High-purity quartz furnace components, customized fused silica plates, and observation viewports manufactured with direct ISO-certified Chinese factory precision.
High temperature quartz windows, manufactured from synthetic fused silica or natural high-purity fused quartz, represent the ultimate sight glass solution for extreme thermal, vacuum, and corrosive environments.
Unlike borosilicate or sapphire glasses which crack under severe temperature differentials, fused quartz features an ultra-low coefficient of thermal expansion (5.5 × 10⁻⁷ /°C). Southeast Quartz incorporates specialized vacuum thermal annealing cycles to relieve internal stress birefringence, effectively preventing surface devitrification (cristobalite crystal growth) under continuous operations up to 1,100°C and intermittent loads up to 1,250°C.
Observation ports in vacuum furnaces, plasma CVD, and autoclave reactors must withstand extreme differential pressures. Our engineering team calculates exact quartz disc thickness based on Poisson's ratio, free-supported vs. clamped diameter formulas, and safety factors exceeding 6:1. Precision CNC edge grinding and helium mass-spectrometer testing guarantee vacuum tightness below 10⁻¹⁰ mbar·L/s.
Depending on viewport instrumentation requirements—such as infrared pyrometric thermal imaging, Raman spectroscopy, or excimer UV monitoring—our factory selects precise grades: JGS1 (synthetic fused silica for 185nm–2500nm deep-UV transparency), JGS2 (optical grade quartz for visible and industrial pyrometry), or JGS3 (water-free grade transparent up to 3500nm in the infrared spectrum).
| Material Parameter | JGS1 (Synthetic Fused Silica) | JGS2 (Optical Fused Quartz) | JGS3 (Infrared Fused Quartz) | Testing Standard / Methodology |
|---|---|---|---|---|
| SiO₂ Purity Content | ≥ 99.9999% (< 0.1 ppm metal) | ≥ 99.99% (< 15 ppm metal) | ≥ 99.998% (< 2 ppm metal) | ICP-MS Trace Element Analysis |
| Transmission Range (T ≥ 85%) | 185 nm – 2,500 nm (DUV to NIR) | 220 nm – 2,500 nm (Standard Optical) | 260 nm – 3,500 nm (Extended IR) | Spectrophotometer Reflection Corrected |
| Hydroxyl (OH⁻) Radical | Typ. 800 – 1,200 ppm | Typ. 120 – 200 ppm | < 5 ppm (Water-free) | FTIR Infrared Absorption Spectrometry |
| Max Operating Temperature | 1,150°C (Continuous) / 1,300°C (Peak) | 1,100°C (Continuous) / 1,250°C (Peak) | 1,120°C (Continuous) / 1,280°C (Peak) | Dynamic Thermal Annealing Stress Test |
| Thermal Expansion (0–300°C) | 5.4 × 10⁻⁷ / K | 5.5 × 10⁻⁷ / K | 5.5 × 10⁻⁷ / K | Dilatometry ISO 7991 |
| Optical Surface Figure & Polish | λ/4 to λ/10 @ 632.8 nm; 20/10 S-D | λ/2 to 1λ @ 632.8 nm; 40/20 S-D | 1λ to 2λ; 60/40 S-D | Zygo Laser Interferometry / Profilometer |
Located in Qinghu Industrial Park, Donghai County, Jiangsu, Lianyungang Southeast Quartz Products Co., Ltd. leverages the world’s most concentrated quartz processing hub to deliver unmatched value, scale, and technical precision.
Donghai processes over 70% of China’s high-purity quartz raw crystal and synthetic feedstocks. Our factory sits at the direct source of supply, drastically lowering material transit time, securing supply chain resilience during raw material squeezes, and minimizing purchasing premiums compared to European or American re-sellers.
Our manufacturing facility spans over 100 skilled glassblowers, technicians, and CNC machinists. We perform plasma melting, precision wire slicing, diamond-edge chamfering, double-sided optical planetary lapping, chemical acid polishing, and hydrogen-oxygen flame annealing under one roof with zero third-party outsourcing.
Every custom quartz observation window undergoes strict quality validation: laser interferometer wavefront flatness analysis, surface roughness stylus profilometry (Ra < 0.5 nm), bubble classification according to DIN 58927 standards, and 100% helium mass-spectrometry vacuum leak verification before shipment.
Global engineering firms avoid tier-2 trading markup. We provide factory-direct wholesale pricing for annual blanket orders, with rapid turnaround prototyping on custom sizes (diameters from 5 mm to 650 mm, thickness from 0.5 mm to 80 mm) in as little as 3 to 7 working business days.
Accelerating requirements in sub-5nm semiconductor fab tools, N-type photovoltaic wafer processing, and green hydrogen pyrolysis chambers are imposing unprecedented demands on optical sight glass performance.
Next-generation semiconductor atomic layer deposition (ALD) and dry plasma etching chambers utilize aggressive halogen gases (NF₃, CF₄, Cl₂). Conventional observation windows suffer rapid etching, hazing, and optical micro-cracking. The quartz sector is shifting towards plasma-fused ultra-high-density quartz materials, specialized surface glazing, and sapphire-fused quartz hybrid windows to triple component operational lifespans.
The solar photovoltaic transition towards large M10/G12 silicon wafers has expanded monocrystalline Czochralski (CZ) pulling chambers and vacuum induction furnaces. Equipment manufacturers now require oversized quartz viewing windows exceeding 400mm–650mm in diameter, necessitating advanced large-ingot fusion technologies capable of zero-bubble, striation-free optical clarity across massive cross-sections.
Modern sight glasses are no longer passive observation panes. High-temperature optical ports increasingly integrate specialized thin-film AR coatings designed to survive 400°C–600°C without peeling, alongside transparent conductive coatings (ITO) that block radio frequency (RF) and microwave emissions from plasma processing vessels, ensuring laser measurement precision and operator safety.
Explore where precision high-temperature quartz windows serve as vital optical and barrier interfaces across heavy industry, microelectronics, and scientific apparatus.
Installed on horizontal and vertical furnace doors, quartz windows allow non-contact optical pyrometers to monitor silicon wafer temperatures up to 1,200°C in real time, preventing thermal runaway while containing volatile doping gases.
Serving as CF (ConFlat), ISO-KF, and ISO-K flanged viewports, high-temperature quartz windows maintain leak-tight performance at 10⁻¹¹ Torr levels while transmitting coherent synchrotron X-ray and UV radiation.
Engineered thick circular quartz sight glasses enable visual inspection and spectroscopic monitoring of supercritical fluid reactions, biomass hydrothermal liquefaction, and hydrothermal crystal synthesis under 100+ bar pressure.
Functioning as optical shields, these windows protect sensitive laser optics from spatter while allowing high-intensity UV curing wavelengths (254nm, 365nm) and Nd:YAG / Fiber laser beams (1064nm) to pass with zero optical distortion.
Procuring quartz components for mission-critical industrial systems demands precise adherence to geometric, metallurgical, and cleanliness standards.
Standard industrial viewports tolerate ±0.1 mm, but optical viewport applications demand CNC waterjet cutting and CNC edging with dimensional tolerances to ±0.02 mm, surface flatness to λ/4, and wedge angle parallelism within 3 arc minutes to prevent laser beam deviation.
Scratch-dig specifications conform to MIL-PRF-13830B standards (ranging from commercial 80/50 to precision laser-grade 20/10). Bubble and inclusion classes strictly conform to DIN 58927 Class 0/1, eliminating scattered light and thermal localized stress hotspots that induce explosive shatter under load.
All precision quartz windows undergo multi-stage ultrasonic deionized water and HF acid etching wash cycles in Class 1,000 cleanrooms to eliminate organic grease and surface alkali metal contaminants (Na, K, Li, Ca). Windows are vacuum heat-sealed in antistatic cleanroom bags to prevent contamination during overseas transit.
Key technical answers prepared by our senior quartz materials engineers to assist procurement professionals, process engineers, and mechanical system designers.
Transparent fused quartz has a transformation point of ~1,075°C, an annealing point of ~1,180°C, and a softening point of 1,683°C. For continuous operation, the maximum recommended continuous service temperature is 1,100°C. Short-term exposures can safely reach 1,250°C to 1,300°C without plastic deformation, provided the window is free from surface alkali metal contamination (such as fingerprints or dust), which triggers rapid cristobalite crystallization and opacity above 1,100°C.
Choose JGS1 (Synthetic Fused Silica) if your process requires UV light transmission down to 185nm (e.g., excimer lasers, DUV lithography, UV sterilization) or extreme bubble-free optical clarity. Choose JGS2 (Standard Fused Quartz) for general high-temperature sight glasses, industrial furnace viewing, and standard pyrometry operating between 260nm and 2,500nm. Choose JGS3 (Infrared Fused Quartz) when measuring through infrared cameras or spectrometers between 2,500nm and 3,500nm, because JGS3 eliminates the 2.73µm OH⁻ absorption band.
The minimum thickness \(t\) is calculated using the formula: \(t = d \times \sqrt{\frac{C \times P}{\sigma}}\), where \(d\) is the unsupported diameter, \(P\) is the design pressure, \(\sigma\) is the maximum allowable bending stress of fused quartz (typically 50 MPa with a safety factor of 8 to 10 applied, yielding an effective design stress of 5–7 MPa), and \(C\) is a mounting factor (0.25 for clamped flanges, 0.375 for freely supported gasketed flanges). Our engineering department assists clients in computing FEA stress models.
Yes. Due to its exceptionally low thermal expansion coefficient (5.5 × 10⁻⁷ /°C), a fused quartz plate heated to 1,100°C can be plunged directly into cold water (20°C) without fracturing or structural micro-cracking. This makes it infinitely superior to borosilicate glass (which fails around a 100°C–150°C rapid delta) and soda-lime glass (which cracks under a 50°C shift).
We machine circular discs, rectangular observation plates, stepped sight glasses, drilled holes, counter-bored ports, and grooved O-ring sealing faces. We routinely hold diameter tolerances of ±0.02 mm, thickness tolerances of ±0.03 mm, parallelism < 30 arc seconds, and surface roughness Ra < 0.5 nm (10/5 scratch-dig) using computerized 5-axis CNC grinding and double-sided continuous pitch polishing.
Every export shipment includes a Certificate of Conformance (CoC), material spectrometer elemental purity test report (ICP-MS), optical spectrophotometer transmission curve (190nm–3200nm), laser interferometer surface flatness verification report, and a helium leak detection certificate (< 1×10⁻¹⁰ mbar·L/s) for vacuum-rated viewport assemblies.
Explore additional factory-direct oversized quartz furnace tubes, high-purity plates, diffusion boats, and laboratory-grade fused silica instruments.
Need custom viewport diameters, high-pressure sight glass calculations, step-flanged profiles, or specialized optical AR coatings? Send your specifications, CAD drawings (STEP, DWG, PDF), and process atmosphere parameters. Our engineering team responds within 24 hours with manufacturability feedback, material grade recommendations, and direct wholesale pricing.
