Early mice tracked cursor movement with a ball, rolling against two disk-equipped rollers. A major downside was the constant dust accumulation, requiring frequent cleaning. Optical models emerged at the end of the 20th century, replacing these ball mice.

In simple terms, optical mice work by taking pictures of a surface using a sensor. The processor reads data from this sensor, analyzes changes, and controls cursor movement. To enhance the contrast in the photos, an LED or laser illuminates the area beneath them. Both optical and laser mice operate on a similar principle, differing only in the light source used to illuminate the mouse's working surface.

Optical mouse device

The optical sensor's design revolves around a light source, typically an LED in classic optical mice. The LED emits rays that reflect off the working surface and are captured by the sensor. A prismatic lens is introduced to focus the light flux, illuminating the surface at an acute angle of around 25 — 30°. This ensures a clear cut-off pattern, even on surfaces with minor microrelief.

In an optical mouse design, an additional lens amplifies reflected light rays and guides them to a sensor with its optical axis perpendicular to the working surface. The sensor, often a monochrome CMOS camera, captures over 1000 images per second. These frames are divided into small squares, each assigned an average brightness value. A mosaic of these squares creates a coordinate grid, and changes in their brightness from frame to frame act as triggers for the processing processor, initiating cursor movements along the X and Y axes.

Visual design of optical mice with LED and laser light sources.

Note that data from the optical mouse sensor is not transmitted directly to the computer, but through a special chip that also processes button clicks and wheel scrolling. The mouse driver receives data from the chip, processes the incoming information and sends commands to the computer regarding cursor movement and other mouse actions.

Laser mice operate on a similar principle but use an infrared laser diode instead of an LED light source. The laser's precision is higher, as it doesn't require a clear view of surface irregularities that cast shadows. Laser mice function effectively on challenging surfaces like glass and mirrors, which can be problematic for traditional optical mice. They are commonly employed in high-precision professional mice like the Apple Magic Mouse or Lenovo Professional. Additionally, laser mice boast lower power consumption than LED mice, contributing to extended autonomy in wireless models.

Interesting fact. Until recently, it was possible to distinguish an optical LED mouse from a laser one by its characteristic red glow. The fact is that red LEDs are very cheap to produce. However, modern optical mice sometimes use LEDs of other colors or completely colorless light sources, making them outwardly indistinguishable from laser ones.
Popular optical mice

Technical parameters of the optical sensor

Sensor resolution (DPI and CPI)

Sensor resolution or sensitivity is quantified in DPI (Dots Per Inch), indicating the number of dots within one inch of the mouse-visible surface, both vertically and horizontally. In simpler terms, it's the pixels the cursor covers when the mouse physically moves one inch. Higher DPI means the cursor covers more screen distance with less mouse movement. This proves crucial for precise sight positioning in dynamic computer shooters.

Regular mice typically have sensitivity ranging from 800 to 1400 DPI. High-precision gaming and design models demand much higher sensor resolutions, adjustable within a range often spanning from 200 to 16 000 DPI, though the actual DPI setting range is often narrower. Advanced gaming mice can even operate in the range of 100 to 25 600 DPI, with a DPI button facilitating sensitivity adjustments.

The ability to change DPI will come in handy if you have to deal with different types of tasks that require different mouse sensitivity.

In optical mice, a technically precise term is CPI (Counts Per Inch), essentially equivalent to DPI. The distinction lies in DPI representing the dots for every inch the mouse moves, while CPI determines the sensor readings for the same distance. In practice, DPI is more commonly used to designate mouse sensitivity.

Click response time and sensor polling rate

Mouse click response time and sensor polling rate are directly related. The first parameter indicates the time period during which the mouse movement signal will reach the display of the cursor movement on the screen. Click response time is measured in milliseconds (ms).

The polling rate indicates how frequently the sensor captures images of the work surface, providing information about the cursor's current position. A higher number of frames per second leads to smoother cursor movement and faster mouse click response time. Typically measured in Hertz, with a common rate around 1 000 Hz, top gaming mice may boast a sensor polling rate of 15,000 Hz or more, though such values are exceptionally rare.

Optical gaming mice

Speed (IPS)

The IPS (Inches Per Second) parameter gauges the linear speed at which the mouse can accurately read the surface. This measurement, expressed in inches per second, ensures precise sensor recording at different movement speeds. Most mice have an IPS range of 150 – 200 (approximately 4 – 5 m/s), while advanced gaming models often reach maximum speeds of 400–500 ips (around 10 m/s). Some, like the the Razer Basilisk Ultimate, claim speeds up to 650 ips, but this is more of a marketing tactic, as such speeds exceed the practical capabilities of human hand movement.

In practical terms, in games like CS2, if the mouse sensor speed is lower than the hand movement speed, quick jerks may cause the cursor to inaccurately calculate coordinates, leading it to the floor or ceiling unexpectedly. While such failures are rare these days, a more common cause could be a mouse pad clogged with dust and dirt rather than insufficient IPS speed.

Acceleration (G)

The G acceleration metric influences how quickly the cursor responds to your mouse movements. A higher acceleration rate reduces the risk of cursor disruptions during abrupt manipulator movements, crucial in dynamic games to avoid disorienting the character.

The acceleration indicator determines how quickly the cursor will move depending on the speed of the mouse.

In optical mice, the unit of G is usually taken to be the acceleration of gravity (about 9.81 m/s²). As a rule, in inexpensive game devices the acceleration is in the range from 10 to 20 G; in more expensive models this figure is higher and often exceeds the 40 G level. Again, the nature of human muscles does not allow the mouse to accelerate even 10 G. But in fact, a high acceleration rate still really allows the mouse to better respond to sudden movements, preventing the risk of the cursor breaking.

Progressive technologies in optical mice

Some types of optical technology include proprietary developments BlueTrack from Microsoft and V-Track from A4Tech.

BlueTrack, an advanced technology from Microsoft adopted by other manufacturers, distinguishes itself from classic optics through its blue backlight, heightened LED brightness, expanded illumination area, and a high-resolution matrix in the receiver. This combination ensures superior cursor positioning accuracy. Mice equipped with BlueTrack sensors outperform traditional optical ones, excelling in confident performance on surfaces like glass, polished stone, and carpet pile.

The difference between various popular technologies in optical mice.

A4Tech played a key role in developing V-Track sensors, primarily used in its devices. V-Track technology is compatible with both optical and laser sensors, but the latter is rare due to higher costs. These sensors feature a small light spot, high luminous flux density, and a photodetector lens with a narrow aperture. The light beam falls strictly vertically onto the working surface, enhancing accuracy. Thanks to these improvements, V-Track achieves remarkable precision and can even function effectively on voluminous fur, where other sensor types fall short.

Laser mice

The vast majority of mice on the market today are optical LED. Other types of sensors are much less common. Thus, a small caste of laser manipulators are represented by advanced gaming and professional solutions (for designers and artists), and BlueTrack and V-Track sensors are typical for a narrow circle of mice from certain brands.

Finally, we recommend studying the separate material “How to choose a mouse for games, office tasks and creative work”, which gives the specifics of choosing mice in general.