This section provides overview, applications, and principles of profile projectors. Also, please take a look at the list of 6 profile projector manufacturers and their company rankings.
A profile projector is a device that magnifies and projects an object to be measured onto a screen at an accurate magnification to observe and measure its shape and dimensions.
Some of the larger projectors have a screen diameter of 1,000 mm or more.
Because the object is magnified and projected onto the screen, it can be observed by multiple people simultaneously and is easy to handle.
Because it is an optical measuring instrument, it allows non-contact measurement and observation without damaging the object to be measured.
In addition, it has a simple structure and is inexpensive, and can be introduced in any location, so there is a strong demand for this type of measuring instrument.
The profile projectors are used for observation of object contours and dimensional measurement.
As they can be used immediately after power-on, and because they project an enlarged image on the screen, they are often used for comparative measurements using templates.
The main targets of measurement are metal parts and molded resin products. Due to its optical measurement, it can also be used to observe objects that transmit light, such as living organisms.
Some models are also equipped with a simple surface observation function, so they can be used in a wide range of situations and applications.
A projector projects an enlarged image on a screen by passing a shadow created by transmitting light through a lens onto the object to be measured.
Therefore, the part of the stage where the object to be measured is placed must be transparent and have high transmittance so that light can be transmitted through it, such as glass.
Telecentric optics are used for the transillumination optics of the projector.
In this system, light from the light source is made parallel to the optical axis by a lens, transmitted through an object, and then focused again by a lens.
The advantage of telecentric optics is that the projector does not change the size of the image, only blurring it, even when it is out of focus.
In addition, since the projector uses a single lens unit from focus to image formation, the size and magnification of the lens naturally determines the distance from the focus to the screen, which limits the size of the screen or device.
Although there are various types of projectors depending on the position and direction of illumination, there is little difference in the basic illumination method or projection principle, and similar results can be obtained regardless of which model is selected depending on the object to be measured, the magnification to be projected, and the range of the projection.
Typical error factors when measuring with profile projectors are measurement error and magnification error.
Since the profile projectors measures mainly by visually aligning the edges projected on the screen, alignment errors caused by visual inspection and distortions caused by operator habits cannot be ignored. Errors due to the incline of the object being measured and the parallelism of the XY stage not matching, or errors due to the projector itself or the object being measured not being level, can also contribute to measurement errors.
In addition, due to the measurement principle of the profile projectors, the light from the light source to the screen is not parallel. Therefore, if the mirror mounted inside is tilted, there will be a difference in magnification between the center and the edge of the screen. This is called magnification error, and if the magnification error becomes too large, the reliability of measurement values at points off the center of the optical axis will decrease.
*Including some distributors, etc.
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