1. A computer-implemented method for detecting a presence of a sample holder in a biological analysis system comprising an optical detector configured to detect signals from biological reactions occurring in the sample holder, the method comprising: imaging the sample holder including an identifier on the sample holder, wherein the imaging generates image data; determining a portion of the image data including the identifier based on the image data corresponding to a predetermined location of the imaged sample holder; dividing the portion of the image data including the identifier into at least two segments of pixels, each of the at least two segments including differing pixels; extracting, for each of the at least two segments, intensity values from the pixels in each of the at least two segments; comparing, for each of the at least two segments, the intensity values of the pixels to intensity threshold values; verifying a presence of the sample holder when the comparison identifies a number of related intensity values that exceeds a presence threshold for at least one of the at least two segments; and in response to verifying the presence, initiating a biological sample analysis procedure using the biological analysis system.