CN113419247A

CN113419247A - Laser detection system

Info

Publication number: CN113419247A
Application number: CN202010138563.2A
Authority: CN
Inventors: 欧阳奎; 王春晖
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-03-03
Filing date: 2020-03-03
Publication date: 2021-09-21

Abstract

The present application provides a laser detection system. Comprises in order from an object side to an image side: the image space telecentric lens comprises an image space telecentric lens, a first micro lens array, a convergent lens unit and a detector, wherein the focal plane of the image space telecentric lens is superposed with the focal plane of the first micro lens array; the number and the positions of the micro lens units included in the first micro lens array correspond to the number and the positions of the image points on the focal plane of the image-side telecentric lens; the converging lens unit is used for converging the laser beam collimated by the first micro lens array to the photosensitive surface of the detector; the converging lens unit is used for converging the laser beam collimated by the first micro lens array to the photosensitive surface of the detector; the detector is used for calculating and acquiring distance information of a target according to the light pulse of the laser beam converged on the photosensitive surface of the detector. The laser detection system provided by the application can effectively enlarge the detection field range of the laser detection system on the premise of ensuring the response speed of the laser detection system.

Description

Laser detection system

Technical Field

The present application relates to the field of laser detection technology, and more particularly, to a laser detection system.

Background

The laser radar is a radar system that detects a characteristic amount such as a position and a velocity of a target by emitting a laser beam. The working principle of the laser radar is that a laser radar transmitting end transmits a detection signal (laser beam) to a target, and a laser radar receiving end compares a received signal (target echo) reflected from the target with the transmitted signal and obtains related information of the target after appropriate processing. Such as distance, orientation, altitude, speed, attitude, shape, etc. of the target.

The laser radar is a core sensor in a new generation of vehicle-mounted sensing system. The laser radar has the characteristics of low cost, high reliability and high performance. In order to acquire information of the surrounding environment as much as possible, the lidar needs to have certain detection fields in the vertical and horizontal directions. The types of lidar mainly include: the laser radar system comprises a coaxial receiving and transmitting laser radar, a non-coaxial receiving and transmitting laser radar and a non-coaxial receiving and transmitting split type laser radar. The receiving end and the transmitting end of the non-coaxial transceiving split laser radar are separated, and the receiving end and the transmitting end work asynchronously. The receiving end of the non-coaxial receiving and transmitting split type laser radar receives light beams with different incidence angles reflected by the target, namely signal light beams reflected by the target with different view fields, and the whole view field to be detected can be covered through the combination of the plurality of view fields. Therefore, the receiving end of the non-coaxial transmitting-receiving split type laser radar is equivalent to a laser detection system with a large field of view.

The large-field laser detection system generally needs to adopt an area array detector or a detector with a larger photosensitive surface diameter to receive laser echo signals. However, the area array detector has high cost, and the detector with a large photosensitive surface diameter has slow response speed. In addition, the detector with the smaller diameter of the photosensitive surface has a smaller detection field of view, so that the detection requirement of the large-field-of-view laser radar cannot be met.

Therefore, a laser detection system with fast response speed and large detection field is needed.

Disclosure of Invention

The application provides a laser detection system, which is used for expanding the detection field range of the laser detection system on the premise of ensuring the response speed of the laser detection system.

In a first aspect, a laser detection system is provided, in order from an object side to an image side: the image space telecentric lens comprises an image space telecentric lens, a first micro lens array, a convergent lens unit and a detector, wherein the focal plane of the image space telecentric lens is superposed with the focal plane of the first micro lens array; the number and the positions of the micro lens units included in the first micro lens array correspond to the number and the positions of the image points on the focal plane of the image-side telecentric lens; the converging lens unit is used for converging the laser beam collimated by the first micro lens array to the photosensitive surface of the detector; the detector is used for calculating and acquiring distance information of a target according to the light pulse of the laser beam converged on the photosensitive surface of the detector.

Based on the above scheme, the laser detection system provided by the application combines the image space telecentric lens and the micro lens array (i.e. an example of the first micro lens array), and can effectively expand the detection field range of the laser detection system on the premise of ensuring the response speed of the laser detection system.

With reference to the first aspect, in certain implementations of the first aspect, the converging lens unit includes a spherical lens; alternatively, the condensing lens unit includes an aspherical lens.

With reference to the first aspect, in certain implementations of the first aspect, the converging lens unit includes a second microlens array.

With reference to the first aspect, in certain implementations of the first aspect, the convergent lens unit further comprises: the optical fiber array is positioned on the focal plane of the second micro lens array, the number and the positions of optical fiber units included in the optical fiber array correspond to the number and the positions of image points on the focal plane of the second micro lens array, and the optical fiber array is used for transmitting the laser beams focused by the second micro lens array to the surface of the detector.

With reference to the first aspect, in certain implementations of the first aspect, the detector is a detector having a photosurface with a diameter less than or equal to 1 mm.

With reference to the first aspect, in certain implementations of the first aspect, the detector is an area array detector, or the detector includes N discrete detector units, where N is a positive integer greater than or equal to 1.

With reference to the first aspect, in certain implementations of the first aspect, the detector is located at a focal plane of the converging lens unit.

With reference to the first aspect, in certain implementations of the first aspect, the laser detection system further includes: and the optical filter is positioned between the first micro-lens array and the converging lens unit.

With reference to the first aspect, in certain implementations of the first aspect, the filter is a narrowband filter.

With reference to the first aspect, in certain implementations of the first aspect, a mask material with light-absorbing properties is applied to gaps of the microlens units included in the first microlens array.

Drawings

Fig. 1 is a schematic diagram of an application scenario 100 suitable for use in embodiments of the present application.

Fig. 2 is a schematic diagram of an optical structure of a laser detection system 200 according to an embodiment of the present disclosure.

Fig. 3 is a schematic diagram of an optical structure of an image-side telecentric objective 301 suitable for use in the laser detection system provided by the present application.

Fig. 4 is a schematic diagram of an optical structure of a laser detection system 400 according to an embodiment of the present application.

Fig. 5 is a schematic diagram of an optical structure of a laser detection system 500 according to an embodiment of the present application.

Detailed Description

The technical solution in the present application will be described below with reference to the accompanying drawings.

For the purpose of facilitating an understanding of the present application, prior to describing embodiments of the present application, a brief description of related terms referred to in the present application will be provided.

1, image space telecentric optical path

The aperture diaphragm is positioned on the object space focal plane of the objective lens, the chief ray of the emergent light beam is parallel to the optical axis, the exit pupil is positioned at infinity, and the optical path is called as an image space telecentric optical path.

2, optical axis

The optical axis is the center line of the light beam (light pillar), or the axis of symmetry of the optical system.

3, diaphragm

An aperture is an edge, frame or specially provided apertured barrier of an optical element in an optical train assembly. The diaphragm is used to limit the imaging beam size or imaging spatial unit.

4, main beam (chief ray)

The main beam (chief ray) is the beam that the optical fiber exits from the edge of the object, passes through the center of the aperture stop and finally reaches the edge of the image.

5 field of view (FOV)

In an optical instrument, an angle formed by two edges of a lens, which is the maximum range in which an object image of a target to be measured can pass through, is called a field angle. The size of the field angle determines the field of view of the optical instrument, with a larger field angle providing a larger field of view and a smaller optical magnification.

6, space of object space

The space where the subject is located is an object space with the lens as a boundary.

7, image space

The space in which the light emitted by the object passes through the lens to form an image behind the lens is an image space.

8 diffraction Limit (diffraction Limit)

The diffraction limit means that an ideal object point is imaged by an optical system, and due to the diffraction limit, the ideal image point cannot be obtained, but a Fround and Fisher diffraction image is obtained. Since the aperture of a general optical system is circular, the images of Freund and Fischer diffraction are called Airy spots. Therefore, each object point is like a diffuse spot, two diffuse spots are not well distinguished after being close to each other, the resolution ratio of the system is limited, and the larger the spot is, the lower the resolution ratio is.

9, focal point

The focus refers to a convergence point of parallel light rays after being refracted by a lens or reflected by a curved surface mirror. The focal point includes an image-side focal point and an object-side focal point. The object-side focal point is an object position where an image is formed at infinity, and the image-side focal point is an image position where an object is formed at infinity.

10, focal plane

The plane passing through the focal point and perpendicular to the optical axis is called the "focal plane". The focal plane includes an object-side focal plane and an image-side focal plane. The focal plane at the object focus is called the "object focal plane". The focal plane at the image focus is called the "image focal plane".

11, positive lens (i.e. convex lens)

The positive lens is also called a convex lens because the middle is thick and the periphery is thin and is convex. The positive lens (i.e., convex lens) has the ability to converge light.

12, negative lens (i.e. concave lens)

The negative lens is thin in the middle and thick at the edge and is concave, so the negative lens is also called a concave lens. The negative lens (i.e., the concave lens) has a diverging effect on the light.

13, stray light

Stray light refers to harmful light projected onto an image plane through an optical system without participating in imaging.

14, microlens array

The micro lens array is an array composed of lenses with micron-sized clear aperture and relief depth. The micro lens array has basic functions of focusing, imaging and the like of a traditional lens. In addition, the microlens array has the characteristics of small unit size and high integration, so that the microlens array can complete the functions which cannot be completed by the traditional optical element and can form a plurality of novel optical systems.

15, object side

The side where the object is located is the object side with the lens as a boundary. The surface of the lens near the object side may be referred to as the object side surface.

16, the image side

The side where the image of the subject is located is the image side with the lens as a boundary. The surface of the lens near the image side may be referred to as the image side surface.

17, spherical lens

The light-transmitting surface of the spherical lens is spherical, and the center of the spherical lens to the edge of the lens has a constant curvature.

18, aspherical lens

The aspherical lens has an aspherical surface on a light-transmitting surface, and the curvature of the aspherical lens from the center to the edge of the lens is continuously changed.

Numerical Aperture (NA)

NA is a dimensionless number that measures the angular range of light that can be collected by an optical system.

20, a narrow band filter,

the narrow-band filter is subdivided from the band-pass filter, and is defined as the band-pass filter, that is, the filter allows the optical signal to pass through in a specific wavelength band, while the optical signal is blocked from both sides outside the specific wavelength band, and the passband of the narrow-band filter is relatively narrow.

21 beam diameter

The beam diameter is the diameter along a specified line perpendicular to and intersecting the beam axis.

22 effective pore diameter

The effective aperture refers to the ratio of the maximum aperture diameter of the lens to the focal length.

Time of flight ranging (TOF) 23

TOF is a method of obtaining a target distance by continuously transmitting light pulses to a target, receiving light returning from the target by a sensor, and detecting the time of flight (round trip) of the light pulses.

For the convenience of understanding, an application scenario applicable to the laser detection system provided by the embodiment of the present application is first described in detail with reference to fig. 1.

Fig. 1 shows a schematic diagram of an application scenario 100 suitable for use in an embodiment of the present application.

As shown in fig. 1, the application scenario 100 includes a laser detection system 110, a lidar controller 120, a laser transmitter 130 and a scanner 140, and an object 150.

The laser detection system 110 is composed of an image-side telecentric lens 101, a microlens array 102, a filter 103, a converging lens unit 104 and a detector 105. In other embodiments, the laser detection system may not include the filter 103. In other words, the laser detection system may include the image-side telecentric lens 101, the microlens array 102, the condenser lens unit 104, and the detector 105 in the laser detection system 110 as shown in fig. 1.

In the application scenario 100, the lidar controller 120 controls the laser transmitter 130 to emit a laser beam that is transmitted via the scanner 140. Wherein the scanner 140 can scan the target 150 under different fields of view. The target 150 diffusely reflects the laser beam emitted from the scanner 140. The laser detection system 110 receives a portion of the laser beam diffusely reflected by the target 150 and detects the target 150 based on the laser beam. Detection of the position and distance of the target 150 may be achieved, for example, from light pulses of a laser beam focused onto a photosensitive surface of the detector 105, in conjunction with TOF methods.

It should be understood that fig. 1 is only an illustration, but this should not constitute any limitation to the application scenario of the laser detection system provided in the embodiment of the present application.

Hereinafter, the laser detection system provided by the embodiment of the present application is described in detail with reference to fig. 2 to 5.

Example 1

Fig. 2 shows an optical structure schematic diagram of a laser detection system 200 provided in an embodiment of the present application.

As shown in fig. 2, for convenience of description, the left side of the laser detection system 200 is defined as the object side, and a surface of the lens facing the object side may be referred to as an object side surface, which may also be understood as a surface of the lens close to the object side. That is, in fig. 2, the lens surface on the left side of each lens is the object side surface. The right side of the laser detection system 200 is the image side. The surface of the lens facing the image side can be referred to as the image side surface, which can also be understood as the surface of the lens close to the image side. That is, in fig. 2, the right lens surface of each lens is an image side surface. From the object side to the image side, the laser detection system 200 sequentially includes: an image-side telecentric lens 201, a microlens array 202 (i.e., an example of a first microlens array), a filter 203, a condenser lens unit 204 (i.e., an example of a second microlens array), and a detector 205.

Optionally, the filter 203 may not be included in the laser detection system 200. That is, in another implementation, the laser detection system 200 sequentially includes, from the object side to the image side: an image-side telecentric lens 201, a microlens array 202, a converging lens unit 204, and a detector 205.

An image space telecentric lens 201, wherein the image space telecentric lens 201 is an optical device with an aperture stop placed on an object space focal plane of the lens, and a chief ray of an emergent beam of the image space telecentric lens 201 is parallel light. That is, after the light beams with different incident angles pass through the image-side telecentric lens 201, the chief rays of the light beams are parallel to the normal direction of the focal plane of the image-side telecentric lens 201. Wherein, the focal points at different positions on the focal plane of the image-side telecentric lens 201 represent the focal points obtained by different incident angles after passing through the image-side telecentric lens 201.

In the embodiment of the present application, the optical structure of the objective telecentric lens 201 is not particularly limited. The image-side telecentric lens 201 may include N lenses, where i positive lenses and N-i negative lenses, N is a positive integer greater than or equal to 1, and i is a positive integer greater than or equal to 1 and less than or equal to N. For example, the image-side telecentric lens 201 may include 7 lenses, the 7 lenses including 4 positive lenses and 3 negative lenses. For example, the image-side telecentric lens 201 may also include 7 lenses, and the 8 lenses include 5 positive lenses and 3 negative lenses. For example, the image-side telecentric lens 201 may further include 5 lenses, where the 5 lenses include 3 positive lenses and 2 negative lenses. For example, only 1 positive lens may be included in the image-side telecentric lens 201.

As shown in fig. 2, in one implementation, the image-side telecentric lens 201 includes 5 lenses. For convenience of description, the 5 lenses may be referred to as: lens 1, lens 2, lens 3, lens 4 and lens 5. Comprises in order from an object side to an image side: lens 1, lens 2, lens 3, lens 4 and lens 5. The lens 1 is a positive lens. The lens 2 is a negative lens. The lens 3 is a negative lens. The lens 4 is a positive lens. Lens 5 is a positive lens. Wherein, the positive lens is used for condensing light, and the negative lens is used for dispersing light.

Table 1 shows the radius of curvature and the thickness of each constituent lens of the image-side telecentric lens 201 in the embodiment of the present application, as shown in table 1.

TABLE 1

In table 1, STO denotes a stop surface, S1 denotes an object-side surface of the lens 1, S2 denotes an image-side surface of the lens 1, S3 denotes an object-side surface of the lens 2, S4 denotes an image-side surface of the lens 2, S5 denotes an object-side surface of the lens 3, S6 denotes an image-side surface of the lens 3, S7 denotes an object-side surface of the fourth lens 4, S8 denotes an image-side surface of the lens 4, S9 denotes an object-side surface of the lens 5, and S10 denotes an image-side surface of the lens 5. In table 1, positive and negative of the curvature radius indicate that the optical surface is convex toward the object side or the image side, positive indicates that the optical surface is convex toward the object side near the optical axis, and negative indicates that the optical surface is convex toward the image side near the optical axis. When the value of the curvature radius is infinite, the optical surface is a plane. For example, the radius of curvature of the diaphragm surface has an infinite value, i.e., the diaphragm surface is a plane.

According to the settings of the parameters of the lenses in table 1, the focal length of the image-side telecentric lens 201 is 40mm, the field angle is 50 °, the laser wavelength is 1064nm, and the total optical length is about 93.330 mm. The image space telecentric lens 201 has the characteristics of telecentric image space and large relative aperture.

As described above, the image space telecentric lens 201 including 5 lenses has a light path that a part of light beams diffusely reflected by the target object is converged after passing through the lens 1, the converged light beams are diverged after passing through the lens 2, the diverged light beams are further diverged by the lens 3 after passing through the optical billows, the further diverged light beams are converged after passing through the lens 4, and the converged light beams are further converged into an image point after passing through the lens 5. Therefore, after the light beams with different incident angles pass through the lenses 1 to 5, the echo light beam is shaped into a light beam with the principal ray parallel to the normal direction of the focal plane of the image-side telecentric lens 201, and the light beam is converged on the focal plane of the image-side telecentric lens 201.

Fig. 3 shows a schematic diagram of an optical structure of an image-side telecentric lens 301 suitable for use in the laser detection system provided by the present application. In another implementation, as shown in fig. 3, the image-side telecentric lens 301 includes only 1 lens, which is a positive lens. The curvature radius of the object side surface of the lens is 99mm, the thickness of the object side surface of the lens is 50mm, the curvature radius of the image side surface of the lens is infinite, the thickness of the image side surface of the lens is 100mm, and the distance between the diaphragm and the lens is 100 mm. In this case, the focal length of the image-side telecentric lens 301 is 133mm, the field angle is 20 °, the laser wavelength is 1064nm, and the total optical length is about 300 mm. The image space telecentric lens 301 has the characteristics of telecentric image space and large relative aperture.

It should be noted that the material of each lens included in the image-side telecentric lens 201 or the image-side telecentric lens 301 may be a plastic material, a glass material, or other materials that can meet the performance requirements of the lens, such as a composite material.

It should be understood that image-side telecentric lens 201 provided in fig. 2 and image-side telecentric lens 301 provided in fig. 3 are merely illustrative and do not constitute any limitation to the present application. Other configurations of image-side telecentric lenses may also be used in the laser detection system 200.

And a microlens array 202, wherein the focal plane of the microlens array 202 is coincident with the focal plane of the image-side telecentric lens 201, and the number and the positions of the microlens units included in the microlens array 202 correspond to the number and the positions of the image points on the focal plane of the image-side telecentric lens 201. The microlens array 202 serves to collimate a light beam (parallel light beam). That is, the divergent light beams pass through the microlens array 202 to form parallel light beams to be emitted. For example, the microlens array 202 receives the divergent light beam output by the image-side telecentric lens 201, and the divergent light beam passes through the microlens array 202 to output a light beam parallel to the normal direction of the focal plane of the image-side telecentric lens 201.

The number and the position of the microlens units included in the microlens array 202 correspond to the number and the position of the image points on the focal plane of the image-side telecentric lens 201 one by one. It is understood that the microlens array 202 includes microlens units having the same horizontal pitch as the horizontal pitch between the image points, and the microlens array 202 includes microlens units having the same vertical pitch as the vertical pitch between the image points. The image point is a spot point of the scanning beam focused on the focal plane after being subjected to diffuse reflection by the target and through the image telecentric lens.

In one implementation, the microlens array 202 includes the same number of microlens elements as the number of image points in the focal plane of the image-side telecentric lens 201. For example, the image-side telecentric lens 201 has S rows and Q columns of image points on the focal plane, and the microlens array includes S rows and Q columns of microlens units. The horizontal position and the vertical position of the microlens unit of the jth row and the kth column included in the microlens array are the same as those of the image point of the jth row and the kth column on the focal plane of the image-side telecentric lens 201. S and Q are positive integers greater than or equal to 1, j is less than or equal to S, and k is less than or equal to Q. The number S × Q of the image points on the focal plane of the image-side telecentric lens 201 may be greater than 200 according to different application scenes.

By way of example and not limitation, the telecentric lens 201 at the image side has 3 rows and 1 column of image points in the focal plane, and the microlens array includes 3 rows and 1 column of microlens elements. The horizontal positions and the vertical positions of the 1 st row and 1 st column microlens units included in the microlens array are the same as those of the 1 st row and 1 st column image points on the focal plane of the image-side telecentric lens 201; the horizontal and vertical positions of the microlens units of the 2 nd row and the 1 st column included in the microlens array are the same as those of the image points of the 2 nd row and the 1 st column on the focal plane of the image-side telecentric lens 201; the horizontal position and the vertical position of the microlens unit of the 2 nd row and the 1 st column included in the microlens array are the same as those of the image point of the 2 nd row and the 1 st column on the focal plane of the image-side telecentric lens 201.

In another implementation, the number of microlens units included in the microlens array 202 is greater than the number of image points on the focal plane of the image-side telecentric lens 201, which includes the following three cases:

the first condition is as follows: the microlens array 202 includes a larger number of rows of microlens elements than the number of rows of image points in the focal plane of the image-side telecentric lens 201. For example, the telecentric lens 201 on the image side has S rows and Q columns of image points on the focal plane, S is a positive integer greater than or equal to 1, and Q is a positive integer greater than or equal to 1. The microlens array comprises Y rows and Z columns of microlens units, Y is a positive integer greater than or equal to 1 and is greater than S, Q is a positive integer greater than or equal to 1 and is equal to Z.

By way of example and not limitation, the image-side telecentric lens 201 has 3 rows and 1 column of image points in the focal plane, and the microlens array includes 4 rows and 1 column of microlens elements. The horizontal positions and the vertical positions of the 1 st row and 1 st column microlens units included in the microlens array are the same as those of the 1 st row and 1 st column image points on the focal plane of the image-side telecentric lens 201; the horizontal and vertical positions of the microlens units of the 2 nd row and the 1 st column included in the microlens array are the same as those of the image points of the 2 nd row and the 1 st column on the focal plane of the image-side telecentric lens 201; the horizontal position and the vertical position of the microlens unit of the 3 rd row and the 1 st column included in the microlens array are the same as those of the image point of the 3 rd row and the 1 st column on the focal plane of the image-side telecentric lens 201. Or, the horizontal positions and the vertical positions of the microlens units in the 2 nd row and the 1 st column included in the microlens array and the image points in the 1 st row and the 1 st column on the focal plane of the image-side telecentric lens 201 are the same; the horizontal and vertical positions of the microlens units of the 3 rd row and the 1 st column included in the microlens array are the same as those of the image points of the 2 nd row and the 1 st column on the focal plane of the image-side telecentric lens 201; the horizontal position and the vertical position of the microlens unit of the 4 th row and the 1 st column included in the microlens array are the same as those of the image point of the 3 rd row and the 1 st column on the focal plane of the image-side telecentric lens 201.

Case two: the microlens array 202 includes a larger number of columns of microlens elements than the number of columns of image points in the focal plane of the image-side telecentric lens 201. For example, the telecentric lens 201 on the image side has S rows and Q columns of image points on the focal plane, S is a positive integer greater than or equal to 1, and Q is a positive integer greater than or equal to 1. The microlens array comprises Y rows and Z columns of microlens units, Z is a positive integer greater than or equal to 1, Z is greater than Q, Y is a positive integer greater than or equal to 1, and Y is equal to S.

By way of example and not limitation, the image-side telecentric lens 201 has 1 row and 2 columns of image points on the focal plane, and the microlens array includes 1 row and 4 columns of microlens elements. The horizontal positions and the vertical positions of the 1 st row and 1 st column microlens units included in the microlens array are the same as those of the 1 st row and 1 st column image points on the focal plane of the image-side telecentric lens 201; the horizontal and vertical positions of the microlens units of the 1 st row and the 2 nd column included in the microlens array are the same as those of the image points of the 1 st row and the 2 nd column on the focal plane of the image-side telecentric lens 201. Or, the horizontal positions and the vertical positions of the 1 st row and 2 nd column microlens units included in the microlens array and the 1 st row and 1 st column image points on the focal plane of the image-side telecentric lens 201 are the same; the microlens units of the 1 st row and the 3 rd column included in the microlens array are horizontally the same as the image point of the 1 st row and the 2 nd column on the focal plane of the image-side telecentric lens 201, and the vertical positions are the same.

Case three: the microlens array 202 includes a greater number of rows of microlens elements than the number of rows of image points in the focal plane of the image-side telecentric lens 201, and the microlens array 202 includes a greater number of columns of microlens elements than the number of columns of image points in the focal plane of the image-side telecentric lens 201. For example, the telecentric lens 201 on the image side has S rows and Q columns of image points on the focal plane, S is a positive integer greater than or equal to 1, and Q is a positive integer greater than or equal to 1. The microlens array comprises Y rows and Z columns of microlens units, Y is a positive integer greater than or equal to 1 and is greater than S, Q is a positive integer greater than or equal to 1 and is greater than Z.

By way of example and not limitation, the image-side telecentric lens 201 has 3 rows and 2 columns of image points in the focal plane, and the microlens array includes 4 rows and 3 columns of microlens elements. The horizontal positions and the vertical positions of the microlens units in the jth row and the kth column included in the microlens array are the same as those of the image points in the jth row and the kth column on the focal plane of the image-side telecentric lens 201. j is greater than or equal to 1 and less than or equal to 3, k is greater than or equal to 1 and less than or equal to 2. Or, the horizontal position and the vertical position of the microlens unit of the kth column in the j +1 th row included in the microlens array are the same as those of the image point of the kth column in the jth row on the focal plane of the image-side telecentric lens 201. j is greater than or equal to 1 and less than or equal to 3, k is greater than or equal to 1 and less than or equal to 2. Or, the horizontal position and the vertical position of the microlens unit of the (j + 1) th row and the (k + 1) th column included in the microlens array are the same as those of the image point of the (j) th row and the (k) th column on the focal plane of the image-side telecentric lens 201. j is greater than or equal to 1 and less than or equal to 3, k is greater than or equal to 1 and less than or equal to 2.

In the embodiment of the present application, the number, pitch, focal length, spherical surface or aspherical surface, etc. of the microlens units included in the microlens array 202 can be designed and selected according to the design parameters of the laser detection system 200.

Depending on the application scenario, a two-dimensional microlens array or a one-dimensional microlens array may be used as the microlens array 202 in the laser detection system 200. It should be understood that the two-dimensional microlens array may be a planar lens array of M rows × P columns, which refers to: the lens array is composed of M × P pieces of microlenses, each row of M pieces of microlenses has P rows of lens arrays, and M and P are positive integers greater than 1. When M or P is equal to 1, the array is a one-dimensional micro-lens array.

In the embodiment of the present application, the material of the microlens array 202 is not particularly limited. For example, the material of the microlens array 202 may be fused silica. For example, the material of the microlens array 202 may also be silicon. For example, the material of the microlens array 202 may also be a microlens array of other materials.

In the present embodiment, by combining the microlens array 202 and the image-side telecentric lens 201 having a very large effective received beam aperture, a very large beam diameter compression ratio (20 times or even more than 40 times) can be achieved, so that detection of a distant target (e.g., ranging, etc.) can be achieved. That is to say, the larger the zoom ratio of the microlens array 202 is, the larger the effective receiving aperture of the image-side telecentric lens 201 is, the stronger the effective echo signal received by the image-side telecentric lens 201 is, and the farther the distance of the detection target of the image-side telecentric lens 201 is.

For example, when the field of view of the image-side telecentric lens 201 is 40 ° × 20 °, and the angular intervals in the horizontal and vertical directions are both 0.2 °, the pixel point on the focal plane of the image-side telecentric objective lens is 200 × 100. If the effective focal length of the image-side telecentric objective lens is 40mm and the numerical aperture number NA is 0.124, the horizontal distance between any two adjacent lenses in the image-side telecentric objective lens is calculated to be 0.272 mm. The microlens array 202 is selected to include microlens elements having a diameter of 0.250mm, and an effective focal length of 1 mm. The diameter of the light beam at the output end of the microlens array 402 is 0.2mm, the ratio of the focal length of the image-side telecentric lens to the focal length of the microlens array is 40, then the diameter of the light beam received by the image-side telecentric lens 201 can be designed to be 8mm, and the compression ratio of the diameter of the light beam is 40. In this case, the image-side telecentric lens can detect the target at 160 m.

Optionally, in order to reduce stray light generated by the gaps of the microlens units included in the microlens array 202, a mask material with a very strong light-absorbing property may be coated on the gaps of the microlens units included in the microlens array 202. Since the black substance can absorb light of all colors, a black material can be used as the mask material with extremely strong light absorption property. For example, the black material may be a carbon nanotube material.

And the filter 203 is positioned between the micro-lens array 202 and the convergent lens unit 204.

Alternatively, the filter 203 may be attached to the microlens array 202.

Alternatively, the filter 203 may be closely attached to one end of the condensing lens unit 204.

Alternatively, the filters 203 may be integrated directly into the optical plane of the microlens array 202 in the form of a coated filter.

Alternatively, the optical filter 203 may be directly integrated into one side optical plane of the condensing lens unit 204 in the form of a coated filter film.

Alternatively, the filter 203 may be a narrowband filter. The size of the transmission bandwidth of the narrowband filter depends on the spectral width of the light beam. For example, the transmission bandwidth of the narrowband filter may be set to be less than or equal to 10 nm. Alternatively, the transmission bandwidth of the narrowband filter may be set to be less than or equal to 1 nm.

Alternatively, the filter 203 may be a filter having other spectral characteristics. For example, the filter 203 may be a spectral filter. For example, the filter 203 may be a cut filter. The filter 204 may also be a reflective filter, for example. Wherein, the transmission bandwidth of the filter depends on the spectral width of the light beam.

And a converging lens unit 204 positioned between the microlens array 202 and the detector 205. The converging lens unit 204 is used for converging the laser beam emitted from the micro lens array 202 to the photosensitive surface of the detector 205.

Optionally, the focal plane of the converging lens unit 204 is located coincident with the location of the photosensitive surface of the detector 205.

Alternatively, the converging lens unit 204 may be a spherical lens.

Alternatively, the condensing lens unit 204 may be an aspherical lens.

Alternatively, the condensing lens unit 204 may employ a plurality of lens combinations. The condensing lens unit 204 includes L lenses, L being a positive integer greater than or equal to 2. For example, the condensing lens unit 204 may include 2 lenses. For example, the converging lens unit 204 may also include 3 lenses. For example, the converging lens unit 204 may also include 5 lenses.

Alternatively, one end surface of the condensing lens unit 204 is a flat surface, and the other side is a convex surface. The plane may be integrated with the filter 203.

And the detector 205 is used for calculating and acquiring distance information of the target according to the light pulse of the laser beam converged on the photosensitive surface of the detector.

Optionally, detector 205 is located at the focal plane of converging lens unit 204.

The wavelength of the detector 205 is not particularly limited in the embodiment of the present application. For example, the detector 205 may be a photodetector with a wavelength of 1550nm, or may be a photodetector with other wavelengths such as 905nm, 1064nm, or visible light wavelength.

The type of the probe 205 is not particularly limited in the embodiment of the present application. For example, the detector 205 may be an Avalanche Photodiode (APD), a PIN photodiode (PIN PD), a photodiode array (PD), or an APD array. The detector 205 may also be of the area array type. For example, single photon avalanche photodiodes (SPADs), multi-pixel photon counters (MPPCs), and the like.

Alternatively, detector 205 may be a detector having a photosurface with a diameter less than or equal to 1 mm. For example, the diameter of the photosurface of detector 205 may be 0.25 mm. For example, the detector 205 may be an indium gallium arsenide (InGaAs) APD detector with a 1mm diameter photosurface and a 120MHz bandwidth. For example, detector 205 may be a detector with a 1mm diameter photosurface and a wavelength of 905 nm.

Alternatively, the detector 205 may be a large-area detector or an area array detector, in case of low response speed requirement or sufficiently large response speed of the optical detector itself.

The optical path principle of the laser detection system 200 provided in the embodiment of the present application is that after the image-side telecentric lens 201 receives the laser beam reflected by the target object (see fig. 2), the principal ray of each output laser beam is parallel to the normal vector of the focal plane of the image-side telecentric lens 201. After receiving the laser beams emitted by the image-side telecentric lens 201, the micro lens array 202 collimates each laser beam, and the light rays of each output laser beam are parallel to the normal vector of the focal plane of the image-side telecentric lens 201. The filter 203 is used for filtering stray light output by the microlens array 202. The converging lens unit 204 receives the laser beams transmitted through the filter 203, and converges each received laser beam on the photosensitive surface of the detector 205.

It should be noted that the shape of each lens, the degree of the concave-convex on the object side surface and the image side surface in fig. 2 are merely illustrative, and the embodiment of the present application is not limited at all. The embodiment of the application does not limit the concave-convex part, the size and the like of the part of the object side surface and the image side surface far away from the optical axis.

In the laser detection system 200 provided in the first example, the laser beam (detection signal) reflected by the target is received by using the image-side telecentric lens 201. As shown in fig. 2 and fig. 3, each light beam emitted from image-side telecentric lens 201 is a light beam whose chief ray is parallel to the normal direction of the chief ray parallel to the focal plane of image-side telecentric lens 201, and a detector with a larger surface element is required to completely receive each light beam. However, the large-area detector has the problems of low response speed, small signal-to-noise ratio, high cost and the like. To solve the above problem, in example one, by combining the image-side telecentric lens 201, the microlens array 202, and the condenser lens unit 204, a small-area detector is realized to detect a large field of view. Specifically, by combining the image-side telecentric lens 201 with the microlens array 202, an extremely high beam diameter zoom ratio (20 times or even more than 40 times) can be achieved. For the microlens array 202 with a fixed size, the larger the scaling ratio of the beam diameter, the larger the effective receiving aperture of the image-side telecentric lens 201, the stronger the echo signal received by the image-side telecentric lens 201, and the farther the distance of the detection target of the image-side telecentric lens 201. Further, in the laser detection system 200, the collimated beam of the large spot emitted from the microlens array 202 is focused on the photosensitive surface of the detector 205 (small-area detector) using the condensing lens unit 204. Because the large light spot light beam is a collimated light beam, the circle of confusion of the focused light spot reaches the level of near diffraction limit, so that an ideal point light spot can be focused on the photosensitive surface of the detector, and the ideal point light spot has smaller size and can be completely received by the small surface element detector.

The laser detection system 200 provided in the first example can effectively extend the detection range and the detection distance of the detection system on the premise of ensuring the response speed of the laser detection system.

Example two

Fig. 4 shows an optical structure schematic diagram of a laser detection system 400 provided by the embodiment of the present application.

As shown in fig. 4, for convenience of description, the left side of the laser detection system 400 is defined as the object side, and a surface of the lens facing the object side may be referred to as an object side surface, which may also be understood as a surface of the lens near the object side. That is, in fig. 4, the lens surface on the left side of each lens is the object side surface. The right side of the laser detection system 400 is the image side. The surface of the lens facing the image side can be referred to as the image side surface, which can also be understood as the surface of the lens close to the image side. That is, in fig. 4, the right lens surface of each lens is the image side surface. From the object side to the image side, the laser detection system 400 sequentially includes: an image-side telecentric lens 401, a first microlens array 402, a filter 403, a second microlens array 404 (i.e., one example of a converging lens unit), and a detector 405.

Optionally, the laser detection system 400 may not include the filter 403. That is, in another implementation, the laser detection system 400 includes, in order from an object side to an image side: an image-side telecentric lens 401, a first microlens array 402, a second microlens array 404, and a detector 405.

In the embodiment of the present application, the optical structure of the objective telecentric lens 401 is not particularly limited.

In one implementation, image-side telecentric lens 401 is structurally and functionally identical to image-side telecentric lens 201 of fig. 2. For brevity, detailed description is not provided herein.

In another implementation, image-side telecentric lens 401 is structurally and functionally identical to image-side telecentric lens 201 of fig. 2. For brevity, detailed description is not provided herein.

It should be understood that image-side telecentric lens 401 provided in fig. 4 and image-side telecentric lens 301 provided in fig. 3 are merely illustrative and do not constitute any limitation to the present application. Other configurations of image-side telecentric lenses may also be used in the laser detection system 400.

The first microlens array 402 has the same structure and function as the microlens array 202 in fig. 2. For brevity, detailed description is not provided herein.

The filter 403 and the filter 403 have the same structure and function as the filter 204 in fig. 2. For brevity, detailed description is not provided herein.

The specification of the second microlens array 404 is not particularly limited in the present application. The second microlens array 404 may be the same size microlens array as the first microlens array 402, or different sizes microlens array may be selected according to the requirements of the laser detection system. For example, the second microlens array 404 includes a microlens unit having a size corresponding to the size of N microlens units included in the microlens array 402 in fig. 4, where N is a positive integer greater than or equal to 2.

Alternatively, the second microlens array 404 may be closely attached to the first microlens array 402 and the filter 403.

Alternatively, the second microlens array 404 and the first microlens array 402 may be combined into a double-sided microlens array without the addition of the filter 403.

Through the second microlens array 404, optical signals of different fields of view can be incident on different detector units of the detector 405, so that synchronous receiving and processing of signal light of different fields of view can be realized, scanning and receiving efficiency of the system is improved, interference between signal light of different fields of view can be avoided, and signal-to-noise ratio is further improved.

A detector 405, wherein the detector 405 may be a detector array or an area array detector. When the detector 405 is a detector array or an area array detector, the number and the positions of the detector units included in the detector 405 correspond to the number and the positions of the image points included in the focal plane of the second microlens array 404, and it is understood that the horizontal spacing between the detector units included in the detector 405 is the same as the horizontal spacing between the image points included in the focal plane of the second microlens array 404, and the horizontal spacing between the detector units included in the detector 405 is the same as the vertical spacing between the image points included in the focal plane of the second microlens array 404. If the focal plane of the second microlens array includes M rows and N columns of image points, the detector 405 may include at least M rows and N columns of detectors, in other words, the detector 405 includes at least M rows and N columns of detectors to form a side detector array or an area array detector.

Optionally, detector 405 is located at the focal plane of converging lens unit 404.

In one implementation, the detector 405 includes the same number of detector cells as the number of image points included on the focal plane of the second microlens array 404.

By way of example and not limitation, the second microlens array 404 includes 2 rows and 1 column of image points in the focal plane, and the detector 405 may include 2 rows and 1 column of detector cells. The horizontal position and the vertical position of the 1 st row and 1 st column image point included in the focal plane of the second microlens array are the same as those of the 1 st row and 1 st column detector unit included in the detector 405. The image point of row 2 and column 1 included in the focal plane of the second microlens array has the same horizontal position and the same vertical position as the detector unit of row 2 and column 1 included in the detector 405.

In another implementation, the detector 405 includes a greater number of detector cells than the number of image points included on the focal plane of the second microlens array 404.

By way of example and not limitation, the second microlens array 504 includes 2 rows and 1 column of image points in the focal plane, and the detector 405 may include 3 rows and 2 columns of fiber units. The horizontal position and the vertical position of the image point of the jth row and kth column included on the focal plane of the second microlens array are the same as those of the optical fiber unit of the jth +1 row and kth column included in the detector 405, j may be equal to 1 or 2, and k may be equal to 1. Alternatively, the image point of the jth row and kth column included in the focal plane of the second microlens array has the same horizontal position and the same vertical position as the optical fiber unit of the jth +1 row and kth +1 column included in the detector 405.

Alternatively, the detector 405 may be located at the focal plane of the second microlens array.

Alternatively, the detector 405 may be located near the focal plane of the second microlens array. For example, the position may be determined based on the remaining of the effective photosensitive area of the detector 405 relative to the spot size.

It should be understood that the laser detection system 400 provided in fig. 4 is merely illustrative, and should not be construed as limiting the laser detection system provided in the practice of the present application in any way.

The laser detection system 400 provided in example two can effectively expand the detection range of the detector on the premise of ensuring the response speed of the laser detection system. Compared with the first example, the second microlens array 404 is adopted in the laser detection system 400, the second microlens array can inject light beam signals of different fields of view onto different detector units of the detector 405, and the laser detection system 400 can synchronously receive and process the light signals of different fields of view, so that the scanning and detection efficiency of the laser detection system is improved. Meanwhile, the interference between signal lights among different fields of view can be avoided, and the signal-to-noise ratio of the laser detection system is further improved.

Example three

Fig. 5 shows an optical structure schematic diagram of a laser detection system 500 provided in an embodiment of the present application.

As shown in fig. 5, for convenience of description, the left side of the laser detection system 500 is defined as the object side, and a surface of the lens facing the object side may be referred to as an object side surface, which may also be understood as a surface of the lens close to the object side. That is, in fig. 5, the lens surface on the left side of each lens is the object side surface. The right side of the laser detection system 500 is the image side. The surface of the lens facing the image side can be referred to as the image side surface, which can also be understood as the surface of the lens close to the image side. That is, in fig. 5, the right lens surface of each lens is the image side surface. From the object side to the image side, the laser detection system 500 sequentially includes: the image space telecentric lens system comprises an image space telecentric lens 501, a first micro lens array 502, a filter 503, a second micro lens array 504, an optical fiber array 506 and a detector 505.

Optionally, the filter 503 may not be included in the laser detection system 500. That is, in another implementation, the laser detection system 500 sequentially includes, from the object side to the image side: an image-side telecentric lens 501, a first microlens array 502, a second microlens array 504, a fiber array 506, and a detector 505.

In the embodiment of the present application, the optical structure of the objective telecentric lens 501 is not particularly limited.

In one implementation, image-side telecentric lens 501 is structurally and functionally identical to image-side telecentric lens 201 of fig. 2. For brevity, detailed description is not provided herein.

In another implementation, image-side telecentric lens 501 is structurally and functionally identical to image-side telecentric lens 301 of fig. 3. For brevity, detailed description is not provided herein.

It should be understood that image-side telecentric lens 501 provided in fig. 5 and image-side telecentric lens 301 provided in fig. 3 are merely illustrative and do not constitute any limitation to the present application. Other configurations of image-side telecentric lenses may also be used in the laser detection system 500.

The first microlens array 502 has the same structure and function as the microlens array 202 in fig. 2. For brevity, detailed description is not provided herein.

The filter 503 has the same structure and function as the filter 203 in fig. 2. For brevity, detailed description is not provided herein.

The second microlens array 504 has the same structure and function as the second microlens array 405 in fig. 4. For brevity, detailed description is not provided herein.

It should be noted that the second microlens array 504 can converge the parallel light beams emitted from the optical filter 503 or the first microlens array 502 onto the fiber end face of the fiber array 506. The fiber array 506 can input light beams incident on the end face of the fiber array onto the photosensitive surface of the detector 505. Thus, the second microlens array 504 and the optical fiber array 506 can be regarded as one body, i.e., one side of the condensing lens unit.

A detector 505, wherein the detector 505 may be a detector array formed by combining a plurality of discrete facet element detectors. Wherein the spatial position of the discrete multiple facet element detectors comprised by the detector 505 is flexibly selectable. For example, detector 505 includes 2 discrete facet element detectors, where the position of the 1 st detector may be different from the position of the 2 nd detector. For example, detector 505 includes 3 discrete small facet detectors, where the position of the 1 st detector, the position of the 2 nd detector, and the position of the 3 rd detector are different.

Alternatively, the detector 505 may be a small facet detector having a diameter less than or equal to 1 mm. For example, the diameter of the photosurface of detector 205 may be 0.25 mm. For example, detector 205 may be an InGaAs APD detector with a 1mm diameter photosurface and a 120MHz bandwidth. For example, detector 205 may be a detector with a 1mm diameter photosurface and a wavelength of 905 nm.

Alternatively, the detector 505 may be an area array detector.

And an optical fiber array 506 located at the focal plane of the second microlens array 504. The fiber array 506 includes a plurality of fiber input ports and a plurality of fiber output ports. The fiber array 506 includes fiber units corresponding in number and position to the number and position of image points on the focal plane of the second microlens array 504.

The number and the positions of the optical fiber units included in the optical fiber array 506 correspond to the number and the positions of the image points on the focal plane of the second microlens array 504, and it is understood that the horizontal pitch between the optical fiber units included in the optical fiber array 506 is the same as the horizontal pitch between the image points included in the focal plane of the second microlens array 504, and the horizontal pitch between the optical fiber units included in the optical fiber array 506 is the same as the vertical pitch between the image points included in the focal plane of the second microlens array 504. If the focal plane of the second microlens array includes M rows and N columns of image points, the detector 405 may include at least M rows and N columns of detectors, in other words, the detector 405 includes at least a side detector array or an area array detector formed by M rows and N columns of detectors, where M and N are positive integers greater than or equal to 1.

In one implementation, fiber array 506 includes the same number of fiber units as the number of image points included on the focal plane of second microlens array 404.

By way of example and not limitation, the second microlens array 504 includes 2 rows and 1 column of image points in the focal plane, and the fiber array 506 may include 2 rows and 1 column of fiber units. The horizontal position and the vertical position of the image point of the 1 st row and the 1 st column included on the focal plane of the second microlens array are the same as those of the optical fiber unit of the 1 st row and the 1 st column included in the optical fiber array 506. The horizontal position and the vertical position of the 2 nd row and 1 st column optical fiber unit included in the optical fiber array 506 are the same as the horizontal position and the vertical position of the 2 nd row and 1 st column optical fiber unit included in the focal plane of the second microlens array.

In another implementation, fiber array 506 includes a greater number of fiber units than the number of image points included on the focal plane of second microlens array 404.

By way of example and not limitation, the second microlens array 504 includes 2 rows and 1 column of image points in the focal plane, and the fiber array 506 may include 3 rows and 2 columns of fiber units. The horizontal position and the vertical position of the image point of the jth row and the kth column included on the focal plane of the second microlens array are the same as those of the optical fiber unit of the jth +1 row and the kth column included in the optical fiber array 506, j may be equal to 1 or 2, and k may be equal to 1. Alternatively, the image point of the jth row and kth column included in the focal plane of the second microlens array is the same as the horizontal position and the vertical position of the optical fiber unit of the jth +1 row and kth +1 column included in the optical fiber array 506.

Alternatively, the second microlens array 504 and the fiber array 506 may be combined into a single body to form a collimator array.

Alternatively, in the case that the laser detection system 500 does not include the filter 503, the second microlens array 504, the first microlens array 502, and the optical fiber array may be combined into a collimator array. For example, combining the second microlens array 504 with the first microlens array 502 into a double-sided microlens array, and then combining the double-sided microlens array with the fiber array 506 into a collimator array, further reduces the volume of the laser detection system 500.

The fiber array 506 is used for effectively coupling the laser beam emitted by the second microlens array 504 into the fiber channel and transmitting the laser beam to the surface of the detector 505. For example, the laser beam passing through the second microlens array 504 may be directly incident on the photosensitive surface of the detector 505 through the fiber array 506. Alternatively, the laser beam passing through the second microlens array 504 enters the fiber array 506, and then the optical fibers of the plurality of channels are focused by the multi-fiber head, and then enter the photosensitive surface of the detector 505 after being focused by the lens.

It should be understood that the laser detection system 500 provided in fig. 5 is merely illustrative, and should not be construed as limiting the laser detection system provided in the practice of the present application in any way.

The laser detection system 500 provided in example three operates on the principle that parallel laser beams can be obtained after laser beams of different fields of view pass through the image-space telecentric lens 501, the first microlens array 502 and the optical filter 503. The parallel laser beams are focused by the second microlens array 504, coupled to different fiber channels of the fiber array 506, and output to the photosensitive surface of the detector 505. The detector 505 can detect the target object according to the light spot on the light sensitive thereof.

The laser detection system 500 provided in example three can effectively expand the detection range of the detector on the premise of ensuring the response speed of the laser detection system. In contrast to example two, an optical fiber array 506 is placed between the second microlens array 504 and the detector 505 of the laser detection system 500. After the optical fiber array 506 is adopted, the detectors 505 can flexibly select the number of the detectors 505 and the spatial positions of the detectors 505 included in the laser detection system 500 according to the signal-to-noise ratio index of the laser detection system 500 and the cost and the assembly difficulty of the detectors, so as to adapt to the installation of various scenes.

It should be noted that, due to the limitation of the manufacturing process, the actual product cannot be absolutely parallel, absolutely perpendicular, absolutely coincident, and absolutely the same spacing. So in the embodiments of the present application, the term parallel is also understood to mean approximately parallel, perpendicular to the perpendicular to the perpendicular to the substrate.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A laser detection system, in order from an object side to an image side, comprising: an image space telecentric lens, a first micro lens array, a convergent lens unit and a detector,

the focal plane of the image space telecentric lens is superposed with the focal plane of the first micro lens array;

the number and the positions of the microlens units included in the first microlens array correspond to the number and the positions of the image points on the focal plane of the image-side telecentric lens;

the converging lens unit is used for converging the laser beam collimated by the first micro lens array to the photosensitive surface of the detector;

and the detector is used for calculating and acquiring distance information of the target according to the light pulse of the laser beam converged on the photosensitive surface of the detector.

2. The laser detection system of claim 1,

the converging lens unit includes a spherical lens; alternatively, the first and second electrodes may be,

the condensing lens unit includes an aspherical lens.

3. The laser detection system of claim 1,

the condensing lens unit includes a second microlens array.

4. The laser detection system of claim 3,

the condensing lens unit further includes: the optical fiber array is positioned on the focal plane of the second micro lens array, the number and the positions of optical fiber units included in the optical fiber array correspond to the number and the positions of image points on the focal plane of the second micro lens array, and the optical fiber array is used for transmitting the laser beams focused by the second micro lens array to the surface of the detector.

5. A laser detection system as claimed in claim 2 or 4 wherein the detector is a detector having a photosurface with a diameter less than or equal to 1 mm.

6. The laser detection system according to claim 3 or 5, wherein the detector is an area array detector, or the detector comprises N discrete detector units, N being a positive integer greater than or equal to 1.

7. A laser detection system according to any of claims 1-3 wherein the detector is located at the focal plane of the converging lens unit.

8. The laser detection system of any one of claims 1-7, further comprising:

an optical filter positioned between the first microlens array and the converging lens unit.

9. The laser detection system of claim 8, wherein the filter is a narrowband filter.

10. A laser detection system as claimed in any one of claims 1 to 9 wherein a masking material having light absorbing properties is applied to the interstices of the microlens elements comprised by the first microlens array.