CN108759711B

CN108759711B - Non-mechanical laser three-dimensional scanning system

Info

Publication number: CN108759711B
Application number: CN201810297082.9A
Authority: CN
Inventors: 时光; 黑克非; 郑磊珏; 王文
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2018-04-04
Filing date: 2018-04-04
Publication date: 2020-04-28
Anticipated expiration: 2038-04-04
Also published as: CN108759711A

Abstract

The invention discloses a non-mechanical laser three-dimensional scanning system. The existing non-mechanical laser scanning technology has low precision and small scanning range. Laser emitted by the tunable laser enters the light intensity modulator through the collimating lens, the modulated laser is focused on the virtual image phase array through the cylindrical lens and is deflected in the vertical direction, the deflected laser strikes the blazed grating and is also deflected in the horizontal direction, emergent light of the blazed grating is reflected to a target, and is converged by the receiving lens through diffuse reflection and then is received by the photoelectric detector; the photoelectric detector converts the optical signal into an electric signal, the electric signal is transmitted to the phase method data processing system through the amplifying and filtering circuit, the phase method data processing system carries out phase detection on the electric signal transmitted by the amplifying and filtering circuit and the sine wave electric signal transmitted by the signal source to obtain a target distance, and a distance measurement result is transmitted to the upper computer. The invention has high precision and wide scanning range.

Description

Non-mechanical laser three-dimensional scanning system

Technical Field

The invention belongs to the technical field of optics, and particularly relates to a non-mechanical laser three-dimensional scanning system.

Background

In the field of three-dimensional precision measurement, a three-dimensional imaging system based on a laser scanning technology is widely applied, the laser three-dimensional scanning technology is mainly divided into a mechanical type and a non-mechanical type, and the scanning mechanism of the existing mechanical laser scanning technology is complex in structure and high in purchase and maintenance cost. However, the related research of the current non-mechanical laser scanning technology is less, and the general defects are low precision and small scanning range.

Disclosure of Invention

The invention aims to provide a non-mechanical laser three-dimensional scanning system aiming at the defects of the prior art, and laser three-dimensional scanning measurement in a certain range is realized by combining a non-mechanical optical device with a phase method distance measurement principle.

The device comprises an upper computer, a laser controller, a tunable laser, a collimating lens, a light intensity modulator, a cylindrical mirror, a virtual image phase array, a blazed grating, a receiving lens, a photoelectric detector, an amplifying and filtering circuit, a phase method data processing system and a signal source; the tunable laser is controlled by a laser controller to be started and stopped. The tunable laser emits laser with wavelength circularly changing in 1520 nm-1560 nm. Laser emitted by the tunable laser enters a light intensity modulator which inputs an electric signal from a signal source through a collimating lens, the light intensity modulator modulates the light intensity of the laser by a sine wave signal with the frequency of k, and the value of k is 20 MHz-300 MHz. The modulated laser is focused on the virtual image phase array through the cylindrical mirror, deflection is generated in the vertical direction through the virtual image phase array, and the deflection angle is in direct proportion to the wavelength of the modulated laser. The deflected laser is irradiated on the blazed grating, incident light of the blazed grating forms an angle with a grating macro-plane of the blazed grating, the incident light of the blazed grating is also deflected in the horizontal direction through the blazed grating, and the deflection angle is in direct proportion to the incident light wavelength of the blazed grating. Emergent light of the blazed grating is reflected to a target, is converged by a receiving lens through diffuse reflection, and is received by a photoelectric detector. The photoelectric detector converts the optical signal into an electric signal, and the electric signal is transmitted to the phase method data processing system through the amplifying and filtering circuit, the phase method data processing system simultaneously receives the sine wave electric signal of the signal source, and the distance of the target is obtained by detecting the phase of the electric signal transmitted by the amplifying and filtering circuit and the sine wave electric signal transmitted by the signal source; and the phase method data processing system transmits the ranging result to the upper computer. And the upper computer controls the signal source and the laser controller. The upper computer measures distance data corresponding to the laser point reflected to the target surface through two deflection angles, the distance from the emergent light emergent point of the virtual image phase array to the grating macro plane of the blazed grating and the phase method distance measuring principle, and obtains three-dimensional measurement data of the laser point reflected to the target surface.

The wavelength cyclic change rule is that firstly, the wavelength changes from minimum to maximum according to the step length of 10pm, and then changes from maximum to minimum according to the step length of-10 pm.

When the laser wavelength changes for one period, the number of periods of laser deflection through the virtual image phase array is 10-20 times of the number of the periods of laser deflection through the blazed grating; and returning the laser to the initial angle again when the deflection angle of the laser reaches the maximum through the virtual image phase array, so that a plurality of laser point track oblique lines exist on the laser track of the target surface in a laser wavelength change period.

The invention has the following beneficial effects:

the invention realizes laser three-dimensional scanning measurement in a certain range by combining the non-mechanical optical device with the phase method distance measurement principle, has the advantages of high precision, large scanning range, low cost, simple structure and the like, and provides a new thought for the non-mechanical laser three-dimensional measurement technology.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention;

FIG. 2 is a schematic diagram of a laser trace formed on a target surface according to the present invention.

In the figure: 1. the device comprises an upper computer, 2, a laser controller, 3, a tunable laser, 4, a collimating lens, 5, a light intensity modulator, 6, a cylindrical mirror, 7, a virtual image phase array, 8, a blazed grating, 9, a target, 10, a receiving lens, 11, a photoelectric detector, 12, an amplifying and filtering circuit, 13, a phase method data processing system, 14 and a signal source.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings.

As shown in fig. 1, a non-mechanical laser three-dimensional scanning system includes an upper computer 1, a laser controller 2, a tunable laser 3, a collimating lens 4, a light intensity modulator 5, a cylindrical mirror 6, a virtual image phase array 7, a blazed grating 8, a receiving lens 10, a photodetector 11, an amplifying and filtering circuit 12, a phase method data processing system 13, and a signal source 14; the tunable laser 3 is controlled by the laser controller 2 to be started and stopped. The tunable laser 3 emits laser with wavelength circularly changing in 1520 nm-1560 nm, and the rule of the wavelength circularly changing is that firstly the wavelength changes from minimum to maximum according to the step length of 10pm and then changes from maximum to minimum according to the step length of-10 pm. Laser emitted by the tunable laser 3 enters a light intensity modulator 5 which inputs an electric signal from a signal source 14 through a collimating lens 4, the light intensity modulator 5 modulates the light intensity of the laser by a sine wave signal with the frequency of k, and the value of k is one of 20 MHz-300 MHz. The modulated laser is focused on a virtual image phase array 7 through a cylindrical mirror 6, and is deflected in the vertical direction through the virtual image phase array 7, and the deflection angle is in direct proportion to the wavelength of the modulated laser. The deflected laser is irradiated on the blazed grating 8, the incident light of the blazed grating forms an angle with the grating macro-plane of the blazed grating, the incident light of the blazed grating is also deflected in the horizontal direction through the blazed grating, and the deflection angle is in direct proportion to the incident light wavelength of the blazed grating.

The modulated laser is deflected and reflected twice to the target 9, then converged by the receiving lens 10 through diffuse reflection, and then received by the photodetector 11. The photoelectric detector 11 converts the optical signal into an electrical signal, and then the electrical signal is transmitted to the phase method data processing system 13 through the amplifying and filtering circuit 12, the phase method data processing system 13 simultaneously receives the sine wave electrical signal (the sine wave electrical signal is used as a reference signal) of the signal source 14, and the distance of the target is obtained by detecting the phase of the electrical signal transmitted by the amplifying and filtering circuit 12 and the sine wave electrical signal transmitted by the signal source 14; the phase method data processing system 13 transmits the ranging result to the upper computer 1. The upper computer 1 controls the signal source 14 and the laser controller 2. The upper computer 1 measures distance data corresponding to the laser point reflected to the surface of the target 9 through two deflection angles, the distance from the emergent light emergent point of the virtual image phase array 7 to the grating macro plane of the blazed grating 8 and the phase method distance measurement principle, and obtains three-dimensional measurement data of the laser point reflected to the surface of the target 9.

The free spectral range of the virtual image phase array 7 is generally 50GHz, which is smaller than the free spectral range of the blazed grating 8, that is, the resolution of the deflection angle of the virtual image phase array 7 is higher than that of the blazed grating 8, so that when the laser wavelength changes by one period, the number of periods (in this embodiment, values are taken in 8 to 18 periods) for laser to deflect through the virtual image phase array 7 is greater than the number of periods for deflecting through the blazed grating 8, and is 10 to 20 times (in this embodiment, 15 times) the number of periods for deflecting through the blazed grating 8, and the laser returns to the initial angle again when the deflection angle of the laser reaches the maximum through the virtual image phase array 7, so that in one period (in this embodiment, 1520nm to 1560nm) for laser wavelength, a plurality of laser point trajectory oblique lines exist in the laser; the step length of the laser wavelength emitted by the tunable laser 3 is small, so that the distance between two adjacent laser point track oblique lines is small, and the scanning measurement precision is high; in addition, when the laser beam is deflected by the blazed grating 8, the difference between the maximum deflection angle and the minimum deflection angle is relatively large, and therefore the scanning measurement range is large.

In the invention, the laser track on the surface of the target 9 is shown in fig. 2, a solid circular point is a starting point of the laser track, a solid line is a laser point track oblique line, a broken line is a head-tail line of two adjacent laser point track oblique lines, and laser points are scanned from bottom to top along the laser point track oblique line from the starting point until a wavelength period is finished; and in the next wavelength period, the laser point scans along the next laser point track from bottom to top in an inclined line until the wavelength period is ended, and the steps are repeated.

While the present invention has been described with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are illustrative only and not restrictive, and various modifications which do not depart from the spirit of the present invention and which are intended to be covered by the claims of the present invention may be made by those skilled in the art.

Claims

1. The utility model provides a non-mechanical type laser three-dimensional scanning system, includes host computer, laser controller, tunable laser, collimating lens, light intensity modulator, cylindrical mirror, virtual image phased array, blazed grating, receiving lens, photoelectric detector, amplifying and filtering circuit, phase method data processing system and signal source, its characterized in that: the tunable laser is controlled to be started and stopped by a laser controller; the tunable laser emits laser with wavelength circularly changing in 1520 nm-1560 nm; laser emitted by the tunable laser enters a light intensity modulator which inputs an electric signal from a signal source through a collimating lens, the light intensity modulator modulates the light intensity of the laser by a sine wave signal with the frequency of k, and the value of k is 20 MHz-300 MHz; the modulated laser is focused on the virtual image phase array through the cylindrical mirror, and is deflected in the vertical direction through the virtual image phase array, and the deflection angle is in direct proportion to the wavelength of the modulated laser; the deflected laser is irradiated on the blazed grating, the incident light of the blazed grating forms an angle with the grating macro-plane of the blazed grating, the incident light of the blazed grating is also deflected in the horizontal direction through the blazed grating, and the deflection angle is in direct proportion to the incident light wavelength of the blazed grating; the emergent light of the blazed grating is reflected to a target, is converged by a receiving lens through diffuse reflection, and is received by a photoelectric detector; the photoelectric detector converts the optical signal into an electric signal, and the electric signal is transmitted to the phase method data processing system through the amplifying and filtering circuit, the phase method data processing system simultaneously receives the sine wave electric signal of the signal source, and the distance of the target is obtained by detecting the phase of the electric signal transmitted by the amplifying and filtering circuit and the sine wave electric signal transmitted by the signal source; the phase method data processing system transmits the ranging result to an upper computer; the upper computer controls the signal source and the laser controller; the upper computer measures distance data corresponding to the laser point reflected to the target surface through two deflection angles, the distance from the emergent light emergent point of the virtual image phase array to the grating macro plane of the blazed grating and the phase method distance measuring principle, and obtains three-dimensional measurement data of the laser point reflected to the target surface.

2. The non-mechanical laser three-dimensional scanning system according to claim 1, wherein: the wavelength cyclic change rule is that firstly, the wavelength changes from minimum to maximum according to the step length of 10pm, and then changes from maximum to minimum according to the step length of-10 pm.

3. The non-mechanical laser three-dimensional scanning system according to claim 1, wherein: when the laser wavelength changes for one period, the number of periods of laser deflection through the virtual image phase array is 10-20 times of the number of the periods of laser deflection through the blazed grating; and returning the laser to the initial angle again when the deflection angle of the laser reaches the maximum through the virtual image phase array, so that a plurality of laser point track oblique lines exist on the laser track of the target surface in one laser wavelength change period.