Preoperative α-blockade and slow sheath placement may reduce maximal ureteral access sheath insertion force. If the force exceeds 600 G, a smaller diameter sheath may be an alternative. Alternatively the procedure can be terminated and followed later by pre-stented retrograde intrarenal surgery.

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Diffractive optical elements (DOEs) are key components in the miniaturization of optical systems because of their planarity and extreme thinness. We demonstrate the fabrication of DOEs by use of gray-scale photolithography with a high-energy-beam sensitive glass photomask. We obtained DOE lenses with continuous phase profiles as small as 800 microm in diameter and 5.9 microm in the outermost grating pitch by selecting a suitable optical density for each height level and optimizing the process variables. Microlenses patterned with eight levels and replicated by UV embossing with the polymer master mold showed a diffraction efficiency of 81.5%, which was sufficiently high for the devices to be used as optical pickups. The effects of deviations in diffraction efficiency between the DOE height and profile design were analyzed.

In a solid immersion lens (SIL) based near-field recoding (NFR) system which is one of the emerging technologies for nextgeneration optical data storage systems, it is essential that the air gap between the SIL and the rotating disk is maintained at less than 50 nm without collision in order to obtain the proper coupling efficiency of evanescent waves. To fabricate a reliable near-field air gap servo system, various disturbances such as disk vibration, external shock and overshoot have to be considered, and these possible disturbances have to be prevented effectively. We propose an improved gap servo system using a disturbance observer (DOB), which has a reduced overshoot and rejection performance for the previously mentioned disturbances. The effectiveness of the proposed controller is verified by experimentally. The experiment results, show that the overshoot was reduced using the proposed near-field air gap servo system with a DOB. In the case of the ramp approach mode with and without the hand-over mode in the mode-switching servo, the overshoots were decreased to 50.9% and collision was avoided, respectively. In addition, in the case of the modified approach mode with and without the hand-over mode in the mode-switching servo, the overshoot was decreased to 2.9 and 3.7%, respectively. Consequently, the access time was decreased in each approach case without the hand-over mode using the DOB-based controller. In addition, the disturbance rejection performance of the external shock was improved to 9.11%.

We propose a measurement system using dual-wavelength digital holography and low-coherence interferometry to measure micro- and nanostructure surface heights. To achieve an extended axial step-measurement range and better image quality, a single light-emitting diode generates two distinct light sources by filtering different center wavelengths and narrower bandwidths. The system can measure surface profile with higher step heights and lower speckle noise in a large field-of-view. Using single-source lighting and a simple configuration, the method supports compactly configured and lower-cost surface-topography measurement systems applicable in various fields. Experimental results for a standard step sample verify the system's performance.

Microactuators for micromirror system have found many applications in various areas including projection displays, optical switches, RF switches and so on. In this paper we demonstrated micromirror actuator using ionic polymer metal composites (IPMC) that is a suitable candidate, since it has many attractive qualities such as durability, aquatic, miniature and light-weighted. Specially, IPMC has extraordinary advantages which are simple bending motion for low driving voltage (1-2 V), low power consumption, and simple structure. The IPMC actuator is made of Nafion NE-1110 (Dupont Co, Ltd., 260 lm thick) layer and electrode (platinum) layers and driven by 1-4 V. The displacement measured vertically is 0.25 mm and tilting angle is 11.3°. The angular motion, which is more than 10°, is a good advantage in the field of display module. This paper shows that the IPMC actuator has enough possibility for other applications.

A multilayer ceramic capacitor (MLCC) vibrates when an electrical signal containing an alternating current (AC) component is applied to it. The piezoelectric and electrostrictive coefficients of the dielectric layer are needed to analyze such vibrations because both affect the vibration. Also, they must be determined for various direct current (DC) biases because an MLCC is operated with various electrical signals and the coefficients vary as the DC bias changes. We determined the coefficients by measuring the vibration of an MLCC under a range of DC biases. When a single‐frequency AC voltage is applied to an MLCC, it vibrates with both fundamental and second‐harmonic frequencies because of piezoelectricity and electrostriction. These frequencies were measured and separated into their piezoelectric and electrostrictive components to derive the piezoelectric and electrostrictive coefficients. Because of the difficulty of calculating the coefficients, a finite element (FE) method was adopted in consideration of the complicated structure of the MLCC. The derived piezoelectric coefficients were cross‐checked and verified by impact testing. The electrostrictive vibration component was greater than the piezoelectric one except when the applied DC electric field was near zero. This showed that both piezoelectricity and electrostriction must be considered in vibrational analyses of MLCCs.

This paper analyzes the effects due to the angular motion of a small-sized imaging system equipped with an optical image stabilizer (OIS) on image quality. Accurate lens moving distances for the OIS required to compensate the ray distortion induced by the angular motion are determined. To calculate the associated modulation transfer function, the integrated and the compensated point spread functions are defined. Finally, the deterioration of the image resolution due to angular motion and the restorative performance of the OIS are analyzed by isolating seven types of angular motion.