	Deep Profile Measurement Microscopes

Principle of a Confocal Laser

A confocal laser optical system eliminates beams emitted from spots other than the focused focal point of the objective lens by placing a pinhole at the image focus location (in front of the light-receiving element). This optical system can be used as a sensor to detect the displacement magnitude at the focused point (height information). (See Measurement Principle of the Laser Focus Method) If this system is used as a microscope, clearer images those from an optical microscope can be obtained without flare. Super-deep profile measurement microscopes allow the user to obtain high-resolution confocal images and gauge the height (shape, roughness) of the object(s) by combining a high-speed X-Y scanner with the optical system.

When the Target is in Focus

Regardless of which system is used, all of the reflected light enters the light-receiving element.

When the Target is out of Focus

While all reflected light enters the light-receiving element in the case of a normal optical system, only part of the light enters in the case of a confocal laser optical system.

High-speed X-Y Scanning Optical System

A super-deep profile measurement microscope scanner consists of separate resonant and galvano scanners.
The resonant scanner is used for high-speed horizontal scanning while the galvano scanner is used for vertical scanning where positioning accuracy is critical.

The Light-receiving Element of a Super-deep Color 3D Profile Measurement Microscope

The photomultiplier (PMT) is adopted as the light-receiving element of a Super-deep color 3D profile measurement microscope. The PMT is one of the most highly sensitive and rapid response photo detectors available in the optical sensor field. It is a vacuum container with a built-in cathode which converts light into electrons (photoelectric surface), convergence electrode, electron multiplier, and an electrode which gathers electrons. When light enters the photoelectric surface, photoelectrons are discharged into the vacuum from the photoelectric surface and they multiply. The multiplied electrons will then cluster at the anode as an output signal. Because of this multiplication, caused by the secondary electron emission effect, the PMT has outstanding sensitivity and low noise operation when compared to all light-receiving elements used to measure ultraviolet light, visible light, and near infrared light. Moreover, it is also characterized by its rapid response.

The PMT is also adopted as the light-receiving element of laser microscopes and its high sensitivity and wide-range dynamic lens allows the following features to be added to the traditional CCD (charge-coupled device) type laser microscope.

	Measurement of objects with low surface reflectance.
	Measurement of areas with a larger gradient angle.
	The measurement time is shortened, making it compatible with high-speed scanners.
	It clearly projects an image with optimum contrast of light and shade for observation.