Quantum efficiency (QE) measures how efficiently a pixel converts the energy of incident photons into electrical charge. It varies with the wavelength of the light. The higher the QE percentage, the less light is required to produce a usable image. Here are some examples:

• Most CCD sensors achieve a QE of 55 to 60 percent.
• Sony Pregius Gen2 CMOS sensors have a QE of 65 to 70 percent.
• Sony STARVIS rolling shutter sensors achieve QE in excess of 80 to 85 percent.

The meaning of quantum efficiency:

A high QE means higher light sensitivity and therefore better image quality, especially in low light.

The saturation capacity refers to the number of electrons a single pixel can store in the photodiode before it becomes oversaturated. It is directly related to the size of the pixel. Larger pixels can store more electrons and therefore have a higher saturation capacity.

Meaning of saturation capacity:

• Larger value ranges when capturing light: Higher saturation allows the sensor to process a wider range of values when capturing light. This results in better detail in bright areas of the image.
• Low noise indicator: High saturation sensors tend to produce less noise in bright areas of the image. This significantly improves overall image quality.

Saturation is measured in electrons (e-). This unit indicates how many electrons a pixel can hold before it becomes saturated.

The temporal dark current noise is caused by the electronics and the readout circuits of the sensor, even if no light falls on the sensor. It is strongly temperature-dependent, but is not influenced by the exposure time or the shot noise of the photons.

Meaning of temporal dark current noise:

• Low light performance: in low light applications, dark current noise can dominate. A sensor with low dark current noise delivers better results under such conditions.
• Dependence on temperature: The dark current noise increases as the temperature rises. It is therefore important to control the temperature conditions in order to achieve optimum results.

The dark current noise is measured in electrons (e-). This unit indicates how many electrons the noise generates in the sensor.

The dynamic range of a camera sensor describes the maximum image contrast at which the sensor can distinguish all grey values from the brightest to the darkest area without the highlights being oversaturated or the shadows becoming zero.

It represents the ratio difference between the maximum signal level (saturation capacity) and the minimum signal level (temporal dark noise).

Meaning of the dynamic range:

A high dynamic range is important for applications where both bright and dark areas are equally important, as it allows for more detail in shadows and highlights. The unit of measurement for dynamic range is decibel (dB).

The absolute sensitivity threshold indicates how little light is required to produce a detectable signal above the sensor's background noise level. This is particularly important in low-light situations, as sensors with a low sensitivity threshold can provide better images.

Meaning of absolute sensitivity threshold

• Better low-light performance: Sensors with a lower absolute sensitivity threshold are able to deliver better results in low-light environments. They can still generate usable signals in minimal light.
• Improved image quality: A low sensitivity threshold means that the sensor can capture fine details in low light, improving overall image quality.

The absolute sensitivity threshold is measured in photons (γ). This unit indicates how many photons are required to produce a measurable signal above the noise level of the sensor.

The signal-to-noise ratio (SNR) is a critical parameter for evaluating the image quality of camera sensors according to the EMVA 1288 standard.

The SNR indicates how well useful image data can be distinguished from noise. A higher SNR means a clearer and sharper image. The value of SNR is influenced by various factors such as dark noise, photon shot noise, saturation capacity and quantum efficiency.

Meaning of signal to noise ratio:

• Image clarity: The higher the SNR, the clearer and more detailed the image. A high SNR is particularly important in low light conditions or when capturing fine detail.
• Quality indicator: A high SNR indicates that the sensor is able to provide more useful image information in relation to the noise. This is an indicator of the sensor's high performance.