following information to set the initial drive state of the filter with an initial drive parameter set;

[0158] b) Use the model to determine / estimate the initial set of driving parameters (here, V1-V4), which is based on the desired state Xset for which the filter should be adjusted (e.g., this might be achieved by realizing F1 in the desired state Xset to determine a vector of multiple driving parameters F2; ​​and

[0159] c) Use the estimated parameters to set the initial pre-calibration operation of the tunable filter so that the calibration process becomes shorter and / or more efficient.

[0160] For example, model F1 can be a matrix function of the geometric parameters (w, θ, Ф) of the filter, in the following form:

[0161]

[0162] It should be noted that in some embodiments, the compliance matrices F1 and F2 are derived from the analytical electrostatic model of the filter. Furthermore, it should be noted that in this example, the conformity function of the tunable filter is independent of the plurality of driving parameters.

[0163] B. Use the model to determine the incremental correction during calibration iterations:

[0164] Alternatively, or additionally, besides whether a model is used or the initial pre-calibration state of the filter is set, according to embodiments of the invention, model F1 can be used to determine the required incremental corrections, such as V1-V4, of the driving parameters in order to achieve proper calibration / adjustment of the filter more efficiently (e.g., using fewer / reduced calibration iterations). In this regard, considering the definition G2 = dF2 / dV, it comes from Equation 1:

[0165] Equation 2:

[0166]

[0167] Equation 2 is a derivative model derived from the model represented by Equation 1, which can evaluate the change in activation parameter V required to achieve the expected change in the filter state (specified vector X).

[0168] The position / state error e of the filter can be defined as the difference between the filter states measured by the optical response during calibration (e.g., during a calibration iteration), and the desired specified vector X can be defined as: c = dx = Xset - X.

[0169] The inventors of this invention have understood that, taking model F1 into account, the required correction of the plurality of drive parameters (voltage adjustment) can be obtained from Equation 3 (e.g., numerically):

[0170] Equation 3:

[0171]

[0172] For example, V' (adjusted voltage) is equal to V + K *dV.

[0173] In one example, K is a constant.

[0174] Therefore, in view of the above, in some implementations, the method of the present invention includes providing the above-described model F1 (or its derivative) and, using the model d=Xset-X, determining the plurality of updated driving parameters for the next iteration based on previous driving parameters during one or more calibration iterations by performing the following operations:

[0175] a. Using the model (e.g., Equation 3), based on the position error e = dx, determine the incremental correction dV for the preceding plurality of driving parameters V of the tunable filter; and

[0176] b. Update the multiple driving parameters V based on the previous multiple driving parameters V and the incremental correction dV: V -> V+dV.

[0177] C. Effectively determine incremental corrections during calibration iterations without acquiring the model:

[0178] However, alternatively or additionally, it should be noted that in some embodiments of the invention, the incremental correction of the plurality of driving parameters can also be efficiently determined without relying on the filter model. For example, this can be achieved in the following way:

[0179] (a) Presenting / converting the plurality of actual driving parameters [V1, V2, ... V] of the filter driver. N ] as the three driving parameter sets for diagonalization - [V θ V Ф V w ], which is formed into the plurality of actual driving parameters [V1, V2,...V N A predetermined linear combination of ] makes the diagonalized three driving parameter sets -[V θ V Ф ,...V w The feature of ] is the plurality of diagonalization driving parameters [V w V θ V Ф The change of each of the geometric parameters w, θ and Ф affects the change of one of the corresponding geometric parameters, while having virtually no effect on the changes of the other geometric parameters.

[0180] (b) The optical response from the filter is then processed to determine the current state X of the tunable filter based on the geometric parameters C = {ω, θ, Ф}; and

[0181] (c) Based on a difference between the current state and the desired state of the tunable filter, determine the desired incremental correction dV of the plurality of diagonalized driving parameters, thereby generating a corrected set of diagonalized driving parameters.

[0182] (d) Finally, the at least three driving parameters [V1, V2, ... V] are determined based on the corrected diagonalized driving parameter set. N Correction of ];

[0183] In light of the above discussion, it should be understood that the calibration of the tunable filter involves two aspects: one is determining the driving parameters that, when applied, would cause the multiple tunable filter elements to align (e.g., alignment between movable and fixed elements) to provide the most uniform optical response possible across the entire tunable filter; the other is identifying the driving parameters that maximize transmission at the desired CWL.

[0184] According to the first method, calibration can be performed using two separate sub-procedures, one designated for the first aspect and the other for the second aspect, while according to the second method, calibration can be performed using a single procedure that addresses both aspects of the calibration. An example of the second method is described above with reference to Equations 1-3.

[0185] According to the first method, the alignment process of the tunable filter can be followed by a peak detection process. According to one example, the alignment of the tunable filter is performed as described above with reference to Figure 7; however, the tunable filter is illuminated with light having a specific narrowband wavelength, such as red, green, blue, etc., to obtain the calibration parameters required to align the tunable filter in the corresponding filter state. This process can be repeated using different wavelengths, thereby providing a set of drive parameters for aligning the tunable filter in different filter states, i.e., simultaneously illuminated by a corresponding wavelength. To determine the drive parameters that provide a peak optical response at each wavelength (e.g., peak transmission or reflection), one of the following can be done:

[0186] I.

[0187] a. The central portion of the gap can be adjusted while being illuminated with light of a specific wavelength, and the optical response can be monitored until a peak optical response at the corresponding wavelength is achieved.

[0188] b. After identifying the peak CWA, the alignment process can be repeated (Figure 7) to ensure that the alignment of the tunable filter is not affected by the peak calibration.

[0189] c. In cases where alignment is determined to be impaired, alignment calibration is repeated near the peak CWA.

[0190] d. Repeat operation ac until both the CWA and the alignment converge to an acceptable value.

[0191] II.

[0192] a. Once multiple sets of driving parameters (referred to as the "basic sets" in this paper) are determined, each set for a specific filter state (gap), the additional sets of driving parameters are interpolated based on the values ​​in the basic sets. Given the driving parameters of the basic sets, the driving parameters of the filter states located between the filter states of the basic sets can be determined. The specific intervals between the additional sets can be defined according to the required resolution. For example, an average voltage interval of 1 volt can be used to interpolate the additional sets.

[0193] b. Once the driving parameters for the basic and additional groups are available, providing a high-resolution distribution of the groups across the spectrum, the tunable filter is illuminated with white light and a scanning process is performed.

[0194] i. During the scanning process, the optical gap of the tunable filter is switched between filter states defined by the collection of groups (basic and supplementary).

[0195] ii. For each filter state, determine the optical response (spectrometer reading) of the tunable filter, thereby determining a corresponding optical response for each set of drive parameters. Determine the center wavelength of each optical response, thereby determining a CWL for each set of drive parameters.

[0196] iii. The CWL value and the corresponding drive parameters are stored in a computer data repository for future reference.

[0197] III.

[0198] a. Once multiple sets of driving parameters (referred to as the "basic sets" in this paper) are determined, each set for a specific filter state (gap), the additional sets of driving parameters are interpolated based on the values ​​in the basic sets. Given the driving parameters of the basic sets, the driving parameters of the filter states located between the filter states of the basic sets can be determined. The specific intervals between the additional sets can be defined according to the required resolution. For example, an average voltage interval of 1 volt can be used to interpolate the additional sets.

[0199] b. Once the driving parameters for the basic and additional groups are available, providing a high-resolution distribution of the groups across the spectrum, the tunable filter is illuminated by a tunable light source and a scanning process is performed.

[0200] i. During the scanning process, the optical gap of the tunable filter is switched between filter states defined by the collection of groups (basic and supplementary).

[0201] ii. For each filter state, the tunable light source is continuously tuned within the sensitivity range of the tunable filter to determine the maximum optical response of the tunable filter in that filter state. The wavelength of light at the maximum optical response represents the transmission CWL in that filter state.

[0202] iii. The CWL value and the corresponding drive parameters are stored in a computer data repository for future reference.

Claims

1. A calibration device for an adjustable filter, characterized in that, include: A processing circuit is operatively connected to a detector; The calibration device is configured to cooperate with an adjustable filter placed between the light source and the detector, and to allow light emitted by the light source to illuminate multiple different spatial portions of the adjustable filter; the processing circuit is configured to: Based on different optical responses, determine whether each optical response received at the detector from a corresponding illumination of a light source in a specific spatial portion of the tunable filter meets a desired condition, wherein the different optical responses include transmission and reflection; if not, apply multiple updated driving parameters to multiple drivers of the tunable filter to bring the state of the tunable filter to the desired condition and repeat the determination.

2. The calibration device according to claim 1, characterized in that: The processing circuitry is configured to iteratively apply multiple updated driving parameters and compare different optical responses until the state of the tunable filter is determined to be under the desired conditions.

3. The calibration device according to claim 2, characterized in that: The calibration device further includes a light selection unit located between the tunable filter and the light source, the light selection unit being configured to selectively transmit light illuminated by the light source during a corresponding illumination period to a specific spatial portion of the tunable filter, thereby generating a corresponding optical response; the light selection unit is configured to switch between different light selection states, wherein a different spatial portion of the tunable filter is illuminated in each light selection state, and wherein when the light selection unit is in a corresponding light selection state, the different optical responses compared by the processing circuit are all obtained.

4. The calibration device according to claim 3, characterized in that: The processing circuit is configured to automatically switch the light selection unit between the different light selection states.

5. The calibration device according to claim 1 or 2, characterized in that: The processing circuit is also configured to store the driving parameters in a computer data storage device when the desired conditions are obtained.

6. The calibration apparatus according to claim 1 or 2, characterized in that: The calibration device also includes an adjustable filter holder for holding the adjustable filter.

7. The calibration apparatus according to claim 6, characterized in that: The adjustable filter holder includes an adjustable filter housing for receiving the adjustable filter and holding it in place.

8. The calibration apparatus according to claim 7, characterized in that: The adjustable filter housing includes a recess adapted to the adjustable filter.

9. The calibration apparatus according to claim 7 or 8, characterized in that: The adjustable filter housing includes a holding mechanism for holding the adjustable filter in place.

10. The calibration device according to claim 3, characterized in that: The calibration device includes guiding optics for guiding illumination having a given illumination spectrum toward the tunable filter via the light selection unit.

11. The calibration device according to claim 3, characterized in that: The calibration device includes an adjustable filter holder for holding the adjustable filter, wherein the adjustable filter holder includes an adjustable filter housing for receiving the adjustable filter and holding it in place; and an optical component clamp configured to hold the light source such that the light source illuminates in the direction of the adjustable filter; and wherein the light selection unit is located between the optical component clamp and the adjustable filter housing.

12. The calibration apparatus according to claim 11, characterized in that: The optical component clamp is configured to hold the light source such that one optical axis of the light source is coaxial with the optical axis of an adjustable filter.

13. The calibration apparatus according to claim 3, characterized in that: The light selection unit is configured to allow light to be transmitted to a single portion of the tunable filter at a time.

14. The calibration apparatus according to claim 3, characterized in that: The light selection unit is configured to selectively apply a filter to filter a desired illumination wavelength range that is directed to one or more portions of the tunable filter.

15. The calibration apparatus according to claim 3, characterized in that: The light selection unit includes a fixed surface having one or more fixed pinholes, wherein different portions of the tunable filter are illuminated by illumination from a light source through each of the fixed pinholes.

16. The calibration apparatus according to claim 15, characterized in that: Each of the one or more fixed pinholes is configured to be switched between a transmission mode and a blocking mode and / or a bandwidth filter mode.

17. The calibration apparatus according to claim 15 or 16, characterized in that: The one or more fixing pinholes are extended.

18. The calibration apparatus according to claim 15 or 16, characterized in that: The light selection unit includes a movable surface located on top of or below the fixed surface and including one or more movable pinholes. The movable surface is configured to move to switch between different light selection states, wherein in each state, different movable pinholes are aligned with different fixed pinholes, thereby allowing different portions of the tunable filter to be illuminated in each state and obtain the corresponding optical response.

19. The calibration apparatus according to claim 18, characterized in that: The moving surface is configured to move at an angle, wherein each light selection state is defined by a different angle state of the moving surface.

20. The calibration apparatus according to claim 19, characterized in that: Each angular state results in a single optical transmission on a single portion of the tunable filter.

21. The calibration apparatus according to claim 18, characterized in that: The size of the movable pinhole is larger than that of the fixed pinhole.

22. The calibration apparatus according to claim 3, characterized in that: The light selection unit includes a movable surface including one or more movable pinholes, wherein the movable surface is configured to move to switch between different light selection states, each state being configured to (i) expose different portions of the tunable filter to illumination and / or (ii) expose one or more portions of the tunable filter to a different illumination bandwidth.

23. The calibration apparatus according to claim 11, characterized in that: The optical component fixture includes a longitudinal aperture, which includes guiding optics for guiding light through it.

24. The calibration apparatus according to claim 3, characterized in that: The light selection unit includes a plane, wherein a first region of the plane is a light blocking region configured to block light irradiated by the light source, and a second region is transparent to light irradiated by the light source, and wherein, in each light selection state, the specific spatial portion illuminated depends on a position of the light blocking region relative to the tunable filter.

25. The calibration apparatus according to claim 24, characterized in that: The light-blocking region comprises half of the plane.

26. The calibration apparatus according to claim 3, characterized in that: The adjustable filter is encapsulated in a camera, the camera including a lens barrel holding one or more lens elements, the lens barrel being located between the adjustable filter and the detector.

27. The calibration apparatus according to claim 26, characterized in that: The device includes a camera bracket for holding the camera and aligning the camera and the light source along a common optical axis.

28. The calibration apparatus according to claim 1 or 2, characterized in that: The detector has a surface area divided into at least two parts, and the processing circuitry is configured to compare multiple optical responses, each of which is integrated on a corresponding part of the detector.

29. The calibration apparatus according to claim 28, characterized in that: The detector is an image sensor, wherein the surface area of ​​the image sensor is divided into two halves, and wherein the processing circuitry is configured to compare among the plurality of optical responses, each optical response being integrated on a corresponding half of the image sensor.

30. The calibration apparatus according to claim 1, characterized in that: The calibration apparatus further includes an optical component clamp configured to hold the light source for illuminating the tunable filter.

31. The calibration device according to claim 1, characterized in that: The light source is configured to emit white light.

32. The calibration apparatus according to claim 1 or 2, characterized in that: The detector is a spectrometer.

33. The calibration device according to claim 1, characterized in that: The light source and the detector are formed in a single optical unit.

34. The calibration apparatus according to claim 1, characterized in that: The processing circuit is configured to control the execution of one or more of the following: (a) applying multiple driving parameters to control the state of a movable component of the tunable filter, the state of the movable component defining the optical response of the tunable filter; (b) controlling a light selection unit to illuminate a selected portion of the tunable filter through the light source; (c) controlling illumination through the light selection unit; (d) analyzing the optical response of one or more portions, determining the state of the tunable filter based on this, and determining whether the state of the tunable filter satisfies the desired condition; and (e) adjusting the illumination spectrum of the light source.

35. The calibration apparatus according to claim 34, characterized in that: If the state of the tunable filter does not meet the desired condition, the processing circuit is further configured to iteratively apply multiple new driving parameters to bring the state of the tunable filter to the desired condition. And after obtaining the desired conditions, the driving parameters are stored in a memory.

36. The calibration apparatus according to claim 34, characterized in that: The light is characterized by a given illumination spectrum, and the processing circuit is configured to match the optical response of the given illumination spectrum in the tunable filter with reference data indicating a predetermined optical response distribution for identifying a state of the tunable filter.

37. The calibration apparatus according to claim 36, characterized in that: The predetermined optical response distribution includes one or more intensity distributions of the optical response over one or more wavelength ranges.

38. A method for calibrating an adjustable filter, characterized in that, include: Multiple driving parameters are applied to the tunable filter; The light from the light source is selectively directed to two or more spatially different portions of the tunable filter, wherein the tunable filter is located between a light source and a detector, and light from the light source is selectively directed to the two or more spatially different portions of the tunable filter. Detect the optical response from the two or more spatially distinct portions of the tunable filter; Analyze the optical response of illumination from different parts of the two or more spaces, and determine whether the state of the tunable filter satisfies a predetermined condition.

39. The method according to claim 38, characterized in that: If the state of the tunable filter does not meet the predetermined condition, the method further includes iteratively applying a plurality of new driving parameters to bring the state of the tunable filter to the predetermined condition. And after obtaining the predetermined conditions, the driving parameters are stored in a computer data storage device.

40. The method according to claim 39, characterized in that: Applying multiple new driving parameters involves applying multiple different driving parameters to different parts of the tunable filter.

41. The method according to claim 38 or 39, characterized in that: The method further includes filtering the illumination to illuminate the two or more different portions of the space with a desired wavelength bandwidth.

42. The method according to claim 38 or 39, characterized in that: The detection of the optical response includes detecting a spectral distribution of the illumination.

43. The method according to claim 38 or 39, characterized in that: The analysis includes identifying a predetermined distribution of the optical response to determine the state of the tunable filter.

44. The method according to claim 43, characterized in that: The predetermined distribution is characterized by a rate of change of the transmission or reflection distribution of a specific wavelength passing through or from the tunable filter.

45. The method according to claim 39, characterized in that: The method includes matching the optical response with reference data indicating a predetermined optical response distribution.

46. ​​The method according to claim 45, characterized in that: The reference data includes one or more intensity distributions of the optical response for one or more wavelength ranges.

47. A computer-readable non-transitory program storage device, characterized in that, It tangibly contains a computer-readable instruction that can be executed by the computer to perform a computerized method as claimed in claim 38 or 39.

48. A method for adjusting an adjustable filter, characterized in that, The tunable filter includes a movable component and a stationary component, and at least three drivers of a plurality of components, the at least three drivers of a plurality of components being adapted to control the state of the tunable filter by driving a relative position of the movable component relative to the stationary component; the method includes: A model is provided that indicates an estimated state of a general filter of a type of the tunable filter; Using the model, based on the desired state of the tunable filter, an initial driving parameter set for the initial operation of the tunable filter is determined, and the initial driving is applied to the tunable filter, the initial driving including driving the plurality of drivers of the general filter of the type with the corresponding driving parameter set; Illuminate multiple different spatial portions of the tunable filter; Multiple optical responses are detected, each optical response obtained in response to illumination of multiple different spatial portions of the tunable filter; the detected multiple optical responses indicate the state of the tunable filter, the state of the tunable filter being associated with multiple geometric parameters of a gap between the movable component and the stationary component; and Multiple incremental corrections are made to multiple driving parameters of the tunable filter using the model or its derivative to obtain the multiple optical responses; Multiple updated driving parameters are determined based on the multiple driving parameters and multiple defined incremental corrections; The plurality of drivers are operated using the plurality of updated driving parameters to adjust the state of the tunable filter to the desired state.

49. The method according to claim 48, characterized in that: The plurality of at least three drives includes at least four drives.

50. The method according to claim 48, characterized in that: The model includes a compliance function of the tunable filter, wherein the compliance function is independent of the plurality of driving parameters.

51. The method according to any one of claims 48 to 50, characterized in that: The plurality of drive parameters includes at least three drive parameters [V1, V2, ... V] respectively associated with the at least three drivers. N A number N; and wherein the state of the tunable filter is characterized by at least the following geometric parameters of the gap: the size w of the gap is a nominal distance between the movable part and the stationary part, and the relative lateral orientation angles θ and Ф between the movable part and the stationary part.

52. The method according to claim 51, characterized in that: Determining the plurality of updated driving parameters includes performing the following operations: (a) providing three driving parameters [V θ V Ф V w The diagonalized group of the three driving parameters [V] θ V Ф V w The diagonalized group of ] is formed as the at least three driving parameters [V1, V2, ... V N A predetermined linear combination of the plurality of diagonalized driving parameters [V], characterized in that... w V θ V Ф A change in each of the geometric parameters w, θ, and Ф affects a corresponding change in one of them, while not substantially affecting the changes in the other geometric parameters. (b) Processing the plurality of optical responses to determine a current state of the tunable filter based on the geometric parameters; (c) Determine a desired incremental correction of the plurality of diagonalized driving parameters based on a difference between the current state and the desired state of the tunable filter, thereby generating a set of corrected diagonalized driving parameters; (d) Determine the at least three driving parameters [V1, V2, ... V] based on the set of corrected diagonalized driving parameters. N The correction of ].

53. A calibration device for an adjustable filter, characterized in that, It includes a processing circuit that is operatively connected to an adjustable filter and configured to perform the method as described in any one of claims 50 to 51.

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