Browsing by Author "Kao, CF"

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Double-diffraction planar encoder by conjugate optics
(2005-02-01)
Kao, CF
;
Chang, CC
;
Lu, MH
;
光電工程學系
;
Department of Photonics
A planar encoder using conjugate optics is proposed for sensing the 2-D displacement of a 2-D grating. A Doppler frequency shift of diffracted light is generated when the grating moves. The optical conjugate path can compensate for the error arising from the relative tilt between the optical head and the scale (head-to-scale tilt). Additionally, the optical head is easily integrated, having high tolerance in component-to-component placement. The 2-D displacement system with the 2-D grating, which has period of 1.6 mu m in both the X and Y directions, provides a signal period of 0.4 mu m by using a double-diffraction configuration. This system and associated electronics provide interpolation with a factor of 400, corresponding to a measurement resolution of 1 nm. (c) 2005 Society of Photo-Optical Instrumentation Engineers.
Efficient fibre-coupled laser diode end-pumped NYAB laser
(1996-08-01)
Chen, YF
;
Wang, SC
;
Kao, CF
;
Huang, TM
;
光電工程學系
Under optimum pump conditions, 60mW of green laser output corresponding to a conversion efficiency 6% was obtained from a self-frequency-doubling NYAB crystal when pumped by a 1W fibre-coupled laser diode. The prospect of higher conversion efficiency is also discussed.
Efficient fibre-coupled laser diode end-pumped NYAB laser
(1996-08-01)
Chen, YF
;
Wang, SC
;
Kao, CF
;
Huang, TM
;
光電工程研究所
Under optimum pump conditions, 60mW of green laser output corresponding to a conversion efficiency 6% was obtained from a self-frequency-doubling NYAB crystal when pumped by a 1W fibre-coupled laser diode. The prospect of higher conversion efficiency is also discussed.
High resolution planar encoder by retro-reflection
(2005-08-01)
Kao, CF
;
Lu, SH
;
Lu, MH
;
光電工程學系
;
Department of Photonics
This investigation presents a planar diffractive laser encoder system (PDLENS), which serves as a two-dimensional (2D) position detection apparatus for precision machine applications. Traditional 2D position detection utilizes a pair of linear encoders in crossed construction and so maintaining the perpendicularity between this pair of encoders is difficult. Besides, the rigorous alignment requirements among various components of the encoder system impose a serious user adaptation bottleneck. Of all alignment tolerances, the head-to-scale alignment tolerance is the most important problem for applications. In this work, a 2D grating is employed as the scale and the PDLENS is based on the retro-reflection configuration. Therefore the new encoder can provide good perpendicularity and tolerate larger alignment errors than the conventional encoder does. The grating pitch is 1.6 mu m and the period of the output signal is 0.4 mu m due to the double diffraction. Electronic interpolation with a factor of 400 leads to a readout resolution of 1 nm. The new encoder and a capacitive sensor were employed to simultaneously measure a circular motion with a radius of 1 mu m generated by a piezo stage. Comparing the measured positions, the deviation is less than 30 nm and the repeatability is better than 8 nm. (c) 2005 American Institute of Physics.
Investigation of fiber-coupled laser-diode-pumped NYAB green laser performance
(1996-10-01)
Chen, YF
;
Wang, SC
;
Kao, CF
;
Huang, TM
;
光電工程研究所
The optimum pump condition for a fiber-coupled diode end-pumped NYAB laser has been determined by including the effect of pump beam quality into the analysis. Under the optimum pump condition, 67 mW of the green laser output corresponding to a conversion efficiency 10.3% was obtained from a self frequency-doubling NYAB crystal when pumped by a 650 mW fiber-coupled laser diode. The prospect of higher conversion efficiency is also discussed.
Investigation of fiber-coupled laser-diode-pumped NYAB green laser performance
(1996-10-01)
Chen, YF
;
Wang, SC
;
Kao, CF
;
Huang, TM
;
光電工程學系
The optimum pump condition for a fiber-coupled diode end-pumped NYAB laser has been determined by including the effect of pump beam quality into the analysis. Under the optimum pump condition, 67 mW of the green laser output corresponding to a conversion efficiency 10.3% was obtained from a self frequency-doubling NYAB crystal when pumped by a 650 mW fiber-coupled laser diode. The prospect of higher conversion efficiency is also discussed.
Optical encoder based on the fractional Talbot effect
(2005-06-01)
Kao, CF
;
Lu, MH
;
光電工程學系
;
Department of Photonics
This paper presents a reflective optical encoder based on the Talbot self-image of binary phase grating. The proposed encoder has several advantages in comparison to conventional Moire effect based encoders, including larger gap between gratings, higher gap tolerance and greater light passage efficiency. This encoder with gap 220 mu m can accurately measure the position of linear stages which move at high-speed. The encoder includes a grating scale with period 20 mu m and provides a signal period of 20 mu m with a frequency response of approximately 200 kHz. This system and the associated electronics provide an interpolation factor of 200 that gives a resolution of 0.1 mu m. The repeatability is 0.2 mu m for a traveling length of 600 mm. (C) 2005 Elsevier B.V. All rights reserved.