Method and device for expanding resolution of DLP projection device in extended optical three-dimensional measurement

Abstract

The present invention discloses a method and a device for expanding the resolution of a DLP projection device in optical three-dimensional measurement. The method includes the following steps: transmitting half of the light intensity of the fringe image projected by the DLP projection device through a semi-transmissive and semi-reflective lens to the first area of the object to be measured, forming a first fringe image, and reflecting the other half of the light intensity to a front-coated mirror; reflecting the fringe image reflected by the semi-transmissive and semi-reflective lens to the second area of the object to be measured through the front-coated mirror, forming a second fringe image; adjusting the angle of the front-coated mirror so that the first fringe image in the first area and the second fringe image in the second area are seamlessly synthesized. By adding a semi-transmissive and semi-reflective lens and a front-coated mirror, the present invention can achieve higher-precision three-dimensional measurement, which is of great significance for realizing ultra-high-precision three-dimensional measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional precision measurement, and particularly relates to a method and device for expanding the resolution of a DLP projection device in optical three-dimensional measurement. Background Art

[0002] Traditional optical precision three-dimensional measurement systems all use binocular cameras and DLP projection devices to achieve. The DLP projection device projects multiple phase-shifted grating stripes onto the object to be measured. At the same time, the binocular camera synchronously triggers to collect the stripe images, and then calculates the global phase of each pixel of the binocular camera for matching calculation, and then obtains the three-dimensional coordinates of the object to be measured.

[0003] The DLP projection device is responsible for projecting the stripe image onto the object to be measured. After the projection field of view is determined, the resolution of the spatial stripe image is determined by the resolution of the DMD chip in the DLP projection device. The higher the resolution of the spatial stripe image, the higher the corresponding three-dimensional measurement accuracy. Therefore, effectively improving the resolution of the spatial stripe image is an important way to improve the three-dimensional measurement accuracy. However, the DMD chip in the DLP projection device is composed of an array of a huge number of MEMS micro-reflection lenses. It is very difficult to further increase its quantity (the current highest resolution can only reach 2716x1528). However, in the occasion where ultra-high-precision measurement is required, a higher resolution is needed to achieve, and multiple groups of DLP projection devices need to be combined for projection to achieve, which is not only very expensive but also large in volume, and is not conducive to the miniaturization of products. Summary of the Invention

[0004] The main object of the present invention is to propose a method and device for expanding the resolution of a DLP projection device in optical three-dimensional measurement, aiming to improve the resolution of the DLP projection device.

[0005] To achieve the above object, the present invention provides a method for expanding the resolution of a DLP projection device in optical three-dimensional measurement. The method is applied to a device for expanding the resolution of a DLP projection device in optical three-dimensional measurement. The device for expanding the resolution of a DLP projection device in optical three-dimensional measurement includes a DLP projection device, a semi-transmissive semi-reflective lens, and a front-coated mirror. The method includes the following steps:

[0006] Transmit half of the light intensity of the stripe image projected by the DLP projection device through the semi-transmissive semi-reflective lens to the first area of the object to be measured to form a first stripe image, and reflect the other half of the light intensity to the front-coated mirror;

[0007] Reflect the stripe image reflected by the semi-transmissive semi-reflective lens to the second area of the object to be measured through the front-coated mirror to form a second stripe image;

[0008] Adjust the angle of the front coated mirror so that the first stripe image in the first region and the second stripe image in the second region are seamlessly synthesized.

[0009] To achieve the above object, the present invention also provides a device for expanding the resolution of a DLP projection device in extended optical three-dimensional measurement. The device includes a DLP projection device, a semi-reflective semi-transmissive lens, and a front coated mirror. Among them, the semi-reflective semi-transmissive lens and the front coated mirror are located between the DLP projection device and the object to be measured, and the initial position of the front coated mirror is parallel to the semi-reflective semi-transmissive lens;

[0010] The semi-reflective semi-transmissive lens is used to transmit half of the light intensity of the stripe image projected by the DLP projection device to the first region of the object to be measured to form a first stripe image, and reflect the other half of the light intensity to the front coated mirror;

[0011] The front coated mirror is used to reflect the stripe image reflected by the semi-reflective semi-transmissive lens to the second region of the object to be measured to form a second stripe image; when the front coated mirror is adjusted from the initial position to another angular position, the first stripe image in the first region and the second stripe image in the second region are seamlessly synthesized.

[0012] The beneficial effects of the method and device for expanding the resolution of a DLP projection device in extended optical three-dimensional measurement of the present invention are as follows: By adding a semi-reflective semi-transmissive lens and a front coated mirror, the spatial stripe resolution of the DLP projection device can be increased to 2 times. By increasing the number of semi-reflective semi-transmissive lenses and front coated mirrors, higher multiples of expansion can be achieved, and simultaneous expansion in the horizontal and vertical directions can be realized, thereby achieving higher-precision three-dimensional measurement, which is of great significance for realizing ultra-high-precision three-dimensional measurement. Description of the Drawings

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0014] Figure 1 It is a schematic flowchart of a preferred embodiment of the method for expanding the resolution of a DLP projection device in extended optical three-dimensional measurement of the present invention;

[0015] Figure 2 It is a schematic structural diagram of a preferred embodiment of the device for expanding the resolution of a DLP projection device in extended optical three-dimensional measurement of the present invention.

[0016] The implementation, functional features, and advantages of the present invention will be further described in conjunction with embodiments and with reference to the accompanying drawings. Specific Embodiments

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0018] It should be noted that if there are directional indications (such as up, down, left, right, front, back,...) involved in the embodiments of the present invention, then such directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If this specific posture changes, then such directional indications will also change accordingly.

[0019] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, then such descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and / or" appearing throughout the text includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, or scenario B, or the scenario where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0020] Considering that in current DLP projection devices, the DMD chip is composed of an array of a huge number of MEMS micro-reflection lenses, and it is very difficult to further increase its quantity (the current highest resolution can only reach 2716x1528). However, in occasions that require ultra-high-precision measurement, a higher resolution is needed to achieve it, and it can only be achieved by combining multiple groups of DLP projection devices for combined projection. This is not only very expensive but also large in volume, which is not conducive to the miniaturization of the product. Therefore, the present invention proposes a method for expanding the resolution of the DLP projection device in optical three-dimensional measurement.

[0021] The technical solution adopted by the method for expanding the resolution of the DLP projection device in optical three-dimensional measurement of the present invention mainly uses a semi-transparent and semi-reflective lens and a front-coated reflector to seamlessly synthesize the fringe image directly transmitted through the semi-transparent and semi-reflective lens and the fringe image reflected by the semi-transparent and semi-reflective lens and then reflected by the front-coated reflector in space and project it onto the object to be measured. By adjusting the distance between the DLP projection device and the object to be measured, the field of view of the fringe image is made half of the original. The field of view of the spatial fringe image expanded by the method described in the present invention will be the same as the original spatial fringe image field of view, but the fringe density increases to 2 times the original.

[0022] By increasing the number of semi-transparent and semi-reflective lenses and front-coated reflectors, the present invention can achieve a higher multiple of expansion and can achieve simultaneous expansion in the horizontal and vertical directions. When maintaining the same field of view, the projected brightness after expansion is slightly lower than that before expansion (there will be certain losses due to multiple reflections of the lens). Although the projected brightness after expansion will decrease slightly, for three-dimensional measurement, the widely used phase-shifting method for phase unwrapping is not sensitive to the absolute change in brightness (it can accurately calculate the phase under a large absolute change in brightness), thereby completing high-precision three-dimensional measurement. The present invention is of great significance for realizing ultra-high-precision three-dimensional measurement.

[0023] Specifically, please refer to Figure 1 and Figure 2 , the preferred embodiment of the method for expanding the resolution of the DLP projection device in optical three-dimensional measurement of the present invention is applied to the device for expanding the resolution of the DLP projection device in optical three-dimensional measurement. Among them, the device for expanding the resolution of the DLP projection device in optical three-dimensional measurement includes a DLP projection device, a semi-transparent and semi-reflective lens, and a front-coated reflector. As Figure 1 shown, the preferred embodiment of the method for expanding the resolution of the DLP projection device in optical three-dimensional measurement of the present invention includes the following steps:

[0024] Step S10, transmitting half of the light intensity of the fringe image projected by the DLP projection device through the semi-transparent and semi-reflective lens to the first area of the object to be measured to form a first fringe image, and reflecting the other half of the light intensity to the front-coated reflector.

[0025] Step S20, reflecting the fringe image reflected by the semi-transparent and semi-reflective lens to the second area of the object to be measured through the front-coated reflector to form a second fringe image.

[0026] Step S30, adjusting the angle of the front-coated reflector so that the first fringe image in the first area and the second fringe image in the second area are seamlessly synthesized.

[0027] It should be noted that in this embodiment, higher magnification expansion can be achieved by increasing the number of semi-reflective semi-transmissive lenses and front-coated mirrors, and simultaneous expansion in the horizontal and vertical directions can be realized, thereby achieving higher-precision three-dimensional measurement.

[0028] The following will Figure 2 elaborate in detail on the operating principle of this embodiment.

[0029] The fringe image projected by the DLP projection device reaches the semi-reflective semi-transmissive lens through optical path A. Half of the light intensity passes through the semi-reflective semi-transmissive lens and then reaches area A (the first area) of the object to be measured through optical path B, forming fringe image A (the first fringe image). The other half of the light intensity is reflected by the semi-reflective semi-transmissive lens and then reaches the front-coated mirror through optical path C for reflection, and then reaches area B (the second area) of the object to be measured through optical path D, forming fringe image B (the second fringe image).

[0030] Then, adjust the angle of the front-coated mirror so that the fringe images in area A and area B are seamlessly synthesized. Since each fringe period of the fringe image is the same, the fringe image synthesized in the space of area A and area B has the same characteristics as the original fringe image.

[0031] The beneficial effect of the method for expanding the resolution of the DLP projection device in the extended optical three-dimensional measurement of the present invention is as follows: By adding one semi-reflective semi-transmissive lens and one front-coated mirror, the spatial fringe resolution of the DLP projection device can be increased to 2 times. By increasing the number of semi-reflective semi-transmissive lenses and front-coated mirrors, higher magnification expansion can be achieved, and simultaneous expansion in the horizontal and vertical directions can be realized, thereby achieving higher-precision three-dimensional measurement, which is of great significance for realizing ultra-high-precision three-dimensional measurement.

[0032] To achieve the above object, the present invention also proposes a device for expanding the resolution of the DLP projection device in the extended optical three-dimensional measurement. Please refer to Figure 2 again. The preferred embodiment of the device for expanding the resolution of the DLP projection device in the extended optical three-dimensional measurement of the present invention includes a DLP projection device, a semi-reflective semi-transmissive lens, and a front-coated mirror. Among them, the semi-reflective semi-transmissive lens and the front-coated mirror are located between the DLP projection device and the object to be measured, and the initial position of the front-coated mirror is parallel to the semi-reflective semi-transmissive lens.

[0033] The semi-reflective semi-transmissive lens is used to transmit half of the light intensity of the fringe image projected by the DLP projection device to the first area of the object to be measured, forming the first fringe image, and reflecting the other half of the light intensity to the front-coated mirror.

[0034] The front coated mirror is used to reflect the fringe image reflected by the semi-transmissive and semi-reflective lens to the second area of the object to be measured, forming a second fringe image; when the front coated mirror is adjusted from the initial position to another angular position, the first fringe image in the first area and the second fringe image in the second area are seamlessly synthesized.

[0035] The principle of operation of the device for the resolution of the DLP projection device in the extended optical three-dimensional measurement of the present invention will be described in detail below.

[0036] The fringe image projected by the DLP projection device reaches the semi-transmissive and semi-reflective lens through optical path A. Half of the light intensity passes through the semi-transmissive and semi-reflective lens and then reaches area A (the first area) of the object to be measured through optical path B, forming fringe image A (the first fringe image). The other half of the light intensity is reflected by the semi-transmissive and semi-reflective lens and then reaches the front coated mirror through optical path C for reflection, and then reaches area B (the second area) of the object to be measured through optical path D, forming fringe image B (the second fringe image).

[0037] Then, the angle of the front coated mirror is adjusted so that the fringe images in area A and area B are seamlessly synthesized. Since each fringe period of the fringe image is the same, the fringe image synthesized in the space of area A and area B has the same characteristics as the original fringe image.

[0038] The beneficial effects of the device for the resolution of the DLP projection device in the extended optical three-dimensional measurement of the present invention are as follows: By adding a semi-transmissive and semi-reflective lens and a front coated mirror, the spatial fringe resolution of the DLP projection device can be increased to 2 times. By increasing the number of semi-transmissive and semi-reflective lenses and front coated mirrors, a higher multiple of expansion can be achieved, and simultaneous expansion in the horizontal and vertical directions can be realized, thereby achieving higher-precision three-dimensional measurement, which is of great significance for realizing ultra-high-precision three-dimensional measurement.

[0039] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for expanding the resolution of a DLP projection device in optical three-dimensional measurement, characterized in that, the method is applied to a device for expanding the resolution of a DLP projection device in optical three-dimensional measurement. The device for expanding the resolution of a DLP projection device in optical three-dimensional measurement includes a DLP projection device, a semi-transparent and semi-reflective lens, and a front-coated mirror. Among them, the semi-transparent and semi-reflective lens and the front-coated mirror are located between the DLP projection device and the object to be measured, and the initial position of the front-coated mirror is parallel to the semi-transparent and semi-reflective lens. The method includes the following steps: Transmit half of the light intensity of the fringe image projected by the DLP projection device through the semi-transparent and semi-reflective lens to the first area of the object to be measured to form a first fringe image, and reflect the other half of the light intensity to the front-coated mirror; Reflect the fringe image reflected by the semi-transparent and semi-reflective lens to the second area of the object to be measured through the front-coated mirror to form a second fringe image; Adjust the angle of the front-coated mirror so that the first fringe image in the first area and the second fringe image in the second area are seamlessly synthesized.

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