CN107589541B - Image scanning system and laser beam module thereof - Google Patents

Abstract

The invention discloses an image scanning system and a laser beam module thereof, wherein the concentricity of a lens of the laser beam module and a rotating shaft of a scanning motor is adjustable, so that the position of the lens is finely adjusted in a direction vertical to an optical axis, and further, the symmetry of scanning beams relative to the rotating shaft is ensured. The laser beam module of the image scanning system comprises a laser and a lens barrel, wherein one or more lenses used for adjusting light beams emitted by the laser to generate scanning light beams are arranged in the lens barrel, the laser beam module further comprises a light beam module support used for being arranged on a scanning motor support of the image scanning system, and the lens barrel can be movably arranged on the light beam module support along the direction perpendicular to the optical axis of the laser beam module.

Description

Image scanning system and laser beam module thereof

Technical Field

The invention relates to the field of computer X-ray photography imaging, in particular to a laser beam module of a system for scanning image information recorded by an image plate by using laser.

Background

Computed Radiography (CR) has been widely used in the medical health field, and is mainly characterized by using a flexible, erasable Image Plate (IP) instead of a silver halide film, and storing and displaying image information with a computer, compared to the conventional X-ray Radiography technology.

The X-ray penetrating object is irradiated onto an Image plate containing photo-excited fluorescent powder, and a Latent Image (Latent Image) is generated and stored in the Image plate. When irradiated by laser with a certain wavelength (600-700 nm), the imaging plate can excite fluorescence with a specific wavelength (350-450 nm), the energy distribution characteristic of the fluorescence is completely related to the form of the latent image, and the fluorescence is collected, converted into an electric signal and digitized, so that the latent image is converted into a two-dimensional digital image which can be stored and transmitted.

The imaging method has the advantages of fast imaging speed, wide display dynamic range, reusability of the film and the like compared with the traditional film imaging method. An optical scanning system, which is one of the core components, is related to the speed of the entire imaging process and the image quality.

In general, image reading methods such as point scanning, line scanning, and surface scanning can be used in the optical system of the CR scanner. The point scanning is to scan the image plate with a beam of converging light to form a scanning track and collect fluorescent signals excited by the laser spots at certain time intervals (0.75 mu s). The line scanning can acquire the latent image information of the image plate line by adopting a line light source, and then the fluorescent signals acquired by each line are decoupled to obtain the latent image information of each point. The surface scanning can be understood as a common image pickup process, a laser light source is a surface light source, fluorescence on the whole image plate surface excited by the surface scanning is collected by an area array consisting of a large number of sensors, and image information of each pixel point is obtained through complex decoupling calculation.

Whether line scanning or surface scanning is performed, a CCD (Charge-coupled Device) or a CCD CMOS (Complementary Metal Oxide Semiconductor) is required as an image capturing Device, each photosensitive unit receives a line signal (line scanning) or a surface signal (surface scanning) from an image board, and then a physical minimum display unit is divided at a certain space interval, and a latent image signal of each display unit is obtained through decoupling calculation. To obtain high resolution, high gray scale image signals requires that the image acquisition device have a sufficient number of photosensitive elements and a wide dynamic range and accurate and fast calculation process.

The imaging mechanism is not essentially different in point, line and surface scanning, but only slightly different in implementation, and particularly the line scanning and surface scanning are basically the same in implementation principle and mode. The point scanning directly reads the latent image information of each point by using the image acquisition equipment or PMT (PhotoMultiplier Tube), so that the signal of each pixel point can be obtained more accurately in theory, and the image information can be reflected more truly.

The point scanning mode adopted at present can be realized in several different modes, and the typical main modes are as follows:

rotary mirror scanning system

The rotary mirror scanning system is the simplest in structure, and the rotating speed of the servo motor is relatively low (50% of that of the prism scanning system); due to structural symmetry, the speed stability is also good; the optical path is reflected once, the optical loss is small, and the optical fiber is widely applied to the fields of measurement, 3D imaging and the like. But the machining and mounting requirements are very stringent, which also limits their application in the field of precision scanning.

Galvanometer scanning system

The galvanometer scanning system is widely applied to a laser marking machine, can be purchased directly, can perform 1D scanning and 2D scanning, and is flexible in design of an image plate feeding module. In terms of economy, the accuracy requirement is mainly limited, and the linearity of the scanning speed can only reach about 99.9%, which cannot meet the requirements for the accuracy of 20 mu m of the scanning spot diameter and the scanning speed of 5 s.

Prism scanning system

The prism scanning system is relatively simple in structure, main parts can be purchased directly (part of the process can be customized), and the processing and installation requirements on the pentaprism are low. The speed linearity of a single servo motor is an order of magnitude higher at equivalent cost to that of a galvanometer.

The pentaprism scanning system described in patent US 2009/0267006 A1 and US 6,599,014 B2 (hereinafter referred to as AB type) has obvious disadvantages for the design of the optical path, mainly but not limited to: the divergence angles of the light beams emitted by the laser light source in two mutually perpendicular directions are different, so that the light beams are not symmetrical about the scanning rotation axis, and the light beams are in flat elliptic light spots on the imaging surface, the energy distribution range is not concentrated, and fluorescence in adjacent areas is easily excited, so that the resolution is reduced.

Disclosure of Invention

In view of the foregoing, an object of the present invention is to provide an image scanning system and a laser beam module thereof, wherein concentricity of a lens of the laser beam module and a rotation axis of a scanning motor is adjustable, so that the lens is finely adjusted in a direction perpendicular to an optical axis, and further symmetry of a scanning beam with respect to the rotation axis is ensured.

In order to achieve the above purpose, the invention adopts a technical scheme that:

the laser beam module of the image scanning system comprises a laser and a lens barrel, wherein one or more lenses used for adjusting light beams emitted by the laser to generate scanning light beams are arranged in the lens barrel, the laser beam module further comprises a light beam module support used for being arranged on a scanning motor support of the image scanning system, and the lens barrel can be movably arranged on the light beam module support along the direction perpendicular to the optical axis of the laser beam module.

Preferably, the light beam module support comprises a body used for being installed on a scanning motor support of the image scanning system and an inner tube used for being connected with the lens barrel, the body is hollow, the inner tube is movably inserted in the body along the direction perpendicular to the optical axis, the laser beam module further comprises a second jackscrew movably penetrating through the side wall of the body, and the inner end of the second jackscrew is abutted with the inner tube to drive the inner tube to move.

More preferably, the laser beam module further includes a second elastic member for resetting the inner tube.

Further, the laser beam module further comprises a second wedge block movably arranged on the body so as to limit one end part of the inner tube between the body and the second wedge block, and the second elastic piece is a pressure spring arranged between the inner tube and the second wedge block or between the body.

More preferably, the lens barrel is movably disposed on the inner tube along an optical axis of the laser beam module, and the inner tube is movably disposed on the body along a direction perpendicular to the optical axis.

Further, the beam module support and the inner tube are connected with the optical axis in parallel or collinear screw threads through the central line.

Furthermore, the lens cone is provided with external threads, the inner tube is provided with matched internal threads, and the lens cone is arranged in the inner tube and is connected with the internal threads through the external threads.

Preferably, the laser beam module further comprises a light source base arranged on the lens cone and a laser mounting seat arranged on the light source base, the laser is arranged on the laser mounting seat, the light source base can be arranged on the lens cone in a horizontal direction in a movable mode, and the laser mounting seat can be arranged on the light source base in a movable mode along an optical axis.

Preferably, the lens barrel is internally provided with a second lens for collimating the light beam to form a parallel light beam and a third lens for focusing the light beam to form a scanning light beam, and a first lens for adjusting the divergence angle of the light beam emitted by the laser to be consistent to form a cone-shaped light beam with rotational symmetry is arranged between the laser and the second lens.

The invention adopts another technical scheme that:

an image scanning system is provided with the laser beam module.

By adopting the technical scheme, the invention has the following advantages compared with the prior art:

the lens barrel can move along the direction perpendicular to the optical axis relative to the light beam module support, that is to say, the concentricity of the lens and the rotating shaft of the scanning motor can be finely adjusted, so that the position of the lens is finely adjusted in the direction perpendicular to the optical axis, and further, the symmetry of the scanning light beam relative to the rotating shaft is ensured, light spots projected onto the image plate are circular, the energy distribution range is concentrated, and the problem of resolution reduction caused by fluorescence excited out of adjacent areas is avoided.

Drawings

FIG. 1 is a block diagram showing an image scanning system;

fig. 2 shows a perspective view of an optical scanning device according to the present invention;

FIG. 3a shows a partial schematic view of a laser beam module according to the present invention prior to assembly;

FIG. 3b shows a partial schematic view of a laser beam module in assembly according to the present invention;

FIG. 3c shows a partial schematic view of a laser beam module according to the present invention after assembly;

FIG. 4a shows a schematic diagram of the structure of an F-theta lens package according to the present invention;

FIG. 4b shows a schematic mirror view of a lens system according to the present invention;

FIG. 5 shows a schematic diagram of an F-theta lens package according to the present invention;

FIG. 6a shows a schematic diagram of a light collector assembly according to the present invention;

FIG. 6b shows a schematic diagram of a light collector assembly and F-theta lens assembly according to the present invention;

FIG. 7 shows a schematic diagram of a prior art collector assembly;

FIG. 8 shows a schematic view of another optical collector assembly according to the present invention;

FIG. 9 shows a schematic diagram of a further optical collector assembly and F-theta lens assembly according to the present invention;

FIG. 10 shows a schematic diagram of a fourth optical collector assembly and F-theta lens assembly according to the present invention.

In the above-mentioned figures of the drawing,

1. a laser beam module; 101. a laser driving circuit; 102. a laser diode; 103. an O-ring; 104. a laser mounting base; 104a, a first stepped hole; 104b, a first step surface; 104c, a second step hole; 104d, a second step surface; 104e, a third step hole; 105. a light source base; 105a, a first inclined plane; 106. a lens barrel; 107. a first jackscrew; 107a, a second inclined plane; 108. a first wedge block; 108a, a second inclined plane; 109. a pressure spring; 110. a body; 111. an inner tube; 111a, a third inclined plane; 112. a second jackscrew; 112a, a fourth incline; 113. a second wedge block; 113a, a fourth inclined plane; 114. a pressure spring;

121. a first lens; 122. a second lens; 133. a third lens;

2. a light reflection module; 20. a pentaprism; 21. a motor; 22. a motor bracket;

3. an F-theta lens group; 30. a lens system; 31. a sleeve; 32a, sleeve jackscrews; 32b, sleeve jackscrews; 33. a sleeve pressure spring; 34. a sleeve adjusting block;

4. a light collector assembly; 40. a light collector; 401. a reflective film; 402. a collection window; 41. a transflector; 42. a light filter; 43. PMT; 44. a reflection cylinder;

5. an image plate.

Detailed Description

Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art. The description of these embodiments is provided to assist understanding of the present invention, but is not intended to limit the present invention. In addition, technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.

The present invention provides an image scanning system and a laser beam module thereof, the image scanning system is used for scanning a computer X-ray photographic image, and the optical scanning system is a core optical component for the image scanning system.

Referring to fig. 1, the optical scanning device continuously and rapidly scans an image plate driven by a stepping motor point by point under the driving of a servo motor with a rotating mirror by emitting laser with a certain wavelength (600-700 nm), the image plate records latent images of tooth images, can be excited to emit fluorescence with a certain wavelength (350-450 nm), and then the fluorescence is collected to a PMT through a fluorescence collecting device (light collector) to complete signal collection, photoelectric conversion and A/D conversion. The latent image recorded on the image plate is converted into digital information, and a two-dimensional image is synthesized and output to the workbench.

In fig. 1, the image plate transmission module mainly includes:

the motor #1 and the driving and controlling circuit #1 thereof, wherein the motor #1 can be a stepping motor or other motors capable of realizing accurate rotation or movement and is used for driving the whole executing mechanism to drive the image plate to move at a constant speed; the motor driving and controlling circuit #1 is used for driving and controlling the motor #1 to realize accurate speed control;

the motion executing mechanism is used for driving the image plate to move at a constant speed under the drive of the motor # 1; the image plate can be kept relatively static through a magnetic attraction, negative pressure, viscous silica gel or a compression form and an executing mechanism; and

the position sensor consists of a plurality of groups of photoelectric pairs or photodiodes, can detect whether the image plate is inserted into or removed from the scanning device, and can perform initial zero positioning on each row of image scanning; the position detection circuit is used for driving the position sensor to work and detecting effective signals.

The main functions of the optical scanning device are: starting a laser to output a laser beam with stable power, focusing the light speed to a certain spot size, vertically incident the laser beam onto a small area on an image plate, and exciting a fluorescent signal in proportion to the gray value of the latent image in the area; the excited fluorescent signals are collected through an optical path, subjected to photoelectric conversion, A/D conversion and the like, and converted into digital signal streams in an equal proportion; the laser beam must pass through a mirror reflection device, and the device can rotate at high speed under the drive of a motor, so that the scanning of all areas on the image plate is realized. Referring to fig. 1, the optical scanning device of the present invention mainly includes:

the laser provides a light source for image scanning, the laser outputs red light, the wavelength of the light is 600 nm-700 nm, and a helium-neon laser or a semiconductor laser with specific wavelength can be selected to be used; the laser driving circuit provides constant current driving for the laser and ensures the temperature stability of the laser;

the laser adjusting light path consists of a group of lenses and a supporting structure thereof and is used for adjusting an output light source of the laser to ensure that the size of a light spot projected on the image plate is continuously stable within a required range, for example, the light spot is smaller than 50 microns;

the scanning motor is used for driving laser to adjust a light path, particularly driving a light reflecting mirror in the light path to rotate, so that the laser can continuously and uniformly scan along the circumference; the motor driving and controlling circuit #2 is used for driving the motor #2 to run and providing speed precision control;

the fluorescence collecting light path, the laser facula projects to the corresponding position of the image plate, can instantly excite the fluorescence of a certain wavelength range, and the intensity of the fluorescence has a proportional relation with the latent image information recorded on the image plate; the fluorescence is scattered outwards according to a certain angular distribution rule and is collected by a fluorescence collection light path; the fluorescence collection light path is composed of a group of lenses or reflecting mirrors, and is used for focusing scattered fluorescence and projecting the fluorescence into a light collection window of a corresponding photoelectric conversion device; and

the photoelectric conversion device and the signal acquisition control circuit are used for collecting the focused fluorescent signals, amplifying the fluorescent signals and converting the fluorescent signals into current signals with certain intensity in proportion; typically, laser scanning devices employ photomultiplier tubes (PMTs) for optical signal amplification and photoelectric conversion; the signal acquisition control circuit provides driving and control for the photoelectric conversion device on one hand, and realizes A/D sampling of the electric signal on the other hand, converts the current signal into a digital signal, and the sampling rate is set by the central controller.

Referring to fig. 1, the network driving module is used for realizing interconnection between a central control module of the scanning device and a workbench or other control platforms, so that the workbench is convenient for sending control parameters and control instructions to the scanning device, and the scanning device transmits image data, working state information and abnormal information to the workbench; the image processing module is mainly used for extracting latent image information of the image plate from the acquired signal flow under the dispatching of the central control module and accurately splicing the latent image information into a two-dimensional rectangular image, and the image processing module can be integrated with the central control module or can be formed by independent hardware such as FPGA, DSP and the like; the power supply module is used for supplying power to each functional module of the whole scanning system, the voltage is not more than 24V, and the central control module is used for controlling the power supply; the central control module is used for connecting and controlling peripheral execution function modules and controlling the orderly operation of the whole scanning device, and the central control unit can be an ARM+FPGA platform, an FPGA+DSP platform or an independent FPGA module.

The mechanical structure of the optical scanning device according to the present invention will be described in detail with reference to fig. 2 to 10. In order to facilitate the observation of the internal structure, the views shown in fig. 3a to 3c and fig. 4a, 6b, 7, 9, and 10 are views in which all or part of the components are substantially cut away in the axial direction by a fan having a central angle of 45 ° or 180 °, for example, the light collector shown in fig. 9 and 10 is the light collector 40 cut away in the axial direction by a fan having a central angle of 45 °.

Referring to fig. 2, the optical scanning device includes a laser beam module 1, an optical reflection module 2, an F-theta lens group 3, and a light collector assembly 4. The laser beam module 1 generates a scanning beam capable of generating a light spot with a certain shape and size, the light reflection module 2 reflects the scanning beam to the F-theta lens group 3, so that the light spot formed by the scanning beam on the image plate 5 moves at a constant speed to perform flat field scanning on the image plate 5, the scanning beam is projected onto the image plate 5 to form a light spot with a certain energy density, fluorescent light with a certain wavelength range is instantaneously excited, the intensity of the fluorescent light and latent image information recorded on the image plate 5 have a proportional relation, the fluorescent light is scattered outwards according to a certain angular distribution rule, and the fluorescent light is collected by the light collector component 4.

Referring to fig. 3a-3c, a laser beam module 1 includes a laser light source and a beam generating lens set sequentially arranged from top to bottom, and a laser beam emitted from the laser light source is adjusted to a laser beam capable of generating a spot of a specific shape and size by the beam generating lens set. The laser light source is a laser, such as a laser diode 102, provided on a laser driving circuit 101. The light beam generating lens group includes a first lens 121, a second lens 122, and a third lens 123; the first lens 121 is used for adjusting the beam divergence angle of the beam emitted from the laser diode 102 to be consistent, so as to form a cone-shaped beam with rotation symmetry, and a D-shaped lens can be specifically selected; the second lens 122 is used for collimating the cone-shaped light beam to form a parallel light beam, and an aspheric lens can be selected; the third lens 123 is used for focusing the parallel light beam, i.e. forming a scanning light beam with a certain focal length, and a spherical lens is specifically selected.

The laser diode 102 is specifically disposed on the laser driving circuit 101 through a flexible connection member, and the flexible connection member may be an annular O-ring 103, which has elasticity and is deformable so as to implement soft connection between the laser diode 102 and the laser driving circuit 101. The laser driving circuit 101 is mounted on the laser mounting seat 104 through a connecting component such as a bolt, in this embodiment, a first step hole 104a, a second step hole 104c and a third step hole 104e are sequentially formed in the middle of the laser mounting seat 104 along the up-down direction, the first step hole 104a, the second step hole 104c and the third step hole 104e are sequentially connected from top to bottom and the center lines of the three are collinear, wherein the aperture of the first step hole 104a is greater than the aperture of the second step hole 104c and greater than the aperture of the third step hole 104e, so that a first step surface 104b surrounding the second step hole 104c is formed at the joint of the first step hole 104a and the second step hole 104c, and a second step surface 104d surrounding the third step hole 104e is formed at the joint of the second step hole 104c and the third step hole 104 e; at least the lower part of the O-ring 103 is located in the first step hole 104a and clamped on the first step surface 104b, and the laser diode 102 is located in the second step hole 104c, and as the O-ring 103 can deform, the lower end surface of the laser diode 102 and the second step surface 104d can be tightly attached by deforming the O-ring 103, so that the requirement of mounting precision can be met, the parallelism of the center lines of the laser diode and the laser mounting seat can be ensured as much as possible, the direction of the principal ray of the light beam can be ensured, the thermal resistance from the laser diode 102 to the laser mounting seat 104 can be reduced, and the temperature reduction is facilitated; the laser mount 104 is preferably a copper mount with good thermal conductivity. The third step hole 104e is located directly below the laser diode 102, and forms a diaphragm for the laser diode 102. The first lens 121 is disposed in the laser mounting seat 104 and located under the diaphragm, and may be fixedly connected in the cavity under the third stepped hole 104e of the laser mounting seat 104 by using photosensitive resin or other adhesives.

The laser mounting base 104 is movably mounted on the light source base 105 along the optical axis (specifically, up-down direction) of the laser beam module 1. Specifically, in this embodiment, the light source base 105 is hollow and provided with an internal thread, the outer side wall of the laser mounting base 104 has a matched external thread, the center line of the internal thread and the external thread are parallel or collinear with the optical axis of the laser beam module 1, and the laser mounting base 104 is located in the light source base 105 and connected by a thread (p=0.5 mm). In the present invention, the distance from the light source of the laser beam module 1 to the beam generating lens group is adjustable, that is, by rotating the laser mounting base 104, fine adjustment of the object distance can be achieved, so as to change the diameter and position of the entrance pupil of the scanning beam. The above connection method is not limited to the use of a specific fine thread, and the laser mount may be mounted on the light source base by means of a transition fit.

The lower portion of the light source base 105 is movably installed in the lens barrel 106 in a direction perpendicular to the optical axis of the laser beam module 1 (specifically, in a horizontal direction), and the second lens 122 is disposed in the upper portion of the lens barrel 106 below the light source base 105. In this embodiment, the lens barrel 106 is hollow, the lower part of the light source base 105 is movably disposed on the upper part of the lens barrel 106, at least one first jackscrew 107 capable of moving in the horizontal direction is arranged on the upper part of the lens barrel 106 in a penetrating manner, the inner end part of the first jackscrew 107 is abutted against the light source base 105, and the light source base 105 can be pushed to move in the horizontal direction by screwing the first jackscrew 107. The upper part of the lens barrel 106 is provided with a first wedge-shaped block 108 capable of moving along the horizontal direction, specifically, a plugging mode can be adopted, when the assembly is carried out, the lower part of the light source base 105 is firstly placed in the upper part of the lens barrel 106, then the first wedge-shaped block 108 is fixed on the upper part of the lens barrel 106, and the first wedge-shaped block 108 is positioned above the lower part of the light source base 105, so that the lower part of the light source base 105 is limited between the first wedge-shaped block 108 and the lens barrel 106. The light source base 105 has a first inclined surface 105a, and an inner end portion of the first jackscrew 107 and one of the first wedge blocks 108 (specifically, the first wedge block located on the opposite side of the first jackscrew 107) have second inclined surfaces 107a and 108a respectively, which are matched, and the first inclined surface 105a is always closely fitted with the second inclined surfaces 107a and 108 a. A first elastic member, such as a compression spring 109, is further disposed between the first jack screw 107 and the lens barrel 106, and is used for resetting the light source base 105, where the first elastic member and the first jack screw 107 are respectively disposed on two opposite sides of the light source base 105, and cooperate with each other to drive the light source base 105 to reciprocate in a horizontal direction, so as to adjust concentricity of the center of the light source and the center line of the beam generating lens group. The lower end face of the light source base and the upper end face of the lens barrel are kept parallel, and therefore the alignment of the central lines of the light source base and the lens barrel is guaranteed. An insulating gasket is arranged between the lens barrel and the light source base at intervals so as to ensure that the laser diode is not interfered by the impedance of other metal parts.

The lower part of the light source base 105 is movably disposed in the beam module holder along the optical axis (specifically, up-down direction) of the laser beam module 1, and the third lens 123 is disposed at the bottom of the lens barrel 106. Specifically, the beam module support includes a hollow inner tube 111 with internal threads, the center line of the internal and external threads is parallel or collinear with the optical axis of the laser beam module 1, the external side surface of the lower part of the light source base 105 is provided with external threads matched with the internal threads, and the lower part of the light source base 105 is arranged in the inner tube 111 and connected through threads. The distance between the beam generating lens group of the laser beam module 1 and the focal plane (image plate 5) is adjustable, and fine adjustment of the image distance is realized by rotating the lens barrel 106, so that the spot size is controlled. The above connection is not limited to the use of a specific fine thread, and the lens barrel may be mounted on the inner tube by means of a transition fit.

The second lens 122 and the third lens 123 are respectively and fixedly connected to opposite ends of the lens barrel 106 (as shown in fig. 3a-3c, respectively and fixedly connected to the upper and lower ends of the lens barrel 106), and may be specifically connected by a photosensitive resin or other adhesives.

The beam module support further includes a body 110, and the inner tube 111 is movably disposed on the body 110 along a direction perpendicular to an optical axis of the laser beam bundle module (specifically, a horizontal direction). Specifically, the body 110 is hollow, the inner tube 111 is movably inserted into the body 110 along a horizontal direction, the side wall of the body 110 is movably threaded with a second jackscrew 112 along the horizontal direction, the inner end of the second jackscrew 112 is abutted against the inner tube 111, and by screwing the second jackscrew 112, the inner tube 111 can be pushed to move along the horizontal direction, so as to drive the lens barrel 106 in the inner tube 111 to move along the horizontal direction. The body 110 is provided with a second wedge-shaped block 113 movably along the horizontal direction, specifically, a plugging manner can be adopted, when the assembly is performed, the upper end part of the inner tube 111 is placed in the body 110, then the second wedge-shaped block 113 is fixed in the body 110, and the second wedge-shaped block 113 is positioned below the upper end part of the inner tube 111, so that the upper end part of the inner tube 111 is limited between the second wedge-shaped block 113 and the body 110. The upper end of the inner tube 111 has a third inclined surface 111a, and the inner end of the second jackscrew 112 and one of the second wedge blocks 113 (specifically, the second wedge block located on the opposite side to the second jackscrew 112) has fourth inclined surfaces 112a and 114a which are matched, and the third inclined surface 111a is always closely adhered to the fourth inclined surfaces 112a and 114 a. A second elastic member, such as a compression spring 114, is disposed between the inner tube 111 and the second wedge block 113, and is used for resetting the inner tube 111, the second jackscrew 112 and the second elastic member are respectively located at two opposite sides of the inner tube 111, and the inner tube 111 is driven by the second jackscrew 112 and the second elastic member to reciprocate in the horizontal direction, so that the concentricity of the central line of the beam generating lens group of the laser beam module 1 and the rotating shaft of the servo motor is adjustable, and the fine adjustment of the position of the lens group in the horizontal direction is realized by screwing the second jackscrew 112, so that the symmetry of the beam about the scanning rotating shaft is ensured.

The beam module support is directly arranged on the scanning motor support of the optical scanning device, and the mounting hole of the beam module support is tightly matched with the boss of the scanning motor support so as to ensure the concentricity requirement of the lens and the output shaft of the scanning motor.

The laser beam module 1 of the embodiment can realize the adjustment of the fast and slow axes of the laser diode 102, the collimation and focusing of the laser beam. In order to eliminate the degradation of the quality of the light spot caused by manufacturing and installation errors, the device also has the function of adjusting the concentricity of the light beam and the object distance of the image, thereby realizing the optimization of the geometric shape and the size of the light spot.

The light reflection module 2 at least comprises a light reflection mirror and a scanning motor 21 for driving the light reflection mirror to rotate. In this embodiment, the optical reflector specifically selects the pentaprism 20, the pentaprism 20 is disposed below the third lens 123 of the laser beam module 1, and the scanning motor 21 (i.e. the motor #2 mentioned above) drives the pentaprism 20 to rotate, so that the scanning beam generated by the laser beam module 1 continuously and uniformly scans the image plate 5.

Referring to fig. 4a, the F-theta lens group 3 is disposed in the reflection optical path of the pentaprism 20, and includes a lens system 30 for generating negative distortion of the third lens 123, wherein the lens system 30 includes an aspherical mirror, and may include three or more spherical lenses, thereby generating a certain negative distortion. The lens system 30 is designed as an image-side telecentric optical system so that the scanning beam can be projected perpendicularly onto the image plate 5. Fig. 4b provides a specific example of a lens system 30, and in conjunction with fig. 4b, the lens system 30 includes five spherical lenses M1, M2, M3, M4, and M5, each having two mirror surfaces, and the curvatures and radii of the mirror surfaces of the lenses M1, M2, M3, M4, and M5 may be the same or different.

The principle of the F-theta lens group 3 comprising three spherical lenses is described below with reference to fig. 5.

For a typical focusing lens, an object at infinity (parallel light) is imaged by the lens to a high y and angle of incidenceθIs proportional to the tangent of (a), namely:

when such a lens is used in a laser scanning system, the scanning speed of an incident beam deflected at an equiangular speed at the focal plane is not constant, since it is conceivable that the height and the scanning angle do not have a linear relationship. In order to achieve constant velocity scanning and to move the projected spot at a constant velocity, the focusing lens (i.e., the third lens 123) should be subjected to a negative distortion, i.e., the actual image heightThe image height should be smaller than the ideal image height of geometrical optics calculation, and the corresponding distortion amount is as follows:

that is, the lens system 30 having the above-described distortion amount, its actual image height and scanning angle satisfy a linear relationship:

。

for a conventional optical scanning device that does not include an F-theta lens assembly 3, the imaging plate 5 needs to be curved to a shape that accommodates the linear relationship between servo motor speed and spot movement speed. The optical scanning device can avoid the defects and realize flat field scanning.

According to another embodiment of the invention, the beam generating lens of the laser beam module 1 comprises only the first lens 121 and the second lens 122, without the third lens 123, since the lens system 30 of the F-theta lens group 3 itself has a focusing effect on the light beam.

Preferably, as shown in connection with fig. 4, the lens system 30 is movably arranged in a sleeve 31 in the direction of the optical axis of the F-theta lens set 3. Specifically, in this embodiment, the outer side surface of the lens system 30 is provided with an external thread, the inner side surface of the sleeve 31 is provided with an internal thread matching with the external thread, the lens system 30 is disposed in the sleeve 31 and is connected through threads, and the axial position of the lens system 30 can be adjusted by rotating the lens system 30.

Further, a sleeve 31 is provided movably on the scan motor holder 22 in a direction perpendicular to the optical axis of the F-theta lens group 3, and is movable in at least two directions. Specifically, at least two sleeve jackscrews 31a and 31b are movably arranged on the scanning motor support 22, wherein the first sleeve jackscrew 31a moves along the horizontal direction, the second sleeve jackscrew 31b moves along the vertical direction, and the inner ends of the two sleeve jackscrews 31a and 31b respectively abut against the sleeve 31. The servo motor support 22 is movably provided with two sleeve adjusting blocks 34 corresponding to the two sleeve jackscrews respectively, in particular to an inserted connection mode, the sleeve adjusting blocks 34 and the corresponding sleeve jackscrews are respectively positioned on two opposite sides of the sleeve, each sleeve adjusting block 34 and the scanning motor support 22 are respectively provided with two sleeve pressure springs 33, the first sleeve jackscrew 31a and the two sleeve pressure springs 33 corresponding to the first sleeve jackscrew are respectively positioned on two opposite sides of the sleeve 31, and the second sleeve jackscrew 31b and the two sleeve pressure springs 33 corresponding to the second sleeve jackscrew are respectively positioned on two opposite sides of the sleeve 31 and are used for resetting the sleeve 31 in the horizontal direction and the vertical direction. The sleeve jackscrews are screwed, and the sleeve 31 is driven to move in the horizontal direction and the vertical direction by the cooperation of the two pairs of sleeve jackscrews 31a and 31b and the sleeve compression spring 33, so that the position of the sleeve 31 can be adjusted in the 2 directions, and the position of the lens system 30 can be adjusted. The scanning motor 21, specifically a servo motor, is fixed on the scanning motor bracket 22.

Figures 6a and 6b show an improved light collector assembly 4 of the present invention and its combination with an F-theta lens block 3. Referring to fig. 6a, the collector assembly 4 mainly includes a collector 40, a transreflective mirror 41, an optical filter 42, and a PMT 43 (photomultiplier tube). The collector 40 has a collection window 402, and the collection window 402 faces the image plate 5 during scanning to collect fluorescence excited on the image plate 5. The reflection mirror 41 is provided on the front side of the light collector 40, and transmits the laser beam to the image plate 5, thereby reflecting the fluorescence passing through the collection window 402 of the light collector 40; the transparent and reflective mirror 41 has to have a small thickness, for example, less than 3mm, and can transmit laser light with a certain wavelength range, and the reflective surface is coated with a reflective film, so that fluorescence with a certain wavelength range can be reflected; the transflective mirror 41 is not limited to a total reflection film in a certain wavelength range, and a polarizing reflection film may be used to transmit light waves vibrating in a certain direction. PMT 43 is disposed in the reflected light path of the transflector 41, and PMT 43 also has an entrance window for the entry of fluorescent light, the entrance window being disposed on the end of PMT 43 that faces the transflector 41. The optical filter 42 is arranged between the transflector 41 and the entrance window, preferably over the entrance window, the optical filter 42 comprising, but not limited to, an absorption filter which is insensitive to the direction of light, the optical filter 42 preferably being designed as a lens so that scattered fluorescence can be concentrated. Referring to fig. 6b, the collector 40 has a fluorescent collection chamber in communication with the collection window 402, and the collector 40 has an exit port in communication with the fluorescent collection chamber, the exit port facing the entrance window of the PMT 43. The inner wall of the fluorescent collection chamber of the collector 40 is coated with a reflective film 401 including, but not limited to, an aluminized film, a silver-plated film, and the like. The collection window 402 of the laser has opposite front and rear ends, the cross section of the front end is circular or oval, the rear end is rectangular or rounded rectangular, and the front and rear ends are smoothly transitioned, so that the collection window 402 is generally duckbill-shaped, and the fluorescence collection efficiency is improved. The terms "front", "rear", and the like are used herein with reference to a laser source, and when scanning, the side closer to the laser source is the front, and vice versa. The lens 41 and the F-theta lens group 3 are sequentially arranged in the light collector 40 at intervals, and the lens 41 is positioned in front of the F-theta lens group 3.

In the example provided in fig. 6a and 6b, the image plate 5 passes through the collection window 402 at a uniform speed in the vertical direction by means of vertical film feeding. The scanning beam emitted from the pentaprism 20 enters the light collector 40, passes through the transflective mirror 41 to be projected onto the F-theta lens group 3, passes through the collecting window 402 of the light collector 40 to be projected onto the image plate 5, and forms a light spot with certain energy distribution; the light spot excites fluorescence in a certain wavelength range (typically 390nm peak) and distribution form (typically cosine distribution) on the image plate 5; the excited fluorescence has a certain divergence angle, so that the main light rays enter the fluorescence collection cavity after being reflected by the transparent mirror 41, and are emitted from the emergent port of the light collector 40 without being reflected or after being reflected for a plurality of times; and then passes through the filter 42 and into the PMT 43 through an entrance window to complete the photoelectric conversion, the gain of the electrical signal, and the a/D conversion.

Fig. 7 is a schematic diagram of a typical light collector assembly 4 in the prior art, and it can be seen that the entrance window at the top of the PMT 43 faces the collection window 402 of the light collector 40, and fluorescence is emitted from the entrance window at the side, and is received, converted, and amplified into an analog electrical signal. Referring to fig. 6a and 8, the invention is improved to reduce the material cost of the whole machine. In the collector assembly 4 shown in fig. 8, the PMT 43 faces the collection window 402 of the collector 40 laterally, and receives fluorescence from the side, which is compact and reduces the overall length of the device.

Fig. 9 shows an example of a further collector assembly 4 and F-theta lens block 3 of the invention. Which is substantially the same as the example provided in fig. 6b, except that: the PMT 43 adopts an opposite form, that is, the reflecting window of the PMT 43 faces the collecting window 402 of the light collector 40, although the structure is not very compact, the laser beam can enter the F-theta lens group 3 perfectly because the reflecting mirror 41 is omitted, and the scanning accuracy is higher; the reflecting tube 44 is used for connecting the PMT 43 and the F-theta lens group 3, and the laser beam and the excited fluorescence pass through the reflecting tube, and a reflecting film is required to be coated inside the reflecting tube, and the reflecting tube is mainly used for collecting the fluorescence.

Fig. 10 shows an example of a fourth collector assembly 4 and F-theta lens block 3 of the present invention. Referring to fig. 10, the image plate 5 passes horizontally through a collection window 402, the collection window 402 is disposed downward, the F-theta lens group 3 is disposed beside the light collector 40, the PMT 43 is disposed above the laser and its entrance window is also disposed downward, and the transflector 41 is disposed between the three. By adopting the horizontal feeding mode of the image plate 5, the problem that the service life of the image plate 5 is possibly damaged due to the fact that the image plate 5 needs to be fixed by applying the pressing force on the front and back surfaces of the image plate 5 when the image plate 5 is driven to move from top to bottom by the feeding mechanism in the vertical feeding mode can be avoided. The laser beam passes through the F-theta lens group 3, is reflected by the lens-reflector 41 and then is projected onto the image plate 5; the fluorescence emitted from the image plate 5 is received by the PMT 43 through the transflector 41; the inside of the light collector 40 is plated with a reflective film 401; the transreflective mirror 41 can reflect laser light with a certain wavelength range and transmit fluorescence with a certain wavelength range; the image plate 5 does not need to apply a pressing force on the front under the action of self gravity.

For the medical image scanning equipment, the invention can optimize the light spot quality, facilitate the whole machine debugging and prolong the service life of the image plate 5. According to the invention, firstly, the diaphragm is designed on the laser mounting seat 104 to block light rays with overlarge divergence angles, the D-shaped lens is added on the laser mounting seat 104, the fast axis can be subjected to preliminary correction, the divergence angles of the fast axis and the slow axis are modulated to be relatively close, and the modulated light beams are collimated by the double-aspheric lens and then become parallel light beams. In addition, the adjustment of the light source position is flexible, free adjustment in 3 directions can be realized, and the lens barrel 106 for supporting the lens is also designed as a movable part capable of being freely adjusted in 3 directions, so that the position of the lens can be directly changed when the spot diameter is adjusted. By the improvement, a relatively regular circular light spot can be obtained, and the diameter of the light spot can be conveniently adjusted.

The invention changes the scanning mode into flat field scanning through the F-theta lens group 3, namely the image plate 5 can move straightly, and the light beam can more easily keep vertical projection. The defects brought by traditional curved field scanning, such as reduction of the service life of the image plate 5, influence on the design of the feeder, high requirements on the placement accuracy of the influence plate and the like, are overcome.

The above-described embodiments are provided for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the present invention and to implement the same, not to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.

Claims (8)

1. The laser beam module of the image scanning system comprises a laser and a lens barrel, wherein one or more lenses used for adjusting light beams emitted by the laser to generate scanning light beams are arranged in the lens barrel; the beam module support comprises a body used for being arranged on a scanning motor support of the image scanning system, an inner tube used for being connected with the lens barrel, the body is hollow, the inner tube is movably inserted into the body along the direction perpendicular to the optical axis, the laser beam module further comprises a second jackscrew movably penetrating through the side wall of the body, and the inner end of the second jackscrew is abutted with the inner tube to drive the inner tube to move; a second wedge block is movably arranged on the body along the horizontal direction, and is positioned below the upper end part of the inner tube so as to limit the upper end part of the inner tube between the second wedge block and the body; the upper end part of the inner end is provided with a third inclined surface, the inner end parts of the second jackscrew and one of the second wedge blocks are provided with a fourth inclined surface which is matched with the second jackscrew, and the third inclined surface is attached to the fourth inclined surface; and a second elastic piece for resetting the inner tube is arranged between the inner tube and the second wedge block, and the second jackscrew and the second elastic piece are respectively positioned at two opposite sides of the inner end.

2. The laser beam module of claim 1, wherein: the second elastic piece is a pressure spring arranged between the inner tube and the second wedge block or the body.

3. The laser beam module of claim 1, wherein: the lens cone is movably arranged on the inner tube along the optical axis of the laser beam module, and the inner tube is movably arranged on the body along the direction perpendicular to the optical axis.

4. A laser beam module as claimed in claim 3, wherein: the beam module support and the inner tube are connected with the optical axis in parallel or collinear screw threads through the central line.

5. The laser beam module as set forth in claim 4, wherein: the lens cone is provided with external threads, the inner tube is provided with matched internal threads, and the lens cone is arranged in the inner tube and is connected with the internal threads through the external threads.

6. The laser beam module of claim 1, wherein: the laser beam module further comprises a light source base arranged on the lens cone and a laser mounting seat arranged on the light source base, the laser is arranged on the laser mounting seat, the light source base can be movably arranged on the lens cone along the horizontal direction, and the laser mounting seat can be movably arranged on the light source base along the optical axis.

7. The laser beam module of claim 1, wherein: the lens barrel is characterized in that a second lens used for collimating light beams to form parallel light beams and a third lens used for focusing the light beams to form scanning light beams are respectively arranged in two opposite ends of the lens barrel, and a first lens used for adjusting the beam divergence angle of the light beams emitted by the laser to be consistent to form cone-shaped light beams with rotational symmetry is arranged between the laser and the second lens.

8. An image scanning system, characterized in that: a laser beam module as claimed in any one of claims 1 to 7.