Most optical mice (as in those that cast light to a surface via a non-laser LED) using digital image correlation tend to use edge illumination (LED is positioned in a way that it casts light to a surface at a certain angle, usually around 25º, focused by a lens), thus causing different light reflections and shadows on the surface, which are being captured by the sensor (which is no more than a matrix of photodiodes, or, vulgarly put, a camera) as different values of light intensity.
Now, if the light being cast is the same color as the surface, we'll have light reflection.
If the surface was completely flat, we would have the same incidence angle as the angle of reflection (specular reflection), and there would be no case for us.
But since most mouse surfaces do have a texture (cloth fabric usually has weaves, even if tiny; rubber is rough and has pores; plastic mouse pads tend to be made with lots of small protuberances, and so on), the angle of reflection will depend on what part of the surface texture the light ray shines to, so in rough-textured surfaces (some cloth pads and plastic pads mostly), there's a higher chance that the reflection is aimed upwards to the sensor, since the angle between the emitted light and the surface's normal will be variable across the surface (diffuse reflection).
What this means is that if red light is being cast on a red, non-uniform surface, chances are that some reflections can be sent up to the sensor.
If the optical sensing package has been designed for the usage of a red LED, the photodiodes (or any other sensing elements they may use) will be extremely sensitive to red light, thus being able to continuously get consistently (assuming surface doesn't change or degrade) brighter spots (those where the roughness of the surface permits the reflection to be perpendicular to the sensor) may help the sensor to identify certain patterns, if and only if those roughness on the mouse mat is sharp enough to create small spots of reflection (if the roughness would have a flat surface all of it would reflect light into the sensor, we would have a big blob of light and the mouse would probably stop tracking), which would create images with more contrast.
So, back to square one :
- You have a red LED illuminated mouse.
- You have a mouse pad that is red and has tiny grooves.
Then, there's a chance that you'll have less tracking errors, thus tracking quality might be slightly better (and probably LOD will be higher since you'll be getting reflections from the surface until the light cone of the light passes the point on the surface where the vertical cavity of the sensor is).
However, keep in mind that :
a) Benefits might not be worth the hassle.
b) There's a chance that using a red mouse mat induces more tracking errors than it avoids, if the surface is too glossy and reflects too much light, or if the roughness isn't part of a specific pattern.
c) While as of late more and more mouse pads (specially plastic ones) are being engineered with patterns to favor higher contrast images on mice sensors, it cannot be taken for granted.
So, you may ask :
- Then why most mouse pads to come out are black?
Three main answers :
- Not all sensors use red LED anymore, so they have to cater to other, different market (laser and infrared).
- Black doesn't reflect any light, thus it should be more stable - you eliminate the chance of an unwanted reflection that might produce a tracking error.
- Creating a pattern that would exploit those principles, while not excessively hard, is more expensive than just leaving a random pattern, for a small profit that is often not understood and hard to market.
As always, those are my two cents.
Feel free to correct if necessary.