Signal noise reduction for imaging in biological analysis

A method of characterizing signal noise associated with operation of a charge-coupled device (CCD), wherein the signal noise comprises at least a dark current contribution, readout offset contribution, and spurious change contribution, the method comprising:

• providing a plurality of first data points associated with first outputs provided from the CCD under a substantially dark condition during a first exposure duration;
• providing a plurality of second data points associated with second outputs provided from the CCD under the substantially dark condition during a second exposure duration wherein the second exposure duration is different from the first exposure duration;
• providing a plurality of third data points associated with third outputs provided from a cleared output register of the CCD without having charge transferred thereto;
• determining the dark current contribution per unit exposure time by comparing the first data points and the second data points;
• determining the readout offset contribution from the third data points;
• and
• determining the spurious charge contribution based on the dark current contribution and the readout offset contribution.

A method for reducing signal noise from an array of pixels of a segmented detector configured to detect samples, wherein the signal noise comprises at least a dark current contribution, the method comprising:

• providing a substantially dark condition for the array of pixels, wherein the dark condition comprises being substantially free of light;
• providing a first output signal from a binned portion of the array of pixels by collecting charge for a first exposure duration, transferring the collected charge to an output register and reading out the output register, wherein transferring of the collected charge from the binned pixels comprises providing a gate voltage to a region near the binned pixels to move the collected charge from the binned pixels, and wherein the collected charge is transferred in a manner that causes the collected charge to be shifted to the output register;
• providing a second output signal from each pixel by collecting charge for a second exposure duration, transferring the collected charge to the output register, and reading out the output register;
• and
• determining the dark current contribution the first output signal and the second output signal.