Several features of confocal optical microscopy
High contrast, high resolution
In a conventional optical microscope, interference occurs due to reflected light from the out-of-focus portion, which overlaps with the imaging portion of the focal point, resulting in a reduction in image contrast. In contrast, in a confocal optical system, scattered light outside the focal point and inside the objective lens is almost completely eliminated, resulting in images with very high contrast. In addition, the resolving power of the microscope is improved because the light passes through the objective lens twice, sharpening the point image.
Optical localisation function
In the confocal optical system, the reflected light is shielded by the micro-aperture at the point other than the focal point. Therefore, when observing a three-dimensional sample, the image is formed as if the sample had been sliced with the focal point, and this effect is called optical localisation, which is one of the features of the confocal optical system.
Focus shift memory function
Reflected light outside of the focal point is blocked by the microvia, so that all points on the image created by the confocal optical system can be considered to coincide with the focal point. By moving the stereo sample in the direction of the Z-axis (optical axis) and accumulating the images in the memory, an image is obtained in which all points of the sample coincide with the focal point. The function of deepening the depth of focus indefinitely in this way is called the moving memory function.
Surface shape measurement function
By adding a surface height recording circuit to the focus shift function, the surface shape of a sample can be measured non-contact. With this function, it is possible to record the Z-axis coordinates of the maximum luminance value of each pixel and obtain information about the surface shape of the sample based on this information.
High-precision microdimension measurement function
A 1D CCD imaging sensor is used in the light receiving unit, which enables high-precision measurement without being affected by the scanning tilt of the scanner. In addition, a focus shift memory function with adjustable depth of focus (deepening) makes it possible to eliminate measurement errors caused by focus shift.
