CN115777055A - Line scanning three-dimensional sensing system - Google Patents

Abstract

A line-scanning three-dimensional sensing system measures a surface profile of an object. In this system, a Dispersive Optical Module (DOM) performs a forward optical process, disperses a polychromatic linear beam into a graded narrow-band linear beam (CNLLB), and focuses the CNLLB at different focal planes to form a rainbow light pattern to illuminate a scanned surface of an object. The illuminated object exhibits an information-bearing color image (IBCI) that contains height information of the scanned surface. The DOM captures an IBCI and performs backward optical processing to optically converge the captured IBCI to form an elongated light pattern. The backward optical processing is the reverse of the forward processing. The slits spatially filter the elongated light pattern to form output light. By analyzing the spectral content of each point on the output ray, the height profile of the scanned surface can be obtained.

Description

Line scanning three-dimensional sensing system

List of abbreviated terms

Two dimensions of 2D

3D three-dimensional

CNLLB gradual change narrow-band linear light beam

DOM dispersion optical module

FOV field of view

IBCI information-containing color image

LED light-emitting diode

NIR near Infrared

PLLB multicolor Linear light Beam

TIR Total internal reflection

Technical Field

The present invention generally relates to a line-scanning three-dimensional sensing system for measuring the surface profile of an object. More particularly, the present invention relates to a system that disperses a polychromatic linear beam into a graded narrow-band linear beam and focuses the graded narrow-band linear beam at different heights above a reference surface to form an iridescent light pattern for surface profile measurements.

Background

Currently, bright surfaces, multi-layer transparent surfaces, and precision electronic surfaces are the most complex surfaces to be inspected at present, and almost become the bottleneck in the field of machine vision. Products such as electronic components, semiconductor wafers, cover glasses for cellular phones, metal parts for automobiles, etc. are always difficult to be inspected. It has been noted that two-dimensional machine vision does not meet the requirements and therefore a fast, accurate three-dimensional measurement technique is required. Line-scan three-dimensional sensing is the most advanced technique for detecting such surfaces.

Conventional line-scanning three-dimensional sensing systems have problems in some situations. A tilt-axis scanning three-dimensional sensing system, such as that disclosed in US 7,936,464 B2, suffers from shadowing problems. Smaller features behind larger objects cannot be detected. In addition, deep holes and grooves cannot be measured. Systems using pinhole arrays or digital micromirror device panels, as disclosed in US 2020/0363619 A1 and DE 102006007172 B4, can be used for measuring deep holes and recesses. However, alignment is critical, resolution is limited by pinhole size, and crosstalk is a serious drawback. Various problems also exist with systems using cylindrical lenses and diffractive elements, as disclosed in US 8,654,352 B1. Due to the cylindrical lenses used, rotational tolerances during lens assembly are critical, which results in stringent requirements for lens alignment. Diffractive elements also cause zeroth and higher order diffraction noise.

There is a need in the art to develop a new line-scanning three-dimensional sensing system to address the shadowing problem described above (so that deep holes and recesses can be measured) while making the system easier to align.

Disclosure of Invention

A first aspect of the invention provides a line-scanning three-dimensional sensing system for measuring a surface profile of an object.

The system comprises a light source module, a first slit, a DOM and a second slit. The light source module is used for generating a multicolor light beam. The first slit is used to spatially filter the polychromatic beam to form a PLLB. The DOM is configured to perform forward optical processing to disperse the PLLB received from the first slit into CNLLBs and focus the CNLLBs onto different focal planes, respectively, to form an iridescent light pattern for illuminating the scanned surface of the object during surface profile measurement, thereby causing an IBCI to be displayed on the illuminated object. The IBCI contains height information for the scanned surface. The DOM is further configured to capture an ibii and perform backward optical processing of the captured ibii to form an elongated light pattern. The backward optical processing is the reverse of the forward optical processing. The second slit is used to spatially filter the elongated light pattern to form output light rays. By analyzing the spectral content of each point of the output light, a height profile of the scanned surface can be obtained, whereby the surface profile can be determined from the respective height profiles obtained for a plurality of scanned surfaces of the object.

Preferably, the DOM comprises first and second sets of lenses. The first group of lenses is aligned on a first optical axis. The first group of lenses is configured to disperse the PLLB into the CNLLB and focus the CNLLB on different focal planes distributed over a predetermined length of the first optical axis, respectively, to form an iridescent light pattern. The second set of lenses is configured to optically converge the captured IBCI to form an elongated light pattern. The first and second groups of lenses share one or more shared lenses. At least one shared lens is used to output the rainbow light pattern and the input IBCI simultaneously. Thus, it avoids the burden of having to align the first and second groups of lenses to output the rainbow light pattern and input the IBCI.

Preferably, the DOM further comprises an optical splitter optically coupled to the one or more shared lenses and positioned in the first set of lenses such that the captured IBCI is replicated into two copies, one of which is directed to the second slit.

Preferably, the second group of lenses comprises one or more additional lenses not shared with the first group of lenses. The one or more additional lenses are disposed between the beam splitter and the second slit for optically processing the captured IBCI before the captured IBCI reaches the second slit. The one or more additional lenses are replicas (replicas) of respective one or more lenses of the first set of lenses for optically processing the PLLB and are disposed between the beam splitter and the first slit.

In certain embodiments, the first slit is configured such that PLLB emitted to the DOM at any point on the first slit has a first set of chief rays with divergence angles within 1 ° as measured based on the first optical axis. Further, the first group of lenses is configured such that CNLLB received at any point on the rainbow light pattern has a second group of chief rays whose convergence angle is within 1 ° when measured based on the first optical axis. The system also includes a stage for positioning the object during surface profile measurement. The platform includes a reference plane on which the object is adapted to be placed. Furthermore, the first set of lenses is oriented such that the first optical axis is perpendicular to the reference plane, resulting in the rainbow light pattern being perpendicular to the reference plane, thereby allowing the surface profile to be measured also when the scanning surface comprises grooves.

In certain embodiments, the light source module is a color mixing light source module comprising a light source and a color mixing rod. The light source is used to generate primary light rays that collectively provide polychromatic light. The color mixing rod is optically coupled to the first slit to provide a polychromatic light beam to the first slit for spatial filtering. The color mixing rod is in the shape of a long strip and is used for mixing original light rays to generate a multicolor light beam, so that at least one part of the multicolor light beam received by the first slit has a substantially uniform color.

In some embodiments, the light source includes one or more LEDs that collectively generate the raw light. In addition, the color mixing light source module further comprises an asymmetric TIR lens for directing primary light generated from the one or more LEDs towards the color mixing rod. An asymmetric TIR lens has different lengths in the X and Y directions.

In certain embodiments, the light source comprises one or more LEDs, each LED deposited with a solar spectrum phosphor fill, wherein the solar spectrum phosphor fill is formulated to produce a spectrum at least in the range of 400nm to 700 nm. One or more LEDs are configured to optically excite the solar spectrum phosphor fill to produce primary light rays that collectively provide polychromatic light. In addition, the color mixing rod is optically coupled to the light source to directly receive the raw light from the light source.

In certain embodiments, the system further comprises a grating, an imaging sensor, a collimating lens module, and a condenser lens module. The grating is for diffracting the output light, thereby forming a spectral image of the output light. The imaging sensor is used for imaging the spectral image. The spectral content of each point of the output light can be determined from the spectral image. The collimating lens module is positioned between the second slit and the grating and is used for collimating the output light before the output light is diffracted by the grating. The condenser lens module is disposed between the grating and the imaging sensor for focusing the spectral image onto the imaging sensor.

In certain embodiments, the system further comprises a prism for reflecting the spectral image emitted from the grating to the collection optic module. The prism is configured to reorient the spectral image such that the collimating lens module and the condenser lens module are oriented perpendicular to each other, thereby facilitating alignment and assembly of the collimating lens module and the condenser lens module.

In certain embodiments, the system further comprises a third slit and a two-dimensional line scanning camera. The third slit is for spatially filtering a copy of the elongated light pattern received at the third slit to form a second output light ray. The two-dimensional line scanning camera is used for carrying out color imaging on the second output light, and accordingly, after the plurality of scanning surfaces are scanned, a two-dimensional image of the object can be obtained for three-dimensional sensing. In addition, the DOM further comprises a first beam splitter and a second beam splitter. A first beam splitter is provided in the first set of lenses to replicate the captured IBCI into two copies, one of which is directed to the second slot. A second beam splitter is provided in the first set of lenses to replicate the captured IBCI into two copies, one of which is directed to the third slit.

A second aspect of the present invention is to provide another line scanning three-dimensional sensing system for measuring the surface profile of an object.

The system comprises a light source module, a first slit, a first DOM, a second DOM, a double-pass lens module and a second slit. The light source module is used for generating a multi-color light beam. The first slit is optically coupled to the light source module for spatially filtering the polychromatic light beam to form a PLLB. The first dispersion optics module is configured to perform forward optical processing, disperse the PLLB received from the first slit into CNLLBs, and focus the CNLLBs on different focal planes to form an iridescent light pattern. The rainbow light pattern is used to illuminate the scanned surface of the object during surface profile measurement in order for the illuminated object to display an IBCI on the object. The IBCI contains height information for the scanned surface. The second DOM is configured to capture an IBCI and perform backward optical processing to optically converge the captured IBCI into an elongated light pattern. The backward optical processing is the reverse of the forward optical processing. The first and second dispersive optical modules are arranged side by side. The bi-pass lens module is configured to reposition the rainbow light pattern produced by the first dispersive optical module to an offset position where the object is appropriate to be positioned and to direct an IBCI from the offset position to the second dispersive optical module to enable the second dispersive optical module to capture the IBCI. The second slit is used for spatially filtering the elongated light pattern to form output light rays. By analyzing the spectral content of each point of the output light, the height profile of the scanned surface can be obtained, so that from the respective height profiles obtained for a plurality of scanned surfaces of the object, the surface profile can be determined.

Preferably, the first dispersive optical module comprises a first plurality of lenses and the second dispersive optical module comprises a second plurality of lenses. The second plurality of lenses is a replica of the first plurality of lenses.

In certain embodiments, the second dispersive optical module further comprises a reflector disposed in the second plurality of lenses.

In certain embodiments, the light source module is a color mixing light source module comprising a light source and a color mixing rod. The light source is used to generate primary light rays that collectively provide polychromatic light. The color mixing rod is optically coupled to the first slit to provide a polychromatic light beam to the first slit for spatial filtering. The color mixing rod is elongated in shape for mixing the primary light rays to produce a polychromatic light beam such that at least a portion of the polychromatic light beam to be received by the first slit is substantially uniform in color.

In some embodiments, the light source includes one or more LEDs that collectively generate the raw light. In addition, the color mixing light source module further includes an asymmetric TIR lens for mixing raw light generated from the one or more LEDs to form an intermediate light output such that the intermediate light output is substantially uniform in radiant power. The original light in the intermediate light output is fed into the color mixing rod. Furthermore, asymmetric TIR lenses have different lengths in the X and Y directions.

In certain embodiments, the light source comprises one or more LEDs, each LED deposited with a solar spectrum phosphor fill, wherein the solar spectrum phosphor fill is formulated to produce a spectrum at least in the range of 400nm to 700 nm. One or more LEDs are arranged to optically excite the solar spectrum phosphor fill to produce primary light rays that collectively provide polychromatic light. In addition, the color mixing rod is optically coupled to the light source to directly receive the raw light from the light source.

In certain embodiments, the system further comprises a grating, an imaging sensor, a collimating lens module, and a condenser lens module. The grating is used to diffract the output light, thereby forming a spectral image of the output light. The imaging sensor is used for imaging the spectral image. The spectral content of each point of the output light can be determined from the spectral image. The collimating lens module is positioned between the second slit and the grating and is used for collimating the output light before the output light is diffracted by the grating. The condenser lens module is disposed between the grating and the imaging sensor for focusing the spectral image onto the imaging sensor.

Other aspects of the disclosure are disclosed as illustrated by the following examples.

Drawings

Fig. 1 illustrates a first line-scan 3D sensing system for measuring the surface profile of an object, wherein the first system uses a DOM: generating a rainbow light pattern from the PLLB for illuminating an object on the scanning surface, thereby displaying the IBCI on the object; and optically converging the captured IBCI into an elongated light pattern, followed by filtering through a second slit to produce output light rays having spectral content indicative of the height profile of the scanned surface.

Fig. 2 shows a picture of the elongated light pattern in sub-picture (a) and the output light in sub-picture (b), illustrating the filtering effect achieved by the second slit.

Fig. 3 depicts a cross-sectional view of a first color mixing light source module used in a first system.

FIG. 4 depicts two cross-sectional views of an X-X section and a Y-Y section of a first color mixing light source module.

Fig. 5 depicts a cross-sectional view of a second color mixing light source module.

Fig. 6 illustrates a second line-scan 3D sensing system for measuring the surface profile of an object, wherein the second system includes a prism for changing the direction of the spectral image of the output light so as to enable convenient alignment and assembly of the collimating lens module and the condenser lens module in the second system.

Fig. 7 depicts an enlarged view of a prism used in the second system.

Fig. 8 illustrates a third line-scan 3D sensing system for measuring the surface profile of an object, where the third system uses two independent DOMs to generate an iridescent light pattern and optically converge the captured IBCI.

Fig. 9 illustrates a fourth line-scan 3D sensing system for measuring the surface profile of an object, wherein the fourth system is a variation of the third system, which has the advantage of keeping the imaging sensor and the condenser lens module away from the light source module to avoid the difficulty of assembling the condenser lens module to the fourth system and to avoid interference with the imaging sensor due to light leakage that may come from the light source module.

Fig. 10 illustrates a fifth line-scan three-dimensional sensing system for measuring the surface profile of an object, wherein the fifth system has the additional function of taking a two-dimensional image of the object.

FIG. 11 depicts a ray tracing diagram showing the propagation of constituent rays in and around the DOM used in the first line-scan three-dimensional sensing system.

Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale.

Detailed Description

In this description and the appended claims, the spectral content or wavelength spectrum of a light beam defines the "color" of the light beam. The spectrum may have one or more wavelengths. If the light beam is visible, one can easily understand the meaning of the color. For example, red corresponds to a wavelength of about 700 nanometers. In another example, a light beam having a wavelength spectrum uniformly distributed in the visible range of 400nm to 700nm is generally considered to have a white color. The definition of color described above extends the concept of color to invisible light. An invisible light beam, such as a near infrared light beam, possesses a color corresponding to the wavelength content in the near infrared light beam. Further, two beams of non-visible light having different wavelengths are considered herein to have different colors, although the two beams are not visible to humans.

As used herein, a "polychromatic light beam" is a light beam having a spectrum that consists of a plurality of wavelengths. The spectrum may be discrete, continuous, or a mixture thereof. The polychromatic light beam is a superposition of, or can be decomposed into, a plurality of graded narrow-band light beams, each having a spectrum substantially narrower than that of the polychromatic light beam, wherein the spectra of the graded narrow-band light beams do not substantially overlap one another. Each tapered narrow-band light beam may be visible or invisible depending on its wavelength content. It is possible that each of the tapered narrow band beams is a monochromatic beam, i.e., a beam having a single wavelength as actually considered by those skilled in the art.

As used herein, "dispersion" of a polychromatic beam refers to the decomposition of the polychromatic beam into its graded narrowband beams and the spatial separation of the graded narrowband beams. For example, if the tapered narrow-band light beams are respectively directed along different propagation directions, the tapered narrow-band light beams are spatially separated. To achieve dispersion of a polychromatic beam, one can use lenses or prisms that exhibit different indices of refraction for narrow-band beams having different wavelength content.

As used herein, a "linear beam" refers to a beam having a cross-section with a rectilinear shape, wherein the cross-section is perpendicular to the direction of propagation of the beam. The boundaries of the cross-section may be sharp or fuzzy.

As used herein, a "double pass lens" is a lens for forward and backward optical paths in which the traveling directions of the forward and backward optical paths are opposite to each other.

As used herein, a "double-pass lens module" is an optical module consisting of one or more lenses, where each lens is a double-pass lens.

As used herein, a "focal plane" is a plane perpendicular to the optical axis containing the focal point.

In this specification and the appended claims, the "inverse" of the optical treatment is to be interpreted as substantially similar to the inverse of the mathematical function. If the optical treatment is represented by a conversion rule for converting the first light beam into the second light beam, the reverse direction of the optical treatment is represented by another conversion rule for converting the second light beam into the first light beam.

Embodiments of a line-scan three-dimensional sensing system for measuring a surface profile of an object are disclosed herein. Basically, a line-scanning three-dimensional sensing system illuminates an object using a spatial distribution of focused linear light beams having different colors to form a color image on the object, wherein height information of the object is encoded to the color image by the spatial distribution of colors on the color image. In particular, the spatial distribution of the focused linear beam of light forms a rainbow light pattern in the form of a planar sheet of light. Thus, one line or one strip on the surface of the object is scanned at a time, so that line scanning is performed. The surface profile of the object is measured by performing a line scan a plurality of times over different strips of the surface of the object.

Fig. 1 illustrates a first line-scanning three-dimensional sensing system 100 (referred to simply as the first system 100) for measuring a surface profile of an object 95, in accordance with certain embodiments of the disclosed line-scanning three-dimensional sensing system.

In FIG. 1, a frame of reference 80 is shown that defines x, y, and z directions along x, y, and z axes. Reference frame 80 is used herein to assist in explaining the different parts or components in the various embodiments of the disclosed line-scan three-dimensional sensing system.

Illustratively, the first system 100 includes a light source module 130, a first slit 121, a DOM 110, and a second slit 122.

The light source module 130 is used to generate a polychromatic light beam 131. The polychromatic light beam 131 is then used to generate a spatial distribution of focused linear light beams having different colors to illuminate the object 95. The radiant power and color of the polychromatic beam 131 is preferably spatially uniform across the cross-section of polychromatic beam 131. While it is practical to maintain substantial uniformity of color and power over the central region of the cross-section, it is often difficult or expensive to extend this uniformity to the periphery of the cross-section.

Advantageously, first slit 121 is optically coupled to light source module 130 for spatially filtering polychromatic light beam 131 to form PLLB 125. The first slit 121 is positioned relative to the light source module 130 such that a peripheral portion of the polychromatic light beam 131 emitted from the light source module 130 is filtered. Thus, it produces a PLLB125 that is substantially uniform in radiant power and color.

DOM 110 is configured to receive PLLB125 from first slit 121 as an input and output rainbow light pattern 181 to illuminate object 95 for surface profile measurement. In particular, the DOM 110 is configured to disperse the PLLB125 into CNLLB 180 (represented in FIG. 1 by λ 1, λ 2, and λ 3), and to focus the CNLLB 180 on different focal planes (represented by different lines 183a-c of λ 1, λ 2, and λ 3, and distributed along the z-direction of FIG. 1) outside the DOM 110, respectively, to form a rainbow light pattern 181, which displays a series of different colors. Since CNLLB 180 is a linear beam, the rainbow light pattern 181, consisting of CNLLB 180 at focal positions 183a-c, is a planar sheet of light positioned in the x-z plane, having a predetermined length 184 in the z-direction. On the scanning surface 283 of the object 95, the object 95 is illuminated by the rainbow light pattern 181. The scanned surface 283 is the scanned surface. Scanning surface 283 is an elongated strip of the outer surface of object 95, thus enabling a linear scan of object 95. When the object 95 is illuminated by the rainbow light pattern 181, the illuminated object 95 displays the IBCI 282 on the object 95. IBCI 282 contains height information for scan surface 283. Specifically, the altitude information is encoded in the color distribution of the IBCI 282. Note that the predetermined length 184 of the rainbow light pattern 181 determines the maximum measurable change in height of the object 95.

Since the IBCI 282 is displayed on the outer surface of the object 95, the color image is not planar in most cases. When capturing the IBCI 282 displayed on the object 95 directly using the two-dimensional imaging sensor to obtain the color distribution of the IBCI 282, it is necessary to position the two-dimensional imaging sensor directly over the object 95 along the Z-axis; otherwise, some information of the color distribution will be lost, for example, if the object 95 has a deep hole. However, it is not practical to position the two-dimensional imaging sensor directly above the object 95.

Instead of imaging the IBCI 282 directly, the DOM 110 is arranged to capture the IBCI from an overhead location (denoted by λ 2 and referred to as 182 in FIG. 1) and transmit the captured IBCI 182 elsewhere through the DOM 110. In particular, the displayed IBCI 282 (i.e., the IBCI 282 displayed on the object 95) is received by the DOM 110 through the same outlet that outputs the rainbow light pattern 181. Note that the PLLB125 and CNLLB 180 travel along the DOM 110 in a direction opposite to the direction of travel of the captured IBCI 182. It can thus be seen that when PLLB125 is processed as forward optical processing, i.e., PLLB125 is dispersed into CNLLBs 180 and CNLLBs 180 are focused onto different focal planes 183a-c, respectively, captured IBCI 182 undergoes backward optical processing, which is the reverse of the forward optical processing. Since the displayed IBCI 282 may be viewed as a remnant of the rainbow light pattern 181 on the object 95, it is expected that the backward optical processing will convert the captured IBCI 182 into linear segments (corresponding to PLLB125 in the forward optical processing). Sub-figure (a) of figure 2 depicts a graph showing the simulation results showing an elongated light pattern 210 obtained by processing a captured IBCI 182 with backward optics. As a result, the DOM 110 optically converges the captured IBCI 182 to form an elongated light pattern 210.

Unlike the PLLB125, which typically occurs with sharp light rays, the elongated light pattern 210, while containing a major centerline 215, has some surrounding light signal 216 around the major centerline 215. The main centerline 215 is contributed by the rainbow light pattern 181 intersecting the object 95 and contains height information of the scanned surface 283 of the object 95. Since the rainbow light pattern 181 is formed by the CNLLB 180 at the focus positions 183a-c, stray light of CNLLB other than focus exists around the rainbow light pattern 181. It is believed that the enclosed optical signal 216 is due to reflections of stray light rays from the object 95, so the enclosed optical signal 216 is considered noise.

To derive the principal center line 215 from the elongated light pattern 210 while removing the surrounding light signal 216, the second slit 122 is used to spatially filter the elongated light pattern 210 to form output light rays 220. By way of illustration, sub-figure (b) of figure 2 shows a diagram showing output light rays 220 obtained by masking the elongated light pattern 210 with the second slit 122. The output light 220 may be used to obtain a height profile of the scanned surface 283 of the object 95. The height profile may be obtained by analyzing the spectral content of each point of the output light 220. The surface profile of the object 95 may be determined from respective height profiles obtained for a plurality of scanned surfaces of the object 95.

Preferably, the forward and backward optical processing is achieved by a plurality of lenses 112, 113, 116 in the DOM 110. In particular, the DOM 110 includes a first set of lenses 171 and a second set of lenses 172, wherein the lenses in the two sets are selected from the plurality of lenses 112, 113, 116. As shown in fig. 1, the first lens group 171 is composed of lenses 112, 113, and the second lens group 172 is composed of lenses 113, 116. Note that the first and second lens groups 171, 172 share one or more lenses (referred to as a shared lens 113). The lenses 112, 113 of the first lens group 171 are aligned on the first optical axis 111. The first lens group 171 is configured to disperse the PLLB125 into the CNLLB 180 and focus the CNLLB 180 on focal planes 183a-c distributed over a predetermined length 184 on the first optical axis 111, respectively, to form an rainbow light pattern 181. The second lens group 172 is configured to optically concentrate the captured IBCI 182 into an elongated light pattern 210. Advantageously, one or more shared lenses 113 are used to simultaneously output the rainbow light pattern 181 and input the displayed IBCI 282 (i.e., lens 113a shown in FIG. 1). Thus, it avoids such a burden of aligning the first and second lens groups 171, 172 to output the rainbow light pattern 181 and input the displayed IBCI 282.

Since both the CNLLB 180 and the captured IBCI 182 travel in the shared lens 113, it is necessary to separate the captured IBCI 182 (which becomes the elongated light pattern 21) from the CNLLB 180 before the captured IBCI 182 reaches the second slit 122. Thus, the DOM 110 further includes an optical splitter 118 optically coupled to the shared lens 113 and positioned in the first lens group 171 such that the captured IBCI 182 moving in the shared lens 113 is replicated into two copies, one of which is directed to the second slit 122.

By including the beam splitter 118 in the first lens group 171, the captured IBCI 182 moves on a path along the lens 116 of the second lens group 172, while the PLLB125 moves on another path along the lens 112 of the first lens group 171. Since the forward optical processing to process the PLLB125 is the inverse of the backward optical processing to process the captured IBCI 182, the lens 116 (referred to as the extra lens 116 for convenience) disposed between the beam splitter 118 and the second slit 122 may be selected as a replica of the lens 112 (referred to as the corresponding lens 112) disposed between the beam splitter 118 and the first slit 121. Note that although the respective lenses 112 are aligned with the first optical axis 111, the additional lens 116 is aligned with the second optical axis 117 perpendicular to the first optical axis 111.

As described above, one advantage of the DOM 110 is that it avoids the burden of having to align the first and second lens groups 171, 172 to output the rainbow light pattern 181 and input the displayed IBCI 282. Further, the lenses of the plurality of lenses 112, 113, 116 are preferably circular lenses, and need not be cylindrical lenses as used in U.S. 8,654,352 B1, thereby avoiding the need to align cylindrical lenses in the DOM 110. The DOM 110 need only align the first slit 121 with the first optical axis 111 and the second slit 122 with the second optical axis 117. Thus, the manufacturing cost of the DOM 110 is reduced.

In a practical implementation of the first system 100, the platform 192 is typically used to position the object 95 during surface profile measurements. The platform 192 includes a reference plane 190 on which the object 95 is adapted to be placed. The reference plane 190 is a flat surface that is used as a reference for measuring the height profile of the object 95. In the first system 100, the first lens group 171 is oriented such that the first optical axis 111 is perpendicular to the reference plane 190. Which makes the rainbow light pattern 181 perpendicular to the reference plane 190. Advantageously, even if the scanned surface 283 of the object 95 includes grooves or recesses, as long as the propagation directions of the CNLLB 180 reaching the rainbow light pattern 181 are nearly parallel, so that CNLLB 180 of different colors can propagate into the grooves or recesses for measurement, it is possible to allow the surface profile to be measured,

providing CNLLB 180 with nearly parallel propagation directions at the rainbow light pattern 181 is illustrated by means of fig. 11. FIG. 11 depicts a ray tracing diagram showing the propagation of the component rays of PLLB125 and CNLLBs 180 within and around the DOM 110. The ray tracing diagram has an area a and an area B for displaying the light propagation of the PLLB125 around the first slit 121 and the light propagation of the CNLLB 180 around the rainbow light pattern 181, respectively. Fig. 11 also includes enlarged views of regions a and B to show details therein.

In order to make CNLLB 180 almost parallel in the propagation direction, it is preferable to first control the propagation direction of the light rays constituting PLLB 125. The first slit 121 may be divided into a number of points. The PLLB125 fired at each point has a FOV formed by a cone of light. The cone of rays consists of one set of primary rays and another set of the remaining weaker rays, where the primary group of rays has a dominant portion of the total light energy provided by the cone of rays. As used herein, a set of principal rays in a cone of rays is defined as: the main ray group assumes 90% of the total light energy provided by the cone of rays. Preferably, the PLLB125 emitted to the DOM 110 at any point on the first slit 121 has a first set of chief rays (e.g., any one of R1-R4) with a divergence angle δ 1125 within 1 ° as measured based on the first optical axis 111. It can be seen that the PLLB125 is almost collimated throughout the first slit 121, with a divergence angle δ 1125 at any point of the first slit 121 not exceeding 1 °. Note that the first slit 121 may be configured to collimate the polychromatic beam 131 as a collimator when forming the PLLB 125. For example, the first slit 121 is formed as a long passage for guiding and limiting the propagation direction of the PLLB 125.

PLLB125 is processed by a first group of lenses 171 to form CNLLB 180, followed by rainbow light pattern 181. Since the divergence angle δ 1125 of the PLLB125 is within 1, it is preferable that the CNLLB 180 received at any point on the rainbow light pattern 181 has a second set of chief rays (e.g., any set of R1' -R4 ') whose convergence angle δ '1180 is within 1 as measured based on the first optical axis 111. Thus, the rainbow light pattern 181 is able to measure deep holes and grooves (if any) located on the object 95 without the shadow problem. Maintaining the convergence angle δ'1180 within 1 ° can be achieved by appropriate configuration of the first set of lenses 171 in the DOM 110. In one embodiment, the first set of lenses 171 are configured to have very long total focal lengths (telescope-like) for different colors of light, such that the direction of propagation of the CNLLB 180 away from the DOM 110 is approximately parallel to the first optical axis 111.

As described above, the predetermined length 184 of the rainbow light pattern 181 determines the maximum measurable change in height of the object 95. In one practical design of the first system 100, the predetermined length 184 is 6mm for a wavelength spectrum from 400nm to 700nm (i.e., the entire visible spectrum). The rainbow light pattern 181 is positioned above the reference plane 190 such that the measurable working distance (denoted as D in fig. 11) of the rainbow light pattern 181 is between 32mm (at λ 1 at wavelength 400 nm) and 38mm (at λ 3 at wavelength 700 nm). The angle of the chief ray measured from the first optical axis 111 is less than 1 deg. at the first slit 121 and the object 95, so there is no shadowing problem and the first system 100 can measure deep holes or grooves. The image space numerical aperture is 0.45, and thus the first system 100 can measure surfaces with a tilt angle greater than 22 °. In the described design of the first system 100, the plurality of lenses 112, 113, 116 in the DOM 110 includes at least one dispersive lens pair (e.g., lenses 113b, 113 c) for dispersing the PLLB 125.

Additional implementation details of the first system 100 are set forth below.

In certain embodiments, light source module 130 is a color mixing light source module configured to mix raw light of different colors to form a polychromatic light beam 131. As discussed above, it is desirable that the power and color of the polychromatic light beam 131 be spatially uniform across the cross-section of the polychromatic light beam 131.

Fig. 3 depicts a cross-sectional view of a first mixed color light source module 130a as a first embodiment of light source module 130. Fig. 4 depicts two cross-sectional views of the first mixed color light source module 130a in x-x and y-y cross-sections as demonstrations of the mixing of light beams in the light source module 103 a. The first color mixing light source module 130a includes a light source 310, an asymmetric TIR lens 320, and a color mixing rod 330.

Light source 310 is used to generate raw light 415 that collectively provide polychromatic light. Typically, the light source 310 includes one or more LEDs 315 for collectively producing the raw light 415, although other types of light emitters may be used. In certain embodiments, the one or more LEDs 315 comprise large area, high power LEDs (having dimensions greater than 3mm LED width).

The color mixing rod 330 is optically coupled to the first slit 121 to provide a polychromatic light beam (reference numeral 350) for spatial filtering to the first slit 121. The color mixing bar 330 is elongated in shape for mixing the primary light rays 415 to produce a polychromatic light beam 350 such that at least a portion of the polychromatic light beam 350 that will be received by the first slit 121 is substantially uniform in color.

An asymmetric TIR lens 320 is located between the light source 310 and the color mixing rod 330. Functionally, the asymmetric TIR lens 320 serves to direct the raw light 415 produced from the one or more LEDs 315 to the color mixing rod 330. The asymmetric TIR lens 320 serves to direct and efficiently transfer the original light 415 onto the color mixing rod 330. Because the color mixing rod 330 is elongated in shape, the asymmetric TIR lens 320 has an asymmetric shape with different lengths in the X and Y directions.

The inventors of the present invention have determined the following design parameters for an asymmetric TIR lens 320 and color mixing rod 330 to efficiently transport the original light 415 from the light source 310 to the color mixing rod 330. (a) Lx > Ly, where Lx and Ly are the diameters of the asymmetric TIR lens 320 in the X-direction and the Y-direction, respectively; (b) Fx is higher than Fy, where Fx and Fy are the focal points of the asymmetric TIR lens 320 in the X and Y directions, respectively; (c) Dx is larger than 10mm, and Dy is smaller than 2.5mm, where Dx and Dy are the lengths of the color mixing rod 330 in the x-direction and y-direction, respectively; and H > 3 XDx, where H is the height of the color mixing rod 330.

Fig. 5 depicts a cross-sectional view of a second color mixing light source module 130b as a second embodiment of the light source module 130. The second color mixing light source module 130b includes a light source 510 and a color mixing rod 530.

Light source 510 is used to generate original light 511 that collectively provide polychromatic light. Light source 510 includes one or more LEDs (e.g., LED 515) for collectively producing original light 511. The individual LEDs 515 are combined with a solar spectrum phosphor fill. The solar spectrum phosphor fill is formulated to produce light over a visible spectrum of at least 400nm to 700 nm. Individual LEDs 515 are arranged to optically excite the solar spectrum phosphor fill such that one or more LEDs produce primary light 511 that collectively provide polychromatic light.

The color mixing rod 530 is optically coupled to the first slit 121 to provide a polychromatic light beam (reference 550) for spatial filtering to the first slit 121. The color mixing bar 530 is elongated in shape and is configured to mix the primary light rays 511 to produce the polychromatic light beam 550 such that at least a portion of the polychromatic light beam 550 received by the first slit 121 is substantially uniform in color. Unlike the first mixed color light source module 130a, the mixed color rod 530 of the second mixed color light source module 130b is optically coupled to the light source 510 for directly receiving the original light beam 511 from the light source 510.

As described above, by analyzing the spectral content of each point of the output light ray 220, a height profile can be obtained. Please refer to fig. 1. To obtain spectral content, the first system 100 may further include a grating 140 and an imaging sensor 145. The grating 140 is used to diffract the output light 220 to form a spectral image 230 of the output light 220. The spectral image 230 is obtained as a first order diffraction pattern of the output light 220.θ is expressed as the angle at which the first order diffraction pattern is observed, where θ is measured with respect to the second optical axis 117. The imaging sensor 145 is a two-dimensional imaging sensor for imaging the spectral image 230. The imaging sensor 145 is positioned in the θ direction with respect to the second optical axis 117 for imaging the first order diffraction pattern, i.e., the spectral image 230. The spectral content of each point of the output light 220 may be determined from the spectral image 230. The first system 100 may further include a collimating lens module 151 and a condenser lens module 152. A collimating lens module 151 is positioned between the second slit 122 and the grating 140 for collimating the output light rays 220 before the output light rays 220 are diffracted by the grating 140. The condenser lens module 152 is disposed between the grating 140 and the imaging sensor 145 for focusing the spectral image 230 onto the imaging sensor 145. Those skilled in the art will appreciate that the collimating lens module 151 and the condenser lens module 152 can be readily designed based on knowledge in the art and the actual requirements for processing the output light rays 220 and the spectral image 230.

FIG. 6 depicts a second line-scanning three-dimensional sensing system 600 (referred to simply as the second system 600) for measuring the surface profile of the object 95, in accordance with certain embodiments of the disclosed line-scanning three-dimensional sensing system.

The second system 600 is implemented by any embodiment of the first system 100 and further includes a prism 645 for reflecting the spectral image 230 emitted from the grating 140 to the collection optic module 152. The prism 645 is configured to reorient the spectral image 230 such that the collimator lens block 151 and the condenser lens block 152 are oriented perpendicular to each other. On the other hand, in the first system 100, the condenser lens module 152 needs to form a predetermined angle θ with the second optical axis 117 in order to receive the spectral image 230 from the grating 140. Accordingly, the second system 600 has an advantage over the first system 100 in that the second system 600 can easily align and assemble the lens module 151 and the condenser module 152.

Fig. 7 shows an enlarged view of the prism 645 for illustrating its design. The prism 645 includes a first surface 751, an inclined plane 752, and a second surface 753. The first surface 751 is adjacent to the grating 140 for receiving the spectral image 230. The spectral image 230 is reflected by the inclined plane 752 by TIR. The second surface 753 is adjacent the collection mirror module 152. The reflected spectral image 230' exits the second surface 753 perpendicularly into the collection mirror module 152. Furthermore, one possible additional advantage of using the prism 645 is that it can correct distortion of the curvature of the image field due to oblique diffraction angles.

To design the prism 645, a tilt τ between the slope 752 and the z-direction 730 with respect to the reference frame 80 needs to be determined. The Z direction 730 is perpendicular to the second surface 753. The tilt τ is determined as follows. From snell's law, sin θ = n · sin θ' can be derived, where: n is the refractive index of the prism material; θ, is the diffraction angle of the grating 140, and is also the angle of incidence of the spectral image 230 into the prism 645; theta' is the corresponding angle of refraction. From the geometry of the prism 645, since the incident angle is the same as the reflection angle of TIR at the slope 752, we get pi/2 + θ' =2 τ. Thus, the tilt τ is given by the following equation

Fig. 8 illustrates a third line-scanning three-dimensional sensing system 800a (referred to simply as the third system 800 a) for measuring a surface profile of an object 95 in accordance with certain embodiments of the disclosed line-scanning three-dimensional sensing system. The main feature of the third system 800a with respect to the first system 100 is that, instead of using one DOM, two DOMs are used to perform both functions when simultaneously generating the rainbow light pattern 181 and processing the IBCI 182.

The third system 800a is developed based on the first system 100 and includes a light source module 130, a first slit 121, and a second slit 122. The details of the light source module 130, the first slit 121 and the second slit 122 have been disclosed above for the first system 100. The third system 800a further comprises a first dispersion optics module 810, a second dispersion optics module 820a and a double pass lens module 830.

The light source module 130 is used to generate a polychromatic light beam 131.

First slit 121 is optically coupled to light source module 130 for spatially filtering polychromatic light beam 131 to form PLLB 125.

The first dispersion optics module 810 is configured to perform a forward optical process of dispersing the PLLB125 received from the first slit 121 to the CNLLB 180 and focusing the CNLLB 180 on a different focal plane to form an rainbow light pattern 181'. The rainbow light pattern 181' is used during surface profile measurement to illuminate the scanning surface 283 of the object 95 when the object 95 is encountered, so that the illuminated object 95 displays the ibi 282 on the object 95. IBCI 282 contains height information for scan surface 283. Note that the rainbow light pattern 181' produced by the first dispersion optics module 810 is located at a position that does not meet the object 95.

The second dispersive optics module 820a is configured to capture the IBCI 282 and perform a backward optical process that optically converges the captured IBCI 182 into the elongated light pattern 210. The backward optical processing is the reverse of the forward optical processing. Note that the first and second dispersive optical modules 810, 820a are arranged side by side.

The double pass lens module 830 is optically coupled to the first dispersive optical module 810, the object 95 and the second dispersive optical module 820a. In particular, the double pass lens module 830 includes a plurality of lenses 831 configured to reposition the rainbow light pattern 181' produced by the first dispersion optics module 810 to an offset location 890 where the object 95 is positioned such that the repositioned rainbow light pattern 181 satisfies the object 95. The plurality of lenses 831 are further configured to direct the ibii 282 from the offset position 890 to the second dispersive optical module 820a to enable the second dispersive optical module 820a to capture the ibii 282.

The second slit 122 is used to spatially filter the elongated light pattern 210 to form output light rays 220. By analyzing the spectral content of each point of the output light 220, the height profile of the scanned surface 283 may be obtained, such that from the respective height profiles obtained for the plurality of scanned surfaces of the object 95, the surface profile may be determined.

Note that, as described above, the first dispersion optical module 810 and the second dispersion optical module 820a are configured to perform forward and backward optical processing, respectively, where the backward optical processing is the reverse of the forward optical processing. Typically, the first dispersion optics 810 and the second dispersion optics 820a are implemented with a first plurality of lenses 811 and a second plurality of lenses 821, respectively, wherein the second plurality of lenses 821 is a replica of the first plurality of lenses 811.

Similar to the first system 100, the third system 800a may include a grating 140 and an imaging sensor 145. Grating 140 is used to diffract output light 220 to form a spectral image 230. Spectral image 230 is obtained as a first order diffraction pattern of output light 220. The imaging sensor 145 is a two-dimensional imaging sensor for imaging the spectral image 230. The imaging sensor 145 is positioned in a direction 0 with respect to the second optical axis 117 for imaging the first order diffraction pattern, i.e. the spectral image 230. The spectral content of each point of the output light 220 may be determined from the spectral image 230. The third system 800a may further include a collimating lens module 151 and a condenser lens module 152. A collimating lens module 151 is positioned between the second slit 122 and the grating 140 for collimating the output light rays 220 before the output light rays 220 are diffracted by the grating 140. The condenser module 152 is disposed between the grating 140 and the imaging sensor 145 for focusing the spectral image 230 onto the imaging sensor 145.

Similar to the first system 100, the light source module 130 of the third system 800a may be a color-mixing light source module. The light source module 130 of the third system 800a may be implemented as any embodiment of the first or second color mixing light source module 130a, 130 b.

FIG. 9 depicts a fourth line-scan three-dimensional sensing system 800b (abbreviated as fourth system 800 b) for measuring a surface profile of an object 95 in accordance with certain embodiments of the disclosed line-scan three-dimensional sensing system. The fourth system 800b is a variation of the third system 800 a. It is first noted that in the third system 800a, the imaging sensor 145 is close to the light source module 130, and the condenser lens module 152 is rigidly tilted by a diffraction angle to receive the spectral image 230. This may cause a difficulty that the fourth system 800b may cause to advantageously move the imaging sensor 145 and the condenser lens module 152 away from the light source module 130 when the condenser lens module 152 is assembled to the third system 800a and when interference with the imaging sensor 145 due to possible light leakage from the light source module 130 is avoided.

The fourth system 800b is implemented by any embodiment of the third system 800a, but the fourth system 800b modifies the second dispersive optical module 820a. The second dispersive optical module 820b modified and used in the fourth system 800b is implemented together with the second plurality of lenses 821 in the original second dispersive optical module 820a. In addition, the second dispersive optical module 820b is further fitted with a reflector 925 disposed in the second plurality of lenses 821 for reflecting the captured IBCI 182, thereby causing the path of the IBCI 182 captured in the second dispersive optical module 820b to change in direction by an angle, preferably 90. As a result, the imaging sensor 145 and the condenser lens module 152 are moved away from the light source module 130.

Fig. 10 depicts a fifth line-scanning three-dimensional sensing system 1000 (referred to simply as the fifth system 1000) for measuring a surface profile of an object 95 in accordance with certain embodiments of the disclosed line-scanning three-dimensional sensing system. The fifth system 1000 is developed on the basis of the first system 100, and has an additional function of taking a 2D image of the object 95.

The fifth system 1000 is implemented by any embodiment of the first system 100, but the fifth system 1000 modifies the DOM 110 and introduces additional elements related to capturing a 2D image.

Additional elements include a third slit 1123 and a 2D line scanning camera 1200. The third slit 1123 is used to spatially filter the copy 1210 of the elongated light pattern received at the third slit 1123 to form a second output light ray 1220. The two-dimensional line scan camera 1200 is used to color image the second output light 1220. After the plurality of scanning surfaces are scanned for three-dimensional sensing, a two-dimensional image of object 95 may be obtained.

The DOM 1110 modified and used in the fifth system 1000 includes a plurality of lenses 112, 113, 116, 1116 for implementing forward and backward optical processing and outputting certain signals for making 2D images. In particular, DOM 1110 includes a first group lens 171, a second group lens 172, and a third group lens 1173, wherein the three groups are selected from the plurality of lenses 112, 113, 116, 1116. As shown in fig. 10, the first lens group 171 is composed of lenses 112, 113, the second lens group 172 is composed of lenses 113, 116, and the third lens group 1173 is composed of lenses 113, 1116. Note that the three lens groups 171, 172, 1173 share one or more lenses (referred to as a shared lens 113). The lenses 112, 113 of the first lens group 171 are aligned on the first optical axis 111. The first lens group 171 is configured to disperse the PLLB125 into the CNLLB 180 and focus the CNLLB 180 on focal planes 183a-c distributed over a predetermined length 184 on the first optical axis 111, respectively, to form an rainbow light pattern 181. The second lens group 172 is configured to optically converge the captured IBCI 182 to form an elongated light pattern 210. The third lens group 1173 is configured to deliver an elongated light pattern copy 1210 to the third slit 1123 that is substantially similar to the elongated light pattern 210 received at the second slit 122.

Since both the CNLLB 180 and the captured IBCI 182 travel in the shared lens 113, it is necessary to separate the captured IBCI 182 from the CNLLB 180 before the captured IBCI 182 (which becomes the elongated light pattern 210)) reaches the second slit 122 and before the captured IBCI 182 (which becomes the copy 1210 of the elongated light pattern) reaches the third slit 1123. Thus, the DOM 1110 further includes a first optical splitter 1118 and a second optical splitter 1119. The first beam splitter 1118 is optically coupled to the shared lens 113 and positioned in the first lens group 171 such that the captured IBCI 182 moving in the shared lens 113 is replicated into two copies, one of which is directed to the second slot 122. Similarly, the second beam splitter 1119 is optically coupled to the shared lens 113 and positioned in the first lens group 171 such that the captured IBCI 182 traveling in the shared lens 113 is replicated into two, one of which is directed to the third slit 1123.

Based on the above analysis for the first system 100, one skilled in the art will appreciate that: the lens 116 disposed between the first beam splitter 1118 and the second slit 122 may be selected to be a replica of the lens 112 (referred to as the corresponding lens 112) disposed between the second beam splitter 1119 and the first slit 121; and the lens 1116 disposed between the second beam splitter 1119 and the third slit 1123 may also be selected as a replica of the corresponding lens 112.

Some remarks that apply to all embodiments of the invention, including the first, second, third, fourth and fifth systems 100, 600, 800a, 800b, 1000, are given below.

In the present invention, all CNLLBs used to form the rainbow light pattern 181 may be visible or invisible, and thus the entire rainbow light pattern 181 may be visible (for example, if the rainbow light pattern 181 is viewed with a piece of paper as a screen) or may be invisible. There is a practical benefit of using a visible rainbow light pattern in that it becomes easy for a person to set up and fine tune the disclosed line-scan three-dimensional sensing system. On the other hand, if it is not desired to attract the attention of nearby people during surface profiling, an invisible rainbow light pattern (e.g., near-infrared based) is useful. The present invention also includes the case where part of CNLLB 180 is not visible.

Since the backward optical processing is the reverse of the forward optical processing, the major centerline 215 of the elongated light pattern 210 has dimensions close to the PLLB 125. Those skilled in the art will appreciate that enlarging or reducing the size of the elongated optical pattern 210 produced by a DOM does not change the working principle of the disclosed line-scan three-dimensional sensing system in surface profiling. Those skilled in the art will be able to modify the disclosed embodiments without substantial difficulty to implement such a scaling step in accordance with the teachings disclosed in this specification and the accompanying drawings. The scaled backward optical processing results as a cascade of backward optical processing and multiplication blocks that scale the size of the elongated light pattern 210. In view of the above discussion, scaled backward optical processing is considered equivalent to backward optical processing within the scope of the present invention.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (19)

1. A line-scanning three-dimensional sensing system for measuring a surface profile of an object, the system comprising:

the light source module is used for generating a multi-color line beam;

a first slit for spatially filtering the polychromatic light beam to form a polychromatic linear light beam;

a dispersive optical module configured to:

performing a forward optical process of dispersing the multi-color linear beam received from the first slit into tapered narrow-band linear beams and focusing the tapered narrow-band linear beams on different focal planes, respectively, to form a rainbow light pattern; the rainbow light pattern is used to illuminate the scanning surface of the object during surface profile measurement, thereby causing the illuminated object to display an informational color image on the object, the informational color image containing height information of the scanning surface;

capturing the information-containing color image; and

performing backward optical processing to optically converge the captured information-bearing color image to form an elongated light pattern; wherein the backward optical processing is a reverse processing of the forward optical processing; and

a second slit for spatially filtering said elongated light pattern to form output light rays, whereby a height profile of said scanned surface is obtained by analyzing the spectral content of each point of said output light rays, whereby said surface profile is determined from the respective height profiles obtained for a plurality of scanned surfaces of said object.

2. The system of claim 1, wherein the dispersive optical module comprises:

a first group of lenses aligned on a first optical axis, the first group of lenses configured to disperse the polychromatic linear beam into the graded narrow-band linear beams and focus the graded narrow-band linear beams on the different focal planes distributed over a predetermined length of the first optical axis, respectively, to form the rainbow light pattern; and

a second group of lenses configured to optically converge the captured information-bearing color image to form the elongated light pattern, wherein the first group of filters and the second group of lenses share one or more shared lenses, at least one shared lens for simultaneously outputting the rainbow light pattern and inputting the information-bearing color image, thereby avoiding the burden of aligning the first group of lenses and the second group of lenses to output the rainbow light pattern and input the information-bearing color image.

3. The system of claim 2, wherein the dispersive optical module further comprises a beam splitter optically coupled to the one or more shared lenses and positioned in the first set of lenses to replicate the captured information-bearing color image into two, one of which is directed to the second slit.

4. The system of claim 3, wherein the second set of lenses comprises one or more additional lenses not shared with the first set of lenses, the one or more additional lenses disposed between the beam splitter and the second slit for optically processing the captured information-bearing color image before the captured information-bearing color image reaches the second slit, wherein the one or more additional lenses are replicas of respective one or more lenses of the first set of lenses for optically processing the polychromatic linear light beam and disposed between the beam splitter and the first slit.

5. The system of claim 2, wherein:

the first slit is configured such that the polychromatic linear beam emitted to the dispersive optical module at any point on the first slit has a first set of chief rays whose divergence angles are within 1 ° when measured based on the first optical axis;

the first set of lenses is configured such that the tapered narrowband linear light beam received at any point on the rainbow light pattern has a second set of chief rays whose convergence angles are within 1 ° when measured based on the first optical axis;

the system further comprises a platform for positioning the object during the surface profile measurement; the platform comprises a reference plane on which the object is adapted to be placed; and

the first set of lenses is oriented such that the first optical axis is perpendicular to the reference plane, resulting in the rainbow light pattern being perpendicular to the reference plane, thereby allowing the surface profile to be measured also when the scanning surface includes grooves.

6. The system of claim 1, wherein the light source module is a color mixing light source module comprising:

a light source for generating primary light rays which together provide polychromatic light; and

a color mixing rod optically coupled to the first slit for providing a polychromatic light beam to the first slit for spatial filtering; the color mixing rod is in the shape of a long strip and is used for mixing the original light rays to generate the multicolor light beam, so that at least one part of the multicolor light beam received by the first slit is generally uniform in color.

7. The system of claim 6, wherein:

the light source comprises one or more Light Emitting Diodes (LEDs) which are used for jointly generating the original light; and

the color mixing light source module further comprises an asymmetric total internal reflection lens for directing the primary light rays generated from the one or more light emitting diodes towards the color mixing rod, wherein the asymmetric total internal reflection lens has different lengths in the X-direction and the Y-direction.

8. The system of claim 6, wherein:

the light source comprises one or more light emitting diodes, each light emitting diode having a solar spectrum phosphor fill deposited thereon, the solar spectrum phosphor fill formulated to produce a spectrum in a range of at least 400 nanometers to 700 nanometers; the one or more light emitting diodes are configured to optically excite the solar-spectrum phosphor fill to produce the primary light rays, which collectively provide the polychromatic light; and

the color mixing rod is optically coupled to the light source to directly receive the raw light from the light source.

9. The system of claim 1, further comprising:

a grating for diffracting the output light rays to form a spectral image of the output light rays;

an imaging sensor for imaging said spectral image, said spectral content of each point of said output light being determinable from said spectral image;

a collimating lens module positioned between the second slit and the grating to collimate the output light rays before they are diffracted by the grating; and

and the condenser lens module is positioned between the grating and the imaging sensor and is used for focusing the spectral image on the imaging sensor.

10. The system of claim 9, further comprising:

a prism for reflecting the spectral image emitted from the grating to the condenser module, the prism being configured to reorient the spectral image such that the directions of the collimating lens module and the condenser module are perpendicular to each other, thereby facilitating alignment and assembly of the collimating lens module and the condenser module.

11. The system of claim 2, further comprising:

a third slit for spatially filtering a copy of the elongated light pattern received at the third slit to form a second output light ray; and

the two-dimensional line scanning camera is used for carrying out color imaging on the second output light; accordingly, after the plurality of scanning surfaces are scanned, a two-dimensional image of the object can be obtained for three-dimensional sensing;

wherein the dispersive optical module further comprises:

a first beam splitter disposed in the first set of lenses to replicate the captured information-bearing color image into two, one of which is directed toward the second slit; and

a second beam splitter disposed in the first set of lenses to replicate the captured information-bearing color image into two copies, one of which is directed to the third slit.

12. The system of claim 11, further comprising:

a grating for diffracting the output light rays to form a spectral image of the output light rays;

an imaging sensor for imaging said spectral image, said spectral content of each point of said output light being determinable from said spectral image.

A collimating lens module positioned between the second slit and the grating to collimate the output light before it is diffracted by the grating; and

and the condenser lens module is positioned between the grating and the imaging sensor and is used for focusing the spectral image on the imaging sensor.

13. A line-scanning three-dimensional sensing system for measuring a surface profile of an object, the system comprising:

the light source module is used for generating a multicolor light beam;

a first slit optically coupled to the light source module for spatially filtering the polychromatic light beam to form a polychromatic linear light beam;

a first dispersion optics module configured to perform forward optical processing, disperse the polychromatic linear light beam received from the first slit into a tapered narrowband linear light beam, and focus the tapered narrowband linear light beam on different focal planes to form an iridescent light pattern; the rainbow light pattern is used to illuminate the scanning surface of the object during surface profile measurement, thereby causing the illuminated object to display an information-bearing color image on the object, the information-bearing color image containing height information of the scanning surface;

a second dispersive optical module configured to capture the information-bearing color image and perform backward optical processing that optically converges the captured information-bearing color image to form an elongated light pattern; wherein the backward optical processing is a reverse processing of the forward optical processing, and the first and second dispersive optical modules are arranged side by side;

a bi-pass lens module configured to reposition the rainbow light pattern produced by the first dispersive optical module to an offset position where the object is suitable to be positioned and to direct the information-bearing color image from the offset position to the second dispersive optical module to allow the second dispersive optical module to capture the information-bearing color image; and

a second slit for spatially filtering said elongated light pattern to form output light rays, whereby a height profile of said scanned surface is obtained by analyzing the spectral content of each point of said output light rays, whereby said surface profile is determined from the respective height profiles obtained for a plurality of scanned surfaces of said object.

14. The system of claim 13, wherein:

the first dispersive optical module comprises a first plurality of lenses; and

the second dispersive optical module comprises a second plurality of lenses; wherein the second plurality of lenses is a replica of the first plurality of lenses.

15. The system of claim 14, wherein the second dispersive optical module further comprises a reflector disposed in the second plurality of lenses.

16. The system of claim 13, wherein the light source module is a color mixing light source module comprising:

a light source for generating primary light rays which together provide polychromatic light; and

a color mixing rod optically coupled to the first slit for providing a polychromatic light beam to the first slit for spatial filtering; the color mixing rod is in a long strip shape and is used for mixing the original light rays to generate the multicolor light beam, so that at least one part of the multicolor light beam received by the first slit is generally uniform in color.

17. The system of claim 16, wherein:

the light source comprises one or more light emitting diodes for collectively generating the original light; and

the color mixing light source module further comprises an asymmetric total internal reflection lens for mixing the primary light rays generated from the one or more light emitting diodes to form an intermediate light output such that the radiant power of the intermediate light output is substantially uniform; the original light rays in the intermediate light output are fed into the color mixing rod, where the asymmetric total internal reflection lens has different lengths in the X-direction and the Y-direction.

18. The system of claim 16, wherein:

the light source comprises one or more light emitting diodes, each light emitting diode having a solar spectrum phosphor fill deposited thereon, the solar spectrum phosphor fill being formulated to produce a spectrum in a range of at least 400 nanometers to 700 nanometers; the one or more light emitting diodes are configured to optically excite the solar-spectrum phosphor fill to produce the primary light rays, which collectively provide the polychromatic light; and

the color mixing rod is optically coupled to the light source to directly receive the raw light from the light source.

19. The system of claim 13, further comprising:

a grating for diffracting the output light rays to form a spectral image of the output light rays;

an imaging sensor for imaging said spectral image, said spectral content of each point of said output light being determinable from said spectral image;

a collimating lens module positioned between the second slit and the grating to collimate the output light rays before they are diffracted by the grating; and

and the condenser lens module is positioned between the grating and the imaging sensor and is used for focusing the spectral image on the imaging sensor.

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