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Self-Balancing Position-Sensitive Detector (SBPSD).

Porrazzo R, Lydecker L, Gattu S, Bakhru H, Tokranova N, Castracane J - Sensors (Basel) (2015)

Bottom Line: Fabricated prototype devices demonstrate linear, symmetric coordinate characteristics and a spatial resolution of 200 μm for a 74 mm device.PSDs are commercially available only up to a length of 37 mm.Prototype devices were fabricated with various lengths up to 100 mm and can be scaled down to any size below that.

View Article: PubMed Central - PubMed

Affiliation: Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12222, USA. rporrazzo@albany.edu.

ABSTRACT
Optical position-sensitive detectors (PSDs) are a non-contact method of tracking the location of a light spot. Silicon-based versions of such sensors are fabricated with standard CMOS technology, are inexpensive and provide a real-time, analog signal output corresponding to the position of the light spot. An innovative type of optical position sensor was developed using two back-to-back connected photodiodes. These so called self-balancing position-sensitive detectors (SBPSDs) eliminate the need for external readout circuitry entirely. Fabricated prototype devices demonstrate linear, symmetric coordinate characteristics and a spatial resolution of 200 μm for a 74 mm device. PSDs are commercially available only up to a length of 37 mm. Prototype devices were fabricated with various lengths up to 100 mm and can be scaled down to any size below that.

No MeSH data available.


Related in: MedlinePlus

Coordinate plot over a 4-mm distance with 200 μm.
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sensors-15-17483-f011: Coordinate plot over a 4-mm distance with 200 μm.

Mentions: The theoretical spatial resolution of a PSD is the minimum detectable light spot displacement. For a 1-D PSD, as the active area increases, the position resolution decreases. For an active area of 6 mm, 12 mm and 37 mm, the corresponding position resolution is 0.2 µm, 0.3 µm and 2.8 µm respectively [20]. The theoretically smallest detectable position displacement can be expressed as(2)∆x=L×InITotwhere L is the length of the detector, ITot is the total photocurrent from all contacts, and In is the noise current [13]. The theoretical spatial resolution for a 74 mm device was determined to be approximately 200 µm using Equation (2) in conditions where the photogenerated current exceeds the dark current by approximately 300 times. Theoretical spatial resolution was then verified by moving the microscope head on the probe station in 200-µm steps and the output voltages were recorded (Figure 11). A plot of voltage vs. position shows a highly linear coordinate plot (R2 = 0.99529) over a 4-mm distance.


Self-Balancing Position-Sensitive Detector (SBPSD).

Porrazzo R, Lydecker L, Gattu S, Bakhru H, Tokranova N, Castracane J - Sensors (Basel) (2015)

Coordinate plot over a 4-mm distance with 200 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541945&req=5

sensors-15-17483-f011: Coordinate plot over a 4-mm distance with 200 μm.
Mentions: The theoretical spatial resolution of a PSD is the minimum detectable light spot displacement. For a 1-D PSD, as the active area increases, the position resolution decreases. For an active area of 6 mm, 12 mm and 37 mm, the corresponding position resolution is 0.2 µm, 0.3 µm and 2.8 µm respectively [20]. The theoretically smallest detectable position displacement can be expressed as(2)∆x=L×InITotwhere L is the length of the detector, ITot is the total photocurrent from all contacts, and In is the noise current [13]. The theoretical spatial resolution for a 74 mm device was determined to be approximately 200 µm using Equation (2) in conditions where the photogenerated current exceeds the dark current by approximately 300 times. Theoretical spatial resolution was then verified by moving the microscope head on the probe station in 200-µm steps and the output voltages were recorded (Figure 11). A plot of voltage vs. position shows a highly linear coordinate plot (R2 = 0.99529) over a 4-mm distance.

Bottom Line: Fabricated prototype devices demonstrate linear, symmetric coordinate characteristics and a spatial resolution of 200 μm for a 74 mm device.PSDs are commercially available only up to a length of 37 mm.Prototype devices were fabricated with various lengths up to 100 mm and can be scaled down to any size below that.

View Article: PubMed Central - PubMed

Affiliation: Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12222, USA. rporrazzo@albany.edu.

ABSTRACT
Optical position-sensitive detectors (PSDs) are a non-contact method of tracking the location of a light spot. Silicon-based versions of such sensors are fabricated with standard CMOS technology, are inexpensive and provide a real-time, analog signal output corresponding to the position of the light spot. An innovative type of optical position sensor was developed using two back-to-back connected photodiodes. These so called self-balancing position-sensitive detectors (SBPSDs) eliminate the need for external readout circuitry entirely. Fabricated prototype devices demonstrate linear, symmetric coordinate characteristics and a spatial resolution of 200 μm for a 74 mm device. PSDs are commercially available only up to a length of 37 mm. Prototype devices were fabricated with various lengths up to 100 mm and can be scaled down to any size below that.

No MeSH data available.


Related in: MedlinePlus