
ToF (Time of Flight) Technology
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Overview
In addition to imaging in X and Y directions, ToF image sensors also acquire the Z-direction information, enabling 3D sensing. 3D sensing opens up the possibility of discerning things that are difficult with conventional 2D images, as in inspection based on volume or shape, or discerning overlapped objects. It is also a promising technology for applications utilizing relative distance information in real time, such as automated control or collision avoidance systems.
In the industrial equipment area, movements towards automation and reduction of manpower are rapidly spreading in various applications. These include the “smartification” of manufacturing lines, logistics systems, agriculture, and farming. ToF image sensors, which are small in size and can instantly acquire 3D information, are anticipated for use in a wide range of areas and applications as sensors well-suited to respond to rising demands for recognition, measurement, and automation.
Technical Features
dToF capable of measurement at long distances and iToF offering high speed and high image resolution
ToF depth sensors measure the distance to a target object by emitting light from a source, usually a laser or LED, and detecting the reflected light, based on the time elapsed between the two. They can be classified into two types: direct ToF (dToF), which involves a direct measurement of the time until reflection is detected, allowing it to also be used for measurement of targets at long distances; and indirect ToF (iToF), which measures distance by accumulating the electric charge generated by the reflected light and discerning any phase shift between emitted and reflected light.
Direct ToF (dToF)
This measures the time between the emission of light and detection of the reflected light. The sensor uses single photon avalanche diode (SPAD) pixels with a structure enabling “avalanche multiplication,” to amplify electrons from a single incident photon, causing a cascade like an avalanche. This ensures the sensors can detect even a faint light while also being capable of measuring longer distances. Sony’s products such as the IMX560 utilize dToF depth sensors to acquire range information in a wide area including long distances with high accuracy and low noise.

Indirect ToF (iToF)
This measures distances by accumulating the electric charge generated by the reflected light in each pixel and detecting any phase differences. This type of sensor can utilize the conventional CMOS image sensor structure and deliver high-resolution 3D images of the target object. Sony’s products such as the IMX556/IMX570 utilize iToF, which makes them excel especially at near- to mid-range sensing, and they are capable of high-speed acquisition of high-resolution 3D information.

Applications
Various types of automation in logistics
ToF image sensors can contribute to automation in various applications uniquely suited to them, from improving efficiency of material handling by measuring pallet and cargo positions, sizes, and content ratios; to detecting collisions and recognizing external conditions of moving bodies such as AGVs (Automated Guided Vehicles)/AMRs (Autonomous Mobile Robots) and “last one mile” robots.
iToF image sensors are suitable for near- to mid-range applications that require high resolution. SPAD ToF depth sensors are suitable for long-range applications indoors and outdoors.
Related sectors

Factory automation
ToF image sensors can be used in various applications such as management of shortages according to content level; automation of tasks such as target position detection for robotic picking; improvements to process efficiency by monitoring the operations of site workers; and safety assurance by detecting intrusion into hazardous areas.
Related sectors

Recognition of humans at industrial and public facilities
Even in settings where judgment by two-dimensional sensors is difficult, such as where the images of people overlap each other at high density, ToF image sensors easily recognize humans. Therefore, they can be used in applications such as identifying crowding conditions in locations such as shops, airports, and theme parks, carrying out advanced-level recognition of the open/closed status of automatic doors, and managing room entries and exits. By estimating the poses of human bodies in a three-dimensional manner, they can also support customer behavior data analysis in shops.
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Support for harvesting in farming and agriculture
They can be used in quality management and productivity improvements by supporting automatic milking machines for dairy cows as well as monitoring body shape, walking patterns, and the remaining amount of feed. In the field of agriculture, they can contribute to automatic thinning and harvesting of fruits through three-dimensional picking, and automatic operation of agricultural equipment through three-dimensional monitoring of the surroundings.
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Support for civil engineering work
ToF image sensors can be applied to the ICT conversion of heavy machinery, which can include operator support, automation, and safety assurance by monitoring the surrounding conditions. They are also anticipated to be applied to visualization and record-keeping of construction conditions, through three-dimensional measurement of soil volume in civil engineering work, construction conditions in building construction work, and infrastructure installation status.
SPAD ToF depth sensors are expected to be useful in construction sites that are dangerous to enter, hazardous areas in general, and indoor areas that do not allow positioning by GPS or other satellite navigation systems. They can easily create 3D maps of nearby areas by measuring the surroundings.
In addition, 3D data with RGB information can be acquired by combining a SPAD ToF depth sensor and an RGB sensor. These 3D models that come with RGB information are useful for verifying the progress of construction and for private viewing of completed buildings.
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Railroad monitoring
SPAD ToF depth sensors also have great potential in the field of smart infrastructure. For example, they are expected to play a crucial role in railway monitoring.
Station platforms and railway tracks are prone to the influence of outdoor light and a lot of noise. In such an environment, long-range monitoring is required. SPAD ToF depth sensors, which detect even faint light with high accuracy, are resistant to the influence of outside light such as outdoor sunlight. They are also capable of long-range measurement, which make them useful for checking and monitoring for any person or object on the track, or an umbrella or a bag getting in the way when railcar doors open and close.
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Monitoring with consideration for privacy
ToF image sensors acquire information on people and objects as 3D data. If applied to the nursing care facilities, for example, this feature will make it possible to capture the existence or poise of the care recipients accurately without using RGB images to prevent them from falling or to detect the accidents early. They are expected to be applied to privacy-conscious safety monitoring.
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Download
A List of Cameras with ToF Image Sensors
Download a list of cameras that incorporate Sony's ToF image sensors.
IMX560-AAMV Product Overview
This document summarizes the product overview, features, and specifications.
IMX556PLR Product Overview
This document summarizes the product overview, features, and specifications.
IMX570PLR Product Overview
This document summarizes the product overview, features, and specifications.
Related Products & Solutions
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Image Sensor
Time of Flight Image Sensor (Overview)
See here for the ToF image sensor overview page
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Image Sensor
SPAD ToF Depth Sensor IMX560
Compact, high-accuracy SPAD ToF depth sensor capable of measurement over long distances
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Image Sensor
iToF Image Sensor IMX556/IMX570
High-speed, high-resolution iToF image sensor that excels at near- to mid-range sensing
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