Confocal Microscopy
In confocal microscopy, laser light is focused by an objective lens on to the object, and the reflected beam is focused onto a photo detector via a beam splitter. An image is built up by scanning the focused spot relative to the object, which is then stored in an imaging system for subsequent display. Through the use of a confocal pinhole, only light incident from the focal plane is permitted to pass through to the photo detector. Light not returning from the specific optical plane is blocked by the pinhole. Hence, an extremely thin optical section is created, providing a high-resolution image. Because thermal radiation is also blocked by the confocal pinhole, only the polarized reflection of the high intensity laser beam reaches the imaging sensor and a sharp image is produced. The use of pinhole optics increases the resolution such that with a 0.5 mm diameter beam,

Magnifications up to 500× at a resolution of 500 nm can be obtained, using a He–Ne laser with a wavelength of 632.8nm. In the system used a laser beam, 0.5mm diameter is reflected and scanned by an acoustic optical deflector in the horizontal direction at a rate of 15.7 kHz and a galvano mirror in the vertical direction at 60Hz. Specimens are placed at the focal point of a gold plated ellipsoidal cavity in an infrared furnace beneath a quartz view port.