{"id":2752,"date":"2026-08-06T01:29:38","date_gmt":"2026-08-06T01:29:38","guid":{"rendered":"https:\/\/www.sapphire-windows.com\/?p=2752"},"modified":"2026-08-06T01:29:46","modified_gmt":"2026-08-06T01:29:46","slug":"sapphire-window-clear-aperture-and-edge-exclusion-how-to-specify-the-usable-optical-area","status":"publish","type":"post","link":"https:\/\/www.sapphire-windows.com\/pt\/sapphire-window-clear-aperture-and-edge-exclusion-how-to-specify-the-usable-optical-area\/","title":{"rendered":"Sapphire Window Clear Aperture and Edge Exclusion: How to Specify the Usable Optical Area"},"content":{"rendered":"<p class=\"wp-block-paragraph\">A sapphire window may have a precisely controlled outside diameter, thickness and polished surface, but this does not mean that every part of the component can be used as an optical area.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The region near the perimeter may contain an edge bevel, mounting contact, coating transition, polishing roll-off or allowable cosmetic imperfections. For this reason, optical drawings commonly distinguish between the full physical size of the sapphire window and the smaller area over which the optical specifications must be satisfied.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This usable optical region is generally called the <strong>abertura livre<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Clear aperture is the diameter or area of an optical component that must meet the specified optical requirements. The selected clear aperture can directly affect manufacturing difficulty, testing strategy, cost and production lead time.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Para <a href=\"https:\/\/www.sapphire-windows.com\/pt\/product-category\/sapphire-windows\/\">janelas de safira personalizadas<\/a>, buyers should specify the clear aperture, edge exclusion and coating aperture as separate requirements. Without this information, the manufacturer may not know whether flatness, surface quality, transmitted wavefront, coating performance and cosmetic limits apply across the entire polished surface or only within a smaller central area.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.sapphire-windows.com\/wp-content\/uploads\/2026\/08\/Sapphire-Window-Clear-Aperture-and-Edge-Exclusion-1024x768.png\" alt=\"\" class=\"wp-image-2753\" srcset=\"https:\/\/www.sapphire-windows.com\/wp-content\/uploads\/2026\/08\/Sapphire-Window-Clear-Aperture-and-Edge-Exclusion-1024x768.png 1024w, https:\/\/www.sapphire-windows.com\/wp-content\/uploads\/2026\/08\/Sapphire-Window-Clear-Aperture-and-Edge-Exclusion-300x225.png 300w, https:\/\/www.sapphire-windows.com\/wp-content\/uploads\/2026\/08\/Sapphire-Window-Clear-Aperture-and-Edge-Exclusion-768x576.png 768w, https:\/\/www.sapphire-windows.com\/wp-content\/uploads\/2026\/08\/Sapphire-Window-Clear-Aperture-and-Edge-Exclusion-16x12.png 16w, https:\/\/www.sapphire-windows.com\/wp-content\/uploads\/2026\/08\/Sapphire-Window-Clear-Aperture-and-Edge-Exclusion-600x450.png 600w, https:\/\/www.sapphire-windows.com\/wp-content\/uploads\/2026\/08\/Sapphire-Window-Clear-Aperture-and-Edge-Exclusion.png 1448w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">What Is the Clear Aperture of a Sapphire Window?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The clear aperture is the defined portion of the sapphire window through which the optical beam is intended to pass and within which the required optical specifications must be met.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Depending on the application, the clear aperture may be expressed as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>A percentage of the outside diameter<\/li>\n\n\n\n<li>A specific diameter<\/li>\n\n\n\n<li>A rectangular length and width<\/li>\n\n\n\n<li>A distance from each finished edge<\/li>\n\n\n\n<li>A custom shape defined on the drawing<\/li>\n\n\n\n<li>A region referenced to a mechanical datum<\/li>\n\n\n\n<li>An off-center aperture aligned with the optical axis<\/li>\n\n\n\n<li>Multiple separated optical zones<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">For example, a round sapphire window with an outside diameter of 50 mm might have a clear aperture specified as:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Clear aperture: \u00d846 mm minimum, concentric with outside diameter<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This means that the optical requirements apply within the specified 46 mm circular region. The remaining annular area between the clear aperture and the physical edge is outside the primary usable optical zone.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For a rectangular window, the requirement may instead be written as:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Clear aperture: 36 mm \u00d7 56 mm minimum, centered within a 40 mm \u00d7 60 mm window<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The exact clear aperture should be selected according to the optical beam size, alignment tolerance, mounting design and inspection method rather than copied from an unrelated component.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Clear Aperture Is Not the Same as Outside Dimension<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The outside dimension defines the physical size of the sapphire part.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The clear aperture defines the region that must satisfy specified optical performance.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">These two dimensions serve different purposes.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The outside diameter or rectangular outline may be controlled for:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Housing fit<\/li>\n\n\n\n<li>Mechanical alignment<\/li>\n\n\n\n<li>Gasket compression<\/li>\n\n\n\n<li>Colagem com adesivo<\/li>\n\n\n\n<li>Retaining-ring assembly<\/li>\n\n\n\n<li>Brazing or metallization<\/li>\n\n\n\n<li>Structural load distribution<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The clear aperture may be controlled for:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Transmiss\u00e3o \u00f3tica<\/li>\n\n\n\n<li>Qualidade da superf\u00edcie<\/li>\n\n\n\n<li>Planicidade da superf\u00edcie<\/li>\n\n\n\n<li>Erro de frente de onda transmitida<\/li>\n\n\n\n<li>Coating reflectance<\/li>\n\n\n\n<li>Cosmetic defect limits<\/li>\n\n\n\n<li>Imaging performance<\/li>\n\n\n\n<li>Laser-beam passage<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">A sapphire window can therefore meet its outside diameter tolerance while failing the clear-aperture requirements, or meet its central optical requirements while containing acceptable non-functional imperfections near the perimeter.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Both regions should be clearly defined on the purchase drawing.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What Is Edge Exclusion?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Edge exclusion is the band between the physical perimeter of the sapphire window and the boundary of the clear aperture or inspection area.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For a round part, the relationship can be understood as:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Edge exclusion per side = (outside diameter \u2212 clear-aperture diameter) \u00f7 2<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Por exemplo:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Outside diameter: 50 mm<\/li>\n\n\n\n<li>Clear-aperture diameter: 46 mm<\/li>\n\n\n\n<li>Edge exclusion: 2 mm per side<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">For a rectangular component, edge exclusion may be specified independently for each side.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A rectangular sapphire window may have:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>2 mm exclusion on the long edges<\/li>\n\n\n\n<li>3 mm exclusion on the short edges<\/li>\n\n\n\n<li>A larger exclusion near a mounting feature<\/li>\n\n\n\n<li>A custom exclusion around a hole or notch<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Edge exclusion should not automatically be interpreted as a defective region. It is usually a controlled non-clear-aperture area in which different acceptance criteria may apply.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Why Is an Edge Exclusion Necessary?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The edge region of a sapphire window is affected by several manufacturing and assembly conditions that do not normally occur in the center of the optical surface.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Edge Bevels and Chamfers<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Most sapphire windows require some form of edge break, bevel or chamfer to reduce sharp-edge damage and improve handling.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The bevel occupies part of the physical diameter and cannot normally be treated as a usable optical surface. The clear aperture should stop before the bevel begins.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If the clear aperture is specified too close to the finished perimeter, the manufacturer may need to control optical quality directly beside the bevel, which can significantly increase processing and inspection difficulty.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Polishing Edge Effects<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The polishing process can behave differently near the perimeter than in the central region.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Possible edge-related effects include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Surface roll-off<\/li>\n\n\n\n<li>Local flatness change<\/li>\n\n\n\n<li>Reduced polishing stability<\/li>\n\n\n\n<li>Edge-zone scratches<\/li>\n\n\n\n<li>Small chips at the bevel transition<\/li>\n\n\n\n<li>Uneven material removal<\/li>\n\n\n\n<li>Difficulty supporting thin components<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Requiring full optical specifications extremely close to the edge may increase the number of polishing steps, reduce manufacturing yield and require more specialized tooling.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">ZYGO notes that clear-aperture design can have a substantial effect on the cost and lead time of demanding optical windows.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Coating Transition<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Anti-reflection, conductive or protective coatings may not remain uniform at the extreme edge of the sapphire window.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The outer region may contain:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Coating runout<\/li>\n\n\n\n<li>Masking marks<\/li>\n\n\n\n<li>Thickness transition<\/li>\n\n\n\n<li>Fixture contact<\/li>\n\n\n\n<li>Overspray<\/li>\n\n\n\n<li>Uncoated mounting area<\/li>\n\n\n\n<li>Edge-bead effects<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The coated optical aperture may therefore be smaller than the polished clear aperture.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Mounting and Sealing<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A housing, gasket, adhesive or retaining ring often covers part of the sapphire perimeter. The covered area does not need to function as an optical aperture, but it may require separate mechanical or cosmetic controls.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The drawing should distinguish between:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Optical clear aperture<\/li>\n\n\n\n<li>Sealing area<\/li>\n\n\n\n<li>Adhesive-bonding area<\/li>\n\n\n\n<li>Metallized area<\/li>\n\n\n\n<li>Mechanical contact zone<\/li>\n\n\n\n<li>Non-functional outer edge<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Clear Aperture and Optical Specifications<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The clear aperture should identify exactly where each optical requirement applies.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Typical requirements controlled within the clear aperture include:<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Qualidade da superf\u00edcie<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Surface-quality limits define acceptable scratches, digs and other localized imperfections.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">ISO 10110-7 specifies methods for indicating acceptable surface imperfections within a defined test region, including localized imperfections, scratches and edge chips. The standard applies to finished transmitting and reflecting surfaces, whether coated or uncoated.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A drawing should make clear whether the surface-quality requirement applies to:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The complete polished surface<\/li>\n\n\n\n<li>The clear aperture only<\/li>\n\n\n\n<li>The clear aperture with a separate outer-zone criterion<\/li>\n\n\n\n<li>Multiple optical zones with different requirements<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Por exemplo:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Clear aperture: 20-10 scratch-dig<\/li>\n\n\n\n<li>Outside clear aperture: 40-20 scratch-dig<\/li>\n\n\n\n<li>Bevel: visual workmanship standard<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This type of zoning can reduce unnecessary manufacturing cost while protecting the functional optical region.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Nivelamento da superf\u00edcie<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Surface flatness is usually evaluated over a specified test aperture.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If the drawing states only \u201cflatness \u03bb\/4\u201d but does not define the test area, the supplier may not know whether the requirement applies over:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The full outside diameter<\/li>\n\n\n\n<li>The clear aperture<\/li>\n\n\n\n<li>A reduced central diameter<\/li>\n\n\n\n<li>Several local subapertures<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The test aperture should be compatible with the actual beam footprint and the available interferometric inspection setup.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Transmitted Wavefront Error<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">For imaging, laser and precision sensor applications, the sapphire window may require a transmitted wavefront specification.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">ISO 10110-14 provides drawing rules for specifying permissible wavefront deformation of optical elements and assemblies.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The specified test aperture, wavelength, incidence angle and measurement configuration should be stated because transmitted wavefront performance depends on how the window is evaluated.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Modern interferometric systems can separately characterize properties such as surface flatness, physical thickness variation, parallelism and transmitted wavefront error in plane-parallel windows.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Coating Performance<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Reflectance or transmission requirements should be tied to a defined coating aperture.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A coating specification may apply over:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The same area as the optical clear aperture<\/li>\n\n\n\n<li>A slightly larger area than the clear aperture<\/li>\n\n\n\n<li>A superf\u00edcie totalmente polida<\/li>\n\n\n\n<li>A smaller central region<\/li>\n\n\n\n<li>One side only<\/li>\n\n\n\n<li>Both major surfaces<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The drawing should also define whether coating performance is tested at normal incidence or at a specified angle.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Clear Aperture, Coating Aperture and Mechanical Aperture<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">These three apertures are often confused.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Abertura livre<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The surface area over which the specified optical quality must be achieved.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Coating Aperture<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The region over which the coating must meet its reflectance, transmission, uniformity or electrical requirements.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Mechanical Aperture<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The physical opening in the housing, retaining structure or sealing component through which light can pass.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">These regions may be the same, but they do not have to be.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Por exemplo:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Sapphire outside diameter: 50 mm<\/li>\n\n\n\n<li>Polished clear aperture: 46 mm<\/li>\n\n\n\n<li>Coating aperture: 47 mm<\/li>\n\n\n\n<li>Housing opening: 44 mm<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">In this example, the coating extends beyond the usable optical beam, while the housing masks the outer portion of the clear aperture.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This arrangement provides alignment margin and reduces the risk that coating transition or edge effects enter the system\u2019s field of view.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">How Much Larger Should the Clear Aperture Be Than the Beam?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The optical beam should not normally be designed to fill the clear aperture exactly.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Additional margin may be needed for:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Assembly decenter<\/li>\n\n\n\n<li>Beam movement<\/li>\n\n\n\n<li>Angular misalignment<\/li>\n\n\n\n<li>Expans\u00e3o t\u00e9rmica<\/li>\n\n\n\n<li>Housing tolerances<\/li>\n\n\n\n<li>Field-of-view variation<\/li>\n\n\n\n<li>Vibra\u00e7\u00e3o<\/li>\n\n\n\n<li>Manufacturing variation<\/li>\n\n\n\n<li>Inspection uncertainty<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The correct margin depends on the optical system and should be calculated by the equipment designer.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The sapphire manufacturer can confirm whether the requested clear aperture is manufacturable, but the supplier cannot determine the system\u2019s required beam margin without information about the final assembly.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Clear Aperture for Round Sapphire Windows<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Round sapphire windows are commonly specified using one of two methods.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Percentage Method<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Exemplo:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Clear aperture: \u226590% of outside diameter<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This method is simple but can become ambiguous when applied to different part sizes.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For a 10 mm window, 90% clear aperture leaves only 0.5 mm edge exclusion per side. For a 100 mm window, the same percentage leaves 5 mm per side.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The manufacturing implications are therefore very different.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Direct-Dimension Method<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Exemplo:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Clear aperture: \u00d846 mm minimum<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A direct dimension usually provides a clearer inspection requirement.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The drawing should also state whether the clear aperture must be concentric with:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>O di\u00e2metro exterior<\/li>\n\n\n\n<li>The mechanical mounting diameter<\/li>\n\n\n\n<li>A central hole<\/li>\n\n\n\n<li>The coating aperture<\/li>\n\n\n\n<li>The defined optical axis<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Clear Aperture for Rectangular Sapphire Windows<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Rectangular windows should define both the aperture size and its location.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Possible drawing notes include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Clear aperture centered on outside dimensions<\/li>\n\n\n\n<li>Equal edge exclusion on all four sides<\/li>\n\n\n\n<li>Different exclusions on long and short edges<\/li>\n\n\n\n<li>Aperture referenced to datum edges<\/li>\n\n\n\n<li>Aperture offset from the mechanical center<\/li>\n\n\n\n<li>Rounded-corner clear aperture<\/li>\n\n\n\n<li>Clear aperture excluding holes, slots or notches<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">A requirement such as \u201c90% clear aperture\u201d may be unclear for a rectangular part because it does not explain whether 90% applies to length, width or total surface area.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A dimensional callout is normally more practical:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Clear aperture: 46 mm \u00d7 26 mm minimum, centered within the finished outline<\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Clear Aperture Around Holes and Cutouts<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A sapphire window may include precision holes, slots or notches inside or near the optical area.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The drawing should define whether these features are:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Outside the optical aperture<\/li>\n\n\n\n<li>Inside the clear aperture<\/li>\n\n\n\n<li>Excluded from the optical inspection area<\/li>\n\n\n\n<li>Surrounded by a local exclusion zone<\/li>\n\n\n\n<li>Required to meet separate edge-quality criteria<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">For example, a drilled hole may require a 0.5 mm exclusion band around its perimeter. The surface-quality and flatness requirements may then apply to the remaining clear optical area but not directly at the hole edge.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Without a defined local exclusion zone, the supplier may incorrectly assume that the same optical criteria apply immediately adjacent to the machined opening.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Edge Chips and the Clear Aperture Boundary<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Edge chips require special attention because their acceptability depends on location.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A chip at the outside bevel may be cosmetic or mechanically acceptable if it remains outside the sealing area.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A similar chip extending into the clear aperture may interfere with:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Beam transmission<\/li>\n\n\n\n<li>Imaging<\/li>\n\n\n\n<li>Scattering<\/li>\n\n\n\n<li>Coating continuity<\/li>\n\n\n\n<li>Structural strength<\/li>\n\n\n\n<li>Veda\u00e7\u00e3o herm\u00e9tica<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">ISO 10110-7 includes edge chips among the surface imperfections that can be controlled within a defined test region.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A practical drawing can define separate limits for:<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li>Chips entering the clear aperture<\/li>\n\n\n\n<li>Chips contained within the edge-exclusion zone<\/li>\n\n\n\n<li>Chips located on the bevel<\/li>\n\n\n\n<li>Chips located in the sealing area<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">The acceptance criteria should include maximum size, quantity and location.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Inspection of Clear Aperture<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Inspection should confirm both the optical quality and the physical position of the clear aperture.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Inspe\u00e7\u00e3o visual<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Controlled lighting and magnification can be used to evaluate:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Scratches<\/li>\n\n\n\n<li>Digs<\/li>\n\n\n\n<li>Chips de borda<\/li>\n\n\n\n<li>Defeitos no revestimento<\/li>\n\n\n\n<li>Part\u00edculas<\/li>\n\n\n\n<li>Stains<\/li>\n\n\n\n<li>Aperture-boundary defects<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The test region and lighting conditions should be agreed when cosmetic limits are important.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Inspe\u00e7\u00e3o dimensional<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A vision-measuring system or measuring microscope can verify:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Clear-aperture diameter<\/li>\n\n\n\n<li>Aperture location<\/li>\n\n\n\n<li>Concentricidade<\/li>\n\n\n\n<li>Edge-exclusion width<\/li>\n\n\n\n<li>Coating-mask position<\/li>\n\n\n\n<li>Relationship to holes and mechanical datums<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Interferometric Inspection<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Interferometry may be used to evaluate:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Planicidade da superf\u00edcie<\/li>\n\n\n\n<li>Erro de frente de onda transmitida<\/li>\n\n\n\n<li>Paralelismo<\/li>\n\n\n\n<li>Optical thickness variation<\/li>\n\n\n\n<li>Full-aperture or subaperture performance<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Large-aperture interferometric systems are available for measuring planar optical components such as windows and wafers, including components up to hundreds of millimeters in diameter.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The inspection report should identify the actual test aperture so that the result can be compared directly with the drawing.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Common Specification Mistakes<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Frequent RFQ and drawing problems include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Specifying only the outside diameter<\/li>\n\n\n\n<li>Using \u201cfull aperture\u201d without defining whether the bevel is included<\/li>\n\n\n\n<li>Giving a percentage without explaining how it is calculated<\/li>\n\n\n\n<li>Omitting the location of an off-center aperture<\/li>\n\n\n\n<li>Treating clear aperture and coating aperture as the same requirement<\/li>\n\n\n\n<li>Applying tight flatness over the entire physical surface unnecessarily<\/li>\n\n\n\n<li>Allowing the housing to obscure part of the specified optical area<\/li>\n\n\n\n<li>Failing to define an exclusion zone around holes<\/li>\n\n\n\n<li>Omitting edge-chip requirements<\/li>\n\n\n\n<li>Not identifying the test wavelength<\/li>\n\n\n\n<li>Not stating whether both surfaces use the same aperture<\/li>\n\n\n\n<li>Requesting a clear aperture that extends into the bevel<\/li>\n\n\n\n<li>Failing to account for assembly decenter and beam movement<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">These mistakes can lead to inaccurate quotations, inconsistent inspections or sapphire windows that meet the component drawing but do not work correctly in the final optical assembly.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Recommended RFQ Information<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Buyers should provide the following information when requesting custom sapphire windows:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><th>RFQ Item<\/th><th>Information to Specify<\/th><\/tr><tr><td>Sapphire orientation<\/td><td>C-plane, A-plane, M-plane or other<\/td><\/tr><tr><td>Dimens\u00f5es exteriores<\/td><td>Diameter, length and width<\/td><\/tr><tr><td>Espessura<\/td><td>Nominal value and tolerance<\/td><\/tr><tr><td>Abertura livre<\/td><td>Diameter, dimensions or defined shape<\/td><\/tr><tr><td>Aperture location<\/td><td>Centered, offset or datum-referenced<\/td><\/tr><tr><td>Edge exclusion<\/td><td>Width on each side<\/td><\/tr><tr><td>Qualidade da superf\u00edcie<\/td><td>Requirement within the clear aperture<\/td><\/tr><tr><td>Outer-zone quality<\/td><td>Separate cosmetic limit, if applicable<\/td><\/tr><tr><td>Planicidade da superf\u00edcie<\/td><td>Value and test aperture<\/td><\/tr><tr><td>Frente de onda transmitida<\/td><td>Value, wavelength and test setup<\/td><\/tr><tr><td>Paralelismo ou cunha<\/td><td>Maximum allowable value<\/td><\/tr><tr><td>Abertura de revestimento<\/td><td>Coated area and mask tolerance<\/td><\/tr><tr><td>Spectral range<\/td><td>Operating wavelength or wavelength band<\/td><\/tr><tr><td>\u00c2ngulo de incid\u00eancia<\/td><td>Normal or specified angle<\/td><\/tr><tr><td>Mechanical aperture<\/td><td>Housing opening dimensions<\/td><\/tr><tr><td>Acabamento das arestas<\/td><td>Bevel, chamfer or radius<\/td><\/tr><tr><td>Holes or slots<\/td><td>Dimensions and local exclusion zones<\/td><\/tr><tr><td>Relat\u00f3rio de inspe\u00e7\u00e3o<\/td><td>Standard, dimensional or interferometric report<\/td><\/tr><tr><td>Candidatura<\/td><td>Imaging, laser, sensor, vacuum or protection<\/td><\/tr><tr><td>Quantidade<\/td><td>Prototype and production demand<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Example Drawing Notes<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A round window could be specified as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Material: Optical-grade single-crystal sapphire<\/li>\n\n\n\n<li>Outside diameter: \u00d850.00 mm \u00b10.05 mm<\/li>\n\n\n\n<li>Thickness: 2.00 mm \u00b10.05 mm<\/li>\n\n\n\n<li>Clear aperture: \u00d846.0 mm minimum<\/li>\n\n\n\n<li>Clear aperture concentric with outside diameter within 0.10 mm<\/li>\n\n\n\n<li>Surface quality within clear aperture: 20-10 scratch-dig<\/li>\n\n\n\n<li>Surface quality outside clear aperture: 40-20 scratch-dig<\/li>\n\n\n\n<li>Flatness: \u03bb\/4 at 632.8 nm over \u00d846 mm<\/li>\n\n\n\n<li>Edge bevel: 0.3 mm \u00d7 45\u00b0<\/li>\n\n\n\n<li>AR coating aperture: \u00d847 mm minimum<\/li>\n\n\n\n<li>Coating performance: Ravg &lt;0.5% over the specified wavelength band<\/li>\n\n\n\n<li>Inspection report required<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The values above are only an example format. The actual tolerances should be selected according to the optical design, manufacturing feasibility and final application.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Conclus\u00e3o<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The physical size of a sapphire window does not automatically define its usable optical area.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A complete specification should distinguish between:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Dimens\u00f5es exteriores<\/li>\n\n\n\n<li>Optical clear aperture<\/li>\n\n\n\n<li>Edge-exclusion zone<\/li>\n\n\n\n<li>Abertura de revestimento<\/li>\n\n\n\n<li>Mechanical opening<\/li>\n\n\n\n<li>Sealing or mounting area<\/li>\n\n\n\n<li>Local exclusions around holes and cutouts<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The clear aperture should also be linked directly to the surface-quality, flatness, wavefront and coating requirements that apply within it.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">By defining these zones clearly, buyers can reduce ambiguity, avoid unnecessary manufacturing cost and ensure that the sapphire window is inspected according to the actual optical function of the finished assembly.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">FAQ<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Is clear aperture the same as the polished area?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">No. The polished surface may extend beyond the clear aperture. The clear aperture is the region that must meet the specified optical requirements, while the outer polished area may have different acceptance criteria.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Can the clear aperture extend to the outside edge?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">It is technically possible to request optical requirements close to the edge, but the bevel, polishing roll-off, edge chips and coating transition can make this difficult and expensive. A suitable edge exclusion is normally recommended.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Should the coating aperture be larger than the clear aperture?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">In many designs, the coating aperture is slightly larger than the clear aperture so that coating transition does not enter the usable optical beam. The required margin depends on the coating process, mounting design and alignment tolerance.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">How should a rectangular clear aperture be specified?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Use a direct length and width, then define its position relative to the outside dimensions or mechanical datums. Avoid using only a percentage because it may be unclear how the percentage applies to a rectangular component.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Does flatness apply outside the clear aperture?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Only when the drawing specifically requires it. Flatness is normally inspected over the stated test aperture. Extending tight flatness requirements into the edge-exclusion zone may increase cost without improving system performance.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Should holes inside the window have their own exclusion zones?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Yes, when the hole edge is not required to meet the same optical criteria as the surrounding surface. The drawing should define the width and shape of the local exclusion zone around the hole.<\/p>","protected":false},"excerpt":{"rendered":"<p>A sapphire window may have a precisely controlled outside diameter, thickness and polished surface, but this does not mean that every part of the component can be used as an optical area. The region near the perimeter may contain an edge bevel, mounting contact, coating transition, polishing roll-off or allowable cosmetic imperfections. For this reason, [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":2753,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[17],"tags":[1123,446,1126,1074,164,1125,1127,1019,1124],"class_list":["post-2752","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry-news","tag-coating-aperture","tag-custom-sapphire-windows","tag-optical-clear-aperture","tag-optical-window-drawing","tag-sapphire-optical-window","tag-sapphire-window-clear-aperture","tag-sapphire-window-edge-exclusion","tag-sapphire-window-inspection","tag-usable-optical-area"],"_links":{"self":[{"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/posts\/2752","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/comments?post=2752"}],"version-history":[{"count":1,"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/posts\/2752\/revisions"}],"predecessor-version":[{"id":2754,"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/posts\/2752\/revisions\/2754"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/media\/2753"}],"wp:attachment":[{"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/media?parent=2752"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/categories?post=2752"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sapphire-windows.com\/pt\/wp-json\/wp\/v2\/tags?post=2752"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}