Nanosecond pulsed laser texturing of optical diffusers

Abstract

High-quality optical glass diffusers have applications in aerospace, displays, imaging systems, medical devices, and optical sensors. The development of rapid and accurate fabrication techniques is highly desirable for their production. Here, a micropatterning method for the fast fabrication of optical diffusers by means of nanosecond pulsed laser ablation is demonstrated (λ=1064 nm, power=7.02, 9.36 and 11.7 W and scanning speed=200 and 800 mm s-1). The experiments were carried out by point-to-point texturing of a glass surface in spiral shape. The laser machining parameters, the number of pulses and their power had significant effect on surface features. The optical characteristics of the diffusers were characterized at different scattering angles. The features of the microscale structures influenced average roughness from 0.8 μm to 1.97 μm. The glass diffusers scattered light at angles up to 20° and their transmission efficiency were measured up to ∼97% across the visible spectrum. The produced optical devices diffuse light less but do so with less scattering and energy losses as compared to opal diffusing glass. The presented fabrication method can be applied to any other transparent material to create optical diffusers. It is anticipated that the optical diffusers presented in this work will have applications in the production of LED spotlights and imaging devices.

Femtosecond laser directed fabrication of optical diffusers

“… 3 – 5 The most widely used surface-relief structures include microlenses, 6 pyramids, 7 and textured surfaces. 8 , 9 Applications of these types of diffusers can be found in filament lamps, 10 LEDs 11 and fiber optics. 12 Fabrication of textured surfaces through femtosecond (FS) laser ablation is a rapidly growing area of interest.…”

Femtosecond laser ablation of transparent microphotonic devices and computer-generated holograms

“…These hydrophilic devices may spread water across their surface to maximize contact based on the Wenzel model (θ < 90°) while hydrophobic devices that naturally repel water and form droplets are defined by the Cassie-Baxter model (90° > θ < 150°) [57]. The hydrophilicity of transparent devices can have a significant impact on the optical and electrical performance in a wide range of applications including selfcleaning [58,59], anti-fouling [60], anti-corrosion [61], anti-fogging [62], icephobicity [63], and drag reduction properties [64,65]. FS lasers can be employed not only to fabricate microphotonic devices but also modify the surface wettability resistance simultaneously, while this will require multisteps in other fabrication techniques [49].…”

Highly Flexible, Stretchable, and Tunable Optical Diffusers with Mechanically Switchable Wettability Surfaces

“…The advanced diffusion capability of a new class of diffusers makes them suitable for most applications that require mechanically stretchable diffusers including flexible OLEDs and wearable strain sensors. Unlike the rigid diffusers, ,, these stretchable diffusers tune the distribution of light based on mechanically applied strain, while the recently developed diffuser as a sensor controls the light diffraction only based on a swelling behavior of hydrogel from chemicals . However, it has limited control over the light distribution pattern, generally making only linear patterns, but it is still suitable for both uniaxial and biaxial applied strains.…”