Focal Plane Array

I’m looking into purchasing a Thermal Imaging unit. Information on the internet is very complex for a newcomer. Additionally, there seems to be an extremely wide range of thermal imaging devices for various applications. At this point I’m very confused about what sort of unit I should get.

First of all, I’m investigating the purchase of TI for use in private security, and I realize this is a forum for inspectors, but there is almost no online TI community so I’ve ended up here.

Here’s a specific question:
FLIR VSR-6 vs. Thermal-Eye X-150

The VSR-6 says it has a “640x480 InSb focal plane array” while the X-150 says it has a “Focal Plane Array Pixel Count (Resolution) 160 x 120”, yet the X150 is more expensive and says it has a much greater range. Can anyone explain what this means?


The FLIR has better resolution (640 x 480) and will produce a clear image, but it is not designed for looking at things far away. It appears to be for use in a survalance camera mode, like a regular security camera.

The Thermal Eye has a smaller resolution, but is built to be smaller, have a farther range and a better lens (the type and quality of the lens is the major price factor). It seems to be more miniaturized. Therefore the higher price.

Call or e-mail me if you have any more questions.

Just a quick scan of the 2 products and it’s obvious one is a hand held unit (X-150) and the other a stationary camera hooked to a remote monitor - which is probably one of the reasons for the price difference, so really 2 different products all together.

I see your using it for private security - how actually are you using it? Is it going to be stationary, or will you be working commando in the boxwoods, scoping out intruders?

Dear Erik:

Although resolution is one of the most important objective charracteristics of a thermal imager, it CANNOT be empirically quantified by any means available including pixel count or detector array size.

Our content-based website, IRINFO.ORG recently featured a Tip of the Week titled, ‘Understanding Imager Resolution.’ This tip explains the concept of thermal imager resolution and how to meaningfully gauge and compare various imaging systems.

This Tip may be found at the following URL:

Another resource that may be of interest is an article titled, *‘Selecting, Specifying and Purchasing Thermal Imagers.’ *

This article is available as a free download at the following URL:…3_seffrin.html

Once you have a clear understanding of imager resolution, you are likely to find that increased resolution will generally cost more money. Prior to purchase, make certain that you evaluate any imaging system(s) under the exact same conditions that you will encounter in the future.

Hope this is helpful.

Jim Seffrin
Infraspection Institute

IR Training from the IR Professionals

Keep in mind that you may need to sell the unit some day.

The one may sell and the other may not?

I’d be happy to talk with you offline if you like as both these products don’t really fit into the scope of this messageboard. Resolution is only one of the issues you will want to consider, even for a security product. We don’t sell cameras but are very familiar with most in the market. If I can help, just call.
Thermally yours,

John Snell
ASNT NDT Thermal/Infrared Level III #48166
Snell Infrared