Wafer-level fabrication of multi-element glass lenses: lens doublet with improved optical performances

Abstract

This Letter reports on the fabrication of glass lens doublets arranged in arrays and realized at wafer level by means of micro-fabrication. The technique is based on the accurate vertical assembly of separately fabricated glass lens arrays. Since each one of these arrays is obtained by glass melting in silicon cavities, silicon is employed as a spacer in order to build a well-aligned and robust optical module. It is shown that optical performance achieved by the lens doublet is better than for a single lens of equivalent numerical aperture, thanks to lower optical aberrations. The technique has good potential to match the optical requirements of miniature imaging systems.

Micromachined phase-shifted array-type Mirau interferometer for swept-source OCT imaging: design, microfabrication and experimental validation

“…In the following discussion, W1 represents the microlens doublet matrix, W2 represents the Z microscanner, and W3 is the spacer while W4 represents the beam-splitter wafer. To build the Mirau interferometer, the doublet of microlenses has been selected instead of single microlenses [14]. Because of lower optical aberrations, the optical performance achieved by the lens doublet is better than for an individual lens having an equivalent numerical aperture.…”

Vertical comb-drive microscanner with 4x4 array of micromirrors for phase-shifting Mirau microinterferometry

“…The device is composed of a doublet of a dense array of plano-convex objective lenses (φ= 1.9 mm, pitch 2 mm), the vertical MOEMS micro-scanner with an array of actuated reference micromirrors, a glass spacer for focus adjustment, and a planar beam splitter. The array of objective lens is fabricated by noncontact vacuum process, based on thermal reflow of glass in a silicon structure [13]. Instead of single array of objective lens, two arrays are arranged in doublet in order to lower the spherical aberrations.…”

Array-type miniature interferometer as the core optical microsystem of an optical coherence tomography device for tissue inspection

“…9 It is then used for the doublet generation where multi-wafer anodic bonding is applied. 10 The latter ensures a high level of alignment both laterally and axially since no additional material is required. Thanks to polishing, the generated lens doublets are then as thin as several hundreds of microns (viz.…”

“…For this purpose, holes are placed in the glass beam-splitter spacer in such a way to enable side access to the contact pads for flip-chip bonding of the mirror substrate, once diced, onto a PCB. x (µm) 10 by physical vapor deposition (PVD). The beam splitting ratio of the planar beam splitter is 70/30, i.e.…”