Signal processing algorithm of a position sensitive detector using amplitude modulation/demodulation

La, Jongpil; Park, Kyihwan

doi:10.1063/1.1835651

Cited by 7 publications

(2 citation statements)

References 4 publications

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“…8 Although it is easy to amplify the signals in the low frequency region or dc value after the demodulation step, the signal is much contaminated by the low frequency noises such as flicker noise and dc drift. 9 Hence, it is advantageous to demodulate using intermediate frequencies in which high gain amplification as well as less contaminated signal are obtained. This method is called a multiple phase demodulation method in this work.…”

Section: Introductionmentioning

confidence: 99%

A multiple phase demodulation method for high resolution of the laser scanner

Yoon

Yeom

Kang

et al. 2009

Review of Scientific Instruments

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To have higher resolution of distance in the laser scanner using the phase demodulation method, signal should be modulated with a high frequency. In the signal processing of modulation and demodulation, it is inevitable to amplify the signals. However, it is not easy to amplify the high frequency since the amplifying gain is restricted by the frequency bandwidth. It is advantageous to demodulate using an intermediate frequency in which high gain amplification as well as less contaminated signal is obtained. Analytical and experimental results are presented to show how the intermediate frequency demodulation method works and how good performance is obtained in the time and frequency domains.

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Section: Introductionmentioning

confidence: 99%

A multiple phase demodulation method for high resolution of the laser scanner

Yoon

Yeom

Kang

et al. 2009

Review of Scientific Instruments

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“…Modulation and demodulation are often used for signal extraction [11][12][13]. The signal which has the same frequency as that of the reference signal can be extracted.…”

Section: Introductionmentioning

confidence: 99%

Applying dual-laser spot positions measurement technology on a two-dimensional tracking measurement system

Lee¹,

Chen²

2009

Meas. Sci. Technol.

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This paper presents a two-dimensional tracking measurement system with a tracking module, which consists of two stepping motors, two laser diodes and a four separated active areas segmented position sensitive detector (PSD). The PSD was placed on a two-dimensional moving stage and used as a tracking target. The two laser diodes in the tracking module were directly rotated to keep the laser spots on the origin of the PSD. The two-dimensional position of the target PSD on the moving stage is determined from the distance between the two motors and the tracking angles of the two laser diodes, which are rotated by the two stepping motors, respectively. In order to separate the four positional values of the two laser spots on one PSD, the laser diodes were modulated by two distinct frequencies. Multiple-laser spot position measurement technology was used to separate the four positional values of the two laser spots on the PSD. The experimental results show that the steady-state voltage shift rate is about 0.2% and dynamic cross-talk rate is smaller than 2% when the two laser spots are projected on one PSD at the same time. The measurement errors of the x and y axial positions of the two-dimensional tracking system were less than 1% in the measuring range of 20 mm. The results demonstrate that multiple-laser spot position measurement technology can be employed in a two-dimensional tracking measurement system.

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