Imaging Topics

Binning

Binning is the process of combining charge from adjacent pixels in a scientific camera during readout. This process has the potential to improve signal-to-noise ratio (SNR) and increase frame rate.

Calculating Electron Multiplication Gain

In this short technical note we describe how to measure actual Electron Multiplication Gain in an EMCCD camera

CCD Grading

Manufacturers of CCDs grade devices according to the number and type of defective pixels. Because the CCD is a large-cost component in the overall camera system, the choice of sensor grade is an important consideration when purchasing a camera.  

Dark Current

Dark current arises from thermal energy within the silicon lattice comprising the camera. Electrons are created over time that are independent of the light falling on the detector. These electrons are captured and counted as signal.

Detection Modes

Many Teledyne Photometrics CCD cameras operate in distinct detection modes that are specifically designed to fully utilize the characteristics of the CCD.

Dynamic Range

Dynamic range refers to intrascene performance (i.e., the ability to quantitatively detect very dim and very bright parts of a single image). In this short technical note we describe how to calculate it.

Fiber Optics

In some situations it is advantageous to use an image-preserving fiber optic bundle in place of conventional imaging optics. Significant gains in the amount of light collected can be achieved by directly coupling the light source to the camera using fiber optics. 

Frame-Transfer CCDs

A frame-transfer CCD has its parallel register divided into two distinct areas: the image array, where images are focused, and the storage array, where the integrated image is temporarily stored prior to readout.

Full-Frame CCDs

Full-frame CCDs have the simplest architecture. The classical full-frame CCD design employs a single parallel register for photon exposure, charge integration, and charge transport.

Full Well Capacity

Full well capacity defines the amount of charge an individual pixel can hold before saturating. Saturation must be avoided in high-performance cameras because it diminishes the quantitative ability of the camera and produces image smearing due to a phenomenon known as blooming.

Gain

Gain refers to the magnitude of amplification a given system will produce. Gain is reported in terms of electrons/ADU (analog-to-digital unit). A gain of 8 means that the camera digitizes the signal so that each ADU corresponds to 8 photoelectrons.

Imaging at LightSpeed

LightSpeed mode enables significantly higher frame rates when using ROIs for imaging on Teledyne Photometrics cameras.

Interline-Transfer CCDs

Interline-transfer CCDs (or interline CCDs) have a parallel register that has been subdivided into stripes so that the opaque storage register fits between columns of pixels. 

Linearity

The transfer function between the incident photonic signal and the final digitized output should vary linearly with the amount of light incident on the CCD. 

Matching Resolution

Researchers using a camera in conjunction with a microscope desire to work at the maximum possible spatial resolution allowed by their system. In order to accomplish this, it is necessary to properly match the magnification of the microscope to the camera.

Metachrome II Coating

Metachrome II* is a composite phosphor coating developed by Teledyne Photometrics for use on its products to improve sensitivity of CCDs in blue-visible and ultraviolet (UV) wavelengths.

MPP Mode

In MPP technology, dark current is significantly curtailed by inverting the signal-carrying channel by populating the silicon-silicon dioxide interface with holes that suppress the hopping conduction process.

Electron-Multiplying (EM) Gain

Formerly referred to as “on-chip multiplication gain”, this technology is used in EMCCD cameras to enable multiplication of charge (i.e., electrons) collected in each pixel of the active array. 

Quantum Efficiency

Quantum efficiency (QE) is the measure of the effectiveness of an imager to produce electronic charge from incident photons.

Readout vs. Frame Rate

In this short technical note, we explain the difference between readout rate and frame rate and how this influences imaging speed.

Saturation and Blooming

Saturation and blooming are phenomena that occur in all cameras and that affect both their quantitative and qualitative imaging characteristics.

Signal-to-Noise Ratio

Signal-to-noise ratio (SNR) describes the quality of a measurement. In digital imaging, SNR refers to the relative magnitude of the signal compared to the uncertainty in that signal on a per-pixel basis. 

Specifically, it is the ratio of the measured signal to the overall measured noise (frame-to-frame) at that pixel. High SNR is particularly important in applications requiring precise light measurement.