Linear excitation of fluorescence with confocal detection. This method is essentially confocal laser scanning microscopy. Fluorescent molecules can be visualised using "fluorescence microscopy" or "confocal microscopy". The protein expression data is derived from antibody-based profiling using immunofluorescence confocal microscopy. Multiphoton microscopy provides considerably greater depth of penetration than single-photon confocal microscopy. An alternative technique is confocal theta microscopy. These techniques are normally used in conjunction with confocal microscopy. This method usually employs a phase-contrast microscope or confocal reflection microscope. Tellurium dioxide is used to create acousto-optic modulators (AOTFs and AOBSs) for confocal microscopy. Two-dimensional systems are essential for most applications in material processing, confocal microscopy, and medical science. This is particularly important in confocal and superresolution microscopy. Each of these classes of confocal microscope have particular advantages and disadvantages. It is probably the first publication using the term "confocal microscope". The discovery was made possible due to improvements in confocal microscopes. This system is considered by some later authors as the first confocal optical system.