Sadao Mori

Laser measurement system for precise and fast positioning

A laser measurement system for precise and fast positioning of an object has been developed. When the object speed is low, the movement of the object is measured by comparing the phase change of a light beam reflected by the object with the phase modulated by an electro-optic crystal (an active device by which the optical phase can be controlled by the application of a voltage). When the object speed is high, the movement is measured by a fringe counting technique. The system achieves an accuracy of 4 nm and a maximum allowable measurement speed of 1100 mm/s.

A spacing sensor for magnetic disk systems

A sensor based on Frustrated Total Reflection (FTR) for measuring spacing between magnetic disks and sliders has been developed. Theoretical evaluation shows that when polarization and incident angle are properly chosen, this sensor should have twice the measurement range and at least three times the resolution of traditional methods of spacing measurement which use interference. The measurement range of the FTR sensor can be optimized for typical disk-slider spacings (<100 nm) easily, by changing the incident angle of the light. To evaluate its operation, the sensor was fabricated on the side of a glass slider by a lithography technique and spacing was measured. Taking the 20 nm offset caused by the beveled edge of the slider into account, measurement error was less than 1 nm for P polarized light and 10 nm for S polarized light. This sensor could potentially measure spacing between real magnetic disks and ceramic sliders,.

Effective refractive index method for frustrated total reflection: application to measurement of flying height

In order to measure the spacing between an actual magnetic disk and a slider, we developed a flying height sensor based on frustrated total reflection (FTR). When optically measuring the flying height of a slider, the phase shift on reflection at the magnetic disk is a significant problem. In this paper, we describe the theoretical treatment of the problem, introduce the modified effective refractive index method, and measure the effective refractive index of an actual magnetic disk. The flying height on a magnetic disk was also measured using the obtained effective refractive index. The result was compared with flying height measurements measured by the traditional interference method. They agreed with each other, with an error of less than 2.5 nm.

Compact Water-Quality Monitors with Micro-Machined Flow-Cells

Compact monitors with micro-machined flow-cells for water-quality multi-point monitoring and control system are described. A micro-mixer and an optical flow-cell were integrated in one chip. Today, two types of monitors are available.

Flying height measurement using frustrated total reflection: determination of the reflectivities by the least-squares method

A new method for determining reflectivities in flying height measurement of a slider using frustrated total reflection (FTR) sensor is evaluated. The method is based on the fact that the reflectivity of FTR has different dependence on flying height for P-polarized light and S-polarized light. The flying height of a slider on a glass disk was measured both by an FTIP sensor using this method and by a traditional flying height tester. The results agree with each other with an error of less than 3 nm.

Characteristics of electro-optic crystals for laser displacement sensor.

We are developing a laser displacement sensor which can be sued for XY-Stage positioning for example. The principle of this sensor is the interference method. It modulates the phase of the reflecting beam form the object by electro-optic crystals, and measures shift of the phase of measurement beam by comparison with that of modulated reference beam. The resolution of this sensor is 5nm, and the possible measurement speed is 1000 mm/s. We also investigated some of important characteristics of E-O Crystals on which the resolution of this sensor depends, and confirmed that they were adequate for our sensor.

A Laser Measurement System For Precise And Fast Positioning

A laser measurement system for precise and fast positioning of an object has been developed. When the speed is low, the movement of the object is measured by comparing the phase change of a light reflected by the object with the phase modulated by an electro-optic crystal (an active device by which the optical phase can be controlled by applying a voltage thereto). When the speed is high the movement is measured using a fringe counting technique. The system achieved an accuracy of 4nm, and a maximum allowable measurement speed of 1100mm/s.