UV Flashlight: 5 Things to Know at One Time


What is the most popular UV LED product? The answer must be the UV flashlight. You may have seen in a movie that forensic researchers use it to scout for the fingerprints of criminals. In fact, people also use it in their daily life, for example, to find pet urine or other stains. It has far more uses than you can imagine. Do you want to learn more about the UV flashlight? Maybe you will have a fresh view of it after reading this passage. Let’s dive in!

Definition and working principle

A UV flashlight is a flashlight that emits ultraviolet light, and most UV flashlights use LED as the light source. UV light originally comes from the sun. Then people first managed to produce artificial UV lights in the 1990s. The wavelength of UV light ranges from 100nm to 400nm. It consists of three types of lights with different wavelengths: UVA (315-400 nm), UVB (280-315 nm), and UVC (100-280 nm). There are two types of flashlights. One is UVA flashlights, which are the mainstream product. When people talk about “UV flashlights”, most of the time they mean UVA flashlights. The other is UVC flashlights that are usually used for sterilization. In the following passage, we will mainly discuss UVA flashlights. For those who would like to know more about UVC light, you can have a look at the previous post, What Is A UV LED.

A UV flashlight takes effect when the surroundings are dark enough. When you shine your UV flashlight on certain substances, these substances will fluoresce or glow. That is because most of them contain phosphors. Phosphors absorb the radiation of UV light and then transform it into visible light; thus, we can see the objects clearly. Thanks to this characteristic of UV light and the continuous exploration of experts, UV flashlights have become very helpful in many fields. For example, it is used to detect bugs, counterfeits, pet urine, hotel stains, hunt for scorpions, and observe minerals… And more cool things are waiting for you to explore!

glow under UV light


UV light, black light, and UV LED flashlights

UV lights include UVA, UVB, and UVC lights. While black light only indicates UVA light. So another name for the UV flashlight is the “black light” flashlight.

Before, people used mercury-vapor UV flashlights. Most of the traditional high-pressure mercury ultraviolet flashlights use 100-watt high-power mercury lamp bulbs. The most obvious feature of this mercury flashlight is the slow start-up time. It takes 5 minutes for it to run at full power. In terms of lifespan, the life of high-pressure mercury bulbs is usually only about 800 hours, and the working temperature reaches between 150 and 200 degrees. Besides, these mercury UV lamps are expensive to sell and maintain. LED ultraviolet flashlights surpass mercury flashlights in terms of price, power consumption, weight, light intensity, lifespan, and maintenance costs. So now mercury-containing UV flashlights have almost disappeared from the market. So now, when people mention UV flashlights, UV LED flashlights are the first that come to mind.

UV light, purple light, and blue light

These three types of light are different, and people are confused about their differences because sometimes UV light looks like purple or blue light. Ultraviolet light is invisible, but when a UV flashlight is working, it also emits a little visible light. Since its wavelength band is near that of purple and blue light, the visible light it emits is blue or purple.

What is worth mentioning is that purple and blue flashlights do exist and have their specific uses. Purple flashlights may be relatively uncommon, and people use them for identifying jade goods and fishing. Blue flashlights are more versatile, as they can be used for hunting, reading maps at night, forensic science, etc. Yet UV flashlights have a wider usage, making them a more popular product than these flashlights of different colors.

Can a phone flashlight be used as a UV light?

In some TV series, people create an “UV” flashlight with their phones, thus making it a life hack. Can we really simply make UV light with our phones? Well, to be honest, we can’t create true UV light. What we can do is mimic some effects of UV light, like showing fluorescent letters. And the method is easy, you just need to use tape to cover the flashlight of your phone and then color it with blue and purple colors. There is a blog teaching the detailed steps, and you can check it out if you are interested: https://www.techadvisor.com/article/729344/how-to-turn-your-phone-into-a-black-light.html


The reason why mobile phones cannot produce UV light is that the flashlight our phones use is a white LED. The wavelength is between 400 and 800nm, so it can only produce visible light. The secret to imitating the UV light is probably to turn the white light purple or blue, making it look like the UV light. Simulating like this won’t have other functions like a true UV flashlight. So if you need a UV flashlight for other purposes, you’d better buy a real one.

Advantages and uses of the UV flashlight


The UV flashlight is used in many areas for its versatility and high performance. Its advantages include:

  • High power: The intensity of a UV LED flashlight is much higher than that of a traditional UV flashlight. The more powerful it is, the further the light can reach. It will be helpful when used outdoors.
  • High efficiency: When using a mercury lamp, you have to wait for 5 minutes or more for it to start working. With an LED UV flashlight, you don’t need to heat it up before using it. So the time is saved. And LED is famous for its high efficiency because it transforms almost all the electricity into light rather than heat.
  • Long lifespan: The service life of a flashlight is closely related to the heat it emits. A mercury lamp sometimes can only last 800 hours because it generates too much heat, which damages the lamp itself. UV flashlights use an LED light source, so they have the capability of emitting low heat. The lifespan of a UV flashlight is as long as 20,000 hours. It will be convenient to use a UV flashlight since you don’t need to maintain it from time to time.
  • Flexible and compact: Normally, a UV flashlight is powered by an AA or AAA battery, and its size is small and easy to carry. Some are even rechargeable, saving you the hassle of changing the batteries.


  • Detect leaks: Many industrial chemicals, such as antifreeze, are fluorescent. Leaks can be easily detected with ultraviolet light. Fluorescent dyes can also be added to the system to detect hard-to-find leaks.
  • Non-destructive material testing (NDT): High-power UV flashlights can be a tool for testing the structural integrity, reliability, and safety of infrastructure projects such as bridges and tunnels. The aircraft, automotive, and marine industries also use UV flashlights for non-destructive testing.
  • Detecting forgery and repairs of artwork: Paints, inks, dyes, and other materials have different levels of fluorescence and will change over time. A long-wave ultraviolet flashlight can show the differences between original artwork and fakes. You can also use a professional ultraviolet flashlight to find traces of repairs in collections.
  • Detect counterfeit currency: The currency in most countries contains watermarks or other anti-counterfeiting markings. UV light can detect security markings on these currencies.


  • Crime scene and room investigation: Many bodily fluids glow under a UV flashlight. This helps investigators obtain fingerprints, footprints, bodily fluids, and other relevant evidence at the crime scene. Of course, the UV flashlight can also check whether there are pet stains in the room or check the cleanliness of the hotel room.
  • Show fluorescent marks: Fluorescences are widely used in our life. For example, you can find them in fluorescent paintings, club tickets, and special cosmetics. With the help of a UV flashlight, these substances will present their original shapes.

Safety of the UV flashlight

Is it safe?

Disclaimer: The following content is just to present general information about the safety of UV flashlights. For more professional details, you should seek the advice of your doctors.

UV light, including UVA, UVB, and UVC, can do damage to our eyes and skin and even lead to cancer. But the harm is related to the wavelength of UV light. As a UVA flashlight, it has the longest wavelength and is the safest among these three. Every day, we come into contact with 95% of the UVA that penetrates the ozone layer. We are wearing sunscreen to avoid sunburn because of this UVA and a small amount of UVB. So this UVA is not as horrible as you imagine. What’s more, the UV light a flashlight produces is far less than that in the sunlight. If anything, UVA can harm your eyes and skin under the circumstances of prolonged exposure.


UV flashlights are not very dangerous to our bodies, but only if you take the necessary precautions while using them. Here are some things you should pay attention to:

  • The most important thing is: don’t look directly into the flashlight. Our eyes are fragile. UV light of high intensity can cause eye problems like inflammation of the cornea, cataracts, etc. You will be fine if you accidentally look into the flashlight, but deliberately staring at the light out of curiosity is harmful. If you are worried about it, you can wear a pair of UV-blocking safety goggles.
  • Don’t expose your skin under the flashlight for a long time: UV light makes our skin darker and causes skin aging. Though the light of a UV flashlight is not as powerful as that in the sunlight, prolonged exposure will increase the danger. Wear sunscreen or long sleeves to block the light.
  • Keep your children away from the UV flashlight: Children like playing with flashlights. Unlike a white LED flashlight, a UV flashlight has potential risks. Especially for the children, whose eyes and skin are still in the growth stage, it is necessary to protect them. When you don’t need to use a UV flashlight, put it away.

How do I choose a UV flashlight?

There are various UV flashlights on the market. How do we choose one that can perform well, fulfill our needs, and last for a long time? Here are some points for you to consider and compare.

  • The wavelength

The wavelength of UV flashlights is usually between 360nm and 400nm. The most common ones are 365nm and 395nm UV flashlights. Due to the wide range of LED ultraviolet wavelengths, especially for the 395nm purple flashlight, it will produce some visible blue light. Yet excessive visible light will affect ultraviolet detection. Especially for precision instrument detection, a 365nm ultraviolet flashlight with less stray light is better. At the same time, filter lenses are also important to reduce excess visible light and ensure the accuracy of test results.

  • Single-LED UV flashlights and multi-LED UV flashlights

According to the number of LEDs, UV flashlights include single-LED flashlights and multi-LED flashlights. With a multi-LED UV flashlight, you need to pay attention to the distance when using the flashlight. If you are too close to the object, the detection quality will be reduced as there are dark areas between two LED beams. When the beams of individual LEDs combine to present a uniform spot on the surface of the illuminated object, this is the minimum working distance. The minimum working distance of single LED UV flashlights and multi-LED UV flashlights is different, so you need to think about it when purchasing.


  • Constant current chips

Ordinary black light UV flashlights are powered by lithium batteries, which makes the flashlights more portable and flexible to use. However, when the battery power drops, the current and voltage will drop, and the intensity of the UV flashlight will decrease accordingly. A black light flashlight using a constant current chip can maintain a relatively stable operating current. Even if the voltage drops, the output ultraviolet rays can still have an ideal intensity.

  • Relevant certification

Different industry applications have different qualifications for UV flashlights. For example, ordinary anti-counterfeiting testing has no relevant industry certification requirements, while high-end non-destructive testing fields such as aerospace non-destructive testing require certifications. Therefore, you should be sure where you want to use this UV flashlight and choose the manufacturer who can meet the certification requirements if needed.

About Mokolight

Mokolight produces UV LEDs of high quality that can fulfill your high-end requirements! We have our own factories, and our products have obtained certifications from different countries. As a LED manufacturer with 16 years of experience, we know how to provide the most suitable UV LED product for you. Come and contact us right now!

Written by ——
Scott Hughes
Scott Hughes
Double Bachelor's degrees in Architecture and Electrical Engineering, 5+ years of experience with LED lighting, intelligent moving lights, and conventional fixtures. Reach Me Now>>
Scott Hughes
Scott Hughes
Double Bachelor's degrees in Architecture and Electrical Engineering, 5+ years of experience with LED lighting, intelligent moving lights, and conventional fixtures. Reach Me Now>>
Share this post
Scroll to Top
Scroll to Top