By seamlessly capturing the third dimension, ToF cameras are becoming indispensable tools in various sectors - paving the way to a future where depth perception is an essential part of automation and machine intelligence. Whether it's streamlining logistics, supporting robotics, improving patient care, or paving the way for the autonomous vehicles of tomorrow, ToF technology is revolutionizing the machine vision industry by providing 3D information.

Theory explaining the concept of Plane-Polarised light, transverse waves, and their type. A Detailed overview on Polarizers as well as Linear, Circular and Elliptical Polarisation

Plane polarized lightuses

Regardless of which principle you use, you can use a light source that can illuminate the entire scene to determine the depth of all points in the scene with one shot. The result is a distance map in which each pixel encodes the distance to the corresponding point in the scene.

Polarisers are used to attain certain polarisations of light while discarding the rest. But in the case of waveplates, they modify polarisations without discarding them or even deviating or displacing the beam. It can be done by delaying one polarisation component against its orthogonal component. They are mostly used to convert polarisation states and linear polarisations into circularly polarised light.

Birefringent Polarizers: They depend on the refractive index of the polarisation of light. Different plane-polarised light can be refracted at different angles, which can be used to select a desired polarisation of light.

Plane polarized lightvs crosspolarized light

Our Experts take a closer look at the Time-of-Flight technology, especially compared to other 3D solutions. With exciting, up-to-date use case presentations from Basler's customers Captic and Magazino.

Light comes under the category of an electromagnetic wave, and the electric field of this wave oscillates in a perpendicular direction to the direction of its propagation. Light is termed unpolarised if this electric field’s focus fluctuates randomly. Some examples of unpolarised light include sunlight, halogen lighting, LEDs, and incandescent bulbs. However, when the direction of this electric field is defined, it is called plane-polarised light. The most common example of this kind is laser lights and devices.

Factory automation and robotic applications benefit greatly from ToF cameras. They help automate complex tasks such as object recognition, picking, assembly, and quality control, e.g. detecting damaged parts or errors during stacking. The 3D data from ToF cameras enables robots to interact more intelligently and autonomously with their environment.

In the fast-paced world of logistics, ToF technology provides precise support for packing, from filling boxes to stacking and scanning volume. Accurate depth information helps to efficiently place labels and monitor loading and unloading operations, ensuring optimal use of space and resources in warehouses and during transportation.

ToF technology in autonomous vehicle systems contributes significantly to navigation accuracy and safety by providing real-time 3D data that can be used by autonomous driving systems to detect obstacles, estimate distances and issue necessary warnings or corrective actions.

In Physics, Polarisation is termed as a phenomenon that is caused due to the wave nature of electromagnetic radiation. Sunlight has to pass through a vacuum to reach Earth, which is another example of electromagnetic waves. They are called electromagnetic waves because they are formed when electric fields interact with a magnetic field.

Plane polarized lightmicroscopy

ToF technology has also found an important role in the healthcare sector. Camera systems based on this technology enable non-invasive patient monitoring and accurate patient positioning during surgery, ensuring both patient safety and improved clinical outcomes.

Polarisers are used to achieve a particular polarization of light. They can be divided into reflective, dichroic, and birefringent polarisers. They act as an optical filter that allows light waves to pass through it while blocking undesirable light waves of other kinds. Another definition suggests it is an optical device used to convert an unpolarised light into a polarised plane light.

As the ToF camera records a normal 2D intensity image in parallel to the depth information, both pieces of information can be merged to create a textured 3D graphic.

Factors such as stray light due to unwanted reflections, multipath effects due to multiple light reflections, saturation by ambient light, and interference from other active vision systems must be taken into account. Nevertheless, the advantages of integrating ToF technology outweigh these limitations in most scenarios.

3D technologies such as stereovision, structured light, laser triangulation and time-of-flight influence many areas of Industry 4.0 and enable advantages in a variety of applications. Our webinars and white papers compare the processes and performance of the various technologies.

Plane polarized lightmeaning

Dichroic Polarisers: They help absorb a specific polarization of light and transmit the rest. Nanoparticle polarisers are an example of this.

Light is the result of the interaction of electrical and magnetic fields that travel through space. The electrical and magnetic vibrations of a light wave happen in perpendicular directions. They move in a perpendicular direction to one another.

Basler's 3D RGB camera solution: combining the spatial depth data from Basler's ToF Camera with RGB data from a color camera results in a colored point cloud in true colors, or RGB-D for short.

Plane polarized lightexamples

In this type of polarisation, the electric field of the light consists of two components. They are perpendicular to each other and have an equal amplitude but a phase difference of π/2. As a result, the electric field rotates in a circle around the direction of prorogation. It is known as circular polarisation. The electrical field of circularly polarized light travels along with a phase difference of π/2 or 90 degrees. Depending on the direction of rotation, they are further classified into left-hand circularly polarised and right-hand circularly polarized light.

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A ToF camera consists of an integrated light source, a lens optimized for ToF, a sensor that stores the captured image data, and an interface for communication with external devices. The camera emits either continuous or pulsed light waves and measures the time or phase shift of the reflected light to calculate the distance of objects in the scene and create a detailed depth map in which each pixel represents distance information.

This case can be seen when an electric field follows an elliptical propagation. It happens due to two linear components that have different amplitudes and phase difference that is not 90 degrees.

What isplane polarized lightin Physics

Plane polarized lightenantiomers

In this type of polarisation, the light’s electric field travels in propagation and is limited to a single plane. Electric field of linearly polarised light will be confined to a single plane. In this case, the electric field remains limited to a single plane, the x-y plane. It is linear polarization.

Let us perform an experiment where we take two planes. The magnetic field occupies one plane while the electrical field occupies the other, and both of them are placed perpendicular to one another. These vibrations can occur in numerous planes. A light wave that vibrates in more than one plane is unpolarised light. The other kind is the polarised light in which the vibrations will occur in a single plane. Plane-polarised light will consist of waves with the same direction of vibrations. The process involving transforming unpolarized light into a polarised light is known as polarisation.

Polarisation is used in various imaging applications where they are placed over a light source or lens to discard excess light, improve contrast, and eliminate hot spots from reflective objects. It is effectively used in sunglasses to reduce glare. The television screen that we watch at home, the LCDs use this concept for its modulating properties of liquid crystals because they do not emit light directly. They are even used to improve contrast and colour effects. When a polariser is used, it filters out some light and reflects it, such that it darkens the perceived colours of these images.

To understand plane polarisation light better, let us know the concept of transverse waves. They are produced when the movement of particles in the wave is perpendicular to the direction of the wave’s motion. Ripples in water and the motion of sound waves could be an example of transverse waves. Longitudinal waves are referred to as particles when they travel in the direction of the motion of the waves.

The polarisation of light has become an important aspect due to its application in optical fields. Optical design is a subject mainly focusing on the wavelength and the intensity of light while often neglecting polarisation. The latter, however, is an important aspect that affects even optical systems that do not measure it explicitly. The polarisation of light affects the laser beams’ focus, cut-off wavelengths of filters, and prevents unwanted reflections. It’s used in many meteorological applications, including stress analysis in glass and plastic, pharmaceutical analysis, and biology. There are different absorption levels for further polarisation of light, like LCD screens, 3D movies, and glass-reducing sunglasses.

Reflective Polarisers: They help transmit the desired light waves while reflecting the rest of it. Grid wires are a suitable example of this. The light that is to be polarised is reflected through the grid wires, while the light that is to be transmitted is polarised perpendicular to these wires.

As the technology continues to evolve and overcome these obstacles, time-of-flight technology remains a robust, fast and cost-effective approach to 3D imaging. As the industry realizes its potential, ToF will become a cornerstone of machine vision and open up the entire spectrum of 3D imaging applications.

Interested in 3D ToF technology? Learn the functional principles, differences compared to other 3D technologies, and how you can integrate ToF into your vision system.

From the figure, you can see how a light beam comes out in the same direction after passing through a polariser. Before the light beam passes through a polarizer, its path keeps varying but as soon as it passes through a polariser, it gets aligned in the same direction.

Plane-polarized lightchiral

Precise 3D images in real time thanks to Sony's DepthSense™ sensor and integrated depth image processing. Available in 850 nm or 940 nm wavelengths.

This feature is crucial because it bypasses the need for complex algorithms to determine depth, which is a challenge for conventional imaging systems such as stereo vision systems. ToF cameras are characterized by their compact design, ease of use, accuracy and high frame rates. This makes them attractive for cost-effective 3D imaging solutions. In addition, ToF technology delivers reliable results even in difficult lighting conditions, which extends its range of applications.

Our White Paper describes the most popular 3D technologies on the market and highlights their respective strengths and weaknesses. It also provides you with criteria for answering the question of whether the third dimension is a worthwhile enhancement for your application.