A high-precision line stripe scanning projection device and method

Abstract

This invention discloses a high-precision line stripe scanning projection device and method, belonging to the field of projection display. The high-precision line stripe scanning projection device includes a single-wavelength light source, a collimating lens, a reflector, a digital micromirror device, a projection lens, and a housing. The digital micromirror device can control the size, position coordinates, number of slits, and slit spacing of the reflective slits. In scanning mode, the reflective slits can be translated in a time-sequential step-by-step manner to achieve scanning of the projected stripes on the projection target. The high-precision line stripe scanning projection method provided by this invention can determine the projection stripe spacing and stripe brightness by controlling the peak width and slit spacing, and determine the projection stripe linewidth by controlling the number of slits, thus improving the accuracy and quality of the line stripes.

Description

Technical Field

[0001] This invention relates to a high-precision line stripe scanning projection device and method, belonging to the field of projection display. Background Technology

[0002] The quality of line structured light directly determines the accuracy of 3D measurements, therefore, the study of high-precision line fringe light is of great significance. Currently, the widely used method is digital projection, which uses a projection imaging system to directly transmit the fringe pattern onto the surface being measured. However, the fringe accuracy of this method depends on the image pixel size, the projection magnification, and the projection range. As the projection range increases, the accuracy of the projected fringe decreases proportionally. This limits the absolute accuracy of 3D measurements, especially noticeable in cross-dimensional measurements. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention provides a high-precision line stripe scanning projection device and method to solve the above-mentioned problems.

[0004] The technical solution for implementing a high-precision line stripe scanning projection device according to the present invention is as follows: The device includes a single-wavelength light source, a collimating lens, a reflecting mirror, a digital micromirror device, a projection lens, and a housing; the single-wavelength light source emits light waves with the same frequency and consistent vibration direction; the collimating lens collimates the light waves emitted by the single-wavelength light source into plane waves; the reflecting mirror reflects the plane waves to the digital micromirror device; the digital micromirror device consists of a base surface and a two-dimensional micromirror element array; the micromirror elements have two flip states, on and off. When in the on state, the micromirror element deflects by +12°, causing diffraction, and the light is reflected by the digital micromirror device to the projection lens; when in the off state, the micromirror element deflects by -12°, and the light is reflected out of the device; the micromirror element array of the digital micromirror device is controlled to present multiple parallel reflective slits in the on state, which reflect the light to produce multi-slit Fraunhofer diffraction; the projection lens converges light rays of the same angle onto the projection target to form projection stripes; the housing is used to fix the optical elements and seal the optical path to prevent external interference light from entering.

[0005] The digital micromirror device described above can control the size, position coordinates, number of slits, and slit spacing of the reflective slits; in scanning mode, the reflective slits can be translated in a time-sequential stepping manner to achieve scanning of the projected stripes on the projected target.

[0006] The present invention proposes a high-precision line stripe scanning projection method, which utilizes the aforementioned high-precision line stripe scanning projection device and follows these steps:

[0007] Step 1: Power on the single-wavelength light source, which then emits a light wave with a single wavelength of λ through photoelectric conversion.

[0008] Step 2: Initially flip the micromirror array of the digital micromirror device to a new state, where there are N parallel reflective slits in the "on" state, with slit width a, slit spacing d >> a, and projection lens focal length f >> x. Then the projection fringe distribution is as follows:

[0009] x=mλf / d (1)

[0010] When m = 0, ±1, ±2, ..., the fringe at x is a principal maximum, i.e., a bright fringe; in other cases, it is a dark fringe.

[0011] Step 3: At the next moment, the reflective slit is moved by a stepping amount of b. The fringe distribution at this moment is as follows:

[0012] x=mλf / d+b (2)

[0013] Step 4: Following this, the reflecting slit is translated in a time-series periodic manner, with a period of T. The fringe distribution at time t is then:

[0014]

[0015] As can be seen, by following steps one through four, high-precision line stripe scanning projection can be achieved.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] The high-precision line stripe scanning projection device and method provided by this invention utilizes the principle of multi-slit interference and employs a digital micromirror device to sequentially and periodically translate the reflective slits, thereby achieving the scanning of projected stripes on the projection target. Compared with existing technologies, the high-precision line stripe scanning projection device provided by this invention can control the size, position coordinates, number of slits, and slit spacing according to requirements. The high-precision line stripe scanning projection method provided by this invention can determine the projected stripe spacing and stripe brightness by controlling the peak width and slit spacing, and determine the projected stripe linewidth by controlling the number of slits, thus improving the accuracy and quality of the line stripes. Attached Figure Description

[0018] Figure 1 A structural diagram of the high-precision line stripe scanning projection device provided by the present invention;

[0019] Figure 2 This is a schematic diagram of the time-series periodic step-translation reflective slit of the present invention.

[0020] In the diagram: 1-Single-wavelength light source, 2-Collimating lens, 3-Reflector, 4-Digital micromirror device, 5-Projection lens, 6-Housing, 7-Projection target. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to specific embodiments.

[0022] like Figure 1 As shown, this invention discloses a high-precision line stripe scanning projection device, comprising a single-wavelength light source 1, a collimating lens 2, a reflecting mirror 3, a digital micromirror device 4, a projection lens 5, and a housing 6. The single-wavelength light source 1 emits light waves with the same frequency and consistent vibration direction. The collimating lens 2 collimates the light waves emitted by the single-wavelength light source into plane waves. The reflecting mirror 3 reflects the plane waves onto the digital micromirror device 4. The digital micromirror device 4 consists of a base surface and a two-dimensional micromirror element array. The micromirror elements have two flip states: on and off. When in the on state... When the micromirror element deflects by +12°, diffraction occurs, and the light is reflected by the digital micromirror device 4 to the projection lens 5. When it is in the off state, the micromirror element deflects by -12°, and the light is reflected by the digital micromirror device 4 out of the device. The micromirror array of the digital micromirror device 4 is controlled to present multiple parallel reflection slits in the on state, which reflect the light and cause multi-slit Fraunhofer diffraction. The projection lens 5 converges the light rays of the same angle onto the projection target 7 to form projection fringes. The housing 6 is used to fix the optical elements and seal the optical path to prevent external interference light from entering.

[0023] like Figure 2 As shown, the digital micromirror device 4 can control the size, position coordinates, number of slits and slit spacing of the reflective slits; in scanning mode, the reflective slits can be translated step by step according to the time sequence to realize the scanning of the projection stripes on the projection target.

[0024] The present invention proposes a high-precision line stripe scanning projection method, which utilizes the aforementioned high-precision line stripe scanning projection device and follows these steps:

[0025] Step 1: Power on the single-wavelength light source 1, and emit a light wave with a single wavelength of λ through photoelectric conversion.

[0026] Step 2: Initially flip the micromirror array of digital micromirror device 4, which has N parallel reflective slits in the "on" state, with slit width a and slit spacing d >> a. The focal length of projection lens 5 is f >> x. Then the projection fringe distribution is:

[0027] x=mλf / d (1)

[0028] When m = 0, ±1, ±2, ..., the fringe at x is a principal maximum, i.e., a bright fringe; in other cases, it is a dark fringe.

[0029] Step 3: At the next moment, the reflective slit is moved by a stepping amount of b. The fringe distribution at this moment is as follows:

[0030] x=mλf / d+b (2)

[0031] Step 4: Following this, the reflecting slit is translated in a time-series periodic manner, with a period of T. The fringe distribution at time t is then:

[0032]

[0033] As can be seen, by following steps one through four, high-precision line stripe scanning projection can be achieved.

[0034] Example:

[0035] The invention will be further illustrated by the following examples:

[0036] Select a single-wavelength light source 1 with wavelength λ = 640nm; slit width a = 7.6um, slit spacing d = 760um, number of slits N = 100; projection lens 5 with focal length f = 760mm; and step translation amount b = 6.4um.

[0037] The initial distribution of the projected fringes on the projected target is: x = 0.64 m, unit mm, m = 0, ±1, ±2, ...

[0038] The reflection slit is translated step by step according to the time sequence. The distribution of the projected stripes on the projected target 7 is: x = 0.64m + 0.0064i, in mm, i = 0, 1, 2, ..., 99, where i is the time sequence.

[0039] To avoid the influence of the single-slit diffraction factor on the light intensity, the range of the projected target 7 is taken as 64 mm; the fringe spacing is 0.64 mm, and there are 100 projected fringes within this range at a certain time.

[0040] stripe width

[0041] Where cosθ≈1.

[0042] It can be seen that continuous and uninterrupted scanning within the 64mm projected target range can be achieved by 100 steps of the reflective slit.

[0043] The present invention can set the seam width, seam spacing, number of seams and values ​​of each main wavelength according to requirements, and is not limited to this embodiment.

[0044] Although the present invention has been described above with reference to the figures, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of the present invention without departing from the spirit of the present invention, and these modifications are all within the protection scope of the present invention.

Claims

1. A high-precision line fringe scanning projection method, characterized by, The line fringe scanning projection method is implemented by a line fringe scanning projection device, which comprises a single-wavelength light source (1), a collimating lens (2), a mirror (3), a digital micromirror device (4), a projection lens (5) and a housing (6); the single-wavelength light source (1) emits light waves with the same frequency and consistent vibration direction; the collimating lens (2) collimates the light waves emitted by the single-wavelength light source into plane waves; the mirror (3) reflects the plane waves to the digital micromirror device (4); the digital micromirror device (4) is composed of a base surface and a two-dimensional micro-mirror element array; the micro-mirror element has two flip states of on and off; when in the on state, the micro-mirror element deflects +12°, and diffraction occurs; the light is reflected by the digital micromirror device (4) to the projection lens (5); when in the off state, the micro-mirror element deflects -12°, and the light is reflected out of the device by the digital micromirror device (4); the micro-mirror element array of the digital micromirror device (4) is controlled to present a plurality of parallel reflection slits in the on state, and the multiple-slit Fraunhofer diffraction occurs through the reflection; the projection lens (5) converges the light rays with the same angle to the projection target (7) to form a projection fringe; the housing (6) is used for fixing the optical elements and sealing the optical path to avoid external interference light from entering; The digital micromirror device (4) can control the size, position coordinates, slit number and slit distance of the reflection slit; in the scanning mode, the reflection slit can be stepwise translated in time sequence cycles to realize the scanning of the projection fringe on the projection target. The line fringe scanning projection method comprises the following steps: Step one, power on the single-wavelength light source, emit light wave with single wavelength of after photoelectric conversion; Step two, initial flipping state of the micro-mirror device's micro-mirror array, where there are N parallel reflective slots in on state, with slot width a and slot pitch , projection lens focal length , the projection stripe distribution is: （1） wherein When x is at the main maximum of the fringe, i.e. a bright fringe; otherwise a dark fringe. Step three, at the next moment, the reflection slit is stepwise translated by b, and then the fringe distribution at this moment is: （2） Step four, the reflection slit is stepwise translated in time sequence cycles, and the cycle is T, then the fringe distribution at the moment t is: （3） It can be seen that the high-precision line fringe scanning projection can be realized through steps one, two, three and four.

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