The small hole, orifice or aperture is the key element of any device or instrument designed to control or measure the flow rate of a gas or liquid. In the recent past, the gasoline piston engine went through a transition that improved performance and reliability. Precision made small holes brought to life the fuel-injection process, an important technology that has superseded the carburetor. For general applications, precision, fixed control of gas flow rate is made possible through placement of a small hole in the flow passage. Under fixed positive pressure conditions, the small hole becomes the flow rate calibration device. In the area of high vacuum helium leak detector calibration devices, the small holes provides the calibrated leak rate.
Semiconductor Integrated circuits and other semiconductor devices are the foundation of today’s electronics industry. The development and production of semiconductor devices and manufacturing equipment bases heavily on ion or molecular beam processing technology. Ion beam drilling devices require the use of small, precise holes for beam forming.
Optical from early days, optics used small holes to illustrate the wave property of light. An annular diffraction pattern of interference fringes may be observed from the passage of light through a small hole. Small holes provide important functions in optical transfer assemblies. They provide the means for beam alignment, spatial filtering, aperture limiting, image analysis, and image processing.
Electron Beam, a mask containing an array of small holes, is used to control the electron beam emission in the color television picture tube. The electron microscope uses apertures as small as 2 microns in diameter to maximize control of electron beam emissions and profiling.