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06 Jan

Thermal – A Hot Topic

Posted by Mark Harris on

I win – this is the first OpticsBlog of 2014, so – Happy New Year.

Not only that, but we are coming very close to the one-year anniversary of the Product Intelligence Team taking over the OpticsBlog from Jne (February 8, for those of you who would like to send anniversary cards or gifts of cash and/or liquor to my attention).

Some of you may live in a more God-forsaken place than Chicago in the winter, but eighteen below zero with a forty-three below zero wind chill gives me the right to say it is damn cold outside.  I found that I had a flat tire this morning, and as far as I’m concerned, it can stay that way until maybe March, when it gets above freezing again.  I mooched a ride off of my lovely wife Wendy this morning.

Since after the first of the year we’re no longer allowed to touch our phones in Illinois while driving, I pulled a safe distance off the road, put the car in park, applied the parking brake, shut the car off and removed the keys to take this photo.  Unfortunately, the thermometer and lights don’t work without the key, so to be compliant, my wife and I exited the car, rolled down the window, started the car from the outside, and then leaned in and pushed the button to take this photo:

Then we shut the car off, retrieved the keys through the window, got in the car, rolled up the windows, stored the phone in a GunVault safe in the rear of the car, started the car, released the parking brake, and put the car into drive.  We weren’t cold, as the knowledge that I hadn’t just taken a photo of the dashboard at a stoplight gave us a warm feeling of safety.  Thank you, State Of Illinois!

As is sometimes the case, this long story actually relates to a product that we sell.  On the drive in, while my wife was talking about… something, and I was thinking about the temperature outside, and about thermal vision.

The manufacturers don’t expect folks to be out in stupid cold like we’re experiencing now, but they do have a decent operating range (for example, the FLIR Systems LS Series Compact 4x Thermal has an operating range of -4°F to 122°F (-20°C to +50°C).  Personally, I tolerate -4 a LOT better than I tolerate 122.  You can always put on more clothes when it’s cold, but you can only take off so many when it’s hot, before you get arrested.

Just for fun, let’s assume you have been in prison, or a coma, or have never seen Predator or any movie based on a Tom Clancy novel, and therefore have no idea what thermal vision is.  The word “thermal”, comes from the French “thermal”, who got it from the Latin “thermalis”, who lifted it from the ancient Greek “therme”.  All fancy names for “heat”.

While night vision is all the rage, night vision has limitations.  If you’re looking for something in the dark – an animal, a trespasser, your 16-year old daughter’s boyfriend – if they can get behind something that breaks up their outline and they stay still, you’re going to have a hard time locating them.

The beauty of thermal vision is that it “sees” differences in temperature.  Compared to most of their surroundings, people are hot.  If you don’t think so, you’ve never watched women’s beach volleyball.   Put that same animal, trespasser or young Romeo behind a bush and take a look with thermal vision, and they light up like a Christmas tree.  Actually, there are models that show difference in heat using different colors, so it really is like a Christmas tree (the kind I prefer).  There are also monochrome models, which are like the Christmas tree that my wife prefers, with only one color of light.

The ability of the unit to read differences in temperature is useful for all sorts of things.  If you do any kind of maintenance, or you happen to appraise homes, or your line of work has to do with energy efficiency, a thermal unit is a great way to show clients just where they are losing heat (or cold, depending on the season).

I’ve borrowed thermal units from work, and since I’m easily amused, I like to check out the cars in our parking lot to see who has just arrived, and who has been here for a while.  The hoods of the cars tell the story – I imagine this could be useful for law enforcement units looking for a car that turned into a parking lot to try and hide among the other cars.  I have a personal interest in that one – I tried to hide in a Chevy dealer’s lot years ago after blowing through a speed trap just north of Bloomington, Indiana around 1:00am.

Thanks to the helpful officer, I now know that shutting off the lights doesn’t help if your foot is on the brake pedal and the brake lights are on.  In my defense, it was a great concert (Steve Miller Band), I was young and had recently seen The Cannonball Run, so I couldn’t help myself.

Those of you who are plagued with feral pigs would find a thermal unit helpful.  No lights needed, and you can do the Predator laugh as you thin the drove.  Yes, drove.  Look it up.

If you’re old like me, you may remember back in 2000 when General Motors released the Cadillac De Ville with an optional thermal imaging system.  $1,995 would get you a genuine Raytheon-designed thermal unit.  The image was projected into the driver’s field of vision via a heads-up display… genuine fighter pilot technology.

The system was optimized for 80 meters down the road, with a fixed focus of 20 meters. The HUD image had a horizontal field of view of 11 degrees and a vertical field of view of 4 degrees, so it wasn’t huge, but drivers of the time must have felt like they were in the Millinneum Falcon.  I had a 2000 Dodge Stratus ES, and it cost $800 to have six 99 cent spark plugs replaced (thanks, Elmhurst Dodge), so $1,995 for in-car thermal vision with a heads-up display sounds like a steal in retrospect.

Did your car have thermal vision in 2000?  Did it have spark plugs?  I rest my case.

Objects in the HUD image are the same size as the objects in the road scene, so a dog wouldn’t look like Godzilla, and a cat wouldn’t look like a moose.  GM discontinued the thermal vision in 2004, so I wouldn’t call it a great success story, but it was probably the first time the general public got to see thermal technology for themselves.

Here’s a youtube video of the system.  It would be a lot more exciting it there had been a dog, cat moose or Godzilla – something – in the heads-up display:

Today, you can own your very own thermal imaging unit without the expensive and large Cadillac De Ville attached.

Why, the savings in shipping weight alone pays for itself.

Mark H.


Mark, who feels uncomfortable referring to himself in the third person, was taught to shoot at age 5 by his father. Mark grew up, or at least increased in age, in east central Indiana. After realizing that he was not going to become an astronaut, he attended design school and spent 25 years in commercial printing before a trip to the emergency room convinced him to abandon this folly. The online purchase of a holster led Mark to OpticsPlanet where he is happier than any person has a right to be, except that his wife refuses to let him buy a dog or a motorcycle. She is, however, pretty darn cute, according to Mark.

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