Take you to know the optical prism

Jun. 17, 2019

The prism is a solid glass optics that has been sanded and polished to a geometrically and optically distinct shape. The angle, position, and number of optical flats help define the type and function. One of the most recognized prisms used by Sir Isaac Newton demonstrates the dispersion of a white light source into the color of its components (Figure 1).

Take you to know the optical prism

Devices that utilize this application are refractometers and spectral components. As a result of this initial discovery, prisms have been used in systems to "refractive" fibers, "folding" the system into a smaller space, changing the direction of the image (also known as spin or co-position), and merging or splitting the beam. Partially reflective surface. These uses are very common in the use of telescopes, magnifiers, measuring instruments and many other applications.

A distinguishing feature of the prism is its ability to mimic a light reflection in a prismatic medium as a flat mirror system. Replacing the mirror assembly is probably the most useful prism application because they both refract or fold the light and change the image to the same position. To achieve the effect of a single prism, it is often necessary to use multiple mirrors. Therefore, replacing a few mirrors with a single prism reduces potential calibration errors, improves accuracy, and reduces the size and complexity of the system.


Prism manufacturing

Before delving into the prism theory, consider the manufacturing process.To be successful in most applications, prisms must be manufactured to very strict tolerances and accuracy.Due to variations in shape, size, and number of most important reflectors, large-scale automated processes are simply not feasible for prism manufacturing.In addition, most high-precision prisms tend to be manufactured in small quantities, meaning that automated processes are unnecessary.

First, obtain a piece of glass (called "glass blank") that conforms to a particular grade and type of glass.The glass is then ground, or a metal diamond grinding wheel is used to produce a nearly finished product.Most glass is removed from this stage to form a flat but still rough surface (figure 2a).

Take you to know the optical prism

At this point, the dimensions of the soon-to-be prism are very close to the required specifications.Next, a fine grinding process to remove subsurface cracks in the surface;This stage is called fine grinding.Scratches from the first phase will be removed in the second phase (figure 2b).After fine grinding, the glass surface should appear cloudy and opaque.In the first two stages, the prismatic surface must be damp in order to speed up the removal of the glass and prevent the glass itself from overheating.

Take you to know the optical prism

The third stage involves polishing the prism to the specified precision according to the specification.In this stage, the glass will be rubbed against a polyurethane polisher moistened with a "grinding slurry", which is an optical polishing compound that usually contains a mixture of water and pumice or cerium oxide (figure 2c).

Take you to know the optical prism

The exact timing of the polishing phase depends heavily on the required mirror size.Once finished, chamfering begins.In this fourth stage, the edge of the prism will be slightly blunted by a rotating SLATE (figure 2d).After chamfering, the finished prism will be cleaned, checked (both manually and automatically), and, where necessary, reverse-reducing (AR) and/or metal-reflecting coatings will be applied to further help improve overall transmittance and/or reflectivity.

Take you to know the optical prism

During the manufacture of the prism, each mirror in progress needs to be continuously adjusted and fixed.Fixing the prism in place involves one of two methods: blocking and contact.Prevents the need to align the prisms in a metal tool for injecting hot wax.Contact, on the other hand, is an optical bonding process at room temperature that binds two clean glass surfaces together through its van der Waals interaction.The contact method is used when high precision tolerances are required because it does not require other adjustments during the generation, smoothing, or polishing phase to take into account the wax thickness between the prism surface and the contact block.

A skilled optometrist is required to manually inspect and adjust the prism surface being processed at every stage of the prism manufacturing process, from generation to blocking and contact.Therefore, it requires a very large injection of labor and requires experience and skill to complete.The whole process usually requires a considerable amount of time, work, and focus.



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