Spectral envelope shaping apparatus and method based on tunable mask array

Abstract

This invention discloses a spectral envelope shaping device and method based on an adjustable mask array. The device includes a light source to be shaped, a collimation unit, a first dispersion unit, a first imaging unit, an adjustable mask array disposed on the spectral modulation surface or its conjugate surface, a spectral reconstruction unit, and a coupling output unit; it may also include a spectroscopic monitoring unit and a closed-loop control unit. After collimation, dispersion, and imaging, the light to be shaped forms a wavelength spatial distribution along the dispersion direction on the spectral modulation surface. The adjustable mask array independently blocks the beam in the corresponding target wavelength range or band through multiple independent blocking units, achieving selective continuous attenuation of energy in each band by changing the blocking area or blocking ratio. The modulated beam is then reconstructed and output after inverse dispersion compensation or equivalent inverse transformation by the spectral reconstruction unit. This invention is applicable to scenarios such as broadband spectral flattening, multi-passband selective output, and attenuation-type spectral envelope shaping of spectrally calibrated light sources.

Description

Technical Field

[0001] This invention relates to the field of optical spectral modulation and light source shaping technology, specifically to a device and method based on a mechanical / physical adjustable mask array, which independently and continuously attenuates different target wavelength ranges or bands after dispersion expansion, and obtains the target output spectral envelope through reflection-folding or transmission-type spectral reconstruction. Background Technology

[0002] In applications such as hyperspectral imaging system calibration, spectrometer and detector response testing, broadband light source flattening, and multi-band simulated light source construction, it is often necessary to obtain output light with controllable spectral morphology. In practical applications, it may be necessary to obtain a nearly flat broadband spectrum within the target wavelength band, or it may be necessary to obtain a multi-passband narrowband spectrum composed of several discrete passbands.

[0003] In existing technologies, one type of approach uses fixed filters, fixed masks, or prefabricated passband elements to select or shape the spectrum. This type of approach has a relatively simple structure, but its passband position, bandwidth, and attenuation are usually difficult to adjust after fabrication, making it difficult to adapt to different input light sources, different testing tasks, and spectral changes during long-term operation, thus limiting the system's reusability and flexibility.

[0004] Another approach involves using programmable modulation devices such as liquid crystal spatial light modulators and digital micromirror devices on the spatially expanded spectral surface to adjust different wavelengths. While this approach offers greater flexibility, it typically requires a more complex drive and control system, resulting in higher device costs. Under certain application conditions, it may also be limited by factors such as polarization sensitivity, stray light, pixelation diffraction effects, power handling capacity, and system maintenance complexity.

[0005] Therefore, a new spectral modulation scheme is needed that can independently adjust the attenuation of broadband or multi-band light sources by band with low system complexity, and can be manually corrected or automatically corrected in closed loop based on the output results; at the same time, the scheme should be easy to implement in engineering and compatible with compact reflective folding optical paths and transmissive reconstruction optical paths. Summary of the Invention

[0006] The purpose of this invention is to provide a spectral envelope shaping device and method based on an adjustable mask array, so as to solve the problems of insufficient flexibility of existing fixed spectral envelope shaping schemes and high cost and large system complexity of programmable modulator schemes.

[0007] The core idea of ​​the device described in this invention is as follows: first, the light to be shaped is spread into a spatial distribution according to wavelength or band on the spectral modulation surface; then, multiple independently adjustable blocking units are used to selectively and continuously block the corresponding target wavelength range or band; finally, the modulated segmented beams are recombined into an output beam through the spectral recombination unit, thereby realizing the control of the output spectral envelope.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A spectral envelope shaping device based on an adjustable mask array includes:

[0010] The light source to be shaped, a collimation unit, a first dispersion unit, a first imaging unit, an adjustable mask array disposed on the spectral modulation surface or its conjugate surface, and a spectral reconstruction unit;

[0011] The light source to be shaped is used to provide the beam to be shaped; the collimation unit is used to collimate the beam; the first dispersion unit is used to disperse the collimated beam according to wavelength; the first imaging unit is used to image the dispersed beam onto the spectral modulation surface or its conjugate surface, so that light of different wavelengths or different bands is distributed at different positions along the dispersion direction.

[0012] The adjustable mask array includes multiple blocking units arranged along the dispersion direction. Each blocking unit can independently adjust the blocking area or blocking ratio of the beam in the corresponding target wavelength range or band to achieve selective and continuous attenuation of the light energy in each target wavelength range or band.

[0013] The spectral reconstruction unit is positioned after the adjustable mask array and is used to reconstruct the modulated band beam into an output beam after reverse dispersion compensation or equivalent inverse transformation.

[0014] Furthermore, the spectral reconstruction unit is a reflective refracting spectral reconstruction unit, including a first reflecting mirror disposed after the adjustable mask array and a beam extraction unit disposed on the return optical path; the first reflecting mirror is used to reflect the modulated beam into a return beam, and has a preset tilt angle relative to the outgoing beam, so that the return beam and the outgoing beam are spatially separated; the return beam passes through the first imaging unit and the first dispersion unit in sequence to achieve reverse dispersion compensation and spectral reconstruction; the beam extraction unit is used to extract and output the reconstructed return beam.

[0015] Furthermore, the spectral reconstruction unit is a transmission-type spectral reconstruction unit, including a second imaging unit and a second dispersion unit arranged sequentially along the beam propagation direction; the transmission beam modulated by the adjustable mask array passes sequentially through the second imaging unit and the second dispersion unit to complete spectral reconstruction before being output; the second imaging unit has the same or equivalent imaging parameters as the first imaging unit, and the second dispersion unit has the same or equivalent dispersion parameters as the first dispersion unit.

[0016] Furthermore, the blocking unit is a light-shielding strip, light-shielding sheet, blade, or leaf; each blocking unit moves along a direction intersecting the dispersion direction to change its overlap area with the beam of the corresponding target wavelength range or band, thereby achieving continuous attenuation adjustment of the corresponding band.

[0017] Furthermore, the adjustable mask array also includes a guide structure, a position holding structure, and / or a drive connection structure; the guide structure is used to define the movement direction of each of the masking units, the position holding structure is used to hold the displacement of each of the masking units at a set position, and the drive connection structure is used to connect to a manual adjustment mechanism or actuator.

[0018] Furthermore, it also includes an output and monitoring unit and a closed-loop control component; the output and monitoring unit includes a beam splitter, an output optical path, a monitoring optical path, and a spectral detector. The beam splitter is used to split the recombined output light into an output optical path and a monitoring optical path. The spectral detector is used to acquire real-time monitoring spectral data that is from the same source as the output light. The closed-loop control component includes a control unit and multiple actuators. Each actuator is connected to a corresponding blocking unit. The control unit is connected to the spectral detector and the actuators and is configured to generate a control signal based on the deviation between the monitoring spectrum and the target spectrum to drive the corresponding blocking unit to adjust the blocking amount so that the output spectrum approaches the target spectrum.

[0019] Furthermore, the actuator is a piezoelectric actuator, a stepper motor linear module, a voice coil motor, a micro lead screw mechanism, or a shape memory alloy actuator; the control unit adopts proportional control, PID control, segmented proportional control, lookup table feedback control, or iterative optimization control.

[0020] A spectral envelope shaping method based on an tunable mask array, employing the aforementioned apparatus, includes the following steps:

[0021] S1. The wavelength-spatial position relationship on the spectral modulation surface is calibrated to establish the correspondence between the target band and the blocking unit;

[0022] S2. Determine the occlusion distribution for each target band based on the input spectrum and the required output spectrum.

[0023] S3. Control one or more blocking units to block and adjust the beam of the corresponding band so that each band after dispersion expansion completes spectral modulation on the spectral modulation surface.

[0024] S4. The modulated beam is passed through the spectral reconstruction unit to complete spectral reconstruction and output the shaped spectrum;

[0025] S5. The occlusion unit is further adjusted manually or automatically according to the output spectrum or the monitoring spectrum until the target spectral morphology is obtained.

[0026] Furthermore, in step S1, a mapping relationship is established between the occlusion unit number, the corresponding target wavelength range, the displacement, the occlusion amount, and the attenuation amount; in step S5, a real-time monitoring spectrum is acquired by a spectral detector, and the control unit iteratively adjusts the real-time monitoring spectrum according to the deviation between the real-time monitoring spectrum and the target spectrum until the real-time monitoring spectrum meets the preset error range.

[0027] Furthermore, the energy of the target output spectrum in each target wavelength range or band is not higher than the upper limit of the available energy of the input spectrum in the corresponding range or band; when the target output spectrum is a flat broadband spectrum, spectral flattening is achieved by selectively attenuating the high-energy band; when the target output spectrum is a multi-passband output spectrum, multi-passband selective output is achieved by retaining the target band and suppressing the non-target band.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] (1) Multiple independently adjustable physical shielding units are used to continuously adjust the attenuation of different target wavelength ranges or bands. The structure is relatively simple and easy to maintain and implement in engineering.

[0030] (2) By independently adjusting multiple blocking units, continuous attenuation of broadband spectrum in different bands can be achieved, which is suitable for broadband flattening, multi-passband narrowband output and construction of specific target spectrum.

[0031] (3) By setting up a reflective or transmissive spectral reconstruction structure, the optical path can be adapted according to different spatial layouts, volume constraints and output forms.

[0032] (4) By setting up a common source spectral monitoring unit, manual correction or closed-loop automatic correction can be implemented based on the output results to improve the adjustment repeatability and operational stability. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall optical path structure of the reflective refracting spectral envelope shaping device of the present invention.

[0034] Figure 2This is a schematic diagram of the overall optical path structure of the transmission-type spectral envelope shaping device of the present invention.

[0035] Figure 3 This is a schematic diagram of the adjustable mask array in this invention.

[0036] Figure 4 This is a schematic diagram of the closed-loop control logic in this invention. Detailed Implementation

[0037] To enable those skilled in the art to understand and implement the present invention, the structure and working process of the present invention will be described below with reference to the accompanying drawings. The following embodiments are used to explain the present invention and not to limit the scope of protection of the present invention.

[0038] In this specification, "dispersion direction" refers to the direction in which the positions corresponding to different wavelengths or different bands on the spectral modulation surface change sequentially; "adjustment direction" refers to the direction in which the blocking unit extends into or out of the corresponding beam region to change the amount of blocking, and the adjustment direction intersects with the dispersion direction, preferably perpendicular to the dispersion direction; "spectral modulation surface" refers to the focal plane or its conjugate plane that forms a spatial wavelength distribution after dispersion and imaging; "target wavelength range or band" refers to the spatial wavelength range that is corresponding to and adjusted by one or more blocking units.

[0039] It should be understood that the spatial distribution on the spectral modulation surface usually corresponds to a target wavelength range with a finite bandwidth, rather than a strict one-to-one correspondence between single wavelength points. In actual systems, different bands may have finite broadening, partial overlap, or aberration-induced extensions in space. Therefore, the adjustment target of this invention is preferably understood as the target wavelength range or band.

[0040] Example 1

[0041] like Figure 1 and 3 As shown, this embodiment provides a reflective refracting spectral envelope shaping device, including a light source to be shaped 1, a collimation unit 2, a first dispersion unit 3, a first imaging unit 4, an adjustable mask array 5, a reflector 6, a beam extraction unit 7, a coupling output unit 8, and an output terminal.

[0042] The light source to be shaped 1 can be a halogen tungsten lamp, a xenon lamp, a supercontinuum light source, a laser-driven white light source, a broadband light-emitting diode array, or other radiation sources capable of providing continuous spectrum, quasi-continuum spectrum, or multi-band spectrum. The light source to be shaped can be either free-space light-emitting or fiber-optic light-emitting.

[0043] The collimation unit 2 can be a collimating lens, lens group, reflective collimating mirror, off-axis parabolic mirror, or fiber collimator, used to shape the divergent light output by the light source to be shaped into approximately parallel light.

[0044] The first dispersion unit 3 is used to disperse the aligned beam and can be a reflective diffraction grating, a transmission diffraction grating, a prism, or a combination thereof. The first imaging unit is used to image the dispersed beam onto the spectral modulation surface and can be a lens group, a reflective imaging mirror group, or other imaging structures. In a typical embodiment, when using broadband light of 450nm-950nm as input, the first dispersion unit can be a 600 lines / mm reflective diffraction grating or a prism structure with equivalent dispersion capability, forming a linear dispersion rate of 0.01mm / nm-0.08mm / nm at the spectral modulation surface; the lateral magnification of the first imaging unit can be 0.8-1.5; the effective size of the spectral modulation surface can be 10mm-60mm along the dispersion direction and 2mm-10mm perpendicular to the dispersion direction; the typical width of each blocking unit in the dispersion direction can be 50um-500um, and the effective travel in the adjustment direction can be 0.1mm-5mm. When the system needs to be further simplified, the first dispersive unit and the first imaging unit can also be integrated using a concave grating.

[0045] After being processed by the first dispersion unit 3 and the first imaging unit 4, light from different target wavelength ranges or bands is distributed at different positions along the dispersion direction on the spectral modulation surface. The adjustable mask array 5 is disposed on the spectral modulation surface or its conjugate surface and includes multiple blocking units arranged along the dispersion direction. Each blocking unit corresponds to a preset target wavelength range and can move independently along the adjustment direction. The blocking unit can be a strip-shaped light-shielding plate, a light-shielding strip, a blade, a leaf-shaped component, or other structural components that can form a variable blocking boundary.

[0046] When a blocking unit extends into the corresponding beam region, the light transmission area of ​​the beam corresponding to the target wavelength range decreases, thereby reducing the output energy of that target wavelength range. When the blocking unit exits the corresponding beam region, the light transmission area of ​​the corresponding beam increases, thereby increasing the output energy of that target wavelength range. By adjusting the displacement, coverage area, or blocking ratio of multiple blocking units, independent and continuous attenuation of different target wavelength ranges or bands can be achieved.

[0047] In a preferred embodiment, the adjustable mask array further includes a guide structure, a position holding structure, and / or a drive connection structure. The guide structure may be a guide groove, a slide rail, or a limiting element, used to limit the movement direction of each masking unit; the position holding structure may be a locking element, an elastic retaining element, or a threaded fine-tuning structure, used to maintain the set position of each masking unit; the drive connection structure is used to connect with a manual fine-tuning mechanism or actuator to meet manual or automatic adjustment needs.

[0048] In this embodiment, the reflector 6 is disposed after the adjustable mask array, and preferably adjacent to the adjustable mask array. The reflector has a preset tilt angle relative to the outgoing beam, which is used to cause the reflected return beam to spatially offset relative to the outgoing beam. Preferably, the preset tilt angle can be 0.5°-5°, more preferably 1°-3°; since the slight tilt of the reflector can cause the return beam to bend relative to the outgoing beam by about twice the mirror tilt angle, the return beam will gradually form a resolvable off-axis offset in the direction perpendicular to the dispersion plane during its backward propagation. Preferably, the spatial offset occurs in the direction perpendicular to the dispersion plane, thereby facilitating subsequent spatial separation from the outgoing beam. The return beam then passes backward through the first imaging unit and the first dispersion unit to achieve reverse dispersion compensation and spectral reconstruction.

[0049] The beam extraction unit 7 is positioned on the propagation path of the return beam after it has been reassembled, and is used to extract the return beam. The beam extraction unit can be an extraction mirror, a beam splitter, a folding reflector, or a reflector integrated with the coupling structure. In a typical embodiment, the return beam, after being tilted by the mirror, can be laterally offset by 1mm-15mm relative to the outgoing beam at the extraction position. The beam extraction unit can be positioned at this offset position and folded out by a 45° mirror or a small-angle beam splitter, while the outgoing beam continues to be incident along its original propagation path, thereby achieving stable spatial separation between the two. As can be understood from the accompanying drawings, the outgoing beam and the return beam are basically corresponding in the dispersion plane, forming a staggered distribution vertically or horizontally in the direction perpendicular to the dispersion plane.

[0050] The coupling output unit may include a coupling lens, a lens group, a mirror group, an off-axis parabolic mirror, a fiber collimator, or a combination thereof, for coupling the recombined output beam to a free-space output end, a fiber output end, an integrating sphere input end, or other subsequent optical systems.

[0051] Example 2

[0052] like Figure 2 As shown, this embodiment provides a transmission-type spectral envelope shaping device. Its front-end optical path is the same as that in Embodiment 1, including a light source to be shaped 1, a collimation unit 2, a first dispersion unit 3, a first imaging unit 4, and an adjustable mask array 5 disposed on the spectral modulation surface or its conjugate surface.

[0053] The difference lies in that, in this embodiment, the beam modulated by the adjustable mask array is not reflected back, but continues to propagate forward into the transmission-type spectral reconstruction unit. The transmission-type spectral reconstruction unit includes a second imaging unit 11 and a second dispersion unit 12 arranged sequentially along the beam propagation direction. After the modulated transmission beam passes through the second imaging unit and the second dispersion unit in sequence, the reverse process corresponding to the previous dispersion unwrapping process is realized, thereby completing spectral reconstruction and output.

[0054] Preferably, the second imaging unit has the same or equivalent imaging parameters as the first imaging unit, and the second dispersive unit has the same or equivalent dispersive parameters as the first dispersive unit, so as to achieve a better spectral reconstruction effect. Preferably, the optical axis eccentricity between the two imaging units is no greater than 0.2 mm, and the tilt angle deviation is no greater than 0.5°; the angular deviation of the dispersive directions between the two dispersive units is no greater than 0.2°, and the relative deviation of the overall dispersive amount is no greater than 3%. When the above deviations exceed the preferred range, it may lead to the offset of the reconstructed spot position, spectral line broadening, increased crosstalk between adjacent bands, or distortion of the target spectral envelope. To address this, assembly calibration can be performed using a six-dimensional adjustment frame, secondary calibration can be performed using standard spectral lines, or an error compensation matrix and lookup table can be introduced into the control unit to compensate for the remaining deviations. Here, "same or equivalent" means that the imaging relationship and dispersive compensation relationship required for spectral reconstruction can be met, without requiring that the device model, focal length, geometric dimensions, or installation method be completely identical.

[0055] Compared to the reflective folding structure, the transmissive structure is not dependent on the return beam's exit path in terms of spatial layout, making it easier to arrange in forward series under specific optical path constraints; while the reflective folding structure can achieve a more compact folding and recombination while reusing the pre-stage dispersion and imaging optical paths. The choice between the two structures can be made based on the specific system volume, device availability, assembly space, and output format.

[0056] Example 3

[0057] like Figure 1 As shown, based on Embodiment 1 or Embodiment 2, this embodiment further includes an output unit 10 and a monitoring unit 9. The output and monitoring units are located after the shaped output beam and include a beam splitter, an output optical path, a monitoring optical path, and a spectral detector.

[0058] The beam splitter can be an optical fiber coupler, beam splitter, beam splitter prism, or other beam splitting element capable of distributing optical power according to a predetermined ratio, used to split the shaped output light into an output optical path and a monitoring optical path. The output optical path provides the target output spectrum to an external system; the monitoring optical path is connected to a spectral detector, such as a spectrometer or other spectral measurement device, for real-time acquisition of monitoring spectral data originating from the same source as the output light.

[0059] After adopting the above-mentioned homogeneous monitoring structure, users can adjust the blocking units individually or in combination according to the monitoring spectrum. When the target is a broadband flat output, the blocking amount of the blocking unit corresponding to the initial high-energy band can be increased first, so that the output spectrum gradually approaches the predetermined reference envelope; when the target is a multi-passband output, the blocking unit corresponding to the target band can be kept with a small blocking amount, while the blocking amount of non-target bands can be increased, thereby forming multiple discrete passbands.

[0060] Example 4

[0061] Based on Embodiment 3, this embodiment further includes a closed-loop control component. The closed-loop control component includes a control unit and multiple actuators, each actuator being drively connected to a corresponding shielding unit.

[0062] The actuator may be a piezoelectric actuator, a stepper motor linear module, a voice coil motor, a miniature lead screw mechanism, a shape memory alloy actuator, or other drive mechanisms capable of providing precise displacement output. The control unit may be a host computer, an embedded controller, an industrial computer, or a dedicated control board.

[0063] During closed-loop automatic adjustment, a pre-established correspondence between "blocking unit number - target wavelength range - displacement - blocking amount - attenuation amount" can be established. This correspondence can be obtained through pre-calibration, experimental measurement, table lookup fitting, or iterative learning. In a typical calibration method, a continuous spectrum light source can be used as input. After pre-stage dispersion and imaging, a beam distribution spatially distributed according to wavelength is formed on the spectral modulation surface. First, each blocking unit is fully blocked, preventing the beam from entering the subsequent optical path. At this time, the output spectrum received by the back-end spectrometer is zero or close to zero. Subsequently, each blocking unit is opened sequentially, allowing the beam at its corresponding position to pass through, and the back-end spectrometer collects the corresponding output spectrum, thereby establishing the correspondence between the spatial position of each blocking unit and its corresponding target wavelength range. To improve calibration efficiency, a multi-channel parallel calibration method can be adopted. This involves simultaneously activating multiple blocking units distributed at fixed intervals, allowing the back-end spectrometer to simultaneously acquire multiple distinguishable wavelength band signals. The band calibration of all blocking units is completed gradually through group scanning. The interval between adjacent simultaneously activated blocking units should be carefully designed to avoid overlap of corresponding output spectra on the spectrometer, which would affect differentiation and identification. After completing the calibration of the corresponding blocking units and the target wavelength range, while keeping the positions of the remaining blocking units unchanged, each blocking unit can be driven sequentially to move at a predetermined step size. The changes in transmittance, blocking amount, or attenuation in the corresponding wavelength range under different displacements are recorded, and the displacement-blocking-attenuation function relationship or lookup table for each blocking unit is fitted. During closed-loop operation, the spectrometer outputs the monitoring spectrum in real time. The control unit maps the deviation between the monitoring spectrum and the target spectrum to the corresponding target wavelength range and then outputs control signals to the corresponding actuators to adjust the displacement of the blocking units.

[0064] The control strategy can employ proportional control, PID control, segmented proportional control, lookup table feedback control, iterative optimization control, or a combination thereof. Preferably, the monitored spectrum and the target spectrum can be sampled in segments according to the target wavelength range corresponding to each blocking unit. The energy error or spectral shape error of each segment is calculated separately, and the target displacement correction amount for the corresponding blocking unit is obtained based on the pre-calibrated displacement-attenuation relationship or its inverse function. For cases where there is coupling influence between adjacent bands, a coupling compensation matrix can be introduced to jointly correct the displacement of multiple blocking units. After the actuator completes one adjustment, the monitored spectrum is collected again, and the control unit continues iterative calculation based on the updated error until the error of each target wavelength range is lower than a preset threshold. Through continuous or intermittent iterative adjustment, the output spectrum can gradually approach the target spectrum and remain stable after meeting the preset error range.

[0065] Example 5

[0066] The present invention also provides a method for spectral envelope shaping using the above-described apparatus, comprising the following steps:

[0067] Step S1: Perform wavelength-spatial position calibration.

[0068] By using known spectral light sources, standard filters, standard spectrometers, or other calibration methods, establish the correspondence between different target wavelength ranges and spatial positions on the spectral modulation surface, and further establish the correspondence between the blocking unit and the target wavelength range (e.g., establish the mapping relationship between the blocking unit number, the corresponding target wavelength range, the displacement, the blocking amount, and the attenuation amount).

[0069] Step S2: Set the target output spectrum.

[0070] Based on application requirements, the target output spectral envelope is given, and combined with the available energy distribution of the input spectrum, the target attenuation amount corresponding to each target wavelength range is determined, i.e., the blocking amount distribution corresponding to each target band. It should be noted that, since this method is an attenuation-type shaping method, the energy of the target output spectrum in the corresponding range is not higher than the upper limit of the available energy of the input spectrum in that range.

[0071] Step S3: Adjust the mask.

[0072] Based on the attenuation distribution obtained in step S2, one or more blocking units are controlled to move along the adjustment direction to partially or completely block the corresponding target wavelength range, thereby completing band-specific spectral envelope modulation on the spectral modulation surface. The adjustment accuracy is related to the achievable spectral resolution. When the linear dispersion at the spectral modulation surface is D (mm / nm) and the minimum displacement step size of the blocking unit is dx (mm), the corresponding minimum wavelength adjustment resolution can be approximately expressed as: Simultaneously, the effective edge width of the occlusion unit in the dispersion direction, the spot broadening caused by system aberrations, and the diffraction broadening also collectively affect the actual resolvable band width. To meet the target spectral precision requirements, the linear dispersion rate and adjustment precision can be selected based on the expected minimum band width, ensuring that the wavelength change corresponding to the minimum displacement step of the occlusion unit is not greater than the minimum band width, and that the edge width of the occlusion unit and the combined dispersion spot width are within a resolvable range. For cases where different band spatial distribution broadening or overlap is caused by aberrations, diffraction, etc., the wavelength interval boundaries corresponding to each occlusion unit can be defined using the spectral centroid, the full width at half maximum (FWHM) boundary, the energy intersection of adjacent bands, or the equivalent boundary based on the deconvolution of the system point spread function.

[0073] Step S4: Perform spectral reconstruction output.

[0074] For the reflective-folding structure, the modulated beam is reflected by a mirror to form a return beam, which then passes through the first imaging unit and the first dispersive unit again to achieve reverse dispersion compensation and spectral reconstruction. For the transmissive structure, the modulated beam passes through an adjustable mask array and sequentially passes through the second imaging unit and the second dispersive unit to complete spectral reconstruction. The reconstructed beam is then output as a shaped spectrum via a coupling output unit.

[0075] Step S5: Correct the results.

[0076] For manual adjustment, the positions of each blocking unit can be manually corrected based on the output spectrum or the monitoring spectrum. For automatic adjustment, iterative control is performed based on the deviation between the real-time monitoring spectrum and the target spectrum until the output spectrum meets the preset error requirements. This step involves acquiring the real-time monitoring spectrum through a spectral detector, and the control unit iteratively adjusting based on the deviation between the real-time monitoring spectrum and the target spectrum until the real-time monitoring spectrum meets the preset error range.

[0077] It should be noted that this invention belongs to the attenuation-type spectral envelope shaping scheme, which obtains the target output spectrum by selectively suppressing different target wavelength ranges or bands in the input spectrum. Therefore, the energy of the target output spectrum in each target wavelength range or band is not higher than the upper limit of the available energy of the input spectrum in the corresponding range or band. In a specific application scenario, when the target is a relatively flat broadband output, the target envelope can be set to be no higher than the lowest available energy in each target wavelength range of the input spectrum or a target curve of the reference envelope can be set. Then, by increasing the blocking amount of the blocking unit corresponding to the high-energy band, the output of different bands gradually tends to be consistent. When the target is a multi-passband output, the corresponding target band can be kept in a state of small blocking or light transmission, while other bands are subject to a larger blocking amount to obtain a discrete multi-passband spectrum.

[0078] This invention is not limited to the embodiments described above. Any equivalent substitutions, modifications, or conventional technical replacements made by those skilled in the art based on the disclosure of this invention without departing from its essential spirit should fall within the protection scope of this invention; the protection scope of this invention is defined by the claims.

[0079] In summary, this invention provides a spectral envelope shaping device and method based on an adjustable mask array. The device includes a light source to be shaped, a collimation unit, a first dispersion unit, a first imaging unit, an adjustable mask array disposed on the spectral modulation surface or its conjugate surface, a spectral reconstruction unit, and a coupling output unit; it may also optionally include a spectroscopic monitoring unit and a closed-loop control unit. After collimation, dispersion, and imaging, the light to be shaped forms a wavelength spatial distribution along the dispersion direction on the spectral modulation surface. The adjustable mask array includes multiple independent blocking units arranged along the dispersion direction. Each blocking unit is used to independently block the beam in the corresponding target wavelength range or band, achieving selective continuous attenuation of energy in each band by changing the blocking area or blocking ratio. The modulated beam is reconstructed and output after inverse dispersion compensation or equivalent inverse transformation by the spectral reconstruction unit. The spectral reconstruction unit can adopt a reflection-folding structure or a transmission structure; in the transmission structure, the beam modulated by the adjustable mask array continues to transmit and sequentially passes through the second imaging unit and the second dispersion unit to complete spectral reconstruction. By performing spectroscopic monitoring of the output spectrum, the blocking unit can be manually adjusted or automatically adjusted in a closed loop to obtain the target spectral shape. This invention is applicable to scenarios such as broadband spectral flattening, multi-passband selective output, and attenuated spectral envelope shaping of spectral calibration light sources.

[0080] The above embodiments are merely typical implementations of the present invention and are not intended to limit the present invention. Any equivalent substitutions or improvements made within the scope of the claims of the present invention are within the protection scope of the present invention.

Claims

1. A spectral envelope shaping device based on an adjustable mask array, characterized in that, include: The light source to be shaped, a collimation unit, a first dispersion unit, a first imaging unit, an adjustable mask array disposed on the spectral modulation surface or its conjugate surface, and a spectral reconstruction unit; The light source to be shaped is used to provide the beam to be shaped; the collimation unit is used to collimate the beam; the first dispersion unit is used to disperse the collimated beam according to wavelength; the first imaging unit is used to image the dispersed beam onto the spectral modulation surface or its conjugate surface, so that light of different wavelengths or different bands is distributed at different positions along the dispersion direction. The adjustable mask array includes multiple blocking units arranged along the dispersion direction. Each blocking unit can independently adjust the blocking area or blocking ratio of the beam in the corresponding target wavelength range or band to achieve selective and continuous attenuation of the light energy in each target wavelength range or band. The spectral reconstruction unit is positioned after the adjustable mask array and is used to reconstruct the modulated band beam into an output beam after reverse dispersion compensation or equivalent inverse transformation.

2. The apparatus according to claim 1, characterized in that, The spectral reconstruction unit is a reflective refracting spectral reconstruction unit, including a first reflecting mirror disposed after the adjustable mask array and a beam extraction unit disposed on the return optical path; the first reflecting mirror is used to reflect the modulated beam into a return beam, and has a preset tilt angle relative to the outgoing beam, so that the return beam and the outgoing beam are spatially separated; the return beam passes through the first imaging unit and the first dispersion unit in sequence to achieve reverse dispersion compensation and spectral reconstruction; the beam extraction unit is used to extract and output the reconstructed return beam.

3. The apparatus according to claim 1, characterized in that, The spectral reconstruction unit is a transmission-type spectral reconstruction unit, including a second imaging unit and a second dispersion unit arranged sequentially along the beam propagation direction; the transmission beam modulated by the adjustable mask array passes sequentially through the second imaging unit and the second dispersion unit to complete spectral reconstruction before being output; the second imaging unit has the same or equivalent imaging parameters as the first imaging unit, and the second dispersion unit has the same or equivalent dispersion parameters as the first dispersion unit.

4. The apparatus according to claim 1, characterized in that, The blocking unit is a light-shielding strip, light-shielding sheet, blade, or blade; each blocking unit moves along a direction intersecting the dispersion direction to change its overlap area with the beam of the corresponding target wavelength range or band, thereby achieving continuous attenuation adjustment of the corresponding band.

5. The apparatus according to claim 1 or 4, characterized in that, The adjustable mask array further includes a guide structure, a position holding structure, and / or a drive connection structure; the guide structure is used to define the movement direction of each of the masking units, the position holding structure is used to hold the displacement of each of the masking units at a set position, and the drive connection structure is used to connect to a manual adjustment mechanism or actuator.

6. The apparatus according to claim 1, characterized in that, It also includes an output and monitoring unit and a closed-loop control component; the output and monitoring unit includes a beam splitter, an output optical path, a monitoring optical path, and a spectral detector. The beam splitter is used to split the recombined output light into an output optical path and a monitoring optical path. The spectral detector is used to acquire real-time monitoring spectral data that is from the same source as the output light. The closed-loop control component includes a control unit and multiple actuators. Each actuator is connected to a corresponding blocking unit. The control unit is connected to the spectral detector and the actuators and is configured to generate a control signal based on the deviation between the monitoring spectrum and the target spectrum to drive the corresponding blocking unit to adjust the blocking amount so that the output spectrum approaches the target spectrum.

7. The apparatus according to claim 6, characterized in that, The actuator is a piezoelectric actuator, a stepper motor linear module, a voice coil motor, a micro lead screw mechanism, or a shape memory alloy actuator; the control unit adopts proportional control, PID control, segmented proportional control, lookup table feedback control, or iterative optimization control.

8. A spectral envelope shaping method based on an adjustable mask array, characterized in that, The apparatus according to any one of claims 1 to 7 comprises the following steps: S1. The wavelength-spatial position relationship on the spectral modulation surface is calibrated to establish the correspondence between the target band and the blocking unit; S2. Determine the occlusion distribution for each target band based on the input spectrum and the required output spectrum. S3. Control one or more blocking units to block and adjust the beam of the corresponding band so that each band after dispersion expansion completes spectral modulation on the spectral modulation surface. S4. The modulated beam is passed through the spectral reconstruction unit to complete spectral reconstruction and output the shaped spectrum; S5. The occlusion unit is further adjusted manually or automatically according to the output spectrum or the monitoring spectrum until the target spectral morphology is obtained.

9. The method according to claim 8, characterized in that, In step S1, a mapping relationship is established between the occlusion unit number, the corresponding target wavelength range, the displacement, the occlusion amount, and the attenuation amount. In step S5, a real-time monitoring spectrum is acquired by a spectral detector, and the control unit iteratively adjusts the real-time monitoring spectrum according to the deviation between the real-time monitoring spectrum and the target spectrum until the real-time monitoring spectrum meets the preset error range.

10. The method according to claim 8, characterized in that, The energy of the target output spectrum in each target wavelength range or band is not higher than the upper limit of the available energy of the input spectrum in the corresponding range or band; When the target output spectrum is a flat broadband spectrum, spectral flattening is achieved by selectively attenuating the high-energy band; when the target output spectrum is a multi-passband output spectrum, multi-passband selective output is achieved by retaining the target band and suppressing the non-target band.

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