In any job, you must have the right tools and resources to do it. Nowhere is this truer than with first responders and others that use their vehicle in their duties. When picking lights, many people make the mistake of just looking at the number of LEDs and whether a unit is SAE certified. But, one of the most important safety features associated with LED lights is optics.

To better understand whether you should install TIR or linear optics, you have to understand the differences between the two. The more you know, the better equipped you will be to choose the right lights for your sete-up.

TIR and Linear Optics are not the Same

The processes used to create TIR, or linear optics are completely different. As you might have already guessed, each type of lens has a specific purpose. We’ll go into how these lenses differ in a minute. But before you read on, you need to consider the following about the lights you are considering:

  •    What do you want to achieve with the light?
  •    How will it be used?
  •    Where will it be placed?
  •    Are you looking for piercing light in a particular direction or a warning light that will cover a wide area (such as an intersection)?

Knowing how and why you are installing LED lights on a vehicle, will help you choose what type of lens will be the most beneficial. Next, we’ll break down the differences between each lens type.

TIR Optics

When LEDs debuted in the emergency vehicle light industry (circa 1995), they had a stand-alone light spread of about 120-degrees. To help control and contain the spread, a unique optic, the TIR, was created.

A TIR (Total Internal Reflector) optic is similar to  the technology used in a flashlight. Each LED in a TIR unit centers at the end of a conical reflector.  The reflector captures scattered light and focuses it forward. As a result, a round, narrow output that projects for great distances is created.

Usually, an emergency light with TIR lenses has vertical ridges across the optics. The ridges let the light spread over a wider area. The problem with TIR optics and the reason they shouldn’t be the only optics included in your set-up, is you don’t get much off-angle performance.

Instead, TIR optics are ideal for forward facing or rear facing light only. For instance, a police officer will want to use a TIR dash light, rear facing surface mount lights, and maybe a traffic advisor in the deck when stopping a driver on the side of a highway.

In this instance, his vehicle is facing forward, and he doesn’t expect any traffic is coming to the side of the car. With TIR optic lights, drivers will see the light from quite a distance, which gives them plenty of time to move over and give the officer room to work.

Now, consider the same situation and vehicle, but with the officer parked at an angle behind a driver. Many cruisers are parked at an angle instead of parallel to a vehicle because it helps defer the risk of rear-end collisions. Parked this way, the patrol car will need off-angle performance technology to make his presence noticeable on the road. This is where linear optics are a better option than TIR optics.

Linear Optics

Lights with linear optics deliver a comprehensive display of illumination. When a vehicle has linear emergency vehicle lights, it is seen from almost any direction the light is facing. What this means is, if an officer is using a linear dash light, and parks at an angle, oncoming traffic will notice the vehicle because the unit has a greater light spread

As we said above, linear and TIR optics are different, which allows them to produce different beams. In a linear light, all LEDs surround an optical reflector. The reflector captures light from all LEDs in a unit at the same time; instead of from each LED separately. Why is this important?

If you talk to warning and utility vehicle drivers, you’ll find out that working in or near an intersection creates a dangerous situation. Linear warning lights in the front and back make a vehicle easier to see and provide visibility from a wider angle. When a driver also adds linear surface mount lights to the side of a vehicle, it increases the visibility in intersections even more.

Like all lights used by first responders, linear optic lenses also have some cons. Because this type of optic creates a brighter light spread, it uses more energy. As a result, a TIR light is going to be stronger than a linear unit with the same number of LEDs and equal wattage.

Our Advice

The topic of TIR and linear lenses is something we discuss with our customers all the time. Many times they want us to tell them what optics they should choose. The bottom line is, it is up to the driver and outfitter to decide. Factors to consider are whether it’s a brand new set-up or an existing set-up? And what the driver is hoping to achieve when using it?

What we tell customers is the best set-up incorporates linear and TIR options. By installing a combination of optics in their set-up, drivers can feel confident in many different situations.

For more information about differences between the various optics available, please visit our Knowledgebase.