The application of Fresnel equations and anti-reflection technology to improve inclined exposure interface reflection and develop a key component needed for Blu-ray DVD–micro-mirrors

Abstract

The goal of this paper is to explore the use of inclined exposure technology to fabricate millimeter-grade thick film polymer optical microstructures on glass substrates and to resolve the partial reflection of optical energy at interfaces that causes the structural problem of unnecessary photo cross-linking, which can affect the structural shape. This paper uses inclined exposure technology to cause UV illumination to impinge on the substrate at a certain non-perpendicular angle and fabricate a three-dimensional optical-grade micro-mirror as part of an effort to develop an integrated, miniature Blu-ray optical pickup head. Although a transparent glass substrate was employed in the experiment, the system included mask glass (n m = 1.53), glass substrate (n g = 1.5) and photopolymerized polymer (n p = 1.67). UV light tends to undergo partial reflection at the interfaces due to the materials' different refractive indices. This optical phenomenon is particularly severe at higher exposure energies (∼14 000 mJ cm −2 ) in the fabrication of millimeter-grade thick films. The Fresnel equations are used to calculate that the maximum interface reflection of optical energy is approximately 1.5%. This paper therefore selects a medium with a matching refractive index (n gl = 1.473) and removable anti-reflection technology in order to resolve the interface reflection problem, and applies this solution to 45 • micro-mirror manufacturing technology, enabling a surface roughness of approximately 20 nm (λ/20, λ = 405 nm) as measured by WYKO.

‘Flip glass substrate’ package technology for LED yield and performance enhancement

“…The presented flip glass substrate package approach has more interfaces than conventional one. As analyzed by using the Fresnel equation [13] (considering that the refractive index of n chip is 2.5, and n phosphor is 1.73), the transmission is 86.8% for the presented flip glass substrate LED and 91.9% for the conventional one. The transmission of the presented flip glass packaging approach can be further improved to 89% if coated with an additional silicone layer.…”

Integrated fluorescence detection of labeled biomolecules using a prism-like PDMS microfluidic chip and lateral light excitation

“…The excitation angle was determined using Snell's and Fresnel's equations 10 to maximize the photon flux exciting the microfluidic channel while still resulting in TIR conditions at the bottom glass-air interface in order to prevent the excitation light from reaching the sensor. For refractive indices of 1.41, 1.34, 1.45 and 1.0 (at 405 nm) for PDMS, water, glass, and air, respectively, it was determined that an angle of incidence of 70°results in the transmission of more than 80% of the total source excitation light reaching the microchannel surface (necessary for excitation of the fluorophores immobilized at both the top and bottom surfaces in microfluidic biosensor applications).…”

Thermal-deformation analysis of a polymer micro-mirror optical device

“…Raising the temperature performance and surface hardness are two major issues associated with plastic optics. However, while many scholars have been able to fabricate mirror structures, very few explored the thermal stability of the materials (Yoon et al 2006;Zhang et al 2001;Strandman et al 1995;Hung et al 2004;Jang et al 2005 Hung andLiang 2008;Hung and Liao 2008) For this study, we designed and fabricated micromirror optical components and tested the thermal stability of the polymer structure by applying it as a DVD optical pick-up head in a 100°C environment. Given the surface roughness of the fabricated inclined surface, we fine tuned the fabrication parameters to derive a better thermal stability.…”