Proposal of a lens that solves the out-of-focus problem that occurs during oblique imaging in visual inspection of substrates and foreign matter
In the visual inspection of substrates and foreign matter, the lens is normally placed perpendicular to the workpiece (object surface). However, depending on the usage conditions and environment, when imaging with the lens axis oblique to the workpiece, there is a limit to the depth of field even if the aperture is adjusted, so there are cases where the entire image is out of focus. .
1. The reason why it is out of focus when shooting at an angle
The reason why the focus is not correct is that the subject is not at the same distance from the lens. This is because the point of focus differs between the far point and the near point.
2. Proposal of a tilt lens that applies the Scheimpflug principle
In response to the above problem, we propose a tilt lens that applies the Scheimpflug principle that can focus on the far point and the near point.
2-1. Scheimpflug principle
The film plane and lens principal plane are mounted parallel in a normal camera, and the film plane and lens principal plane never intersect. However, if the film surface and the lens principal surface are not parallel, the object surface will not be parallel. At this time, the principle of Scheimpflug is that the film plane, the principal plane of the lens, and the object plane intersect on the same line as shown in the figure. Since the object plane is not parallel to the principal plane of the lens, a camera that applies the Scheimpflug principle can focus both near and far objects at the same time.
3. Thorlabs offers telecentric and macro lenses with tilt capability as standard.
In recent years, the demand for projects that require oblique imaging has increased due to the downsizing of equipment and the diversification of workpiece imaging surfaces, and the need for this is also increasing. We have a wealth of experience in custom-made lenses that incorporate a tilt structure based on the Scheimpflug principle. We propose high-quality, low-cost, short-delivery solutions based on our unique know-how cultivated over the years. In addition, the standard products of "Opto Engineering", which we serve as a sales agent in Japan, offer two models of special optical system lenses with a variable tilt function.
For the above two products, we are also lending demonstration machines. For customers who are considering oblique imaging, first evaluate here, and even if you are not satisfied with the results, our staff will interview you and custom-made according to your needs. We also accept.
