The nomenclature of Pulsar products may be slightly confusing for newcomers to the brand. Every Pulsar product has letters and numbers appended to it which indicate the product’s sensor size, objective lens, and thermal resolution.

The numbers on a unit refer to the size of its objective lens and determine its focal length. For example, an XG35 has a 35mm objective lens, while an XP50 has a 50mm lens and so on. The “Pro” tag indicates extra thermal sensitivity, capable of finding minute details in heat signatures. The Thermion 2 LRF XG50 has a NETD of <40mK while the Thermion 2 XQ35, even though its objective lens is smaller, has a more sensitive <25mK thermal sensor.

The letter conventions are tied to specific sensor resolutions, while the numbers stand for the size of a unit’s objective lens.

A quick reference chart follows:

Why is the size of a thermal sensor important?

The size of a thermal sensor affects the level of detail in the image it produces. Just like a high-resolution monitor, a larger sensor with more pixels will give you a clearer and more detailed picture.

Pixel pitch is another determinant factor of a product’s quality. Defined as the distance between two pixels, pixel pitch is measured in microns (µm). The smaller the unit, the closer the pixels are packed, and thus the better the image quality will be.

Why does the size of the objective lens matter in a thermal scope?

The size of the objective lens determines the magnification you can achieve and affects unit’s focal length and display resolution. The focal length of an optical system is a measure of how strongly the system converges or diverges light. An optic with low focal length will display very wide images, while an optic with a high focal length will display single objects in greater detail.

 A larger objective lens and display size also result in higher magnification. Additionally, a larger sensor size and a smaller objective lens focal length provide a wider field of view.

The detection range of a thermal scope also depends on the focal length of the objective lens. A longer focal length allows for a greater detection range, assuming the thermal sensor remains the same. However, high focal lengths lead to higher magnification and a decrease in the field of view.

The resolution of a thermal scope is influenced by the resolution of both the objective lens and the eyepiece. If the objective lens is small, it limits the potential improvement in resolution and image quality of the unit.

Thermal Resolution

Measured in millikelvin (mK), thermal resolution measures the ability of a device to detect even the smallest temperature differences. The smaller the number, the more sensitive the device will be. More sensitive devices result in clearer images.

Thermal resolution compares the signal from the object you're trying to see to the background signal and takes into account any noise from the thermal sensor. A thermal imager with good resolution can clearly show an object that has a temperature very similar to the background, like a pig covered in cool mud against cool, dry earth. The higher the thermal resolution, the smaller the temperature difference between the object and background that can be displayed.

Understanding the importance of certain factors in thermal imaging technology can greatly enhance the hunting experience. The size of the thermal sensor affects the level of detail in the image, with larger sensors producing clearer and more detailed pictures. Similarly, the size of the objective lens plays a role in magnification, field of view, and detection range. A larger objective lens can provide higher magnification and a wider field of view, but it may limit the detection range. The resolution of the thermal scope depends on the resolution of the objective lens and eyepiece, with larger lenses contributing to improved image quality. By considering these factors, hunters can make informed decisions when selecting thermal imaging equipment to optimize their hunting performance.