Taking a camera with you on vacation? If you don’t pay attention to this during security checks, all your photos may be ruined!

As the Mid-Autumn Festival and National Day holidays approach, the passenger flow at airports and train stations across the country has increased significantly. When you rush to the airport due to your flight time, you may see something like the picture below.

When you encounter a long queue at the airport security gate, no matter how anxious you are to catch your flight, you can only wait patiently. Image source: Xiaohongshu @Cat NEKO

While you are anxiously waiting in line and frantically taking out the computer, tablet, camera and other items from your bag to prepare for the security check machine, have you ever thought about this question: Why is the unpacking process so tedious at airport security, while subway security is not so troublesome?

01Why does the airport need to unpack for security check?

In fact, the strict security check procedures at the airport are formulated to meet higher safety standards when flying. As we all know, when flying at an altitude of 10,000 meters, there is no village in front and no shop behind. Once a dangerous accident occurs due to someone carrying prohibited items, all passengers and staff on the plane will be at great risk. Due to the zero tolerance for risks, the airport attaches much more importance to and invests in the security check process than the subway.

Image source: China News Network

So why do airports use such security measures as unpacking and screening? The working principle of the security screening machine is the same as taking an X-ray in a hospital, which uses the penetrating power of X-rays to view the details of the objects inside . However, when taking a plane, the luggage is often large and complicated, with many objects piled together, and even X-rays cannot easily see the exact shape of each item.

Can you tell what's in this box? Image source: Zhihu @DataCastle

Data castles, especially electronic products such as computers, tablets, and cameras, have a high degree of internal circuit integration . Layers of circuit boards and cables overlap each other, and they occupy a large area, which can easily cover the items below . X-rays have a poor effect on such objects. If someone with ulterior motives hides prohibited items inside, they may get away with it. Therefore, unpacking and security checks at airports have become an international practice.

Laptop computer under X-ray scanning by security inspection machine Source: Zhihu @Access Card

02Can’t the camera pass through the security check machine?

The working principle of the commonly used digital cameras nowadays is to focus light through the lens onto the internal CMOS photosensitive element. CMOS is a semiconductor device with many tiny pixels densely arranged on it. When light shines on these pixels, it will stimulate a series of electrical signals. These electrical signals finally form an electronic photo and record the image. Because CMOS is sensitive to visible light , some people worry that X-rays will damage it.

Digital camera imaging principle diagram source: Xiaohongshu @Latte Photography

In theory, any radiation will make the pixels of CMOS fail and turn them into bad pixels, and the same is true for X-rays. But it is just a hooligan to talk about toxicity without considering the dosage. The power of X-rays used by security inspection machines is very small, and the impact on digital cameras is also very limited , so general security inspections will basically not damage digital cameras. But if it is a checked camera, you need to pay attention, because the power of X-rays used to scan checked luggage is generally larger. If you are worried, remember to turn off the camera when going through security inspection. When it is not powered on, CMOS is not sensitive to light, which can reduce the impact.

When the camera was exposed to industrial X-rays, a lot of noise appeared on the screen. Image source: WeChat public account @影像视觉

It seems unnecessary to worry about the X-rays damaging the camera during security checks, but this worry was also based on the film era. Film cameras do not have photosensitive components, so they are not afraid of security checks. What you need to worry about is the film used with them. According to feedback from experienced film camera players online, the effects of X-rays on unexposed film will accumulate , causing the film grain to become coarser and slightly color-shifted, or even strange streaks or even strong gray fog. The higher the sensitivity (ISO value) of the film, the greater the impact of X-rays.

The film is affected after passing through the airport security scanner. Source: WeChat public account @影像视觉

Therefore, if there are films or Polaroid cameras in your luggage, you can consider having the airport security personnel conduct a manual inspection. However, this will take more time and you need to arrange your trip in advance.

03 Can lasers also damage cameras?

In addition to X-rays, netizens often post about laser damage to cameras. Especially the stage lasers at concerts, which can easily "blind" the mobile phone cameras of fans. Compared with ordinary visible light and security X-rays, lasers have high energy , so they are brighter and more accurate. After being gathered by the lens, the energy of the laser is further concentrated, which can easily cause damage to CMOS pixels .

There are some unexpected situations in concert stage lasers that can also cause cameras to be damaged by lasers. In 2017, a doctor used a mobile phone to record the operation process while using a laser to remove a patient's tattoo. As a result, green spots appeared in fixed positions in the videos and photos taken. It turned out that the camera of this mobile phone was damaged by the laser reflected back from the skin.

A mobile phone camera damaged by medical laser has green dots appearing. Image source: Reference [1]

In 2019, a photographer discovered that his camera had vertical bright lines in the same position in all subsequent photos, starting from a certain photo. After checking, the photographer found that the first photo with streaks was taken for a self-driving car. The "culprit" of the camera damage was the laser radar installed on the self-driving car. Although the laser emitted by the laser radar is outside the recognition band of the human eye, it can also cause certain damage to the camera.

When photographing an autonomous vehicle equipped with LiDAR, damaged streaks appear in the camera image Source: Reference [2]

The Golden Week holiday is about to begin. I wish everyone can be elegant and calm during travel security checks, and that both people and camera equipment can be safe and have a wonderful trip!

References
[1] Case Report: Camera Lens Damaged During Filming of Laser Tattoo Removal. https://www.hmpgloballearningnetwork.com/site/thederm/article/case-report-camera-lens-damaged-during-filming-laser-tattoo-removal
[2]Man says CES lidar's laser was so powerful it wrecked his $1,998 camera. https://arstechnica.com/cars/2019/01/man-says-ces-lidars-laser-was-so-powerful-it-wrecked-his-1998-camera/

Author: Wei Anran, Application Engineer, PhD in Mechanics, Shanghai Jiao Tong University Editor: rain