In this report, Optical probe system for modality, optical coherence tomography (OCT) and optical coherence microscope (OCM), is presented. In order to control the back focal length from 2.2 mm to 27 mm, optical probe is designed using two liquid lenses and several lenses. The narrow depth of focus (DOF) in microscope is extended by phase filter such as cubic filter. The filter is modified so that DOF is extended only In the OCM mode. The section for the extended DOF of probe is controlled by iris. Therefore in OCT mode, the phase filter does not affect on the DOF of lens. In OCM mode, the Gaussian light and modified light will affect the DOF. The probe dimension is less than 4 mm diameter and less than 60 mm long. The scan range of system is 0.88 mm wide, 1 mm deep in the OCT and 510 μm wide, 1 mm deep in the OCM mode. The lens curvature and iris aperture are operated by digital microelectrofluidic lens and iris.
Laparoscopic lens module that is capable of zooming is presented. The lens module has a high magnification and a high
resolution such as four zoom and 2M pixels full HD image. The lens module consists of two lens sets to get 3-D images.
Each lens module has several lenses less than conventional laparoscope but has 8 lenses and two liquid lenses. The total
length of module is 19 mm long and the diameter is less than 5 mm. The separated distance of two lens center is 5 mm
and two lens modules are inserted into the 11mm diameter laparoscope. The lens module is designed by Code V™ by
using the 2M pixels CMOS sensor that the pixel size is 1.75 μm. The merit of this fluidic lens design is being convertible
between a convex and concave shape. The effective focal length of zoom-out and zoom-in modes is 3.24 mm and 12.94
mm respectively. The modulation transfer function of zoom-out and zoom-in modes is 40% and 30% at 140 lp/mm
frequency. We have a diffraction of element at near stop to improve image resolution. Also the resolution of zoom-in
mode is improved by using liquid iris. The F-number of a two modes is 4.4 and 5.8 and the optical distortion is 10% and
0.5%. It is expected that the z-direction resolution by this laparoscope is less than 2 mm
This study introduces a multimode compatible forward scanning optical probe which includes tunable iris and varifocal
lens based on micro-electro-fluidics. Concept development and optical design is carried out for the optical probe. The
result shows that it can be adaptively used as a multimodal imaging tool for both optical coherence tomography and
microscopy. It also has been proved that an optical depth scanning with the designed probe can provide optical
coherence tomography with high resolution without any mechanical movement of the optics.
This paper presents a tunable liquid lens based on microelectrofluidic technology which integrates electrowetting and microfluidics. In the novel microelectrofluidic lens (MEFL), electrowetting in the hydrophobic surface channel induces the Laplace pressure difference between two fluidic interfaces on the lens aperture and the surface channel. Then, the pressure difference makes the lens curvature tunable. The previous electrowetting lens in which the contact angle changes at the side wall has a certain limitation of the curvature variation because of the contact angle saturation. Although the contact angle saturation also appears in the surface channel of the MEFL, the low surface channel increases the Laplace pressure and it makes the MEFL to have full variation of the optical power possible. The magnitude of the applied voltage determines the lens curvature in the analog mode MEFL as well as the electrowetting lens. Digital operation is also possible when the control electrodes of the MEFL are patterned to have an array. It is expected that the proposed MEFL is able to be widely used because of its full variation of the optical power without the use of oil and digital operation with fast response.
This paper presents a variable aperture design based on the microelectrofluidic technology which integrates electrowetting and microfluidics. The proposed microelectrofluidic iris (MEFI) consists of two immiscible fluids and two connected surface channels formed by three transparent plates and two spacers between them. In the initial state, the confined aqueous ring makes two fluidic interfaces, on which the Laplace pressure is same, in the hydrophobic surface channels. When a certain voltage is applied between the dielectric-coated control electrode beneath the three-phase contact line (TCL) and the reference electrode for grounding the aqueous, the contact angle changes on the activated control electrode. At high voltage over the threshold, the induced positive pressure difference makes the TCLs on the 1st channel advance to the center and the aperture narrow. If there is no potential difference between the control and reference electrodes, the pressure difference becomes negative. It makes the TCLs on the 1st channel recede and the aperture widen to the initial state. It is expected that the proposed MEFI is able to be widely used because of its fast response, circular aperture, digital operation, high aperture ratio, and possibility to be miniaturized for variable aperture.
Wafer-level lens module comprising of a glass lens as well as polymer lenses is developed for 5 mega-pixel mobile
phone camera. A few institutes and companies have been tried wafer-level lens modules so far, but all of them are made
of only UV curable polymer lenses which have the limitation in resolving power. We designed and fabricated waferlevel
lens module which comprises of a glass lens and two UV curable polymer lenses. Glass lenses are molded one by
one and reconstructed as an array on a wafer by the specially designed precision alignment technique. Polymer lenses are
fabricated by typical replication and UV curing process. Optical evaluation is carried out and it is shown that the quality
of the images captured by the fabricated wafer-level lens module is comparable with that of a commercial 5 mega pixel
phone camera. It is expected that the hybrid type wafer level lens module (with glass and polymer lenses) is a promising
solution for the high resolution and low cost phone camera in the future.