The 2,000-year-old tech (and lots of new tech) behind your smartphone cameras


No invention exists in a vacuum. Every part of the technology we use is based on previous ideas and discoveries. Bluetooth, the humble connectivity standard for your wireless headphones and keyboards, is backed by over 30,000 patents. Smartphones, on the other hand, integrate over 100,000 patents, and the best smartphones all have unique patents that help them stand out from the competition. And each of these patents is based on the prior art that preceded it. Some of these technologies are years old, some decades old, and some over 2,000 years old.


Camera lenses and optical technology

One of the most important aspects of shooting is transmitting light from outside your camera to your film or photo sensor. But light is not a monolith. Light is not just a spectrum of colors. It is also a spectrum of wavelengths, and getting these various wavelengths to diffract and come together coherently has been the work of centuries of scientists.

The first lens

The lens, which deflects the light passing through it, dates back to the 5th century BC. The first lenses were used to light fires by concentrating solar energy at a single point. However, writers of the early Roman Empire were aware of the magnification capability of the lens.

Glasses were invented at the end of the 13th century, which gave rise to the optical industry. Around 1600, someone (we don’t know who) had the idea of ​​using more than one objective, which gave rise to the telescope and the microscope.

The dark room

Along with the development of the lens was the camera obscura, a closed box or room that only lets light in through a small hole (opening). This light is then projected onto the surface opposite the hole. It was first described over 2,000 years ago and was mentioned by Aristotle as being useful for studying eclipses without having to look directly at the sun.

By the 16th century lenses had been incorporated into the apertures to help focus the light. For the next 200 years it remained a tool of artists and scientists. In the 19th century, the secrets of chemical photography were unveiled by Niépce and Daguerre, which was essentially a means of capturing the image focused by the lens of a camera obscura.

Camera lenses

Early cameras used a single lens to focus light. To overcome the optical aberrations that are inevitable when using one lens, lens manufacturers have found ways to overcome some of these limitations by using two lenses made of different types of glass. Over the century, advancements in lenses were marked by advances in understanding the shape and configuration of lens elements.

Modern lenses began to emerge in the late 19th century with the development of anastigmatic lens. These lenses corrected astigmatism, an aberration that blurs areas outside the center of the shot. It was the first lens to correct most of the optical aberrations that plagued photographers until then.

In the 20th century, two developments took place that laid the foundation for mobile photography in the 21st century. The first was aspherical lensesknown for hundreds of years but became viable for commercial use in the 1900s. The profile of most portable camera lenses is spherical, but the more complex geometry of aspherical lenses has allowed them to replace lenses more complex multi-elements.

The next major development was the rise of plastics. In the 1930s, the first optical grade plastic lenses were developed. Kodak led the way with plastic lenses in its cameras in the 1960s, selling millions of plastic-lens Instamatic cameras. The low cost and quick manufacturing of plastic lenses (compared to optically superior glass lenses) led to a boom in low-cost photography in the 1970s, with some cameras costing less than $10.

These two developments, plastic lenses and aspherical lenses, directly solve some of the biggest problems that early mobile phone camera makers would have faced: size and cost. Plastic lenses could be made cheaper and faster, and aspherical lenses could overcome some of the optical deficiencies of plastic and mean fewer lenses would have to be used.

Image sensors and semiconductor technology

Long before the digital camera was a notion, scientists and inventors knew about the tendency of certain chemicals to react to light. As soon as it was discovered how to stop the photochemical reaction in the 19th century, the first photographs became possible. At the beginning of the 20th century, the quantum nature of light and the photoelectric effect were firmly established, opening the theoretical door to electronic images. Even so, it would take decades and a technological revolution for the cameras on our phones to become a possibility.

Integrated circuits

The genesis of today’s image sensors lies in finding a way to combine multiple electronic components into a single device. By the 1950s, vacuum tubes were being replaced by transistors, but the complexity of computers exceeded the human capacity to maintain them. The problem was the number of components that had to be maintained and connected to each other. If something stopped working, it could take days or weeks to find the bug.

Source: Wikimedia Commons/Kimmo Palosaari

By the end of the decade, all the technologies were in place to consolidate complex circuitry onto a single device and also to miniaturize it. The first integrated circuit was invented in 1960, and the unmet need was so great that the industry exploded. As early as 1965, Gordon Moore noticed that the density of transistors in integrated circuits doubled every two years – Moore’s law.

Charge Coupled Device

In 1969, less than 10 years after the invention of the integrated circuit, the charge-coupled device (CCD) was invented at Bell Labs. Initially, researchers were trying to create a memory chip (DRAM would not come to market until 1970), but its potential for capturing images was noted early on.

The CCD is essentially an array of metal-oxide-semiconductor (MOS) capacitors arranged in an array. MOS capacitors act as photodetectors, converting light into stored electrical energy. In 1971, two years after the invention of the CCD, researchers were able to make the theory practical by taking images with a CCD camera. Kodak made its first digital camera in 1975, and by the 1980s CCDs were available in consumer video cameras.

Complementary metal oxide semiconductors

Going back to 1963, a process for manufacturing MOS integrated circuits called complementary MOS (CMOS) was invented, the characteristic of which was its low power consumption. In the 1980s and 1990s, CMOS was the industry standard for computer chips, but CCD was still the standard for digital imaging.

The problem with CCD image sensors was their power consumption and speed. There had already been attempts to use CMOS-based image sensors, but they suffered from noise problems, producing unusable images. from NASA Jet Propulsion Laboratory decided to solve these problems manufacture lighter and more reliable image sensors for their spacecraft. In 1993, they found the solution and quickly licensed the technology for public use. The combination of low power consumption, small size and integrated design lent itself perfectly to the needs of mobile phone camera manufacturers.

imagine the future

This is just the basis of mobile photography that emerged with the new millennium. Since then, the field has grown by leaps and bounds. Early cellphone cameras consisted of four-element lenses and image sensors with less than a million photosites. Today’s cameras have seven or more lenses and image sensors made up of more than ten million photosites. And we’re not even talking about phones with more than one camera and infrared range finders. Given how far we’ve come over the past 20 years, who knows where we’ll be in 10 years?


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