Laser receiver and laser ranging device

Abstract

The utility model provides a laser receiver. The laser receiver comprises an SPAD unit and a control unit. The SPAD unit comprises a dual-mode SPAD array which is uniformly arranged and is used for receiving a laser signal and generating a digital signal according to the laser signal; and the control unit is in communication connection with the SPAD unit and is used for receiving the digital signal sent by the SPAD unit and determining the relative position of the laser receiver and the laser plane according to the digital signal.

Description

Technical Field

[0001] The utility model relates to the field of laser ranging, in particular to a laser receiver and a laser ranging device. Background Art

[0002] When performing alignment work in the field of building construction, a laser rotator or a line laser is often used to create a clearly visible laser plane, which can be a horizontal, vertical or inclined plane at a certain desired angle. The role of the laser receiver is to detect the laser plane. It captures the position where the laser hits within the detection window of the body, thereby determining the position of the receiver relative to the laser plane. In most cases, when detecting a horizontal plane, what is determined is whether the receiver (the zero position scale line) is above or below the laser plane (which is also in the shape of a line when projected onto the surface of the receiver). For precise positioning occasions, the determination of this position must be within millimeters or more precisely.

[0003] At present, the position detection method applied in the market uses a photovoltaic cell. Multiple groups of silicon photovoltaic cells process the target signal, and the received distance is relatively short. External interference signals affect the reliability and accuracy requirements of reception. Based on the existing technology of photoelectric signal processing methods, the performance of the product cannot be further improved.

[0004] Therefore, there is an urgent need for a laser ranging device that is less affected by the external environment and has high precision and stability. Summary of the Utility Model

[0005] In order to overcome the above technical defects, the purpose of the utility model is to provide a laser receiver applying SPAD technology.

[0006] Specifically, the utility model discloses a laser receiver, including: an SPAD unit and a control unit;

[0007] The SPAD unit includes a dual-mode SPAD array arranged uniformly, which is used to receive laser signals and generate digital signals according to the laser signals;

[0008] The control unit is communicatively connected to the SPAD unit and is used to receive the digital signals sent by the SPAD unit and determine the relative position of the laser receiver and the laser plane according to the digital signals.

[0009] Preferably, the dual-mode SPAD array includes n dual-mode SPADs, which are used to collect and receive the laser signals.

[0010] Preferably, the dual-mode SPAD array is a 10*20 dual-mode SPADD array, which is used to collect and receive laser signals with a wavelength of 400nm - 700nm.

[0011] Preferably, the pixel pitch of the dual-mode SPAD array is from 20 microns to 25 microns.

[0012] In another aspect of the present invention, a laser ranging device is also disclosed, which includes the laser receiver as described above and a laser transmitter.

[0013] Preferably, it further includes a condenser lens, which is arranged on the front side of the dual-mode SPAD array and is used to receive and focus the laser signal; the dual-mode SPAD array is used to receive the laser signal passing through the condenser lens.

[0014] After adopting the above technical solutions, compared with the prior art, the following beneficial effects are achieved: it has high stability and measurement accuracy, the detection accuracy can reach 0.2 mm, and the detection distance can reach more than 1 km. This SPAD technology will be extended to digital detection (passive detection method), and the physical spacing of SPAD is controllable. The actual applicable space detection accuracy can reach 0.025 mm (based on the conventional SPAD process size), and the response rate is extremely fast (up to the ns level), which is beneficial for high-speed tracking applications. Among them, the SPAD adopts a unit stacking method to form a detection module, which can be infinitely expanded and is beneficial for large-scene applications. In addition, the SPAD signal processing adopts an integrated design of periodic and aperiodic pulse signal detection, which is easy to implement and has a certain economy. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of a laser receiver in an embodiment that conforms to the present invention. Detailed Embodiments

[0016] The advantages of the present invention are further elaborated below in conjunction with the drawings and specific embodiments.

[0017] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are only examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0018] The terms used in the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The singular forms of "a", "the" and "said" used in the present disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0019] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0020] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms longitudinal, transverse, upper, lower, front, rear, left, right, vertical, horizontal, top, bottom, inner, outer, etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model. In the description of the present utility model, unless otherwise specified and defined, it should be noted that the terms installation, connection, and coupling should be understood in a broad sense. For example, it may be a mechanical connection or an electrical connection, or it may be the communication inside two elements. It may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms may be understood according to specific circumstances.

[0021] In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are only for the convenience of describing the present utility model, and they have no specific meaning in themselves. Therefore, "module" and "component" can be used interchangeably.

[0022] In an embodiment of the present utility model, it includes a laser receiver, as Figure 1 shown. The laser receiver in this embodiment includes a SPAD unit and a control unit; the SPAD unit includes a dual-mode SPAD array arranged uniformly, which is used to receive a laser signal and generate a digital signal according to the laser signal; the control unit is communicatively connected to the SPAD unit and is used to receive the digital signal sent by the SPAD unit and determine the relative position between the laser receiver and the laser plane according to the digital signal.

[0023] Figure 1The laser receiver shown also includes a PC condenser lens, which is a common optical element in the art and will not be elaborated herein. The SPAD mentioned in the present utility model is a single-photon avalanche diode, which can convert the received optical signal into a digital signal and has high sensitivity and response efficiency. In this embodiment, the dual-mode SPAD array receives an external signal, usually a laser signal with a wavelength range of 400nm - 700nm, and converts the laser signal into a digital signal. The control unit is communicatively connected to the SPAD unit and receives the digital signal. When receiving a modulation signal with a frequency range of 5KHZ - 15KHZ or a low-speed pulse signal with a rotational speed of 1200rpm or less, the distance, accuracy, and reliability of position detection can be greatly improved. The detection accuracy can reach 0.2mm, and the detection distance can reach more than 1km.

[0024] In this embodiment, the dual-mode SPAD array is a 10*20 dual-mode SPAD array. Moreover, the SPAD uses a pixel pitch of about 25um and an active area of 0.5*0.25mm, and the silicon area containing the processing circuit is controlled within about 3mm 2 or so. Compared with the light-receiving area of the photocell of the detector on the market, the size of the SPAD array in this embodiment is reduced. In other embodiments, the dual-mode SPAD array includes n dual-mode SPADs for collecting and receiving the laser signal, which can be adjusted according to actual needs and will not be elaborated herein.

[0025] More preferably, in another embodiment of the present utility model, a time-to-digital converter (TDC) unit is further included. In this embodiment, in combination with the signal processing of the variable-clock dual-mode working TDC in the prior art, the digital conversion of the optical signal is realized. Specifically, the delay link length of the TDC unit determines the longest time that the TDC can measure. Due to cost and IC design limitations, it is impossible to infinitely extend the link size. Therefore, in order to adapt to various working scenarios, a variable-clock dual-mode working TDC is adopted, mainly to control the clock frequency of the TDC unit. When working in the remote reception mode, a relatively low clock frequency is selected to achieve a relatively long but slightly less accurate time measurement on the TDC unit of the same length. When a higher time measurement accuracy is required, a higher timing frequency can be selected to increase the adaptability of the TDC measurement unit to different scenarios.

[0026] In another embodiment of the present utility model, a laser ranging device is provided, which includes the laser receiver described in the previous embodiment and a laser emitter. The laser emitter can be any available laser emitter in the art, such as a rotating single-beam laser emitter or an instrument that generates a continuous 360° laser plane by pointing the laser at a conical surface, etc. The present utility model does not limit this.

[0027] In another embodiment of the present utility model, an application method of applying the above laser ranging device to digital detection is disclosed. Specifically, by integrating multiple groups of SPAD detection arrays, in this mode, the pulse signals generated when each SPAD is excited are respectively used to drive 32 counters with a bit width of 10 to perform independent incremental counting. The 8 MHz clock provided by the crystal oscillator is used to drive a time counter. The range (i.e., the measurement time window) of the time counter can be configured through a register, and the typical value can be configured as 12.5 us. When the range is full, the timer automatically resets to 0 and starts the next timing.

[0028] When starting the measurement, the time counter starts timing, and at the same time, 32 pulse counters start counting; when the timer is full, the values of the 32 pulse counters are cached and sent to the subsequent pipeline adder tree for cumulative sum calculation; at the same time, the measurement of the next time window is started.

[0029] The original data obtained by the adder tree operation is sequentially cached into a register Buffer with a length of 128 and a bit width of 20 bits, which can be read by the user at any time. To improve the contrast of data processing, the cache Buffer supports cyclic accumulation operations. Each cache of 16 data is one cycle, and the corresponding register can be configured to control the accumulation times of the register Buffer. By default, the accumulation times register is 1, that is, data accumulation is not performed, and the maximum cyclic accumulation times is 32 times.

[0030] For the plumb line laser detection application with a fixed frequency of 5 KHz or 10 KHz, if the user enables the FFT operation unit by configuring the register, when the cyclic accumulation times of the register Buffer reach the set value, a group of 128 original data will be sent to the FFT operation module in parallel for 128-point FFT operation, and the spectral amplitudes at 5 KHz and 10 KHz frequencies obtained by the operation will be automatically saved to the result register, and at the same time, the interrupt signal INT is pulled high to prompt the host computer that this measurement has been completed.

[0031] The original counting statistical data can be transmitted through the IIC interface. Each chip has 4-bit address coding bits, and chip addressing can be achieved when used in parallel.

[0032] Through the design of integration, array structure arrangement, and circuit chip configuration, the high sensitivity of the silicon SPAD device to optical signals is fully demonstrated. The system output is converted into a full digital signal, completely avoiding the difficulties in signal processing in the later stage of traditional applications that use analog circuits for reception detection and output analog signals. The overall integration is high, the transmission interface of the digital result is simple, it is very easy to interface with a low-end MCU, the system is simple, and the cost has a great advantage.

[0033] Based on the above embodiments, it can be seen that the laser receiver and the laser ranging device in the present utility model have better reliability compared with the prior art, and break through to improve the accuracy of measuring distance.

[0034] It should be noted that the embodiments of the present utility model have good implementability and do not impose any form of limitation on the present utility model. Any person skilled in the art may use the disclosed technical content to change or modify it into an equivalent effective embodiment. However, as long as it does not depart from the technical solution of the present utility model, any modification, equivalent change or modification made to the above embodiments based on the technical essence of the present utility model still falls within the scope of the technical solution of the present utility model.

Claims

1. A laser receiver, characterized in that, Comprising: A SPAD unit and a control unit; The SPAD unit includes a uniformly arranged dual-mode SPAD array for receiving a laser signal and generating a digital signal according to the laser signal; The control unit is communicatively connected to the SPAD unit for receiving the digital signal sent by the SPAD unit and determining the relative position between the laser receiver and the laser plane according to the digital signal.

2. The laser receiver according to claim 1, wherein The dual-mode SPAD array includes n dual-mode SPADs for collecting and receiving the laser signal.

3. The laser receiver according to claim 2, wherein The dual-mode SPAD array is a 10*20 dual-mode SPAD array for collecting and receiving laser signals with a wavelength of 400nm - 700nm.

4. The laser receiver according to claim 3, wherein The pixel pitch of the dual-mode SPAD array is 20 microns to 25 microns.

5. A laser ranging device, characterized in that, Comprising the laser receiver according to any one of claims 1-4, and a laser emitter.

6. The laser distance measuring device according to claim 5, characterized in that, Comprising a condenser lens, The condenser lens is arranged on the front side of the dual-mode SPAD array for receiving and concentrating the laser signal; The dual-mode SPAD array is used for receiving the laser signal passing through the condenser lens.

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