ABSTRACT
We have developed an extremely small integrated microencoder whose sides are less than 1 mm long. It is 1/100 the size of conventional encoders. This microencoder consists of a laser diode, monolithic photodiodes, and fluorinated polyimide waveguides with total internal reflection mirrors. The instrument can measure the relative displacement between a grating scale and the encoder with a resolution of the order of 0.01 microm; it can also determine the direction in which the scale is moving. By using the two beams that were emitted from the two etched mirrors of the laser diode, by monolithic integration of the waveguide and photodiodes, and by fabrication of a step at the edge of the waveguide, we were able to eliminate conventional bulky optical components such as the beam splitter, the quarter-wavelength plate, bulky mirrors, and bulky photodetectors.
ABSTRACT
Optical trapping of transparent ring-shaped micrometer-sized objects with a refractive index lower than that of the surrounding medium has been demonstrated by use of a strongly focused TEM(00)-mode laser beam. Axial trapping of these objects is a result of the upward radiation pressure induced when the incident light strikes the inner wall and transmitted light leaves from the bottom. Transverse trapping of these objects occurs because the total repulsive radiation pressure exerted on the inner wall of the object is directed toward the laser beam axis. Three-dimensional manipulation of f luorinated polyimide micro-objects (refractive index n(1)= 1.525, outer diameter 10 microm, inner diameter 5 microm, and thickness 5.7 microm) in a high-refractive-index liquid (n(2)= 1.605) was experimentally shown to be possible by use of an objective lens with a wide range of numerical apertures from 1.25 to 0.5.
ABSTRACT
This paper describes the fabrication and characteristics of a gradient-index microlens by using a low-stress, high-transmittance film that is deposited by ion-beam sputtering. The key techniques in forming this film are sputtering with N(2) gas, performing ion-beam irradiation during deposition, and stabilizing the deposition acceleration current. An integrated device consisting of the microlens and a laser diode is demonstrated. The focusing spot size is 2 microm x 3 microm at a distance of 11 microm from the lens facet.
