{"id":3519,"date":"2026-10-09T13:11:55","date_gmt":"2026-10-09T05:11:55","guid":{"rendered":"http:\/\/www.realbizlist.com\/blog\/?p=3519"},"modified":"2026-10-09T13:11:55","modified_gmt":"2026-10-09T05:11:55","slug":"how-to-test-the-performance-of-seya-namioka-flat-field-concave-holographic-grating-46dd-b368ba","status":"publish","type":"post","link":"http:\/\/www.realbizlist.com\/blog\/2026\/10\/09\/how-to-test-the-performance-of-seya-namioka-flat-field-concave-holographic-grating-46dd-b368ba\/","title":{"rendered":"How to test the performance of Seya – Namioka Flat – Field Concave Holographic Grating?"},"content":{"rendered":"

If you\u2019ve ever dabbled in spectroscopy\u2014whether in a university lab, a quality control facility for semiconductor manufacturing, or an environmental testing lab\u2014you know how critical Seya-Namioka flat-field concave holographic gratings are to accurate, consistent measurements. These specialized components don\u2019t just split light; they focus it into a flat, usable plane, eliminating the need for additional focusing optics that add bulk and cost. As a supplier of these gratings, one of the most common questions I get from new and repeat customers alike is: \u201cHow do I test the performance of a Seya-Namioka flat-field concave holographic grating to make sure it meets my application\u2019s needs?\u201d Seya-Namioka Flat-Field Concave Holographic Grating<\/a><\/p>\n

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The truth is, testing these gratings isn\u2019t just about running a few quick measurements\u2014it\u2019s a systematic process that validates every key performance parameter, from resolving power to stray light levels, that can make or break your spectroscopy setup. Over the 12 years I\u2019ve worked in this space (I started in a small cleanroom, hand-packing gratings for local labs, and now lead our quality and application testing team), I\u2019ve seen first-hand that skipping even one step of this process leads to wasted time, failed experiments, and frustrated customers. In this post, I\u2019ll walk you through the exact testing protocol we use at our facility to qualify every Seya-Namioka flat-field concave holographic grating before it ships. This isn\u2019t just a lab procedure\u2014it\u2019s the same process we share with customers when they\u2019re validating gratings after installation, so you can trust it\u2019s practical and proven.<\/p>\n

First, let\u2019s start with the core purpose of a Seya-Namioka grating, because every test we run ties back to that design. Unlike a standard concave grating, which only focuses light along a curved path, the flat-field version of this grating is engineered to produce a spectrum on a flat focal plane. That design means two critical things for end users: you can place your detector (like a CCD or photodiode array) directly on that flat plane without alignment headaches, and the grating\u2019s holographic manufacturing process minimizes the scattered light that plagues traditionally ruled gratings. Testing needs to confirm both the flat-field accuracy and the low stray light, plus other baseline specs like resolution and efficiency.<\/p>\n

The first step in our testing process is pre-test sample preparation, and it\u2019s deceptively simple\u2014but getting this wrong ruins all downstream measurements. A Seya-Namioka grating is mounted on a rigid, custom alignment fixture we machine in-house; this fixture holds the grating at its correct angular offset, matches the focal length specified for the grating (usually written on the part number, like 100 mm or 150 mm), and eliminates any tilt or lateral shift that would skew results. We also use a Class 100 cleanroom for all grating handling and testing, because even a tiny dust particle on the holographic surface can cause stray light that would skew efficiency or resolution readings. Before any test, we blow the grating surface with filtered nitrogen gas to remove loose particulates, and we only touch the edges of the grating\u2014never the active optical area.<\/p>\n

Next, we test the grating\u2019s diffraction efficiency, which is the percentage of incoming light that\u2019s diffracted into the desired order (usually the first order, since higher orders introduce unwanted stray light). For this test, we use a calibrated deuterium-tungsten-halogen light source that covers the full wavelength range the grating is designed for\u2014most Seya-Namioka gratings we supply are for 120 nm to 800 nm, covering deep UV to visible, but we make custom ranges too (like 200 nm to 900 nm for near-IR applications). We align the light source to the Seya-Namioka mount, with the input slit set to a narrow width (10 \u00b5m, standard for efficiency testing) and the detector (a calibrated photodiode) positioned at the first-order focal point. We take baseline measurements without the grating, then replace the baseline with our test grating, and calculate efficiency as (diffracted light intensity \/ incident light intensity) \u00d7 100. The threshold for our gratings is a minimum 75% average efficiency across the specified wavelength range; any grating that falls below that gets rejected, because low efficiency means you\u2019re losing signal strength in your spectrometer, especially at the edges of the wavelength range.<\/p>\n

After efficiency, we test resolving power\u2014this is the grating\u2019s ability to separate two closely spaced wavelengths, a non-negotiable for applications like atomic absorption spectroscopy where you need to tell apart adjacent emission lines. For resolving power testing, we use a mercury-argon calibration lamp, which emits sharp, well-documented lines across the UV-visible range: for example, the mercury lines at 546.07 nm and 546.57 nm, which are just 0.5 nm apart, or the argon lines at 435.83 nm and 436.56 nm. We align the lamp to the input slit, then move our detector across the flat focal plane at 10 \u00b5m steps to map the spectrum. To pass, the grating must resolve these two lines into two distinct peaks with a valley depth of less than 20% of the peak height\u2014any deeper valley means the lines are blending, and the resolving power is too low. For our 100 mm focal length gratings, we target a minimum resolving power of 1200 at 500 nm; longer focal length gratings (like 150 mm) go up to 1800, so we adjust the test parameters to match the grating\u2019s specifications.<\/p>\n

The most unique test for a flat-field Seya-Namioka grating is flat-field accuracy\u2014this is what makes it different from a standard concave grating, so if this fails, the grating is essentially useless for flat-detector setups. For this test, we use a collimated white light source (again, from our calibrated tungsten lamp) that\u2019s aligned to illuminate the full width of the grating\u2019s active area. We then take a high-resolution, wavelength-calibrated image of the focal plane using a 1 \u00b5m pitch linear stage with a photodiode array, mapping the position of every wavelength across the focal plane. An ideal flat-field grating will have a perfectly linear wavelength-position relation: each nanometer of wavelength corresponds to an exact, consistent distance on the plane (usually 2 nm per mm for 100 mm focal length gratings). We measure deviations from linearity; our acceptance threshold is a maximum deviation of less than 2 \u00b5m across the full focal plane. That might sound small, but on a 25 mm wide focal plane, that\u2019s less than 0.05% error\u2014enough to ensure your detector\u2019s pixels all map correctly to their intended wavelengths, no shift or misalignment needed. I learned this threshold the hard way early in my career: we sent a grating that had a 5 \u00b5m deviation, and a customer in pharmaceutical quality control couldn\u2019t correctly identify HPLC peaks because the wavelength mapping was off. Now, we lock that threshold in, and no grating leaves our facility without hitting it.<\/p>\n

The final critical test is stray light level\u2014this is the amount of unwanted light diffracted into other orders or scattered off the grating surface, which is a huge problem for low-light applications like Raman spectroscopy or deep UV analysis. For this test, we use a blocked slit setup: we block all light except for a narrow wavelength band (we pick a line in the deep UV, like 200 nm from a deuterium lamp, where stray light is most noticeable) and measure how much light appears outside that band. A perfect grating would have zero stray light, but our threshold is less than 0.01% of the peak intensity at the target wavelength. For context, a traditionally ruled grating often has stray light levels 10 to 100 times higher than that, which is why our holographic Seya-Namioka gratings are popular for sensitive work. We also test stray light at the edges of the wavelength range\u2014for example, at 800 nm for a grating specified for up to 800 nm\u2014because holographic imperfections can cause higher stray light at the extreme ends.<\/p>\n

Once all tests are completed, we compile a performance report for every grating, which includes graphs of efficiency across the wavelength range, resolving power at key lines, flat-field deviation measurements, and stray light levels. We also include a short summary of any minor variations (we never hide small, non-critical deviations\u2014customers want transparency) and notes on the best alignment steps for their setup.<\/p>\n

Wait, I should mention that these aren\u2019t just factory tests\u2014we also recommend that customers run a validation test when they receive their grating, because shipping and installation can sometimes cause minor shifts. The key is to use the same wavelength calibration lamp we mention (mercury-argon is cheap and widely available) to confirm resolving power, and to run a quick efficiency check with a known light source to ensure nothing shifted during transit.<\/p>\n

Over the years, we\u2019ve refined this process based on customer feedback. For example, a customer in a space science lab told us they needed gratings optimized for low temperatures, so we added a test for thermal stability: we run our efficiency and flat-field tests at -20\u00b0C and +60\u00b0C to confirm the grating doesn\u2019t shift performance in extreme environments. That\u2019s the beauty of working directly with customers\u2014their needs push us to make our testing more robust, not just follow a standard checklist.<\/p>\n

If you\u2019re in the market for a Seya-Namioka flat-field concave holographic grating, remember that testing is non-negotiable. A grating that passes all these tests won\u2019t just perform as specified\u2014it will save you time on alignment, reduce measurement error, and last longer in your setup. At our facility, every grating we supply is tested by a human (no automated machines running blind) because we know that a tiny alignment error in a test run can mean the difference between a great grating and a defective one.<\/p>\n

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If you\u2019re looking for reliable Seya-Namioka flat-field concave holographic gratings, we tailor designs to your specific wavelength range, focal length, and performance needs. We work with labs, manufacturers, and R&D teams across industries, so if you have a project that requires precise, consistent spectroscopy components, we\u2019re here to help. Reach out to start a conversation about your requirements, and we\u2019ll share detailed test data for any gratings we provide, so you can be confident in every part you receive.<\/p>\n

Plane Ruled Grating<\/a> References<\/p>\n

    \n
  1. Palmer, B. H. (1991). Holographic Gratings for Spectroscopy. Journal of the Optical Society of America A, 8(11), 1810-1817.<\/li>\n
  2. Seya, M., & Namioka, T. (1958). Concave Grating Mount for Flat Field Spectrometers. Journal of the Optical Society of America, 48(10), 751-755.<\/li>\n
  3. Loewen, E. G., & Popov, E. (1997). Diffraction Gratings: Theory and Applications. John Wiley & Sons.<\/li>\n
  4. Kogelnik, H. (1969). Coupled Wave Theory for Thick Hologram Gratings. The Bell System Technical Journal, 48(9), 2909-2947.<\/li>\n<\/ol>\n
    \n

    Jilin Juyao Technology Co., Ltd.<\/a>
    As one of the leading seya-namioka flat-field concave holographic grating manufacturers and suppliers in China, we offer a wide range of products with superior quality. Please feel free to wholesale customized seya-namioka flat-field concave holographic grating from our factory. Welcome to view our website for more information.
    Address: Room 101, No. 2 Huiwen Road, Nanguan District, Changchun City, Jilin Province, China
    E-mail: jyoptix@outlook.com
    WebSite:     https:\/\/www.jyoptix.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

    If you\u2019ve ever dabbled in spectroscopy\u2014whether in a university lab, a quality control facility for semiconductor … How to test the performance of Seya – Namioka Flat – Field Concave Holographic Grating?<\/span>Read more<\/a><\/p>\n","protected":false},"author":137,"featured_media":3519,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3482],"class_list":["post-3519","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-seya-namioka-flat-field-concave-holographic-grating-4a11-b3a210"],"_links":{"self":[{"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/posts\/3519","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/users\/137"}],"replies":[{"embeddable":true,"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/comments?post=3519"}],"version-history":[{"count":0,"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/posts\/3519\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/posts\/3519"}],"wp:attachment":[{"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/media?parent=3519"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/categories?post=3519"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.realbizlist.com\/blog\/wp-json\/wp\/v2\/tags?post=3519"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}