In the Spotlight: Graticules, Gratings & Resolution Charts18th Jul 2022
Knight Optical supplies a wide range of optical components to industries worldwide. This month, the leading supplier of metrology-tested optics shines a light on three components that are rising in popularity amongst its client base.
Although they’re utilised for a diverse range of uses, most varieties of these optics share one commonality. Besides the precision of all three types, most Gratings, Graticules and Resolution Charts typically include patterns and are highly sought after for optical testing purposes. Dependent on the component in question (and, of course, its end application), these markings serve several roles, such as within testing devices or as weapon sights or range-finding purposes, for example.
Here, we break down each component and run through their main characteristics and traditional uses in today’s sectors.
Here at Knight Optical, we offer two main types of Gratings – Bar Gratings and Diffraction Gratings. Let’s look at the difference between both and explore what makes them suitable for different applications.
Normally, you can find Bar Gratings employed in optical testing situations, such as in a Ronchi Test operation, which is conducted to check the quality of optical components. Here, Bar Gratings are used in combination with a diffuser and a light source to perform tests successfully and accurately.
Bar Gratings are customarily manufactured from a high-quality glass substrate and feature a chromium-based pattern that depicts equally placed bars and blank spaces. The lines that these bars and spaces generate provide the perfect sharp contrast and edge definition for Ronchi mirror testing.
Bar Gratings from Knight Optical
We have an array of readily-available Bar Gratings – which, like all our stock optics, are available for next-day dispatch. Offered with ruling between 2 lines/mm to 125 lines/mm, our stock Bar Gratings are supplied as 1.5mm-thick, 50mm squares.
Click here to view our stock range of Bar Gratings.
We also offer a customisable option for those who require a more bespoke approach to specifying Bar Gratings. Whether you’re looking for an alternative substrate, a specific dimension that’s not listed on our site or a particular optical coating to enhance the performance of your application, our custom-made Bar Gratings can be manufactured to meet your exact requirements.
Find out more about our custom-made Bar Gratings here.
As the name suggests, a Diffraction Grating diffracts light into different beams that span various directions. Usually, a Diffraction Grating is employed when an application requires a component that divides white light into its component wavelengths. For example, they’re particularly useful for lasers and spectrometers.
Diffraction Gratings from Knight Optical
We offer three varieties of Diffraction Gratings – either from stock or as custom-made options.
Commercial Diffraction Gratings
You can choose from four grades of Commercial Diffraction Gratings. These include 100, 200, 300 and 600 lines/mm with an aperture size of 45 x 30m. Often used in straightforward demonstrations, these optics comprise cost-effective transmission replicas mounted between glass plates and are sealed around all four edges.
For more information on our Commercial range, please click here
Holographic Diffraction Gratings
Compared to our ruled option (which we’ll get onto next), Holographic Diffraction Gratings have lower stray-light levels and are available with closer rulings. Thanks to these individualities and the high performance of these gratings, they’re ordinarily used for spectroscopy applications – particularly in the instrumentation and medical testing sector.
Our Holographic Diffraction Gratings are available in both customisable options and from a range of stock.
Ruled Research Diffraction Gratings
Exceptionally popular for near-infrared (NIR) and infrared (IR) applications, Ruled Research Diffraction Gratings feature wider line spacing compared to other types. At Knight Optical, we have a selection of these components available from our in-house catalogue in various blaze angles and a choice of groove dimensions.
Find out more about our stock range here.
Our second component in our spotlight trio is the Graticule. Much like Gratings, these are photolithographically printed with individual patterns. These markings include popular examples such as crosshairs and scales, which support sighting applications by enabling the viewer to measure things like distance and objects within a specified area (commonly cells when employed for microscopy purposes). Thanks to these advantageous features, you can naturally find Graticules in the military and defence industries as well as the healthcare sector.
At Knight Optical, we offer two types of Graticules.
These optics are generally prevalent in the military and are used for gunsights, scopes, and other ranging systems. Outside this sector, they are also used in magnification devices, like loupes. Here, prints like circles, lines and other linear markings are valuable for enhancing vision within end applications. What’s more, when ordering custom-made Eyepiece Graticules from Knight Optical, you can specify bespoke, project-specific patterns as well as personalised sizes and substrates. Of course, as well as our customisable options, we also have a range of Eyepiece Graticules available to order from stock, too.
Click here to scroll through our stock range.
Alongside microscopy, Stage Graticules also play a role in video imaging applications and typically feature a linear dimension pattern for measuring purposes. Much like Eyepiece Graticules, they can also be found in magnifiers and similar handheld measuring tools.
Supplied at 1.5mm thick in 76mm x 25mm glass substrate forms, our catalogue of Stage Graticules is readily available with limited pattern options for next-day dispatch. For projects requiring a tailored strategy, our custom-made alternative may be a better option.
The last in our line-up, Resolution Charts are best known for their use in optical testing arrangements – specifically analysing the resolving power of microscopes used in medical and laboratory environments. They’re also recognised in other commercial and military settings, such as scanners and imaging cameras.
Featuring a variety of metallic patterns, our Stock Resolution Charts are available in an assortment of options, including USAF 1951 0-7, NBS 1963A and Cobb (BS1613) charts. Click here to view the full range.
For bespoke options, such as optical coatings and pattern options, click here to discover more about our Custom-Made Resolution Charts.
Why Choose Knight Optical for your Application?
Discerning customers rely on Knight Optical not only for the premium quality of our output and in-house state-of-the-art Metrology Laboratory and QA Department’s capabilities but because – as well as a range of Stock Optics (available for next-day dispatch) – we also offer our optics as Custom-Made Components.
Last year, we celebrated 30 years in business. With over three decades’ experience under our belt and a whole host of long-standing world-renowned customers on our books, we are proud to have worked on some of the most ground-breaking innovations.
If you are looking for premium-quality, bespoke optical components, please do not hesitate to get in touch with a member of the Technical Sales Team here.
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