Microlens Structure Research Articles

Application of a novel focused microlens to light-emitting diode packaging

The light-emitting diode (LED) has been extensively applied to lighting systems. In this work, a novel optical structure design of a microlens based on reflection/refraction properties can achieve a specific light-focusing effect, and can be applied to LED packaging. The optical microlens structure from basic specifications of conventional LED packaging are modified and redesigned. The light-focusing performance of this novel focused microlens is greatly enhanced, and the energy of the LED light within a range ±15 deg from the center line of the light source can be greatly improved as well. Maximum illuminance is enhanced 99.3% in comparison with conventional LED packaging, and the luminous flux rayed out within a range ±15 deg from the center line of the light source is enhanced 34%. The achievements of this research can be applied to various kinds of working environments to meet specific focusing requirements with energy savings.

Micro Flow Cytometry Chip Device Integrated with Tunable Microlens for Circulating Tumor Cells Detection and Counting Applications

This paper reports a micromachine-based micro flow cytometry chip device integrated with a tunable liquid-filled microlens structure for optical detection, in which is capable of fluorescence detection for circulating tumor cells (CTCs) detection applications. By utilizing two sets of micro-piezoelectric pump device, cell samples can be aligned and focused to flow through the sensing area, and enhanced the accuracy and sensitivity of samples detection. The integrated chip device can be used to detect tumor cells labelled with specific fluorescent dyes successfully, and the optical signals can be enhanced accordingly by utilizing the tunable liquid-filled microlens within specific liquid pressure.

Fast switching characteristics of a microlens array using the electroclinic effect of SmA^* liquid crystals

We present a microlens array characterized by the electroclinic effect of chiral smectic A (SmA(*)) liquid crystals, which show the very fast dynamic switching characteristics required in high-speed optical devices. In order to easily control the intensity at the focal length of the proposed dynamic microlens structure, we adopt a solid-type liquid crystal polymer with optical anisotropy, which can split the beam intensity into two directions, depending on the vectorial portion of the polarization state of the light. The proposed microlens shows a focal intensity tunable by controlling the polarization of light at the SmA(*) liquid crystal. The lens has a very fast switching time of about 24 micros, which is several times faster than conventional microlens arrays with surface-stabilized ferroelectric liquid crystals.

Microcapillary electrophoresis chips utilizing controllable micro‐lens structures and buried optical fibers for on‐line optical detection

In this study, a new design of a controllable micro-lens structure capable of the enhancement of LIF detection system has been demonstrated, which can be further integrated with buried optical fibers on a micro-CE chip for sample separation and detection. Two pneumatic side-chambers were placed between a micro-CE channel and an optical fiber channel. The intervals between the side-chamber and the microchannel were used to form two surfaces of the controllable micro-lens structure. Deformations of the two surfaces can be generated after pressurized index-matching fluid was injected into the pneumatic side-chambers. The side-chambers can be deflected as a double convex lens to focus both the excitation light source and the fluorescent emission signal. The profile and the focal length of the micro-lens structure can be actively adjusted by applying different liquid pressures so that biosamples with a low concentration can be detected. Using low-cost polymeric materials such as polydimethylsiloxane, rapid and reliable fabrication techniques involving standard lithography and replication process was employed for the formation of the proposed chip device. Experimental results revealed the controllable micro-lens structure can be successfully deformed as a convex lens to focus the laser light source and the collected fluorescence signal can be enhanced accordingly. The power amplitude of excitation laser light can be enhanced by 5.4-fold. FITC dye and DNA markers were then utilized for micro-CE testing. The results indicated that the signal amplitude could be enhanced 2.5-fold when compared to the case without the activation of the micro-lens. According to the experimental results, the developed device has a great potential to be integrated with other microfluidic devices for further biomedical applications.

Fabrication of Electrically Controllable Microlens Array using a Birefringent Bilayer

Electrically switchable microlens array is demonstrated using a stacking system of UV curable polymer, liquid crystalline polymer (LCP) and liquid crystal (LC) layers. The birefringent LCP provides the incident beam focusing ability of polymer microlens structure as well as the LC aligning property. By engaging external voltage to the device, we can obtain fine dynamic characteristics of the focus switching from the polarization tuning ability of twisted nematic LC layer on the flat boundary condition and the light focusing role of polymer microlens structure, separately. The measured focal characteristics are well matched to the calculated ones and arrayed focused spots are easily switched by applying external voltage. This active microlens array is expected to play a critical role in the various photonic systems such as optical switches, beam modulators and 3-D imaging units.

Using imprinting technology to fabricate three-dimensional devices from moulds of thermosetting polymer patterns

The fabrication of moulds for imprinting can be simplified significantly by using specialized cross-linking polymers to define the pattern on a silicon wafer. Thermosetting polymers (SU-8) can be used to pattern silicon moulds for imprinting technologies because (1) silicon oxide moulds bearing a thermosetting polymer pattern can be obtained using conventional semiconductor technologies and (2) thermosetting polymers have no obvious glass transition temperature (Tg) because of their cross-linked structure, but the hardness decreases significantly when the temperature is above the Tg. In this study, we used Su-8 resist as the thermosetting polymer pattern to obtain moulds on a silicon wafer. We have tested the thermal properties of thermosetting (SU-8) and thermoplastic polymers (22A4) for use as imprinting patterns and imprinted resists. We fabricated a hill-like structure by applying an electron beam strategy and used this thick film to increase the adhesion between the pattern and the silicon wafer. We used scanning electron microscopy to investigate the resolution of the thermoplastic polymer resist (22A4) pattern that we imprinted using the thermosetting polymer (SU-8) pattern. To define the feature size after imprinting, we determined the feature size shrink factor after separation of the thermosetting polymer pattern (SU-8) from the thermoplastic polymer (22A4) resist. In addition, we have fabricated a microlens of polydimethylsiloxane (PDMS) through replication using the thermoplastic polymer resist (22A4) obtained after imprinting the mould with the microlens structure of the thermosetting polymer (SU-8).

１／３インチ３６万画素ＩＴ‐ＣＣＩ撮像素子

A 1/3-inch 360 kpixel IT-CCD image sensor has been developed to satisfy recent demand for small CCD image-sensors with higher resolution and higher sensitivity. The photo-diode aperture and the microlens structure were optimized using microlens simulation technology. As a result, a minimum object illumination of 3 lux and a low smear level of 0.002% have been achieved.