A new method for measuring plural light-spot positions in a spatially continuous manner using a sensor array

Abstract

Optical measurement systems often need to detect the positions of plural light spots illuminated by various types of light sources. The applications using these systems usually require the measurement performance to be fast, of high accuracy and capable of simultaneously detecting plural points. In this paper, we propose a new method for the measurement of plural light-spot positions that satisfies all three of the requirements listed above. The basic principle of the method is to detect which of the sensor elements produces the peak value and to calculate the actual peak positions of the light spot by employing an analogue interpolating circuit. We have designed and built a prototype position-sensor system that implements the proposed method. The experimental results are as follows: (i) the relative error is at most 1.6%; (ii) the sampling time is 9.5 µs times the number of detected spots; and (iii) the proposed method is insensitive to background light. In addition, with this method one can measure other properties with physical spot-like positions such as pressure and ultrasound.

Method to Measure Light Spot Position in Beacon-Less Inter-Satellite Communication System

“…For multiple light spots position detection, Qian et al [8] proposed to use pulses to modulate the projected light beams at different frequencies and demodulating the combined output signals of the position sensitive detector. Baba et al [9] used a sensor array to detect the position of multiple spots. Jing et al [10] proposed a method for detecting beam deviation angle by using four light spots in the multi-aperture system on a single QD.…”

Application of orthoferrites for light spot position measurements

“…In many cases the existing photoreceivers do not comply with the demands placed by possible application needs. The resolution of charge coupled devices ͑CCDs͒ is limited to the pixel size, which is at best about 5 m. 1 Moreover, the sampling rate of CCD cameras is typically as large as 1 ms, the shortest rates being about 0.1 ms. Continuous tracking of the light spot's position can be done by means of position sensitive detectors ͑PSDs͒ based on the lateral photoeffect.…”

Sensors and actuators on orthoferrites

“…But existing photoreceivers do not provide spatial resolution and speed of measurements necessary for many applications. The resolution of the charge-coupled devices (CCDs) is limited to the pixel size, which is at best about 5 µm [7]. Moreover, the sampling rate of CCD cameras is typically as large as 1 ms, the shortest rates being about 0.1 ms. An alternative solution can be provided by combining of a single element photoreceiver and a moving knifelike diaphragm.…”