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

Abstract

The invention relates to a large-field-of-view gating single-photon detector and a field-of-view gating method thereof, and belongs to the technical field of photoelectric detection, and the method comprises the following steps: an electronic control system controls a pulse laser to emit pulse laser; the field-of-view gating optical element coarsely divides an original large field of view into a plurality of quadrant fields of view, each quadrant field of view is finely divided into a plurality of element fields of view, and the one-to-one correspondence relationship among the element fields of view, reflection and transmission units of the field-of-view gating optical element and pixels of the single-photon detector is determined by using a precise ray tracing method; when target searching is carried out, the element view fields are sequentially controlled to be scanned and gated in the corresponding quadrant view fields, full gating of the quadrant view fields is completed, element view field scanning gating is carried out on all the quadrant view fields at the same time, and full view field gating of an original large view field is completed; and after the target is captured, adaptively controlling the gating density of the element view field containing the target according to the real-time noise intensity. According to the invention, the detection field angle of the single-photon detector can be effectively improved on the premise that the noise is not increased.

Description

Technical Field

[0001] The invention relates to the field of photoelectric detection technology, and in particular to a large-field-of-view gated single-photon detector and a field-of-view gate 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. By calculating the flight time of this photon, the distance to the target point can be measured. The target can be scanned for distance measurement or 3D imaging can be completed using an array detector, breaking the classic laser imaging (the single-point detection threshold is about 10 9 It has overcome the technical limitations of improving performance by only increasing laser power and increasing the area of ​​the telescope (one photon per kilowatt-hour). It has made a huge leap in weak light signal detection, and has obvious advantages in the fields of ultra-long-distance detection, fog-penetrating detection, and small target detection. It can accomplish tasks that traditional optical detection technology cannot accomplish.

[0003] However, environmental noise such as sunlight seriously affects single-photon detection: if the detector receives 3 (1) noise photons at the same time, the probability of its being excited exceeds 95% (50%). Continuous excessive noise will cause the detector to be continuously excited and saturated, and it will be unable to detect signal photons. Therefore, noise reduction is the key to single-photon detection. The noise intensity is proportional to the aperture, field of view, spectral bandwidth (referred to as bandwidth), and single-time detection working time of the detector (referred to as gate width). If you want to perform single-photon detection under sunlight conditions, you need to control the above parameters to the limit to suppress the noise to a suitable level. Therefore, the aperture of such equipment has a maximum limit, and reducing the aperture will reduce the detection distance. Limited by the filter principle, it is difficult to reduce the system bandwidth to less than 5 picometers. The photon flight time is difficult to estimate accurately, especially when the prior information is inaccurate. In order to prevent missing the echo signal photon, the device gate width cannot be too small, usually in the order of tens of nanoseconds; when measuring non-cooperative moving targets, the gate width must be enlarged 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 on 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, such as Figure 1 As shown in the figure, this disadvantage is more obvious when the target is hundreds of 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 in the promotion and application of single-photon detection technology in the engineering field. 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 gating single photon detector, the large field of view gating single photon detector comprising a pulse laser, a single photon detector and an electronic control system, a large field of view gating detection lens is arranged between the single photon detector and the detected target, the large field of view gating 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 extinguisher, the pulse laser, the single photon detector and the field of view gating optical element are respectively connected to the electronic control system through electronic circuits, the pulse laser emitted by the pulse laser irradiates the target, the photons reflected by the target are incident on the field of view gating optical element through the first lens group, the photons collected by a part of the field of view of the field of view gating optical element pass through the second lens group and the optical filter in sequence and then enter the single photon detector, and the photons collected by the remaining part of the field of view pass through the third lens group and then enter the stray light extinguisher;

[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 comprises 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 finely divided into a plurality of elementary fields of view, and 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 is determined by using a precise ray tracing method;

[0010] Step 3: When the large-field-of-view gating 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 in the corresponding quadrant field of view in accordance with a preset sequence and time period, thereby completing the full gating of the corresponding quadrant field of view; all quadrant fields of view perform meta-field of view scanning and gating simultaneously, thereby completing the 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 distribution and number of the corresponding gated meta-fields of view according to the quadrant field of view position of the target, gates all or part of the meta-fields of view containing the target, and closes other meta-fields of view without target coverage. The electronic control system adaptively controls the gate density of the meta-field of view containing the target according to the real-time noise intensity, and controls the number of gated meta-fields of view containing the target to be inversely proportional to the real-time noise intensity.

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

[0013] (1) The present invention increases the detection field of view of a single-photon detector by at least 10 times without increasing the noise entering the single-photon detector, providing technical support for improving the success rate and stability of target search, tracking, and measurement; and enhancing the compatibility of single-photon detection equipment with medium / long-wave optical measurement equipment;

[0014] (2) Compared with introducing an aperture into the optical system to reduce noise and signal strength at the same time, the present invention can keep the field of view containing the target element fully transparent and the field of view without the target element fully closed, that is, reduce noise and improve the signal-to-noise ratio while ensuring that the signal strength remains unchanged;

[0015] (3) When multiple targets appear in the original large field of view, the present invention can flexibly select several targets for detection based on the target signal strength, thereby assisting in distinguishing true from false targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without exceeding the scope of protection required by the present invention.

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

[0018] Figure 2 This is a schematic diagram of the structure of a large field of view gated single photon detector;

[0019] Figure 3 Schematic diagram for adaptively carrying out the regulation of the meta-field cluster.

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

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with 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 creative work are 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 gating single photon detector, wherein the large field of view gating single photon detector comprises a pulse laser 101, a large field of view gating detection lens 103, a single photon detector 104 and an electronic control system 105, wherein the large field of view gating detection lens 103 is arranged between the single photon detector 104 and a detected target 102. The target 102 is an object detected by the large field of view gating single photon detector.

[0023] The large field of view gated detection lens 103 includes a first mirror group 1031, a field of view gated optical element 1032, a second mirror group 1033, a third mirror group 1034, a filter 1035 and a stray light extinguisher 1036, wherein the field of view gated optical element 1032 includes a plurality of independent reflection and transmission units, which can reflect and transmit incident photons in different directions. The field of view gated optical element 1032 is preferably a spatial light modulator (Spatial Light Modulator) or a digital micromirror device (Digitalmicromirror device). The first mirror group 1031 is arranged at the optical front end of the field of view gated optical element 1032, the second mirror group 1033 is arranged between the field of view gated optical element 1032 and the single photon detector 104, the third mirror group 1034 is arranged between the field of view gated optical element 1032 and the stray light extinguisher 1036, and the filter 1035 is arranged between the second mirror group 1033 and the single photon detector 104. The pulse laser emitted by the pulse laser 101 irradiates the target 102, and the photons reflected back by the target 102 are incident on the field of view selection 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 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 which is in the "off" state.

[0024] 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 105 through electronic circuits. The electronic control system 105 provides a unified clock for the pulse laser 101, the single photon detector 104 and the 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 pulse laser emitted by the pulse laser 101, and provides a light source for single photon detection. The electronic control system 105 also controls and records the working gate time, timing start point, timing end point, photon arrival time and photon number 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 working state of the field of view gating optical element 1032.

[0025] Taking the field of view gating optical element 1032 using a digital micromirror device 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 pulsed laser emitted by the pulsed 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 refined and 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 turn according to 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: When the large field of view gated single photon detector captures the target 102, the electronic control system 105 calculates the quadrant field of view position of the digital micromirror device corresponding to the target 102 based on the photon counting image of the target 102 collected by the single photon detector 104, determines the distribution and number of the corresponding digital micromirror device gated meta-fields, gates all or part of the meta-fields containing the target 102, and closes other meta-fields not covered by the target 102. The meta-fields containing the target 102 may be distributed in multiple areas in the original large field of view, so the corresponding meta-fields are adaptively gated according to their coverage and position.

[0031] When performing field of view gating, the electronic control system 105 needs to adaptively control the gating density of the meta-field of view containing the target 102 according to the real-time noise intensity, and adaptively adjust the number of meta-fields contained in this gating field of view cluster. The number of gating meta-fields controlled by the electronic control system 105 is inversely proportional to the real-time noise intensity. When the noise is strong, for example, when the noise intensity is higher than the upper threshold, a single or several meta-fields of view containing the target 102 can be selected and tracked and gated in turn according to the moving trajectory of the photon counting image constructed by the electronic control system 105 collected by the single-photon detector 104 of the target 102. When the noise is weak, for example, when the noise intensity is lower than the lower threshold, all meta-fields of view can be selected to pass light 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, 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 filter 1035 is preferably 1 pm to 20 nm.

[0034] Furthermore, the aperture of the large-field-of-view gated detection lens 103 is 1 mm to 4 m, and the field of view angle is 1urad 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, which will not be described in detail here.

[0037] The present invention designs a large-field-of-view gated single-photon receiving optical system including a large-field-of-view gated detection lens, divides the original large field of view of the single-photon detector into multiple meta-fields of view, and adaptively selects several meta-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, and filters out the noise in the unselected meta-fields of view to achieve large-field-of-view gated detection. The size, number, working sequence, and distribution of the meta-field of view clusters are adaptively controlled to meet the field of view control requirements such as target search, tracking, and measurement, such as Figure 3 As shown. When the noise is reduced, the number of transparent elementary fields of view and their coverage in the original large field of view can be increased until the full field of view is detected. Compared with introducing an aperture in the optical system and reducing noise and signal strength at the same time, the present invention can keep the elementary fields of view containing the target fully transparent and the elementary fields of view without the target fully closed, that is, reduce noise while ensuring that the signal strength remains unchanged, which is a more advantageous noise reduction technology. When multiple targets appear in the original large field of view, the present invention can flexibly select several of them for detection according to the target signal strength, and has a certain ability to distinguish true and false targets.

[0038] At the same time, the present invention is expected to increase the single-photon detection field angle by at least 10 times, laying the foundation for stable, high signal-to-noise ratio detection of dark, small, and distant targets. For example, in terms of anti-UAV early warning, expanding the field angle expands the reconnaissance range and improves the detection success rate. When measuring the miss distance during target shooting, the probability that the equipment covers two targets is greatly improved. In terms of satellite ranging, excessive reliance on the accuracy of prior information is reduced. The implementation method of the specific functions of each module in the business card recognition device of the present invention can refer to the implementation method described in the above-mentioned business card recognition method embodiment, and will not be repeated here.

[0039] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for selecting a field of view of a large field of view selected single photon detector, the large field of view selected single photon detector comprising 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), an optical 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), 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), a part of the photons collected by 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 remaining part of the photons collected by the field of view pass through the third mirror group (1034) and then enter the stray light extinguisher (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) comprises a plurality of independent reflection and transmission units, 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 finely divided into a plurality of elementary fields of view, and 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) is determined by using a precise ray tracing method; 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 perform meta-field of view scanning and gating simultaneously, 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 corresponding gated meta-fields according to the quadrant field of view position where the target (102) is located, selects 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 gated meta-fields containing the target (102) to be inversely proportional to the real-time noise intensity.

2. The method for selecting a field of view of a large field of view 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 of view containing the target (102) are selected in sequence according to the moving trajectory of the target (102); when the noise intensity is lower than the lower threshold, all meta-fields of view are selected for detection.

3. The field of view gating method of a large field of view gating 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-20nm; a pulse width of 1fs-500ns; and a single pulse energy of 1nJ-5J.

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

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

6. The method for selecting a field of view of a large field of view 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 field of view gating method of a large field of view gating single photon detector according to claim 1, characterized in that: 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 method for selecting a field of view of a large field of view 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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