Unveiling the mystery of Orb: How does Worldcoin collect your iris?

Original Title: "OPENING THE ORB: A look inside Worldcoin's biometric imaging device"

Original Source: Worldcoin

Original Translation: Kxp, BlockBeats

Worldcoin will always adhere to a series of principles and values based on privacy, trust, and transparency.

This is why we have always been committed to open sourcing the technologies we create and use as much as possible. We also hope to enable others to develop, build, and operate similar devices integrated with the World ID protocol, with the ultimate goal of achieving complete decentralization of all parts of the project.

In this article, we will share specific and substantial details about the hardware we are building. After three years of research and development, we are excited to showcase Orb, explain how it works, and release the corresponding hardware engineering files. This will be an important step in fulfilling our commitment to transparency and increasing its credibility in the global community.

In the coming months, we will release more articles explaining other parts of Orb and the registration process.

Why do we need customized hardware and why does it need to scan the iris?

When Worldcoin was founded, we did not intend to develop a physical device, let alone build one for biometric imaging. Custom hardware is difficult and expensive, and no one wants to invest in it unless it is necessary. Instead, our goal was to freely distribute a new digital token to everyone in the world to help them enter and participate in the global economy. Only when we realized that biometrics were the only realistic way to achieve our goal did we begin to create Orb.

To learn more about the inclusivity of biometrics and why Worldcoin uses them, please click here.

When exploring various methods to solve sybil resistance and verify unique identities, our research has shown that iris scanning provides the most accurate biometric and has an acceptable user experience, achieving success in large-scale testing. This is because the iris has strong anti-fraud capabilities and rich data, meaning it can accurately distinguish billions of unique human individuals. The higher the richness of data in biometric markers such as iris, the more fair and inclusive the system becomes.

It is important to note that the false rejection rate is not a constant value, but increases with the expansion of data scale. Eventually, most systems will encounter bottlenecks that do not allow any new users to join. This means that existing technologies with low data richness, such as FaceID, can only accommodate a few million people.

Due to the fact that commercially available iris imaging devices cannot meet our technical or security requirements, we have spent years developing our own devices in order to accommodate as many people as possible. For more details, please refer to here.

Orb Hardware Storage Repository

As the first step in open-sourcing Orb, we have released all hardware-related engineering files in the repository, including the current version files. You can download Eagle (PCB) to view the files and use Autodesk's CAD viewer for free. We welcome and encourage feedback and suggestions on the design.

By developing Orb, we are driving the most advanced iris biometric recognition technology. That's why all files are released under the MIT license, but we also prohibit the use of license materials for monitoring and any other application that may be harmful to individual rights.

Next, we will break down Orb and share some interesting stories that happened during the engineering design process.

Orb Disassembly

After three years of research and development, including one year of small-scale field testing and one year of large-scale production testing, we have obtained the current version of Orb.

Today's Orb has achieved a precise balance between development progress, compactness, user experience, cost, and large-scale production, with almost no compromise on image quality and security. In the future, we may release further optimized versions. However, the current version represents an important milestone that allows us to begin large-scale production.

Now, we will take you through some key engineering details of Orb and the working principle of the imaging system. For security reasons, we will omit the anti-tampering mechanism used to capture system intrusions.

Remove the shell

After removing the shell, we can see the mainboard, optical system, and cooling system of the product. Most of the optical systems are hidden in an enclosure structure, which works together with the shell to prevent dust and water, enabling long-term use in various harsh environments.

You are looking at a product that has undergone multiple prototype adjustments and design iterations.

Figure 1 Orb under the shell

The Orb consists of two hemispheres, separated by the motherboard which is tilted at an angle of 23.5°, the same as the tilt of the Earth's rotational axis. The motherboard is equipped with powerful computing units for local processing, ensuring maximum privacy protection. The front half of the Orb is dedicated to a sealed optical system. The optical system consists of several multispectral sensors for biometric verification, and a narrow field of view camera with a two-dimensional gimbal capable of capturing high-resolution iris images. The other hemisphere is dedicated to the cooling system and speaker. Replaceable batteries can be inserted from the bottom for uninterrupted operation in mobile environments.

机械结构

translates to

Mechanical Structure

in English.

After removing the shell, Orb can be divided into four core parts:

· Front section: Optical system 

· Central Region: The motherboard divides the device into two hemispheres (note: the tilt angle is exactly 23.5°, equivalent to the tilt angle of the Earth) 

· Rear: Main computing unit and active cooling system.

· Bottom: Replaceable battery

Figure 2 Explosion CAD of all related components

After removing the shell material (such as the dust cover of the optical system), all related components of Orb will be exposed. This includes a custom lens optimized for near-infrared imaging and fast, durable autofocus. The front of the optical system is sealed with an optical filter to prevent dust from entering and reduce noise in the visible spectrum, optimizing image quality. At the back, a plastic component in the chrome-plated shell can optimize the position of the antenna. The chrome-plated shell is covered with a transparent shell to prevent damage to the coating over time.

We conducted on-site testing of the first batch of prototypes outside the laboratory as early as possible. Of course, this brought us many lessons, including:

Optical System

The registration experience of the first prototype was extremely difficult. After a year of upgrades and improvements, we added automatic focusing and eye tracking functions to the optical system. It became easier to aim when the distance between the person and Orb was within arm's length.

Battery 

All the batteries we tried could not maintain a full day's use after a single charge. Therefore, we built a custom replaceable battery based on the 18650 lithium-ion battery, which has the same shape as the battery used in the Tesla Model S. The battery consists of 8 individual cells with a nominal voltage of 3.7V, arranged in a 4S2P configuration (14.8V), with a capacity of nearly 100Wh, which is the limit set by transportation regulations. This way, the Orb has no limit on its working time.

Figure 3 Customizable and replaceable battery

Orb's custom battery uses Li-Ion 18650 batteries (the same type used in many electric cars), with a capacity of nearly 100Wh. This optimization aims to improve battery life and comply with transportation regulations. It uses a USB-C connector for easy charging.

Outer shell 

The coating on the shell may degrade during handheld use. Therefore, we have added a 2mm transparent shell layer, which not only optimizes the appearance but also protects the chrome plating from scratches and other wear and tear.

UX LED

In order to make the user experience more intuitive, especially in noisy environments where people may not be able to hear audio feedback, we have added an LED ring to help guide people through the registration process. Similarly, we have designed a status LED next to the only button on the Orb to display its current status.

Working principle of optical system 

Our early tests told us that the verification experience needs to be even simpler than we expected.

In order to achieve this, we first tried many methods, such as using mirrors to allow people to align Orb's imaging system based on their mirror reflection. However, these designs that performed well in the laboratory quickly failed in the real world.

Finally, we built a dual-camera system consisting of a wide-angle camera and a telephoto camera, which can adjust the field of view by about 5 degrees through a two-dimensional gimbal. This has increased the registered spatial volume by several orders of magnitude, from the small space of 20x10x5 millimeters per eye to a large cone.

Figure 4 Telephoto lens and 2D gimbal

Orb's main imaging system consists of a telephoto lens and 2D gimbal system, a global shutter camera sensor, and an optical filter. Moving the lens increases the camera system's field of view by more than two orders of magnitude. The optical unit is sealed with a black visible light spectrum filter, isolating high-precision optical components from dust and transmitting only near-infrared light. The image capture process is controlled by multiple neural networks.

Wide-angle cameras capture the scene and predict the position of the eyes through neural networks. Through geometric inference, we direct the field of view of the telephoto camera to the position of the eyes to capture high-resolution images of the iris, which are then further processed by Orb into unique identifiers.

Click here to learn about our measures to protect privacy.

Aside from simplicity, image quality is the main focus. We tested many off-the-shelf products, but did not find one that was compact enough and met our imaging requirements at an affordable price. Therefore, we collaborated with renowned experts in the machine vision industry to create a custom lens.

This lens has been optimized for near-infrared spectroscopy and is equipped with an integrated custom liquid lens that can be automatically focused in milliseconds by a neural network. It pairs with a global shutter sensor to capture high-resolution, distortion-free images.

Figure 5, a)

This telephoto lens is custom-designed for Orb. Its lens is coated to optimize the image capture effect of near-infrared spectrum. The integrated liquid lens enables persistent millisecond-level autofocus. The position of the liquid lens is controlled by a neural network to optimize focus. To capture images without motion blur, the global shutter sensor is synchronized with pulsed light.

b) Comparing the image quality of Worldcoin Orb with industry standards, we have made significant progress in this field.

The camera and corresponding pulsed infrared light are synchronized to minimize motion blur and suppress the influence of sunlight. This way, no matter where Orb is located, it can create laboratory environment conditions for imaging. At the same time, the infrared illumination complies with safety standards (such as EN 62471:2008).

No matter how difficult it is, we have never compromised on image quality. In terms of resolution, Orb's level far exceeds industry standards. This provides a foundation for achieving the lowest error rate and maximizing the system's tolerance.

Electronic Components 

Breaking down Orb further, you will find several printed circuit boards (PCBs), including the front-end PCB which contains all the lighting components, the security PCB for intrusion detection, and the bridging PCB that connects the front-end PCB to the largest main board.

Figure 6 The front of the motherboard 

The front of the motherboard is equipped with capacitors to provide power for pulse near-infrared illumination (certified safe for eyes). There is also a driver for controlling the deformation of the liquid lens in the optical system. The microcontroller controls the precise timing of peripheral devices. The encrypted M.2 SSD can be used to store images for voluntary data retention and image data collection. These images are protected by second-layer irreversible encryption using the server's public key to prevent data exposure in the unlikely event of Orb intrusion. Data contribution is optional and data deletion can be requested at any time through the application. The SIM card slot enables optional LTE connectivity.

Figure 7 Back of the motherboard

There are several connectors on the back of the motherboard for the active components of the optical system. In addition, the GPS module can accurately locate the Orb to prevent fraudulent behavior. The Wi-Fi module enables the Orb to upload iris codes to ensure that each person can only register once. Finally, the motherboard is equipped with an Nvidia Jetson Xavier NX, which can run multiple neural networks in real time, optimize image capture, perform local anti-counterfeiting detection, and compute iris codes locally to maximize privacy protection.

As a custom carrier board for the Nvidia Jetson Xavier NX SoM power orb, the motherboard is equipped with a 250GB M.2 SSD in addition to the Jetson. The SSD can be used to buffer images for voluntary data retention and image data collection. The images are irreversibly encrypted using the server's public key to prevent data leakage in the rare event of Orb intrusion. Data contribution is optional and data can be requested for deletion at any time through the application.

In addition, the STM32 microcontroller controls time-critical peripherals, power sequencing, and Jetson boot. Orb is equipped with Wi-Fi 6 and optional LTE for seamless connectivity, and comes with a GPS module to locate Orb and prevent abuse. Finally, the 12-bit liquid lens driver can precisely control the focus of the telephoto lens with an accuracy of 0.4 millimeters.

Orb's densest circuit board is the front-end circuit board, mainly composed of LEDs. The outermost RGB LED powers the "UX LED ring". Deeper inside, there are 79 near-infrared LEDs with different wavelengths. Orb uses LEDs of 740nm, 850nm, and 940nm to capture the multispectral image of the iris, making the uniqueness algorithm more accurate and detecting fraudulent behavior.

Figure 8 The front-end circuit board has near-infrared illumination.

The front-end circuit board provides multispectral illumination and anti-fraud sensors. High-brightness illumination (certified eye safety) is necessary for high-quality image capture (such as in a photo studio). The anti-fraud algorithm based on multispectral sensors runs locally on Orb to maximize privacy protection. No data will be uploaded unless someone explicitly requests to upload the image data. The circular visible spectrum LED on the edge of the circuit board provides precise user feedback.

Several multispectral imaging sensors are also installed on the PCB board in front. The most basic one is the wide-angle camera, which is used to control the long-focus iris camera. As we have given everyone registered through Orb a share of Worldcoin, the probability of fraud has increased. Therefore, we have also added other imaging sensors to prevent fraud.

When designing anti-fraud systems, we start with first principles: what measurable characteristics do humans have? We then tried many different sensors and eventually narrowed it down to a sensor combination that includes a near-infrared wide-angle camera, a 3D time-of-flight camera, and a thermal camera. The system is designed for maximum privacy protection, so the anti-fraud algorithm based on these sensor inputs will run locally. Unless someone explicitly requests backup data for future upgrades and agrees to help us improve the system, no images will leave the device.

Outlook

In this article, we reveal and explain many key components of Orb and link to the corresponding engineering files. This is an important step in demonstrating Worldcoin's commitment to privacy, trust, and transparency to the public. As stated at the beginning, we are committed to open sourcing our technology as much as possible and ultimately achieving full decentralization of the project.

The manufacturing of the latest generation of Orb has begun in Germany and will be distributed to new Worldcoin operators around the world. In fact, they have already helped Worldcoin gain over one million registered users - an important milestone towards global economic inclusivity.

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