Profile projector | Profile projector

Key Words: parfocal, edge detection, Telecentricity, episcopic illumination, diascopic illumination

Definition:A profile projector (optical comparator / shadowgraph) is an optical measurement tool that magnifies a sample’s surface features to allow measurement on a linear/circular scale

TECHNOLOGY:

A profile projector projects a magnified profile image of an area or feature of a workpiece onto a screen, most commonly using diascopic illumination. Dimensions can be measured directly on the screen or compared to a standard reference at the correct magnification. For accuracy, it is important that the magnification does not change with perspective, i.e. its position or the view point of the operator. Telecentric lenses are, therefore, highly desirable. The screen often has a grid and this grid can often be rotated through 360 degrees to align with an edge as displayed on the screen. Point positions, measurements, and calculations may also be performed using a simple digital read out device. Episcopic lighting is used to measure features such bores, bosses, pockets, pads etc, which would not be revealed on a profile view. A computer may be added to a profile projector system for edge determination, thereby eliminating some human error.

APPLICATIONS:

Profile projectors are robust measuring tools commonly used in machine shops, quality assurance departments and occasionally on assembly shop floors. They are suitable for measuring and quality control for a wide range of size and weights of objects. The most basic use of a profile projector is to identify a point or edge on the shadow and from this point to calculate a length. By magnifying the image, the operator is less likely to make a mistake when deciding where the edge or point starts. Profile images can also be used to make simple stop / go decision by, for example, matching an image against a standard to determine whether a part has been made correctly.

MICROSCOPE CONFIGURATION:

Nikon’s V20-B, 20-inch profile projector and V12-B series 12-inch profile projectors are robust instruments capable of accommodating a large range of workpieces (up to 20kg for the V20-B, while both series accommodate measurements of 250 x 150 mm. A built in digital readout and protractor are a feature of the V20-B andV-12BDC and 12BSC instruments. The V-20B profile projector offers 5x – 20x telecentric lenses and the V-12B series offers 200x and 500x telecentric lenses. All projection lenses have the same parfocal distance, feature long working distances and offer improved image brightness and resolution. Profile projectors can be combined with a DP-E1 processor. This incorporates a suite of metrology functions, with the ability to load previous programs.

RECOMMENDED SYSTEM:

Please talk to your Nikon representative for advice on the system most closely matched to your needs.