汽车倒泊防撞报警器的设计毕业设计论文(编辑修改稿)

汽车倒泊防撞报警器的设计毕业设计论文(编辑修改稿)内容摘要：

ight and the waveguide layout pitch is 250 μm and the length is 7 cm. With this mold, we performed UV embossing to make embedded type waveguides. To fabricate a 12 channel silicon waveguides mold, we etched silicon substrate with KOHsaturated isopropanol solutions in two steps: First is to make a vertical coupling path for the waveguides and the other is to make 45176。 slope for the fabrication of mirror faces. First, a metallic mask is patterned on the silicon substrate and the silicon is vertically etched with KOH to form a waveguide pattern. In the next step to form 45176。 slope, a thin film of SiO2 is grown on patterned waveguide. And photoresist is patterned at the end of the each waveguide structure and the ends of the waveguides are etched with KOHsaturated isopropanol solution to form 45176。 slope. After the SiO2 is stripped, the process of fabricating silicon mold equipped with 45176。 mirror is pleted. We fabricated 12 channel embedded waveguide array by UV embossing using the prefabricated silicon mold. Waveguide fabrication process is shown in Fig. 1. UV curable polymer, which is used as cladding layer with index as at 850 nm wavelength, is dropped in the hollow cavity of a transparent substrate such as PDMS template. After silicon mold is pressed on template the UV light is irradiated. Silicon mold is detached and metallic film is coated on the 45176。 slope at the end of the waveguide to enhance coupling efficiency. And then the core polymer is dropped and a flat substrate is covered and pressed onto the core material which is also UV curable polymer with refractive index of at 850 nm wavelength. The UV light is irradiated once again. After the upper and lower templates are detached, we can get a plete array of polymer waveguides with builtin 45176。 mirror face at each end of the waveguide. 3. Microlensed VCSEL One of the approaches to collimate the light from VCSEL arrays to the waveguide is the use of microlenses [9] and [10]. This method offers an increase in coupling efficiency and alignment tolerance. The volume of a polymer drop to fabricate these lenses is approximately a few tens of picoliters. We are able to control the size of the microlenses by controlling the amount of the polymer drops and by controlling the viscosity of the materials. UV curable polymer is used for inkjetting, of which the viscosity and the refractive index are 300 cps and at 850 nm wavelength. Shows one of the microlensed VCSEL array and microlensed VCSEL has a microlens formed by the inkjetting method on the aperture of VCSEL. Inkjetting of UV curable resin on the VCSEL, lens material is aligned automatically on the aperture of VCSEL. Shows a view of the system where the output power from the microlensed VCSEL arrays is measured for their divergence. The divergence angle of the laser light from the VCSEL is shown to bee narrower by using microlenses by the collimating effect pf the light from VCSEL. Because of the microlens, the higher order modes from the VCSEL are suppressed by the cavity effect [10]. The emitted output from the VCSEL cavity is reflected back by microlens layer and is focused on the VCSEL cavity. During this process, the divergence angle of the VCSEL is reduced. In this case, the divergence angle of the VCSEL decreased from 18176。 to 15176。 after forming microlens. We conducted simulation study about the coupling efficiency between VCSEL and the waveguide by using the ray tracing method. As the divergence angle of the VCSEL was put into the calculation, the coupling efficiency of the VCSEL with microlens was found to be dB is dB which were better than that of VCSEL without microlens as − dB. Here dimension of waveguide is 50 μm width, 50 μm height and 7 cm length. Refractive indices of the core and the cladding are and , respectively, at 850 nm wavelength. The distance between the VCSEL and the waveguide is 100 μm. 4. Passive alignment Solder ball array and pin array are placed on the electrical subboards to bond the O PCB and the electrical subboards with high precision. For precision alignment, solder ball array in diameter of 450 μm are used to thermally attach to the chip module. The solder ball array can be used for vertically alignment between the main O PCB and the subboards within a mismatch below 10 μm. The size of the solder ball is 500 μm on average with standard error of 177。 5 μm. Two types of pin arrays are used. One array with diameter of 1 mm is for alignment and the other with diameter of 200 μm is for electrical interconnection. The 1 mm pin array is used for lateral alignment between the main O PCB and the subboards. Because of the impedance match,。