Confocal Microscope Technical Parameters
1 resolution
The system point spread function distribution of the confocal microscope is equal to the convolution of the objective lens and the point image energy distribution. In the case of the same objective lens, its lateral resolution (x-y plane) is 1.4 times higher than that of traditional optical microscopes, reaching 0.4λ/NA. For example, the resolution of Leica's TcS-NT is 0.18 μm. From the principle of the confocal microscope, we know that the setting of the pinhole at the detector not only effectively suppresses the interference of the out-of-focus point image to the detection plane image, but also suppresses the interference of the non-detection point on the quasi-focus plane to the detection point, which greatly improves the the image resolution. Furthermore, to achieve extreme resolution, confocal microscope systems must be equipped with a vibration-proof stage.
2 Sensitivity
Traditional optical microscopes are often equipped with CCD cameras to collect images, but due to the relatively low sensitivity of CCDs, low-illuminance light such as fluorescence cannot be detected, so photomultiplier tubes are generally used as detection elements in confocal microscope systems. Much more than CCD, it can also show high sensitivity to weak fluorescent signals.
3 Horizontal resolution
Confocal microscopy systems reveal greater detail in magnified images than conventional light microscopy. The magnification mentioned here does not refer to physical magnification, but refers to the morphological details of the image displayed by the confocal microscope under the same magnification condition of the objective lens, which is difficult to see under the traditional optical microscope, so the image is clearer and more subtle. Horizontal resolution is higher.
4 Contrast
Since the object illumination light is only a very small focused light spot in the scan, and the brightness and signal-to-noise ratio are high, the signal light is stronger than other points of the object. On the image plane, the point detector can only receive light passing through the pinhole, while stray light from other parts of the object is filtered out because it cannot be focused at the confocal pinhole. This results in higher contrast images of samples obtained with confocal scanning microscopes than conventional microscopes.
