PSD Photodiodes
Reviewed by: Jon Lowy, consulting engineer
Description
PSD (Position Sensitive Device) photodiodes are specialized photodetectors that are designed to provide information about the position of a light spot on their surface. They are capable of detecting the centroid of the light intensity distribution, which allows them to determine the position of the light source with high precision.
Working Principle
PSD photodiodes operate based on the photoelectric effect, where incident photons generate electron-hole pairs in the semiconductor material. These charge carriers are separated and collected by an electric field, producing a current proportional to the light intensity. The unique feature of PSD photodiodes is their ability to provide continuous position data of the light spot across the detector surface. This is achieved by measuring the photocurrent distribution across the device, which allows for the calculation of the light spot's position. The high-speed response and dynamic range of PSD photodiodes make them particularly useful for applications requiring precise position measurements.
Applications
PSD photodiodes are used in a variety of applications where precise position measurement is critical. For example, they are employed in triangulation sensors for distance measurement, where the position of a laser spot on the PSD is used to calculate the distance to an object. They are also used in optical alignment systems, where they help ensure components are correctly positioned by detecting deviations in light spot positions.
Advantages over other Photodiodes
One of the main advantages of PSD photodiodes is their high-speed response, which allows for rapid position measurements. They also offer high resolution, limited only by the signal conditioning circuitry, and are virtually impossible to saturate with excessive light, making them suitable for applications with varying light conditions. Unlike CCD detectors, PSD photodiodes do not provide an image but rather the precise position of the light spot, which can be advantageous in applications focused solely on position data.
Limitations
PSD photodiodes have some limitations, including their inability to display an image or profile of the light pattern. They also report the center of all light falling on the detector area, which can lead to erroneous signals if multiple light spots are present. Additionally, their responsivity can change with temperature, and there may be non-uniformity in responsivity across the device's active area.
Considerations
When considering PSD photodiodes for an application, it is important to evaluate factors such as initial costs, operating expenses, and maintenance requirements. PSD photodiodes are generally durable and offer high accuracy, but their performance can be affected by environmental conditions such as temperature. Replacement and maintenance costs are typically low, but ensuring proper calibration and alignment is crucial for maintaining accuracy over time.
from OSI Optoelectronics
The Super Linear Position Sensors feature state of the art duo-lateral technology to provide a continuous analog output proportional to the displacement of the centroid of a light spot from the center, on the active area. As continuous position sensors, these detectors are unparalleled; offering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 10
from First Sensor AG
These components utilize the effect of the lateral division of the generated photocurrent. The term "position sensitive detector" (PSD) refers to a component that is based on silicon PIN diode technology and is used to measure the position of the integral focus of an incoming light signal. A light... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 700 to 1000
- Photodiode Spectral Response: IR
- Active Area Diameter or Length: 10
from Micropac Industries, Inc.
The 61010 is an N-P-N Planar Silicon Photodarlington Transistor in a small outline package designed to be housing mounted. Its large effective aperture and narrow angular response make this a highly sensitive device with minimum response to off-axis or stray light. This sensor is also available with... [See More]
- Photodiode Type: PN Photodiode; PIN Photodiode (optional feature)
- Spectral Response Range: 290 to 1200
- Photodiode Spectral Response: UV; Visible; IR
- Peak Sensitivity Wavelength: 800
from OSI Optoelectronics
The Super Linear Position Sensors feature state of the art duo-lateral technology to provide a continuous analog output proportional to the displacement of the centroid of a light spot from the center, on the active area. As continuous position sensors, these detectors are unparalleled; offering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 10
from First Sensor AG
Quadrant photodiodes are discrete components that usually feature four optically active areas separated by a small gap. These photodiodes are used in many applications for detecting the position of laser beams, collimators and other applications to facilitate adjustment. Features: Small gap areas. [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 1064
- Photodiode Spectral Response: IR
- Active Area Diameter or Length: 7.8
from OSI Optoelectronics
The Super Linear Position Sensors feature state of the art duo-lateral technology to provide a continuous analog output proportional to the displacement of the centroid of a light spot from the center, on the active area. As continuous position sensors, these detectors are unparalleled; offering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 2
from OSI Optoelectronics
The Super Linear Position Sensors feature state of the art duo-lateral technology to provide a continuous analog output proportional to the displacement of the centroid of a light spot from the center, on the active area. As continuous position sensors, these detectors are unparalleled; offering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 20
from OSI Optoelectronics
The Super Linear Position Sensors feature state of the art duo-lateral technology to provide a continuous analog output proportional to the displacement of the centroid of a light spot from the center, on the active area. As continuous position sensors, these detectors are unparalleled; offering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 10
from OSI Optoelectronics
The Super Linear Position Sensors feature state of the art duo-lateral technology to provide a continuous analog output proportional to the displacement of the centroid of a light spot from the center, on the active area. As continuous position sensors, these detectors are unparalleled; offering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 3
from OSI Optoelectronics
The Super Linear Position Sensors feature state of the art duo-lateral technology to provide a continuous analog output proportional to the displacement of the centroid of a light spot from the center, on the active area. As continuous position sensors, these detectors are unparalleled; offering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 3
from OSI Optoelectronics
The Super Linear Position Sensors feature state of the art duo-lateral technology to provide a continuous analog output proportional to the displacement of the centroid of a light spot from the center, on the active area. As continuous position sensors, these detectors are unparalleled; offering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 5
from OSI Optoelectronics
The Super Linear Position Sensors feature state of the art duo-lateral technology to provide a continuous analog output proportional to the displacement of the centroid of a light spot from the center, on the active area. As continuous position sensors, these detectors are unparalleled; offering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 76
from OSI Optoelectronics
The UDT-4X4D is a 4 by 4 array of super blue enhanced Photodetectors. Our proprietary design provides virtually complete isolation between all of the 16 elements. The standard LCC package allows easy integration into your surface mount applications. Numerous applications include Ratio and Scattering... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: UV; Visible; IR
- Peak Sensitivity Wavelength: 810
from OSI Optoelectronics
The SPOT Series are common substrate photodetectors segmented into either two (2) or four (4) separate active areas. They are available with either a 0.005" or 0.004" well defined gap between the adjacent elements resulting in high response uniformity between the elements. The SPOT series are ideal... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 4.6
from OSI Optoelectronics
Tetra-lateral position sensing detectors are manufactured with one single resistive layer for both one and two dimensional measurements. They feature a common anode and two cathodes for one dimensional position sensing or four cathodes for two dimensional position sensing. These detectors are best... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 2.54
from OSI Optoelectronics
Tetra-lateral position sensing detectors are manufactured with one single resistive layer for both one and two dimensional measurements. They feature a common anode and two cathodes for one dimensional position sensing or four cathodes for two dimensional position sensing. These detectors are best... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 30
from OSI Optoelectronics
Tetra-lateral position sensing detectors are manufactured with one single resistive layer for both one and two dimensional measurements. They feature a common anode and two cathodes for one dimensional position sensing or four cathodes for two dimensional position sensing. These detectors are best... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 5.3
from OSI Optoelectronics
Tetra-lateral position sensing detectors are manufactured with one single resistive layer for both one and two dimensional measurements. They feature a common anode and two cathodes for one dimensional position sensing or four cathodes for two dimensional position sensing. These detectors are best... [See More]
- Photodiode Type: PIN Photodiode
- Spectral Response Range: 350 to 1100
- Photodiode Spectral Response: Visible; IR
- Active Area Diameter or Length: 10.16