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Understand the Difference Between Stock and Custom Gratings

July 9, 2020

What Are Diffraction Gratings?

Diffraction gratings are passive optical components that redirect—i.e., diffract—light incident upon the surface at an angle that is unique to each wavelength in a given order. This process separates the light into its various wavelengths. Typical applications include use in spectrometers, lasers, and other optical instruments for chemical analysis, educational activities, research operations, and more.

Grating Efficiency Curves

There are two types of diffraction gratings and two methods of producing them, both of which involve a soft metallic coating whose surface is formed by a precision forming tool. The manufacture of ruled gratings requires the diamond tool method, while production operations for holographic gratings use the photolithographic method. When produced properly, ruled diffraction gratings exhibit sharp peaks around their blaze wavelengths and holographic diffraction gratings offer flatter spectral responses. An application’s specific parameters, such as polarization, wavelength, and angles of incidence, usually dictates which type of diffraction grating is best suited to that specific application. At OPCO Laboratory, Inc., we have a number of existing holographic masters; our main focus is on creating high-quality ruled diffraction gratings.

What Are Diffraction Grating Masters and Replications?

In the late 1940s, a process was developed that allowed for multiple diffraction gratings to be precisely replicated from a single grating. The initial grating is referred to as the master grating. During the replication process, the shape, size, and topographical features of the master grating is transferred onto another substrate to tight tolerances, producing a near-perfect replica.

The term “replication” refers to the process of creating a diffraction grating that is a replica of a grating master, either from a new custom-made master or from a pre-existing grating master. These new replica gratings are intended to be as close to an exact copy of the original master as possible. The key to good replication is fidelity from part to part, which ensures that the replicated grating will suit the same applications and maintain the same high performance as its parent master. At OPCO Laboratory, Inc., we can create replications from existing in-stock grating masters, or help to create a new custom grating master for unique applications.

Stock vs Custom Grating

Replicated Diffraction Gratings from Existing Grating Masters

Although many existing, or stock, diffraction grating masters are based on designs produced decades ago, they remain in use today. The replica diffraction gratings produced from them typically find application in spectrometers, monochromators, and other optical instruments that employ components of standard shapes and sizes. They are ideal for generating diffraction gratings intended for applications that demand both lower costs and higher efficiency. Using an existing, stock grating master eliminates the need for custom tooling and lowers the cost associated with creating gratings.

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Benefits of Using Custom Diffraction Gratings

As with all custom products, custom diffraction gratings present several advantages over using existing masters. Many stock grating masters are decades-old and may or may not suit the more modern specifications needed for a unique application today. Investing in a custom diffraction grating master allows industry professionals to produce custom diffraction gratings that perfectly suit needs for parameters such as tuned groove frequency, blaze or dual blaze wavelength, and other precise characteristics.

Ruled Diffraction Gratings Engine

Our new state-of-the-art ruling engine allows us to quickly and cost-effectively produce custom grating masters for ruled diffraction gratings and generate replications from them. When replicated, the gratings achieved exhibit higher efficiency, lower amounts of scattered light, no periodic errors, and zero ghosts.

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High-Quality Custom Grating Masters and Grating Replications From OPCO Laboratory, Inc.

Diffraction gratings are suitable for facilitating reflection or transmission on a variety of materials. The gratings used must be well-suited to the parameters of the intended application to demonstrate optimal performance. At OPCO Laboratories, Inc., we specialize in creating ruled diffraction gratings from our master grating library, as well as creating new custom grating masters to suit more precise optical applications. Our experts can help you choose which type of grating is best suited to your project’s unique needs.

For high-quality gratings, turn to the experts at OPCO Laboratory, Inc. To find out more about our grating capabilities or discuss your unique project’s grating requirements, contact us today.