201006077 ^ 九、發明說明： 【發明所屬之技術領域】 4 本發明涉及雷射裝置，特別係一種具有長焦深之雷射 裝置。 【先前技術】 隨著半導體技術與加工技術之進步，各式電子元件及 光學元件日趨小型化。半導體技術中之微影製程 (Lithography)’或加工技術中之雷射加工，都開始採用短波 ❹長之紫外光雷射裝置（UV Laser)以使電子元件或光學元件 之特徵尺寸（Feature size)及解析度（Res〇iution)達到要求。 由於解析度R反比於λ/NA(又為雷射波長，να為數值孔 徑）’焦深DOF(Depth of Focus)正比於入/ΝΑ2，於此可理解 為雷射作用之有效深度正比於又/Να2，因此若解析度（用雷 射光斑大小進行評估）提高’則焦深就會下降。焦深之下降 將會景/響被加工物件之表面品質，例如銳利度（Sharpness) ❹降低、粗糙度增加。因此，如何提供一種能夠使電子元件 或光學元件具有較高解析度，且具有長焦深之紫外光雷射 裝置便成為值得研發之課題。 先月U技術中採用色差透鏡（Lens with chromatic aberration)將寬頻（Wide band)雷射或多波長雷射之焦點群 集成一線段（不同頻段之光束被聚焦於不同之焦平面上），以 延長焦深。但’此技術需要寬頻雷射或多波長雷射，致使 成本提高。另外，還可利用光學繞射元件（Diffractive 〇ptical Element，DOE)來延長焦深，但這種技術仍需要寬頻雷射或 6 201006077 多波長雷射，且存於光束之高階繞射使得光利用效率降 -有鑑於此，&供一種成本較低、光利用效率較高且耳 .有長焦深之雷射裝置實為必要。 【發明内容】201006077 ^ IX. Description of the invention: [Technical field to which the invention pertains] 4 The present invention relates to a laser device, and more particularly to a laser device having a long focal depth. [Prior Art] With the advancement of semiconductor technology and processing technology, various electronic components and optical components have become increasingly smaller. Laser processing in semiconductor technology or laser processing in processing technology has begun to use short-wavelength ultraviolet lasers (UV Laser) to make the electronic component or optical component feature size (Feature size) And the resolution (Res〇iution) meets the requirements. Since the resolution R is inversely proportional to λ/NA (also the laser wavelength, να is the numerical aperture), the depth of focus DOF (Depth of Focus) is proportional to the input / ΝΑ 2, which can be understood as the effective depth of the laser action is proportional to /Να2, so if the resolution (evaluated by the laser spot size) is increased, the depth of focus will decrease. Decreased depth of focus The surface quality of the object to be processed, such as the sharpness of the sharpness, and the increase in roughness. Therefore, how to provide an ultraviolet laser device having a high resolution of an electronic component or an optical component and having a long focal depth has become a subject worthy of research and development. The Moons U technique uses a Lens with chromatic aberration to cluster the focus of a wide band laser or a multi-wavelength laser into a line segment (beams of different frequency bands are focused on different focal planes) to extend the focus. deep. However, this technology requires broadband lasers or multi-wavelength lasers, resulting in higher costs. In addition, the Diffractive 〇ptical Element (DOE) can be used to extend the depth of focus, but this technique still requires wide-band laser or 6 201006077 multi-wavelength laser, and the high-order diffraction of the beam makes the light utilization Efficiency drop - In view of this, it is necessary to provide a laser device with a lower cost, higher light utilization efficiency and a long focal depth. [Summary of the Invention]
以下將以實施例說明一種成本較低、光利用效率較高 且具有長焦深之雷射裝置。 D 一種具有長焦深之雷射裝置，包括：一個雷射源，其 ❹用於發射單波長紫外光卜個光學模組，其包括—個設置 於該單波長紫外光光路上之第一光學元件，該第一光學元 件具有-個鄰近該雷射源之第一表面及一個與該第一表面 相對之第二表面’該第一表面與該第二表面中至少一者為 非球面以用於使該單波長紫外光會聚於一點。 相對於先前技術，該雷射裝置包括一個第一光學元 件，該第一光學元件所包括之第一纟面與第二表面中至少 一者為非球面，該非球面能夠將該雷射源發出之單波長紫 ❹外光會聚於一點，並延長該雷射裝置之焦深。同時，該非 球面不會產生繞射作用，能夠較大限度之會聚該雷射源發 出之單波長紫外光，使得該雷射裝置之光利用效率較高。 由於該雷射裝置只包括一個具有非球面之第一光學元件， 因此該雷射裝置之結構簡單，製造成本較低。 【實施方式】 下面結合附圖對本發明作進一步之詳細說明。 清參見圖1，本發明第一實施例提供之雷射裝置1()， 其包括雷射源11及光學模組12。 7 201006077 雷射源11用於發射單波長紫外光101。 ‘ 光學模組12為一個透鏡，其設置於單波長紫外光101 . 之光路上。光學模組12具有一個鄰近雷射源11之第一表 面121，及一個與第一表面121相對之第二表面122。第一 表面121為由圓錐常數（conic constant)或非球面係數 (aspheric coefficients)定義之非球面（aspherical surface)。第 二表面122為平面。雷射源η發出之單波長紫外光1〇1經 由光學模組12之第一表面121透射後被會聚到像平面13 ®上並形成一光斑131。 第一表面121為非球面，其可將雷射源11發出之單波 長紫外光101會聚於一點，即於像平面13上形成一光斑 131，並延長了雷射裝置1〇之焦深。同時，設計為非球面 之第一表面121不會產生繞射作用，能夠較大限度地會聚 雷射源11發出之單波長紫外光101，使得雷射裝置1〇之光 利用效率較高。於本實施例中，雷射裝置1〇只包括一個具 ❹有非球面之透鏡，因此雷射裝置1〇之結構簡單’製造成本 較低。 應當指出’第二表面122亦可為平面、球面、圓柱面 或非球面，第一表面121亦可為平面、球面、圓杈面，作 第一表面121與第二表面ι22中至少一者為非球面。 請參見圖2 ’本發明第二實施例提供之雷射裴置2〇， 其與第一實施例提供之雷射裝置1〇基本相同，不间之處在 於：雷射裝置20包括一個光學模組22❶光學模級22為一 個旋轉對稱之錐形透鏡（Axic〇n Lens)。錐形透鏡用於延長 201006077 雷射裝置20之焦深。 4 請參見圖3，本發明第三實施例提供之雷射裝置30， . 其與第一實施例提供之雷射裝置10基本相同，不同之處在 於：光學模組35包括一個第一光學元件31與一個第二光 學元件32。第二光學元件32設置於單波長紫外光101之光 路上且位於第一光學元件31之遠離雷射源11之一侧。第 二光學元件32具有一個鄰近第一光學元件31之第三表面 321及與第三表面321相對之第四表面322。第三表面321 ®與第四表面322為平面、球面、非球面或圓柱面。於本實 施例中，第三表面321為一平面，第四表面322為一内凹 之球面。第二光學元件32用於進一步延長雷射裝置30之 焦深。 若雷射源11發出之紫外光101之波長為355nm且光束 直徑為10.92mm。經由第二光學元件32出射至像平面33 上所形成之光斑331之直徑需要小於或等於6um(即雷射裝 ❹置30之解析度R等於6um)，焦深DOF需要大於或等於 350um。根據雷式判據（Reyleigh Criteria)，R=l.22* 又 *2Fn ; 6um=1.22*0.355um*2Fn，貝丨J Fn=6.93um，Fn(F-number)為焦 數（於此為光學模組之有效焦距與入射光光束直徑之比 值）。另外，焦深DOF=±2(Fn)2A，則焦深DOF=68um。然 而，焦深DOF等於68um之雷射裝置並不能滿足實際需求。 為了延長雷射裝置30之焦深DOF，第一光學元件31 之第一表面311或第二表面312可設計為球面，而第二光 學元件32之第三表面321或第四表面322設計為非球面。 9 201006077 於此，第一光學元件31與第二光學元件32之參數設置參 見表1。 表1光學元件31，32之參數設置（單位:mm) 表面 曲率半徑 厚度 圓錐常數 材料 物體面 — l.OOxlO20 -- 空氣 311 117.717 10.000 0 矽（Si) 312 -1.018xl03 5.033 0 空氣 321 -2.603x10s 10.703 2.72xl04 矽 322 -307.307 159.800 20.61 空氣 表1中，厚度1.00x1020mm係指物體面到第一表面311 之距離，其可被理解為進入光學模組35之光束101為平行 光；厚度10.000mm表示第一表面311與第二表面312之間 之距離；厚度5.033mm表示第二表面312與第三表面321 之間之距離；厚度10.703mm表示第三表面321與第四表面 322之間之距離；厚度159.800mm表示第四表面322與像 平面33之間之距離；材料係指紫外光101通過光學元件之 某一表面後所射向之材料。 將非球面之圓錐常數或非球面係數作為優化之變數並 以點擴散函數（point spread function)作為評薦之參考以量 取焦深D0F及光斑大小，雷射源11發出之紫外光101經 由第一光學元件31及第二光學元件32衍射後得到之光斑 331之直徑為5.8um，焦深D0F為400um，符合實際要求。 若雷射源11發出之紫外光101之波長為355nm且光束 201006077 直徑為10.92mm。經由第二光學元件32出射至像平面33 . 上所形成之光斑331之直徑需要小於或等於2um，焦深DOF . 需要大於或等於80um(微米）。則可將第一光學元件31之第 一表面311或第二表面312設計為非球面，第二光學元件 32之第三表面321或第四表面322亦可設計為非球面。於 此，第一光學元件31之第一表面311與第二表面312，以 及第二光學元件32之之第三表面321與第四表面322均為 非球面，其參數設置參見表2。表2中各參數之定義與上述 ®表1之基本相同，於此不再贅述。 表2光學元件31，32之參數設置（單位：mm) 表面 曲率半徑 厚度 圓錐常數 材料 物體面 — l.OOxlO20 — 空氣 311 40.064 7.595 2.02 矽 312 190.280 5.028 -1.24X103 空氣 321 -18.538 4.497 -1.05χ106 矽 322 0.239 60.190 -7.04χ105 空氣 將非球面之圓錐常數或非球面係數作為優化之變數並 以點擴散函數作為評薦之參考以量取焦深DOF及光斑大 小，雷射源11發出之紫外光101經由第一光學元件31及 第二光學元件32衍射後得到之光斑331之直徑為2um，焦 深DOF為94um，符合實際要求。 請參見圖4與圖5,本發明第四實施例提供之雷射裝置 40，其與第一實施例提供之雷射裝置10基本相同，不同之 11 201006077 處在於：雷射裝置40進一步包括一個第一反射元件44及 ,一個第二反射元件45。第一反射元件44與第二反射元件 45設置於雷射源41與第一光學元件42之間。第一光學元 件42為聚焦透鏡，其折射率等於1.5。第一反射元件44與 第二反射元件45可為橢球面反射鏡（Ellipsoid Mirror)或抛 物面反射鏡（Paraboloid Mirror) 〇 雷射源41發出之紫外光401之光束直徑為B，經由第 二反射元件45反射且進入第一光學元件42之前之紫外光 ® 402之光束直徑為D，則光束放大倍率M=D/B。根據平面 光學擴束器（Planar Beam Expander)之原理，第一反射元件 44之焦距6及第二反射元件45之焦距f2與光束放大倍率 Μ及第一反射元件44與第二反射元件45之頂點間距d，滿 足以下條件式： |fi| + N = d (1) |f2|/|fi|=M (2) @ 如果雷射裝置40由衍射效應（Diffraction Effect)來支 配，根據衍射原理，衍射焦深（Diffractive Depth Of Focus, DDOF)Ddof ’滿足以下條件式：A laser device having a lower cost, higher light utilization efficiency, and a long depth of focus will be described below by way of example. D A laser device having a long depth of focus, comprising: a laser source for emitting a single-wavelength ultraviolet light optical module, comprising: a first optical disposed on the single-wavelength ultraviolet light path An element having a first surface adjacent to the laser source and a second surface opposite the first surface, wherein at least one of the first surface and the second surface is aspherical for use The single wavelength ultraviolet light is concentrated at a point. In contrast to the prior art, the laser device includes a first optical element, and the first optical element includes at least one of a first surface and a second surface that is aspherical, the aspheric surface capable of emitting the laser source The single-wavelength purpuran external light converges at a point and extends the depth of focus of the laser device. At the same time, the aspheric surface does not generate a diffraction effect, and the single-wavelength ultraviolet light emitted from the laser source can be concentrated to a large extent, so that the light utilization efficiency of the laser device is high. Since the laser device includes only one first optical element having an aspherical surface, the laser device has a simple structure and a low manufacturing cost. [Embodiment] The present invention will be further described in detail below with reference to the accompanying drawings. Referring to FIG. 1 , a laser device 1 ( ) according to a first embodiment of the present invention includes a laser source 11 and an optical module 12 . 7 201006077 Laser source 11 is used to emit single wavelength ultraviolet light 101. The optical module 12 is a lens that is disposed on the optical path of the single-wavelength ultraviolet light 101. The optical module 12 has a first surface 121 adjacent to the laser source 11 and a second surface 122 opposite the first surface 121. The first surface 121 is an aspherical surface defined by a conic constant or an aspheric coefficient. The second surface 122 is a flat surface. The single-wavelength ultraviolet light 〇1 emitted from the laser source η is transmitted through the first surface 121 of the optical module 12 and is concentrated on the image plane 13® to form a spot 131. The first surface 121 is an aspherical surface that converges the single-wavelength ultraviolet light 101 emitted by the laser source 11 at a point, i.e., forms a spot 131 on the image plane 13 and extends the depth of focus of the laser device 1〇. At the same time, the first surface 121 designed as an aspheric surface does not cause a diffraction effect, and the single-wavelength ultraviolet light 101 emitted from the laser source 11 can be concentrated to a large extent, so that the light utilization efficiency of the laser device 1 is high. In the present embodiment, the laser device 1 includes only one lens having an aspherical surface, so that the structure of the laser device is simple and the manufacturing cost is low. It should be noted that the second surface 122 may also be a flat surface, a spherical surface, a cylindrical surface or an aspherical surface. The first surface 121 may also be a flat surface, a spherical surface, or a circular surface, and at least one of the first surface 121 and the second surface ι 22 is Aspherical. Referring to FIG. 2, a laser device 2〇 according to a second embodiment of the present invention is substantially the same as the laser device 1〇 provided by the first embodiment, except that the laser device 20 includes an optical mode. The group 22 ❶ optical mode 22 is a rotationally symmetric cone lens (Axic 〇 n Lens). A conical lens is used to extend the depth of focus of the 201006077 laser device 20. 4, a laser device 30 according to a third embodiment of the present invention is substantially the same as the laser device 10 provided in the first embodiment, except that the optical module 35 includes a first optical component. 31 with a second optical element 32. The second optical element 32 is disposed on the optical path of the single-wavelength ultraviolet light 101 and is located on one side of the first optical element 31 away from the laser source 11. The second optical element 32 has a third surface 321 adjacent the first optical element 31 and a fourth surface 322 opposite the third surface 321 . The third surface 321 ® and the fourth surface 322 are planar, spherical, aspherical or cylindrical. In the present embodiment, the third surface 321 is a flat surface, and the fourth surface 322 is a concave spherical surface. The second optical element 32 is used to further extend the depth of focus of the laser device 30. If the laser source 11 emits ultraviolet light 101 having a wavelength of 355 nm and a beam diameter of 10.92 mm. The diameter of the spot 331 formed by the second optical element 32 emerging onto the image plane 33 needs to be less than or equal to 6 um (i.e., the resolution R of the laser device 30 is equal to 6 um), and the depth of focus DOF needs to be greater than or equal to 350 um. According to the Reyleigh Criteria, R=l.22* and *2Fn; 6um=1.22*0.355um*2Fn, Bellow J Fn=6.93um, Fn(F-number) is the focal number (here The ratio of the effective focal length of the optical module to the diameter of the incident light beam). In addition, the depth of focus DOF = ± 2 (Fn) 2A, then the depth of focus DOF = 68um. However, a laser device with a depth of focus DOF equal to 68um does not meet the actual demand. In order to extend the depth of focus DOF of the laser device 30, the first surface 311 or the second surface 312 of the first optical element 31 may be designed as a spherical surface, while the third surface 321 or the fourth surface 322 of the second optical element 32 is designed to be non- Spherical. 9 201006077 Here, the parameter settings of the first optical element 31 and the second optical element 32 are shown in Table 1. Table 1 Parameter setting of optical components 31, 32 (unit: mm) Surface curvature radius Thickness Conic constant Material object surface - l.OOxlO20 - Air 311 117.717 10.000 0 矽(Si) 312 -1.018xl03 5.033 0 Air 321 -2.603x10s 10.703 2.72xl04 矽 322 -307.307 159.800 20.61 In air table 1, the thickness 1.00x1020mm refers to the distance from the object surface to the first surface 311, which can be understood as the light beam 101 entering the optical module 35 is parallel light; the thickness is 10.000 mm. The distance between the first surface 311 and the second surface 312; the thickness 5.033 mm represents the distance between the second surface 312 and the third surface 321; the thickness 10.703 mm represents the distance between the third surface 321 and the fourth surface 322; The thickness 159.800 mm represents the distance between the fourth surface 322 and the image plane 33; the material refers to the material to which the ultraviolet light 101 passes after passing through a certain surface of the optical element. Taking the aspheric constant or aspherical coefficient as the optimized variable and using the point spread function as a reference for the measurement of the depth of focus D0F and the spot size, the ultraviolet light 101 emitted by the laser source 11 passes through The optical spot 31 obtained by diffracting an optical element 31 and the second optical element 32 has a diameter of 5.8 um and a depth D0F of 400 um, which meets practical requirements. If the laser source 11 emits ultraviolet light 101 with a wavelength of 355 nm and the beam 201006077 has a diameter of 10.92 mm. The diameter of the spot 331 formed on the image plane 33 via the second optical element 32 needs to be less than or equal to 2 um and the depth of focus DOF. It is required to be greater than or equal to 80 um (micrometers). The first surface 311 or the second surface 312 of the first optical element 31 can be designed to be aspherical, and the third surface 321 or the fourth surface 322 of the second optical element 32 can also be designed to be aspherical. Thus, the first surface 311 and the second surface 312 of the first optical component 31, and the third surface 321 and the fourth surface 322 of the second optical component 32 are aspherical, and the parameter settings are shown in Table 2. The definitions of the parameters in Table 2 are basically the same as those in Table 1 above, and will not be described here. Table 2 Parameter setting of optical components 31, 32 (unit: mm) Surface curvature radius Thickness Conic constant Material object surface - l.OOxlO20 - Air 311 40.064 7.595 2.02 矽312 190.280 5.028 -1.24X103 Air 321 -18.538 4.497 -1.05χ106 矽322 0.239 60.190 -7.04χ105 Air uses the aspheric constant or aspherical coefficient as the optimized variable and uses the point spread function as a reference for the measurement of the depth of focus DOF and the spot size. The ultraviolet light emitted by the laser source 101 is 101. The spot 331 obtained by diffraction through the first optical element 31 and the second optical element 32 has a diameter of 2 μm and a depth of focus DOF of 94 μm, which meets practical requirements. Referring to FIG. 4 and FIG. 5, a laser device 40 according to a fourth embodiment of the present invention is substantially the same as the laser device 10 provided in the first embodiment, and different from 11 201006077, the laser device 40 further includes a laser device 40. The first reflective element 44 and a second reflective element 45. The first reflective element 44 and the second reflective element 45 are disposed between the laser source 41 and the first optical element 42. The first optical element 42 is a focusing lens having a refractive index equal to 1.5. The first reflective element 44 and the second reflective element 45 may be an Ellipsoid Mirror or a Paraboloid Mirror. The ultraviolet light 401 emitted by the laser source 41 has a beam diameter B, via the second reflective element. The beam diameter of the ultraviolet light® 402 before reflection 45 and entering the first optical element 42 is D, and the beam magnification is M=D/B. According to the principle of a Planar Beam Expander, the focal length 6 of the first reflective element 44 and the focal length f2 of the second reflective element 45 and the beam magnification Μ and the apex of the first reflective element 44 and the second reflective element 45 The spacing d satisfies the following conditional expression: |fi| + N = d (1) |f2|/|fi|=M (2) @ If the laser device 40 is dominated by a diffraction effect, according to the diffraction principle, Diffrative Depth Of Focus (DDOF) Ddof 'satisfies the following conditional expression:
Ddof=土CiFn2X (3)Ddof=土 CiFn2X (3)
Fn=f/D (4) 在此，（^為常數，f表示第一光學元件42之焦距，λ 表示紫外光401於自由空間中之波長。 於像平面43上所形成之光斑431之直徑w，滿足以下 條件式： 12 201006077 w=c2XFn (5) ^等於2.44。結合 於此，c2為常數，於雷式判據中 條件式（3)與（5)，可得以下條件式：Fn = f / D (4) Here, (^ is a constant, f represents the focal length of the first optical element 42, and λ represents the wavelength of the ultraviolet light 401 in the free space. The diameter of the spot 431 formed on the image plane 43 w, satisfies the following conditional formula: 12 201006077 w=c2XFn (5) ^ is equal to 2.44. In combination, c2 is a constant, and in conditional formulas (3) and (5) in the Rayleigh criterion, the following conditional expression can be obtained:
Ddof=土ew2/k (6) (6)可知，如果 已知量，則衍 其中，csc^/c22，c亦為常數。由條件式 光斑431之直徑w與紫外光401之波長λ為 射焦深Dd〇f即可得出。 如果雷射裝置40由幾何光學（Geometric Optics)來支 配’根據幾何焦深（Geometrical Depth of Focus，GDOF)原 理，幾何焦深GD0F與光斑431之直徑w，第一光學元件42 之焦距與紫外光401之光束直徑D之比值Fn ’滿足以下條 件式：Ddof = soil ew2 / k (6) (6) It can be seen that if the amount is known, then csc^/c22,c is also a constant. The diameter w of the conditional spot 431 and the wavelength λ of the ultraviolet light 401 are the focal depth Dd〇f. If the laser device 40 is governed by Geometric Optics, according to the Geometrical Depth of Focus (GDOF) principle, the geometric depth of focus GDOF and the diameter w of the spot 431, the focal length of the first optical element 42 and the ultraviolet light The ratio of the beam diameter D of 401, Fn ', satisfies the following conditional expression:
Gd〇f=2F„w (7) 根據條件式（2)，（4)和（7)，第一反射元件44之焦距fi、 第二反射元件45之焦距f2，與幾何焦深gdof，滿足以下條 ❹件式： |f2|/|fi|=2fw/BGDOF (8) 根據條件式（1)和（8)，可得出第一反射元件44之焦距 fi、第二反射元件45之焦距f2之設計要求。 若雷射裝置40之焦深D0F之設計要求為大於或等於 400um，光斑431之直握之設計要求為小於或專於5um ’而 雷射源41發出之紫外光401之光束直徑B等於1〇.92mm， 第一反射元件44與第二反射元件45之頂點間距d等於 5mm。如果工作距離（通常等效於之有效聚焦焦距）為 13 201006077 160mm，根據條件式（1)和（8)，第一反射元件44之焦距 ,6=3.6595111111，第二反射元件 45 之焦距 f2=l.3405。 ， 由此可見，雷射裝置40所包括之第一光學元件42,第 一反射元件44及第二反射元件45，可依據條件式（1)、（6) 和（8)來設計各自之參數，以延長雷射裝置40之焦深DOF 並得到符合要求之光斑大小。於此，第一光學元件42之第 一表面421為球面，而第二表面422為平面，其與第一反 射元件44及第二反射元件45之參數設置參見表3。表3 ®中各參數之定義與上述表1之基本相同，於此不再贅述。 表3光學元件42與反射元件44、45之參數設置（單位：mm) 表面 曲率半徑 厚度 圓錐常數 材料 物體面 — l.OOxlO20 -- 空氣 44 -7.319 -5 -1 反射面 45 2.681 10 -1 反射面 421 80 1 0 玻璃（折射率1.5) 422 0 160.2 0 空氣 综上所述，本發明確已符合發明專利之要件，遂依法 提出專利申請。惟，以上所述者僅為本發明之較佳實施方 式，自不能以此限制本案之申請專利範圍。舉凡熟悉本案 技藝之人士援依本發明之精神所作之等效修飾或變化，皆 應涵蓋於以下申請專利範圍内。 【圖式簡單說明】 圖1係本發明第一實施例雷射裝置之光路示意圖。 201006077 圖2係本發明第二實施例雷射裝置之光路示意圖。 , 圖3係本發明第三實施例雷射裝置之光路示意圖。 v 圖4係本發明第四實施例雷射裝置之光路示意圖。 圖5係圖4所示雷射裝置之部分光路放大示意圖。 【主要元件符號說明】 雷射裝置 10 ' 20 、 30 、 40 雷射源 11、41 光學模組 12、22、35 紫外光 101 、 102 ' 401 、 402 第一表面 121 、 311 、 421 第二表面 122、312 ' 422 像平面 13 、 33 、 43 光斑 131 、 331 、 431 第一光學元件 31、42 第二光學元件 32 第三表面 321 第四表面 322 第一反射元件 44 第二反射元件 45 15Gd〇f=2F„w (7) According to the conditional expressions (2), (4) and (7), the focal length fi of the first reflecting element 44, the focal length f2 of the second reflecting element 45, and the geometric depth of focus gdof satisfy The following equation: |f2|/|fi|=2fw/BGDOF (8) According to the conditional expressions (1) and (8), the focal length fi of the first reflecting element 44 and the focal length of the second reflecting element 45 can be obtained. The design requirement of f2. If the design of the focal depth D0F of the laser device 40 is greater than or equal to 400um, the design of the straight grip of the spot 431 is required to be less than or exclusively for 5um' and the beam of ultraviolet light 401 emitted by the laser source 41. The diameter B is equal to 1 〇.92 mm, and the vertex distance d between the first reflective element 44 and the second reflective element 45 is equal to 5 mm. If the working distance (usually equivalent to the effective focal length) is 13 201006077 160 mm, according to the conditional expression (1) And (8), the focal length of the first reflective element 44, 6 = 3.6595111111, and the focal length f2 of the second reflective element 45 is 1.33405. Thus, the first optical element 42 included in the laser device 40, first The reflective element 44 and the second reflective element 45 can be designed according to conditional formulas (1), (6) and (8) to extend the Ray The depth of focus DOF of the device 40 is such that a desired spot size is obtained. Here, the first surface 421 of the first optical element 42 is a spherical surface, and the second surface 422 is a flat surface, and the first reflective element 44 and the second reflective element The parameter setting of 45 is shown in Table 3. The definitions of the parameters in Table 3 are basically the same as those in Table 1 above, and will not be described here. Table 3 Parameter setting of optical element 42 and reflective element 44, 45 (Unit: mm) Surface Curvature radius Thickness Conic constant Material object surface — l.OOxlO20 -- Air 44 -7.319 -5 -1 Reflecting surface 45 2.681 10 -1 Reflecting surface 421 80 1 0 Glass (refractive index 1.5) 422 0 160.2 0 Air summing up The present invention has indeed met the requirements of the invention patent, and the patent application is filed according to law. However, the above description is only a preferred embodiment of the present invention, and the scope of the patent application of the present invention cannot be limited thereby. Those who are familiar with the skill of the present invention Equivalent modifications or variations made in accordance with the spirit of the present invention are intended to be included in the scope of the following claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of the optical path of a laser device according to a first embodiment of the present invention. Fig. 2 is a schematic view showing the optical path of the laser device according to the second embodiment of the present invention. Fig. 3 is a view showing the optical path of the laser device according to the third embodiment of the present invention. Fig. 4 is a view showing the optical path of the laser device according to the fourth embodiment of the present invention. Fig. 5 is a schematic enlarged view of a portion of the optical path of the laser device shown in Fig. 4. [Explanation of main component symbols] Laser device 10' 20, 30, 40 Laser source 11, 41 Optical module 12, 22, 35 Ultraviolet light 101, 102 ' 401 , 402 first surface 121 , 311 , 421 second surface 122 , 312 ' 422 image plane 13 , 33 , 43 light spot 131 , 331 , 431 first optical element 31 , 42 second optical element 32 third Surface 321 fourth surface 322 first reflective element 44 second reflective element 45 15