TWI485438B - Optical system and reflection type diffraction grating thereof - Google Patents

Description

Optical system and its reflective diffraction grating

This invention relates to an optical system, and more particularly to an optical system having a reflective diffraction grating.

The composition of a substance can usually be decomposed and isolated by various methods to understand the composition of its composition, such as the composition of the ore, the compound contained in the water source, and the like. The above decomposition, separation, etc. are all destructive tests, and the necessary detection process is generally performed according to requirements. Conversely, the spectrum analyzer is a non-destructive instrument that uses the principle of light reflection and the difference in the degree of reflection, absorption or penetration of different components of the light in the material composition. Different substances will reveal the spectrum of individual features, and then obtain the knowledge of the material structure of the atomic and molecular properties of the substance, the chemical bond properties, etc., and then the composition and characteristics of the substance can be identified.

Please refer to FIG. 1 , which is a schematic diagram showing a conventional spectrum analyzer. After the light 900 generated by the light source 810 is incident on the spectrum analyzer 800 through the slit 820, it is directed into a collimating mirror 830 in free space to convert the light into parallel light and to be directed toward a planar grating 840. The light split by the diffraction structure 842 of the grating 840 is then focused by the focusing mirror 850 and then directed to the optical sensor 860 to detect the intensity of light of different wavelengths to generate a corresponding image. However, the above conventional spectrum analyzer uses a plane grating, which requires the cooperation of a collimating mirror and a focusing mirror to accurately split and focus the light, and precise alignment between the optical components is required, which is complicated and uses a large number of components. Frequently, due to slight vibration, the alignment between the optical components is caused, and the manufacturing and maintenance costs are too high, which is inconvenient to use, and is not conducive to miniaturizing the spectrum analyzer to achieve the portable purpose.

The present invention relates to an optical system. The optical system includes an input portion, a preset output surface, and a reflective diffraction grating. The input unit is for receiving an optical signal. The reflective diffraction grating includes a grating profile curved surface and a plurality of diffraction structures, and the diffraction structure is used to separate the optical signals into a plurality of spectral components. A plurality of diffraction structures are respectively disposed on the grating contour surface with a plurality of grating pitches, and at least part of the grating pitches are different from each other. According to actual optical simulation, the reflective diffraction grating designed according to the principle can make the spectrum The component is directed toward the preset output face in a manner substantially perpendicular to the preset output face. The raster contour surface focuses the spectral components on the preset output surface.

The present invention relates to a reflective diffraction grating. The reflective diffraction grating includes a grating profile curved surface and a plurality of diffraction structures, and the diffraction structure is used to separate the optical signals into a plurality of spectral components. A plurality of diffraction structures are respectively disposed on the grating contour surface with a plurality of grating pitches, and at least part of the grating pitches are different from each other. According to actual optical simulation, the reflective diffraction grating designed according to the principle can make the spectrum The component is directed toward the preset output face in a manner substantially perpendicular to the preset output face. The raster contour surface focuses the spectral components on the preset output surface.

The so-called "substantially perpendicular" means that the spectral component at the central wavelength is directed toward the preset output surface in a manner perpendicular to the preset output surface for the central wavelength of the plurality of spectral components, and the other spectral components are The preset output surface has a better aberration resolution than a predetermined value when focusing. According to the conventional Rowland circle theory, a light diffracted by a grating with a fixed grating pitch and a circular arc profile curved surface will focus on the arc instead of an arbitrary or easier implementation. It is almost impossible to form a vertical or nearly vertical intersection between the diffracted ray and the focused arc tangential line on the preset output surface. Based on the knowledge of Roland's theory, we understand that if the diffracted ray is to be substantially perpendicular to the pre-set output surface, the design conditions of the grating must be open, the grating spacing is allowed to be non-fixed, and the grating contour surface is non-arc Surface, through the optical simulation to find the non-fixed grating spacing and non-circular surface grating contour surface, so that the diffracted light can be directed to the preset output surface in a manner substantially perpendicular to the preset output surface, so that not only the diffraction efficiency It would be better if the preset output surface does not have to be an arc on the Roland circle that is difficult to implement, but can be other output surfaces that are easy to implement, such as a straight line on a plane, then the diffraction grating will have Very high value.

In order to make the above-mentioned contents of the present invention more comprehensible, a preferred embodiment will be described below, and in conjunction with the drawings, a detailed description is as follows:

The following embodiments relate to an optical system and its reflective diffraction grating. The optical system includes an input portion, a preset output surface, and a reflective diffraction grating. The input portion is configured to receive an optical signal, and the reflective diffraction grating includes a grating profile curved surface and a plurality of diffraction structures. The diffraction structure is used to separate the optical signal into a plurality of spectral components, and the diffraction structure is respectively disposed on the grating contour surface by a plurality of grating pitches. At least a portion of the grating pitches are different from one another such that the spectral components are directed toward the predetermined output face in a manner substantially perpendicular to the predetermined output face. A raster contour surface is used to focus spectral components onto the predetermined output surface. The above-mentioned "substantially perpendicular" means that the spectral component at the central wavelength is directed toward the preset output surface in a manner perpendicular to the preset output surface for the central wavelength of the plurality of spectral components, and the other spectral components are made. The focus on the preset output surface has a better aberration resolution than a predetermined value.

Please refer to FIG. 2, FIG. 3 and FIG. 4 at the same time. FIG. 2 is an optical system according to an embodiment of the present invention, and FIG. 3 is a schematic diagram of a diffraction principle. Figure 4 is a diagram showing a reflective diffraction grating in accordance with an embodiment of the present invention. The optical system 10 is, for example, a spectrum analyzer, and the optical system 10 includes an input portion 12, a reflective diffraction grating 14, and an optical sensor 16. The input portion 12 is, for example, a slit or an optical fiber end and is used to receive the optical signal L. The optical sensor 16 includes a preset output surface 162. The preset output surface 162 is a line connecting each preset focus point of each wavelength of light, and is not a solid object. The preset output surface 162 is, for example, a plane. The straight line is, for example, a charge coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) optical image receiving surface.

The reflective diffraction grating 14 includes a grating profile curved surface 142 and a plurality of diffraction structures 144. The diffractive structure 144 is used to separate the optical signal L into spectral components L1 to Ln, and the number of spectral components is at least greater than three. The spectral components L1 to Ln respectively include all rays in a specific wavelength range, and the specific wavelength range can be determined according to the resolution of the optical system 10. For example, if the resolution of the optical system 10 is 1.5 nanometers (nm), the spectral component L1 may include all light in a wavelength range of 1.5 nanometers (nm), including, for example, 400 nanometers (nm) to 401.5 nm. All rays of (nm), such that the spectral component L2 includes light having a wavelength in the range of 401.5 nanometers (nm) to 403 nanometers (nm), and so on. The resolution of the full width Width at Half Maximum (FWHM) of the spectral components L1 to Ln on the preset output surface 162 is less than a preset value. The diffractive structure 144 is not limited to a particular shape, and the diffractive structure 144 can be, for example, triangular, circular, elliptical, or square. For convenience of description, the shape of the diffraction structure 144 illustrated in FIG. 4 is illustrated by a similar triangle. The diffraction structures 144 are respectively disposed on the grating profile curved surface 142 at a plurality of grating pitches (Pitch). At least a portion of the grating pitches are different from one another such that the spectral components L1 through Ln are directed toward the predetermined output face 162 in a manner substantially perpendicular to the predetermined output face 162. The number of different grating spacings can be adjusted according to the actual design. For convenience of description, FIG. 4 illustrates only three different grating spacings d0 to d2 as an example.

The aforementioned grating profile surface 142 is used to focus the spectral components L1 to Ln to the preset output face 162. The grating profile surface 142 further includes a plurality of contour points, and for convenience of explanation, FIG. 4 illustrates only the contour points P ₀ to P ₃ . The subsequent sequence will further describe how to determine the contour point position of the raster contour surface 142 to achieve the purpose of causing the spectral components L1 to Ln to be directed toward the preset output surface 162 substantially perpendicular to the preset output surface 162. The grating pitches d0 to d2 are the lengths of the line segments from the contour points P ₀ to P ₁ , P ₁ to P _{2 ,} and P ₂ to P ₃ , respectively.

Since the reflective diffraction grating 14 of the present invention includes a grating profile curved surface and a diffraction structure, it has the functions of splitting and focusing, and thus can replace the collimating mirror and the focusing mirror in the conventional optical system, thereby reducing the optical system 10 The number of components used and complex alignment issues. Furthermore, since the spectral components L1 to Ln are substantially perpendicularly directed toward the predetermined output face 16, a better optical sensing quality will be obtained.

Please refer to Figures 5, 6 and 7, Figure 5 is a schematic diagram showing aberrations, and Figure 6 is a diagram showing a line connecting a reference point R _k and a central contour point P ₀ . A schematic diagram of the aberration characteristic curve of the simulated region grating R _k P ₀ (local grating R _k P ₀ ), and FIG. 7 is a diagram showing the aberration induced spectral resolution characteristic curve of the region grating R _k P ₀ Schematic diagram. The central contour point P ₀ is the center point of the aforementioned grating contour curved surface 142, and the reference point R _k is the next contour point temporarily selected during optical simulation and adjustment, when a single wavelength ray is directed from a known incident angle α When the length of the line connecting P ₀ and R _k is the simulated area grating R _k P ₀ of the grating pitch, the focus position on the preset focus surface after the diffraction may have an aberration with an ideal focus point. When the different wavelengths of light are emitted from a known angle of incidence α to the diffraction of the simulated area grating formed by the different reference points and the central contour point P ₀ , each of the simulated area gratings will have different aberration characteristics. The so-called ideal focus point refers to a single-wavelength ray from a known incident angle α, when the value of a grating pitch is a central distance point P ₀ of the simulated grating with an initial distance d0', according to the grating formula (Grating Equation) Calculate the intersection of the diffraction angle β and the preset focal plane. For example, suppose that a single wavelength ray A1 has a wavelength of λ1, which should ideally strike the position y1 of the preset output face 162. However, according to the diffraction principle, the single-wavelength ray A1 is diffracted by the simulated region grating R _k P ₀ , and is simulated by the grating formula, but actually hits the position y2 of the preset output surface 162. The distance between the position y2 and the position y1 is called aberration Δy1' (aberration). Similarly, assuming that the wavelength of the single-wavelength ray A1 is λ2, after the diffraction of the simulated region grating R _k P ₀ , the terrain imaging difference Δy2' is also corresponding. The aberration characteristic curve 200 of the sixth image region grating R _k P ₀ is formed by connecting the aberration Δy' values corresponding to the incident light rays of different wavelengths, such as λ1 to λn, on the coordinate plane.

The aforementioned aberration Δy' can be via the Grating Equation Abbreviated induced spectral resolution . Wherein, the grating pitch d0 is the grating pitch of the region grating R _k P ₀ ; the diffraction angle β is the angle of the assumed single-wavelength ray A1 after being circulated by the region grating R _k P ₀ , which is a function of λ; The wavelength of A1; m is the diffraction order; the distance of the diffracted ray whose distance r' is A1 is diffracted by the area grating R _k P ₀ to the preset output surface 162. Under the premise that the grating pitch d0, the diffraction angle β, the wavelength λ, the diffraction order m and the distance r′ are known, the value of each aberration Δy′ can be found by the grating formula to find the corresponding aberration resolution. Δ λ _A . In other words, the aberration characteristic curve 200 illustrated in FIG. 6 can be further converted into the aberration resolution characteristic curve 300 illustrated in FIG. 7 by the grating formula.

In order to cause the spectral components L1 to Ln to be directed to the preset output surface 162 in a manner substantially perpendicular to the preset output surface 162, firstly, according to the basic principle of diffraction, the spectral components L1 to Ln to be split are selected as shown in FIG. a central wavelength ray, an incident angle is selected, and an initial distance d0' is selected as a fixed pitch grating spacing in the basic principle of diffraction, and the grating wavelength formula is substituted to obtain the central wavelength ray. The diffraction angle β. After obtaining the diffraction angle β of the central wavelength light, the preset output surface can be set at an angle perpendicular to the diffracted ray of the central wavelength, and the design condition of the open grating is allowed to be turned, and the variable grating spacing is allowed to be non-fixed, and The grating profile curved surface is allowed to be changed, and the position of the contour point on the grating contour surface 142 of the reflective diffraction grating 14 is obtained through optical simulation, so that after the diffraction of all wavelengths of the incident ray through the simulated grating, one less than one can be obtained. The preferred aberration resolution of the predetermined value. The position of the contour point on the grating contour surface 142 of the reflective diffraction grating 14 can be determined from the central contour point P ₀ as a reference point, and the grating spacing and the local grating profile are repeatedly adjusted by optical simulation to find an image. The position where the difference resolution Δ λ _{A is} smaller than a predetermined value is taken as the position of the preferred second contour point P ₁ , and then the contour point P ₁ is used as the reference point, and the grating spacing and the area grating are repeatedly adjusted by the same optical simulation. The contour is searched for a position where the aberration resolution Δ λ _{A is} smaller than a predetermined value as the position of the contour point P ₂ which is preferably one more, and thus repeated until the grating profile curved surface 142 of the reflective diffraction grating 14 is separated by a different grating pitch. The area of the grating is full, and the thus obtained reflective diffraction grating 14 will be a preferred grating which can be obtained by optical simulation, which is supposed to be substantially perpendicular to the predetermined output surface 162. The ideal grating has an aberration resolution of less than a predetermined value.

The following explains how to adjust the grating pitch and area raster profile repeatedly. First, the symbolic point of the temporarily selected contour point in the optical simulation and adjustment process, that is, the reference point R _ij , in which the indicator i represents the ith adjustment and the indicator j represents the jth reference point, the R _ij represents The jth of the plurality of reference points selected at the time of the i-th adjustment.

Please refer to FIG. 8 , FIG. 9 and FIG. 10 at the same time. FIG. 8 is a schematic diagram showing a central contour point P ₀ and reference points R _1l to R _1m , and FIG. 9 is a reference point R _1l to A schematic diagram of the aberration characteristic curve of the simulated area grating R _1l P ₀ to R _1m P ₀ formed by the line connecting R _1m and the contour point P ₀ , and FIG. 10 is a simulated area grating R _1l P ₀ to Schematic diagram of the aberration resolution characteristic curve of R _1m P ₀ . The central contour point P ₀ of the grating contour surface 142 is the center point of the grating contour surface 142. In order to determine the second contour point P _{1 of the} grating contour surface 142, it is usually initially from the longitudinal direction from the central contour point P _{0 .} Depart from a reference point of d0'.

It is noted that, an initial distance D0 'can generally be process limits determined, to find the initial distance d0 P ₁ is selected apos level (Order) will determine the end of each one raster hierarchy grating pitch 144, if the initial distance D0' about It is a few micrometers. The grating pitch of each grating structure 144 determined by optical simulation is also about a few micrometers. It is generally not a tens of micrometers. However, the initial distance d0' is also a whole with an optical system. The parameters related to total spectral resolution, the smaller initial distance d0' value can theoretically obtain a better overall resolution, but whether such a small grating can be made in the process will be a problem, so the simulation will be accommodated. process limit, the limit may be reached by selecting a process from the initial minimum level d0 'value as a distance value to find first the selection of P _1. In the current semiconductor etching process technology, the process limit for fabricating a diffraction grating made of a semiconductor substrate material is about several micrometers. Therefore, it is actually feasible to select the initial distance d0' of several micrometers. Although the overall resolution of the micron scale may be better, it is already difficult to control the existing semiconductor etching technology.

Therefore, the optical simulation can select a position from the longitudinal direction point P _{0 -} an initial distance d0' as a starting reference point, and try to select m reference points R _1l to R in a lateral direction parallel to the x-axis through the reference point. _1m , the reference point R _1l to R _1m can be selected from the reference point by a fixed distance from the reference point m points, the subsequent simulation can also select the multiple reference points of the simulation in the same way, but the above fixed The distance can be gradually reduced between simulations in order to respond to the final convergence or other appropriate changes. The lengths of the m line segments connected by the reference points R _1l to R _1m and the central contour point P ₀ respectively represent the grating pitch of a simulated region grating (local grating) R _1l P ₀ to R _1m P ₀ during optical simulation. According to the grating formula, the m simulated regional gratings R _1l P ₀ to R _1m P ₀ respectively cause m different degrees of aberration, and the aberrations caused by the different wavelengths of light are recorded as the ninth. The m aberration characteristics 400(l) to 400(m) of Δy'(h) are plotted, and the aberration characteristic curve 400 corresponding to the region grating R _1l P ₀ to R _1m P ₀ ) to 400 (m) through the grating formula can be further converted into the aberration resolution characteristic curves 500 (1) to 500 (m) shown in FIG.

In order to obtain a better focusing effect, a preferred aberration resolution characteristic curve 500(i) can be found from the aberration resolution characteristic curves 500(1) to 500(m), and the aberration resolution characteristic is selected. The reference point R _{1i of the} curve 500(i) is used as a preferred reference point for the region. The definition of the above-mentioned preferred aberration resolution can be simply compared according to the sum of the aberration resolutions of the respective wavelengths, or simply Select one of all the characteristic curves smaller than a preset value, or select another judgment standard and select according to the standard. After selecting R _1i as the preferred reference point for the region of the first simulation, the second optical simulation and adjustment can be performed with R _1i as the reference point, and n are selected in the direction of the longitudinal axis passing through the reference point R _1i . The reference points R _2l to R _{2n are} simulated, and another region with a better aberration resolution is selected in the same way as a preferred reference point R _2j , and then replaced with R _2j as a reference point for the third optical simulation and Adjust, continue to repeat the same method to change the position of the reference point in the horizontal and vertical directions, and continuously select a new region preferred reference point with better aberration resolution until convergence.

Please refer to FIG. 11 , FIG. 12 and FIG. 13 simultaneously. FIG. 11 shows the central contour point P ₀ , reference points R _1l to R _1m , reference points R _2l to R _2n and reference points R _3l to R _3p is a schematic diagram, and FIG. 12 is a diagram showing aberration characteristics of n simulated area gratings R _2l P ₀ to R _2n P ₀ formed by the connection of the reference points R _2l to R _2n and the central contour point P ₀ . Schematic diagram, FIG. 13 is a schematic diagram showing the aberration resolution characteristic curves of the n simulated region gratings R _2l P ₀ to R _2n P ₀ . After the region's preferred reference point R _{1i is} found, the second optical simulation and adjustment is continued with the reference point R _1i as a reference point, and an attempt is made to select n reference points R _2l through the longitudinal axis direction of the reference point R _1i . To R _2n . It should be noted that since the reference point R _1i itself may also be one of the reference points R _2l to R _2n , for convenience of description, in the drawing of FIG. 11 , the reference point R _{1i is} simultaneously used as a reference. Point R _{2l is taken} as an example.

Similarly, the aberration Δy'(w) formed by the n simulated region gratings R _2l P ₀ to R _2n P ₀ is as shown in FIG. 11 , and n simulated region gratings R _2l P ₀ to The aberration characteristic curves 600(1) to 600(n) corresponding to R _2n P ₀ can be further converted into the aberration resolution characteristic curves 700(1) to 700(n) shown in FIG. 12 by the grating formula. In order to obtain a better focusing effect, a better aberration resolution characteristic curve 700(j) can be found from the aberration resolution characteristic curves 700(1) to 700(n), and the aberration resolution is selected. The reference point R _2j of the characteristic curve 700(j) is a region preferred reference point.

Subsequently, the third optical simulation and adjustment is performed with reference point R _2j as a reference point, and p reference points R _3l to R _3p are attempted to be selected in the horizontal axis direction through the reference point R _2j . It should be noted that since the reference point R _2j itself may also be a reference point among the reference points R _3l to R _3p , for convenience of description, in the drawing of FIG. 11 , the reference point R _{2j is} simultaneously referred to. Point R _{3v is taken} as an example. Similarly, according to the reference point R _3l p R _3p analog contour point P ₀ and the center of the connection region formed by the grating R _3l P ₀ to R _3p P ₀ can find p aberration characteristics corresponding to the number of Curves, these aberration characteristics can be further converted into p-number aberration resolution curves by passing through the grating formula. In order to obtain a better focusing effect, a characteristic curve of the preferred aberration resolution can be found from the plurality of aberration resolution characteristic curves, and the reference point R _3k forming the aberration resolution characteristic curve is selected as the region. Preferred reference point.

Please refer to FIG. 14 , FIG. 15 and FIG. 16 . FIG. 14 illustrates a central contour point P ₀ , reference points R _1l to R _1m , reference points R _2l to R _2n , and reference points R _3l to R _{3p .} A schematic diagram of reference points R _4l to R _4q and reference points R _5l to R _5r , and FIG. 15 is a schematic diagram showing a central contour point P ₀ , a contour point P ₁ and a contour point P ₂ , and FIG. 16 depicts a system It is a schematic diagram of the central contour point P ₀ , the contour point P ₁ , the contour point P ₂ and the diffraction structure.

After the region's preferred reference point R _{3k is} found, the fourth optical simulation and adjustment is continued with the reference point R _3k as a reference point, and the q reference points R _4l are attempted to be selected in the longitudinal direction of the reference point R _3k . To R _4q . It should be noted that since the reference point R _3k itself may also be a reference point among the reference points R _4l to R _4q , for convenience of explanation, in the drawing of FIG. 14 , the reference point R _{3k is} simultaneously used as a reference. Point R _{4s is taken} as an example. Similarly, according to q analog reference point R _4l R _4q to the contour point P ₀ of the central connecting region formed with a grating R _4l P ₀ to R _4q P ₀ can find q aberration characteristics corresponding to the number of Curves, these aberration characteristic curves can be further converted into q aberration resolution characteristic curves by passing through the grating formula. In order to obtain a better focusing effect, a characteristic curve of a preferred aberration resolution can be found from the plurality of aberration resolution characteristic curves, and a reference point R _4t forming the aberration resolution characteristic curve is selected as a region. Preferred reference point.

Subsequently, the fifth optical simulation and adjustment is performed with reference point R _4t as a reference point, and r reference points R _5l to R _5r are attempted to be selected in the horizontal axis direction through the reference point R _4t . It should be noted that since the reference point R _4t itself may also be a reference point among the reference points R _5l to R _5r , for convenience of description, the reference point R _{4t is} simultaneously referred to in the drawing of FIG. 14 . Point R _{5u is taken} as an example. Similarly, the reference point r to the analog R _5l R _5r contour point P ₀ and the center of the connection region formed by the grating R _5l P ₀ to R _5r P ₀ r can find aberration characteristics corresponding to the number of Curves, these aberration characteristic curves can be further converted into r aberration resolution characteristic curves by passing through the grating formula. In order to obtain a better focusing effect, a characteristic curve of a preferred aberration resolution can be found from the plurality of aberration resolution characteristic curves, and a reference point R _5r forming the aberration resolution characteristic curve is selected as a region. Preferred reference point.

By repeating the above steps repeatedly, it can be found that the lateral and longitudinal adjustable distances of the reference point become smaller and gradually converge, and the reference point is gradually reduced to a preset value in the horizontal and vertical adjustable distances. When the reference point is taken as the contour point P ₁ on the raster contour surface 142, and then P ₁ is used as the starting point for finding P ₂ , according to the above-mentioned set reference point, the simulation and adjustment method are repeated to find the better one. A contour point P ₂ . Other contour points on the raster contour surface 142 can also be determined in the same manner as described above. When all the contour points on the grating contour surface 142 are determined, a similar triangle, square or other suitable structure may be placed on the line segments of the two contour points to form the diffraction structure 144, and the connection lines of all the contour points are The raster contour surface itself. In this way, the above-described reflective diffraction grating 14 can be realized.

It should be noted that, according to the actual simulation result, the position of the finally selected contour point P ₁ is actually very close to or even equal to the position on the vertical axis from the central contour point P _{1 and} an initial distance d0'. over the focusing point 5 in FIG. y1 is to a grating pitch equal to the initial distance d0 'analog raster substituting the grating equation obtained, thus when to leave the central contour points P ₁ an initial distance d0 on said longitudinal axis' of the position of the point as an analog At the starting point, that point is almost the convergence point with the smallest aberration. However, when the contour point is searched for the outer periphery of the grating contour surface, the aberration value tends to be larger, and finally the convergence point will have a tendency to be farther from the previous contour point, and the semiconductor etching process is For example, if the d0' is 2.5 microns, the distance between P _{0 and} P ₁ is about 2.5 microns, but the grating spacing of the outermost grating structure may be 3 to 4 microns or more. .

The reflective diffraction grating of the present invention has a non-planar grating profile surface and unequal grating pitches, and a conventional diamond knife is used to engrave a diffraction structure on a planar metal or glass surface. It is no longer suitable, the reason for which at least the pitch of the diamond knife is difficult to change and the surface of the non-planar material is difficult to operate. Therefore, the selection of the appropriate diffraction process of the reflective diffraction grating of the present invention is based on the semiconductor substrate material ( For example, bismuth or three-five semiconductor materials are etched to etch the grating profile surface and the grating structure on the vertical plane of the wafer, and then cut out from the wafer.

Referring to FIG. 17, FIG. 18 and FIG. 19, FIG. 17 is an exploded perspective view of an optical system according to an embodiment of the present invention, and FIG. 18 is a view showing light rays in an optical channel of the optical system of FIG. Schematic diagram of the travel, and Fig. 19 is a schematic view showing the extinction mechanism of the extinction element in Fig. 17. The optical system 10 further includes an upper waveguide plate 120, a lower waveguide plate 130, a first extinction element 270, and a second extinction element 272.

The lower waveguide plate 130 is disposed substantially parallel to the upper waveguide plate 120. The upper waveguide plate 120 has a first reflective surface 122, and the lower waveguide plate 130 has a second reflective surface 132 opposite the first reflective surface 122. An optical channel 140 is formed between the first reflective surface 122 and the second reflective surface 132 such that the optical signal 50 from the input portion 12 travels within the optical channel 140 as shown in FIG. The optical channel 140 formed between the first reflective surface 122 and the second reflective surface 132 is generally of a cavity type, which is different from the principle of total reflection used for transmitting light in the optical fiber. The present invention limits optical signals to the reflections. The surface is reflected back and forwarded, but it can also be filled with a suitable medium (such as glass, plastic, or acrylic) for the optical signal to be reflected and forwarded forward, while preventing dust or other pollutants from accumulating. The upper and lower waveguide plates affect the flatness and reflectivity of the waveguide plate.

The upper waveguide plate 120 and the lower waveguide plate 130 must have good flatness and reflectivity, so that the optical signal 50 can travel between the upper waveguide plate 120 and the lower waveguide plate 130 to achieve the lowest loss and the best light source. Concentrate the effect. Therefore, the material of the upper waveguide plate 120 and the lower waveguide plate 130 is, for example, stainless steel, tantalum wafer, glass, optical disk or hard disk. In addition, if the material reflectance of the upper waveguide plate 120 and the lower waveguide plate 130 is less than the required standard, a high-reflection film may be disposed on the first reflective surface 122 and the second reflective surface 132 to solve the problem. Preferably, the material of the highly reflective film is an aluminum film.

In order to prevent oxidation, rust, roughness, etc. of the surfaces of the first reflective surface 122 and the second reflective surface 132 over time, the flatness and reflectivity of the surface of the reflective surface are reduced, and the first reflective surface 122 and the second reflective surface are A first protective film and a second protective film are respectively disposed on the high-reflection film of the surface 132, and the material of the protective film is, for example, cerium oxide.

The traditional spectrum analyzer 800 shown in FIG. 1 transmits light in the internal cavity, and is likely to have divergence, which causes the optical signal to be too weak to be excessively interfered by stray light, and the conventional spectrum analyzer 800 occupies a large volume. By causing the optical signal 50 to travel on the optical channel 140, the light of the optical system 10 can be concentrated and not easily diverged, which can effectively improve the efficiency of the optical system. In addition, since the optical system 10 of the embodiment can additionally add the first extinction element 270 and the second extinction element 272, and thus is less affected by stray light, the optical sensor 16 can be more accurately produced. The image, when the corresponding image is transmitted to the subsequent circuit, the accuracy of the subsequent determination of the physical or biochemical meaning of the optical signal with different wavelengths of light intensity can be further improved.

One side of the cross-section of the first matting element 270 and the second extinction element 272 is serrated, and the zigzag sides face the optical channel 140. For example, the side 270a of the first matting element 270 and the side 272a of the second extinction element 272 face the optical channel 140. The first extinction element 270 and the second extinction element 272 are respectively disposed on both sides of the optical channel 140 for absorbing the optical signal emitted from the input unit 12 and having an emission angle greater than a specific angle. For example, this particular angle is, for example, an angle θ that is related to the sawtooth structure of the first extinction element 270 and the second extinction element 272. It is assumed that the angle of travel from the optical signal 52 is greater than the angle θ. When the angle of travel from the optical signal 52 is greater than the angle θ, the offset optical signal 52 may be incident into one of the triangular recesses of the sawtooth structure. The sawtooth structure of the extinction element allows the deviating optical signal 52 as shown in Fig. 19 to be reflected back and forth in the notch of the sawtooth structure to be weak. In this way, the deviation optical signal 52, which would otherwise cause the stray light signal, can be eliminated by the sawtooth structure, so that the spectral components to be obtained are more clearly defined.

The optical mechanism of the micro spectrometer disclosed in the above embodiments of the present invention regulates the optical signal entering from the input portion and travels in the optical channel between the upper and lower waveguide plates, so that the optical signal is more concentrated and less divergent. Combined with the zigzag extinction element, the optical signal with too large the incident angle is eliminated, thereby reducing the stray light reaching the image capturing component, so that the desired spectral component is not interfered by the stray light, and the clearer is obtained. image.

The optical system disclosed in the above embodiments of the present invention has a plurality of advantages, and only some of the advantages listed below are as follows:

First, reduce the number of components used in the optical system.

Second, the spectral component can be substantially perpendicular to a predetermined output surface to achieve better optical sensing quality.

Third, the optical signal can be concentrated in a waveguide to transmit and filter the stray light, and the grating design that can make the spectral component perpendicular to a predetermined output surface becomes a perfect optical system.

In view of the above, the present invention has been disclosed in a preferred embodiment, and is not intended to limit the present invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

10. . . Optical system

12. . . Input section

14. . . Reflective diffraction grating

16,860. . . Optical sensor

52. . . Deviation from optical signal

120. . . Upper waveguide plate

122. . . First reflecting surface

130. . . Lower waveguide plate

132. . . Second reflecting surface

270. . . First extinction element

270a, 272a. . . Side

272. . . Second extinction element

162. . . Preset output face

142. . . Raster contour surface

144. . . Diffractive structure

200, 400 (l) ~ 400 (m), 600 (l) ~ 600 (n). . . Aberration characteristic curve

300, 500 (l) ~ 500 (m), 700 (l) ~ 400 (n). . . Aberration resolution characteristic curve

61l ~ 61m, 71l ~ 71n. . . Characteristic curve

800. . . Traditional spectrum analyzer

810. . . light source

820. . . Slit

830. . . Collimating mirror

840. . . Grating

850. . . Focusing mirror

900. . . Light

A. . . light spot

D0~d2. . . Grating spacing

D0’. . . Initial distance

L, 50. . . Optical signal

L1～Ln. . . Spectral component

P ₀ . . . Central contour point

P ₁ , P ₂ , P ₃ . . . Outline point

R _k , R _1l to R _1m , R _2l to R _2n , R _3l to R _3p , R _4l to R _4q , and R _5l to R _5r . . . Reference point

Y1, y2. . . position

Δy', Δy'(h), Δy'(w). . . Aberration

α. . . Incident angle

β. . . Reflection angle

θ. . . angle

Δ λ _A . . . Aberration resolution

Δ x 1 , Δ x 2, Δ y 1 , Δ y 2, Δ y 3. . . distance

Figure 1 is a schematic diagram showing a conventional spectrum analyzer.

Figure 2 depicts an optical system in accordance with an embodiment of the present invention.

Figure 3 is a schematic diagram showing the principle of diffraction.

Figure 4 is a diagram showing a reflective diffraction grating in accordance with an embodiment of the present invention.

Figure 5 is a schematic diagram showing the aberration.

Figure 6 is a diagram showing the aberration characteristic curve of a simulated region grating R _k P ₀ (local grating).

FIG. 7 is a schematic diagram showing the aberration resolution characteristic curve formed by the region grating R _k P ₀ .

Figure 8 is a schematic diagram showing the central contour point P ₀ and reference points R _1l to R _1m .

FIG. 9 is a schematic diagram showing aberration characteristics of the region gratings R _1l P ₀ to R _1m P ₀ formed by the line connecting the reference points R _1l to R _1m and the central contour point P ₀ .

FIG. 10 is a schematic diagram showing the aberration resolution characteristic curve of the region gratings R _1l P ₀ to R _1m P ₀ .

11 is a schematic diagram showing a central contour point P ₀ , reference points R _1l to R _1m , reference points R _2l to R _{2n ,} and reference points R _3l to R _3p .

Fig. 12 is a view showing the aberration characteristic curves of the n simulated area gratings R _2l P ₀ to R _2n P ₀ formed by the line connecting the reference points R _2l to R _2n and the central contour point P ₀ .

Figure 13 is a diagram showing the aberration resolution characteristic curves of the n simulated region gratings R _2l P ₀ to R _2n P ₀ .

Figure 14 shows the central contour point P ₀ , reference points R _1l to R _1m , reference points R _2l to R _2n , reference points R _3l to R _3p , reference points R _4l to R _4q and reference point R _5l to Schematic diagram of R _5r .

Figure 15 is a schematic diagram showing the central contour point P ₀ , the contour point P ₁ and the contour point P ₂ .

Figure 16 is a schematic diagram showing the central contour point P ₀ , the contour point P ₁ , the contour point P ₂ and the diffraction structure.

Figure 17 is a perspective exploded view of an optical system in accordance with an embodiment of the present invention.

Figure 18 is a schematic diagram showing the traveling of light in the optical channel of the optical system of Figure 17.

Figure 19 is a schematic view showing the extinction mechanism of the extinction element in Figure 17.

14. . . Reflective diffraction grating

142. . . Raster contour surface

144. . . Diffractive structure

D0~d2. . . Grating spacing

P ₀ . . . Central contour point

P ₁ , P ₂ , P ₃ . . . Outline point

Claims (19)

An optical system comprising: an input portion for receiving an optical signal; a predetermined output surface; and a reflective diffraction grating comprising: a grating profile curved surface, which is a non-arc surface; and a plurality of diffraction structures The optical signal is separated into a plurality of spectral components, and the diffraction structures are respectively disposed on the grating contour surface by a plurality of grating pitches, and at least some of the grating pitches are different from each other, so that The spectral component at the center wavelength is directed toward the predetermined output face in a manner substantially perpendicular to the predetermined output face. The optical system of claim 1, wherein the number of the spectral components is at least greater than three. The optical system of claim 1, wherein the predetermined output surface is a straight line on a plane. The optical system of claim 1, wherein the predetermined output surface is an optical image receiving surface of a charge coupled device (CCD). The optical system of claim 1, wherein the predetermined output surface is an optical image receiving surface of a complementary metal-oxide-semiconductor (CMOS). The optical system of claim 1, wherein the grating profile curved surface and the diffraction structure of the reflective diffraction grating are engraved on a semiconductor substrate material. The optical system of claim 6, wherein the semiconductor substrate material is ruthenium. The optical system of claim 1, further comprising: an upper waveguide plate having a first reflective surface; and a lower waveguide plate disposed substantially parallel to the upper waveguide plate and having a second reflective surface The first reflective surface is opposite to the second reflective surface, and an optical path is formed between the first reflective surface and the second reflective surface, so that the optical signal from the input portion travels in the optical channel. . The optical system of claim 8, wherein the upper waveguide plate and the lower waveguide plate are made of stainless steel, tantalum wafer, glass, optical disk or hard disk. The optical system of claim 8, wherein the optical channel is of a cavity type. The optical system of claim 10, wherein the optical channel is filled with glass, plastic or acrylic. The optical system of claim 8, further comprising a first extinction element and a second extinction element respectively disposed on two sides of the optical channel, the cross-section of the first extinction element and the second extinction element One of the sides is serrated, and the zigzag sides face the optical channel for absorbing the optical signal having an emission angle greater than a specific angle. A reflective diffraction grating comprising: a grating profile curved surface, which is a non-arc surface; and a plurality of diffraction structures for separating an optical signal into a plurality of spectral components, wherein the diffraction structures are respectively a plurality of gratings Pitch is disposed on the grating contour surface, and at least part of the grating pitches are mutually Differently, the spectral component at the central wavelength is directed toward the predetermined output face in a manner substantially perpendicular to a predetermined output face. The reflective diffraction grating of claim 13, wherein the number of the spectral components is at least greater than three. The reflective diffraction grating of claim 13, wherein the predetermined output surface is a straight line on a plane. The reflective diffraction grating of claim 13, wherein the predetermined output surface is an optical image receiving surface of a charge coupled device (CCD). The reflective diffraction grating of claim 13, wherein the predetermined output surface is an optical image receiving surface of a complementary metal-oxide-semiconductor (CMOS). . The reflective diffraction grating of claim 13, wherein the grating profile curved surface and the diffraction structure of the reflective diffraction grating are engraved on a semiconductor substrate material. The reflective diffraction grating of claim 13, wherein the semiconductor substrate material is germanium.