Large field of view gated single photon detector and field of view gating method thereof

Abstract

The present application relates to a kind of large field of view gating single-photon detector and its field of view gating method, belong to photoelectric detection technical field, including steps: electronic control system controls pulse laser to emit pulse laser;Field of view gating optical element is roughly divided into several quadrant fields of view from original large field of view, each quadrant field of view is refined and divided into several element fields of view, the one-to-one correspondence of element field of view, field of view gating optical element reflection and transmission unit, single-photon detector pixel is determined using precision ray tracing method;When carrying out target search, element field of view is sequentially controlled in the corresponding quadrant field of view and is scanned and gated, complete quadrant field of view full gating, all quadrant field of view simultaneously carries out element field of view scanning and gating, complete to original large field of view full field of view gating;When target is captured, the gating density of element field of view containing target is adaptively controlled according to real-time noise intensity.The present application can effectively improve the detection field of view angle of single-photon detector under the premise that noise is not improved.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detection technology, in particular to a large-field-of-view gating single-photon detector and a field-of-view gating method thereof. Background Art

[0002] Single photon detection is a highly sensitive active detection technology. It usually emits high-frequency laser pulses to the target. It only needs to detect one photon reflected by the target and calculate the flight time of this photon to complete the distance to the target point. It can perform surface scanning and ranging of the target or use an array detector to complete 3D imaging, breaking the classical laser imaging (single point detection threshold is about 10 9 It has broken through the technical limitations of improving performance by only increasing laser power and increasing the area of ​​the telescope (photons per photon). It has made a huge leap in weak light signal detection, and has obvious advantages in ultra-long-distance detection, fog-penetrating detection, small target detection and other fields, and can complete tasks that traditional optical detection technology cannot accomplish.

[0003] However, environmental noise, such as sunlight, severely impacts single-photon detection. If a detector simultaneously receives three (or one) noise photons, the probability of its excitation exceeds 95% (or 50%). Continuous excessive noise can lead to detector saturation, rendering it unable to detect signal photons. Therefore, noise reduction is crucial for single-photon detection. Noise intensity is proportional to the device's aperture, field of view, spectral bandwidth (bandwidth), and the detector's single-shot operating time (gate width). To achieve single-photon detection in daylight, these parameters must be controlled to the utmost to suppress noise to an appropriate level. Therefore, the aperture of such devices is limited; reducing the aperture reduces the detection range. Due to filter constraints, it is difficult to reduce the system bandwidth below 5 picometers. Accurately estimating the photon time of flight is difficult, especially when prior information is inaccurate. To avoid missing return signal photons, the device's gate width must be kept constant, typically on the order of tens of nanoseconds. When measuring non-cooperative moving targets, the gate width must be increased accordingly. Therefore, reducing the field of view is an important way to reduce noise, but this will reduce the detection range. Even if the single-photon device is integrated into a theodolite with high tracking accuracy, it is often lost. Even if the medium / long-wavelength large-field-of-view auxiliary tracking and capture device attached to the theodolite captures the target, it is difficult to adjust it into the single-photon detection field of view because the field of view of the auxiliary tracking and capture device is larger than the single-photon detection field of view. Figure 1 As shown in Figure 1, this disadvantage is even more pronounced when the target is over 100 kilometers away. Therefore, how to improve the field of view of single-photon detection without increasing noise has become a problem that must be solved for the promotion and application of single-photon detection technology in engineering fields. Summary of the Invention

[0004] In view of the above problems, the present invention proposes a large field of view gated single-photon detector and a field of view gating method thereof.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A field of view gating method for a large-field-of-view gated single-photon detector, comprising a pulsed laser, a single-photon detector, and an electronic control system. A large-field-of-view gated detection lens is disposed between the single-photon detector and a detected target. The large-field-of-view gated detection lens comprises a first lens group, a field of view gating optical element, a second lens group, a third lens group, an optical filter, and a stray light extinction device. The pulsed laser, the single-photon detector, and the field of view gating optical element are respectively connected to the electronic control system via electronic circuits. Pulsed laser light emitted by the pulsed laser irradiates the target, and photons reflected by the target are incident on the field of view gating optical element via the first lens group. Photons collected by a portion of the field of view of the field of view gating optical element sequentially pass through the second lens group and the optical filter before entering the single-photon detector, and photons collected by the remaining portion of the field of view pass through the third lens group before entering the stray light extinction device.

[0007] The field of view gating method comprises the following steps:

[0008] Step 1: The electronic control system controls and records the wavelength, pulse width, emission time, emission frequency, and single pulse energy of the pulse laser emitted by the pulse laser;

[0009] Step 2: The field-of-view gating optical element includes a plurality of independent reflection and transmission units, and the original large field of view of the large-field-of-view gating single-photon detector is roughly divided into a plurality of quadrant fields of view. Each of the quadrant fields of view is further divided into a plurality of elementary fields of view. A precise ray tracing method is used to determine a one-to-one correspondence between the elementary fields of view, the reflection and transmission units in the field-of-view gating optical element, and the pixels of the single-photon detector;

[0010] Step 3: When the large field of view gated single photon detector performs target search, the electronic control system controls the field of view gating optical element to control the meta-field of view to scan and gate within the corresponding quadrant field of view according to a pre-set sequence and time period, thereby completing full gating of the corresponding quadrant field of view; all quadrant fields of view simultaneously perform meta-field of view scanning and gating, thereby completing full-field gating of the original large field of view;

[0011] Step 4: When the large field of view gated single-photon detector captures the target, the electronic control system determines the corresponding gated meta-field distribution and number according to the quadrant field of view position of the target, gates all or part of the meta-field containing the target, and closes other meta-fields without target coverage. The electronic control system also adaptively controls the gate density of the meta-field containing the target according to the real-time noise intensity, and controls the number of gated meta-fields containing the target to be inversely proportional to the real-time noise intensity.

[0012] The beneficial effects of the present application are:

[0013] (1) The present application at least improves the detection field angle of the single photon detector by 10 times without increasing the noise in the single photon detector, which provides technical support for improving the success rate and stability of target search, tracking and measurement, and enhances the compatibility of the single photon detection equipment with the medium / long wave light measurement equipment.

[0014] (2) Compared with introducing an aperture in the optical system while reducing the noise and signal strength, the present application can maintain full light in the target element field of view and full off in the non-target element field of view, that is, reduce the noise and improve the signal-to-noise ratio under the premise of ensuring the signal strength unchanged.

[0015] (3) When multiple targets appear in the original large field of view, the present application can flexibly select several targets for detection according to the target signal strength, thereby assisting in discriminating true and false targets. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art according to these drawings without exceeding the scope of the present application.

[0017] Figure 1 A schematic diagram of the field of view of the auxiliary tracking and capturing equipment and the single photon detection field of view;

[0018] Figure 2 A structural schematic diagram of the large field of view gating single photon detector;

[0019] Figure 3 A schematic diagram of self-adaptive cluster control of element field of view.

[0020] Explanation of reference signs: 101, pulsed laser; 102, target; 103, large field of view gating detection lens; 1031, first mirror group; 1032, field of view gating optical element; 1033, second mirror group; 1034, third mirror group; 1035, optical filter; 1036, stray light eliminator; 104, single photon detector; 105, electronic control system. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] like Figure 2 As shown, this embodiment provides a field of view gating method for a large field of view gated single-photon detector, wherein the large field of view gated single-photon detector includes a pulsed laser 101, a large field of view gated detection lens 103, a single-photon detector 104, and an electronic control system 105. The large field of view gated detection lens 103 is disposed between the single-photon detector 104 and a target 102 to be detected. The target 102 is the object to be detected by the large field of view gated single-photon detector.

[0023] The large field of view gated detection lens 103 includes a first lens group 1031, a field of view gated optical element 1032, a second lens group 1033, a third lens group 1034, a filter 1035, and a stray light extinction filter 1036. The field of view gated optical element 1032 includes several independent reflection and transmission units that can reflect and transmit incident photons in different directions. The field of view gated optical element 1032 is preferably a spatial light modulator (SLM) or a digital micromirror device (DMD). The first lens group 1031 is provided at the optical front end of the field of view gated optical element 1032, the second lens group 1033 is provided between the field of view gated optical element 1032 and the single photon detector 104, the third lens group 1034 is provided between the field of view gated optical element 1032 and the stray light extinction filter 1036, and the filter 1035 is provided between the second lens group 1033 and the single photon detector 104. The pulsed laser emitted by the pulsed laser 101 irradiates the target 102. The photons reflected by the target 102 pass through the first mirror group 1031 and are incident on the field of view selection optical element 1032. A part of the photons collected by the field of view selection optical element 1032 pass through the second mirror group 1033 and the filter 1035 in sequence and enter the single photon detector 104. The photons collected by the remaining part of the field of view pass through the third mirror group 1034 and enter the stray light extinction device 1036. The stray light extinction device 1036 is used to extinct the photons introduced into the detector by the reflection and transmission units in the field of view selection optical element 1032 in the "off" state.

[0024] The pulsed laser 101, single-photon detector 104, and field-of-view gating optical element 1032 are each connected to an electronic control system 105 via electronic circuitry. The electronic control system 105 provides a unified clock for the pulsed laser 101, single-photon detector 104, and field-of-view gating optical element 1032. The electronic control system 105 controls and records the wavelength, pulse width, emission time, emission frequency, and single-pulse energy of the pulsed laser light emitted by the pulsed laser 101, providing a light source for single-photon detection. The electronic control system 105 also controls and records the operating gating time, timing start and end, photon arrival time, and photon accumulation of the single-photon detector 104, and constructs a photon counting image of the target 102. The electronic control system 105 also controls and records the operating status of the field-of-view gating optical element 1032.

[0025] Taking the field of view gating optical element 1032 as an example, the digital micromirror device includes a plurality of reflective micromirrors. The field of view gating method of the large field of view gating single photon detector proposed in this embodiment specifically includes the following steps:

[0026] Step 1: The electronic control system 105 controls the wavelength, pulse width, emission time, emission frequency, and single pulse energy of the pulse laser emitted by the pulse laser 101.

[0027] Step 2: Based on the digital micromirror device, the original large field of view of the large field of view gated single-photon detector is roughly divided into several quadrant fields of view; further, each quadrant field of view is further divided into several elementary fields of view; then, the precision ray tracing method is used to fully consider the influence of aberrations to determine the one-to-one correspondence between the elementary field of view, the reflective micro-lens in the digital micromirror device, and the pixel of the single-photon detector 104. The above three are actually in a conjugate relationship.

[0028] In order to provide a larger extension and compression space for field of view selection, the system light beam needs to cover as many digital micromirror device reflective microlenses as possible; at the same time, for each pixel of the single-photon detector 104, as many digital micromirror device reflective microlenses as possible are conjugated.

[0029] Step 3: When the large-field-of-view single-photon detector is searching for a target, the electronic control system 105 controls the digital micromirror device to scan and select the meta-field in the corresponding quadrant field of view in accordance with a preset sequence and time period, thereby completing the full selection of the corresponding quadrant field of view; all quadrant fields of view perform meta-field scanning and selection at the same time, thereby completing the full-field selection of the original large field of view.

[0030] Step 4: After the large-field-of-view gated single-photon detector captures target 102, the electronic control system 105 calculates the quadrant of the DMD field of view corresponding to target 102 based on the photon count image of target 102 collected by the single-photon detector 104. It then determines the distribution and number of the corresponding DMD gated meta-fields of view, selects all or part of the meta-field of view containing target 102, and disables other meta-fields of view not covered by target 102. The meta-fields of view containing target 102 may be distributed across multiple regions within the original large field of view. Therefore, the corresponding meta-fields of view are adaptively gated based on their coverage and location.

[0031] When performing field of view gating, the electronic control system 105 must adaptively control the gating density of each meta-field of view containing the target 102 based on the real-time noise intensity, adaptively adjusting the number of meta-fields included in this gated field of view cluster. The number of gated meta-fields controlled by the electronic control system 105 is inversely proportional to the real-time noise intensity. When noise is high, for example, when the noise intensity exceeds an upper threshold, tracking and gating can be performed on one or more meta-fields containing the target 102, based on the movement trajectory of the photon counting image of the target 102 generated by the electronic control system 105 and collected by the single-photon detector 104. When noise is low, for example, when the noise intensity is below a lower threshold, all meta-fields of view can be selected for detection.

[0032] Furthermore, the pulse laser 101 is one or a combination of a visible light band pulse laser and a near-infrared band pulse laser, and the wavelength is preferably any one or any combination of 532±10nm, 850±10nm, 905±10nm, 1064±10nm, 1530±10nm, and 1550±10nm; the spectral linewidth is preferably 1pm~20nm; the pulse width is 1fs~500ns; and the single pulse energy is preferably 1nJ~5J.

[0033] Furthermore, the spectral line width of the optical filter 1035 is preferably 1 pm to 20 nm.

[0034] Furthermore, the aperture of the large-field-of-view strobe detection lens 103 is 1 mm to 4 mm, and the field of view angle is 1 mrad to 500 mrad.

[0035] Furthermore, the single-photon detector 104 is any one of a superconducting single-photon detector, a high-sensitivity photomultiplier tube single-photon detector, and a Geiger-mode avalanche photodiode, or a combination of any of them.

[0036] Another embodiment of the present invention provides a large field of view gated single-photon detector, which uses the field of view gating method described in the above embodiment to perform imaging, and will not be described in detail here.

[0037] The application divides the original large field of view of the single photon detector into a plurality of unit fields of view, and adaptively selects a plurality of unit fields of view to carry out photon detection according to the distribution of noise in the large field of view and the position of the target, filters out the noise in the unselected unit field of view, and realizes large field of view gated detection. Figure 3 When the noise is reduced, the number of light passing unit fields of view and the coverage range thereof in the original large field of view can be increased until full field of view detection. Compared with introducing an aperture in the optical system while reducing the noise and signal strength, the application can keep the unit field of view containing the target fully open and the unit field of view without the target fully closed, that is, reduce the noise on the premise of keeping the signal strength unchanged, which is a more advantageous noise reduction technology. When multiple targets appear in the original large field of view, the application can flexibly select a plurality of targets for detection according to the signal strength of the targets, and has the ability to distinguish true and false targets.

[0038] At the same time, the application is expected to increase the single photon detection field of view angle by at least 10 times, and lay a foundation for stable and high signal-to-noise ratio detection of dark, small and distant targets. In the aspect of anti-UAV early warning, the expansion of the field of view angle expands the reconnaissance range and improves the detection success rate. In the aspect of shooting measurement of the off-target amount, the probability of the device covering two targets is greatly improved. In the aspect of artificial satellite ranging, the excessive dependence on the accuracy of prior information is reduced. The specific function implementation method of each module in the business card recognition device can refer to the implementation method described in the above business card recognition method embodiment, which will not be described here.

[0039] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the description.

[0040] The above-described embodiments only express several implementation manners of the application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which are within the protection scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A method for selecting a field of view of a large field of view single-photon detector, wherein the large field of view single-photon detector comprises a pulsed laser (101), a single-photon detector (104) and an electronic control system (105), characterized in that: A large field of view gating detection lens (103) is arranged between the single photon detector (104) and the detected target (102). The large field of view gating detection lens (103) comprises a first lens group (1031), a field of view gating optical element (1032), a second lens group (1033), a third lens group (1034), a filter (1035) and a stray light extinguisher (1036). The pulse laser (101), the single photon detector (104) and the field of view gating optical element (1032) are respectively connected to the electronic control system (1036) through electronic circuits. 5) connection, the pulse laser emitted by the pulse laser (101) irradiates the target (102), the photons reflected by the target (102) are incident on the field of view gating optical element (1032) through the first mirror group (1031), the photons collected by a part of the field of view of the field of view gating optical element (1032) pass through the second mirror group (1033) and the filter (1035) in sequence and then enter the single photon detector (104), and the photons collected by the remaining part of the field of view pass through the third mirror group (1034) and then enter the stray light extinction device (1036); The field of view gating method comprises the following steps: Step 1: The electronic control system (105) controls and records the wavelength, pulse width, emission time, emission frequency, and single pulse energy of the pulse laser emitted by the pulse laser (101); Step 2: The field-of-view gating optical element (1032) includes a plurality of independent reflection and transmission units, and the original large field of view of the large field-of-view gating single-photon detector is roughly divided into a plurality of quadrant fields of view, and each of the quadrant fields of view is further divided into a plurality of elementary fields of view, and a precise ray tracing method is used to determine a one-to-one correspondence between the elementary fields of view, the reflection and transmission units in the field-of-view gating optical element (1032), and the pixels of the single-photon detector (104); Step 3: When the large field of view gating single photon detector performs target search, the electronic control system (105) controls the field of view gating optical element (1032) to control the meta-field of view to scan and gate in the corresponding quadrant field of view according to a preset sequence and time period, thereby completing full gating of the corresponding quadrant field of view; all quadrant fields of view simultaneously perform meta-field of view scanning and gating, thereby completing full-field gating of the original large field of view; Step 4: When the large-field-of-view gated single-photon detector captures the target (102), the electronic control system (105) determines the distribution and number of the corresponding gated meta-fields according to the quadrant field of view position of the target (102), gates all or part of the meta-fields containing the target (102), and closes other meta-fields not covered by the target (102), and the electronic control system (105) adaptively controls the gate density of the meta-field containing the target (102) according to the real-time noise intensity, and controls the number of the gated meta-fields containing the target (102) to be inversely proportional to the real-time noise intensity.

2. The field of view gating method of a large field of view gated single photon detector according to claim 1, characterized in that: In step 4, when the noise intensity is higher than the upper threshold, a single or several meta-fields containing the target (102) are selected in sequence according to the movement trajectory of the target (102); when the noise intensity is lower than the lower threshold, all meta-fields are selected to pass light for detection.

3. The field of view gating method of a large field of view gated single photon detector according to claim 1, characterized in that: The pulse laser (101) is one or a combination of a visible light band pulse laser and a near infrared band pulse laser, with a wavelength of any one or any combination of 532±10nm, 850±10nm, 905±10nm, 1064±10nm, 1530±10nm, and 1550±10nm; a spectral line width of 1pm to 20nm; a pulse width of 1fs to 500ns; and a single pulse energy of 1nJ to 5J.

4. The field of view gating method of a large field of view gated single photon detector according to claim 1, characterized in that: The spectral line width of the filter (1035) is 1pm to 20nm.

5. The field of view gating method of a large field of view gated single photon detector according to claim 1, characterized in that: The aperture of the large-viewing-field strobing detection lens (103) is 1 mm to 4 m, and the viewing angle is 1 mrad to 500 mrad.

6. The field of view gating method of a large field of view gating single photon detector according to claim 1, characterized in that: The field-of-view gating optical element (1032) is a spatial light modulator or a digital micromirror device.

7. The method for selecting a field of view of a large field of view gated single photon detector according to claim 1, wherein: The single-photon detector (104) is any one of a superconducting single-photon detector, a high-sensitivity photomultiplier tube single-photon detector, and a Geiger-mode avalanche photodiode, or a combination of any of the above.

8. The field of view gating method of a large field of view gated single photon detector according to claim 1, characterized in that: The electronic control system (105) provides a unified clock for the pulse laser (101) and the single-photon detector (104), records the moment when the single-photon detector (104) collects photons, performs cumulative photon counting, and constructs a photon counting image of the target (102).

9. A large field of view gated single photon detector, characterized in that: The large field of view gated single-photon detector uses the field of view gating method described in any one of claims 1 to 8 to perform imaging.

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