glass molding | sapphire windows | sapphire glass | molded glass optics | sapphire spheres | sapphire sight glasses manufacturer | sapphire products | sapphire polishing | sapphire manufacturer | strengthening glass
sight windows
New Sight Window Website, click here



Product Description:
Rayotek seals and fuses a variety of glass and crystalline
materials into threaded and flanged metal housings.

  • Stock sizes available
  • Custom designed and specialty engineered sight windows
    and sight glasses manufactured to customer specs. 
  • Our engineering staff is available for design assistance


We can seal your windows or Rayotek provided windows into most metal and refractory housings.


sight windows



Pressure Ratings:
Sight windows/sight glasses from ultra-high vacuum to in excess of 40,000 PSI.
Pressure classifications:
        • Low pressure: Vacuum to 1000PSI
        • High pressure: up to 4000PSI
        • Very high pressure: up to 8,000PSI
        • Ultra High pressure: up to 40,000PSI +

Pressure ranges are determined by: sealing method, housing design, housing material and window material.

Housing Materials:
        • Stainless Steel 303 and Stainless 17-4 - standard housing metals
        • Inconel, Titanium, Kovar, Aluminum & Alumina - common materials
          for sight windows/sight glasses
        • Specialty metals, alloys and ceramic also available

Glass & Crystalline Materials:
        • Soda Lime
        • Borosilicate (Pyrex™)
        • Fused quartz
        • Fused silica
        • Sapphire
        • Exotic window materials: ZnSe, CaF, ZnS, MgF2, YAG,
          diamond & other exotics

Quality Assurance:
All sight windows/sight glasses undergo rigorous testing procedures including:
        • Thermal cycling
        • Pressure cycling
        • Helium leak detection down to 2x10-10mbar-l/s - when required

Rayotek sight windows/sight glasses have been used in numerous applications, including: 
        • Refrigeration systems
        • Hydraulic systems, oil level gauges
        • Deep sea robotics and inspection systems
        • Petroleum research and down-hole camera systems
        • Furnace, heater flame and pilot indicator windows
        • Pyrometry and thermal sensor windows
        • Medial applications 

  sight window  
  sight window  


Configurations & Materials of our sight windows/sight glasses:


Fused Glass Sealing:
Standard or specialty glass that is thermally fused directly to a metal housing.  Typically sealed into NPT and BSPT housings, these sight window/sight glass systems can be as strong as the equivalent size solid metal NPT or BSPT plug (strength determined by glass thickness). Windows can also be fused into other types of housings, such as: flanges and tubes. These sight windows/sight glasses have been tested and operated at temperatures from cryogenic to in excess of 400C and pressures up to 40,000PSI.
Common applications - level gauges, sight indicators, flow gauges in refrigeration and hydraulics systems, furnace and heater systems, pilot and fire windows.
Usage - where high resolution optical clarity is not required, but reliability and low cost are.

Organic Sealing:

Glass, sapphire and other crystalline windows that are sealed directly into metal or ceramic housings via proprietary organic sealing systems.  In some applications, organic sealing is superior to metal brazing if operating temperatures do not exceed 250C. Our organic sealants are NASA approved for zero out-gassing and are also highly chemical resistant.
Common applications - High pressure research, medial applications, optical analysis, particle counting and measurement, laser windows, plasma chambers, cryo analysis, petroleum research and downhole applications.
Usage - Lower cost than brazing, where high resolution optics are required along with high strength and reliability. Also good for CTE mismatches where flexible sealing system are required.

Braze Sealing:
Glass, sapphire and other crystalline windows that are brazed directly into metal or ceramic housings. The  process is similar to organic sealing except, in lieu of a sealant, high temperature brazes are used. Typical housings are NPT and BSPT fittings, but windows can also be brazed into tubes, flanges and customer designed housings. Depending on design, these windows can be subjected to over 1100C and  40,000PSI.
Common applications - Pyrometry, high pressure research, optical analysis, supercritical applications, medical applications, particle counting and measurement, laser windows, plasma chambers
Usage - where high resolution optics are required along with high strength and reliability.

Compound Annular Ring:
Specialty engineered compound annular sight windows/sight glasses are optimal for high pressure and hazardous applications.  Used when evaluation and observation must be performed by camera or fiber optics viewing and proper lighting is critical. Made from sapphire, these windows are highly durable, scratch and chemical resistant. These superior viewing windows have an outer ring for illumination and an inner optical window for viewing. Pressure range upward of 20,000 PSI.
Common applications - down-hole camera systems, deep sea robotics, petroleum platform inspection, pipe inspection, hazardous inspection systems.
Usage - for high resolution viewing in hostile environments where proper lighting is critical.



Soda Lime Glass:

Sight windows/sight glasses with optically clear soda lime glass are typically sealed into NPT and BSPT housings and CF and ASME flanges.  Most often used as low cost sight window for general applications.
Common applications - high vacuum systems, oil and fluid gauges, water level indicators, flame and pilot indicators.
Usage -a low cost option where window clarity is important,  there is no exposure to temperatures over 350C and only minimal abrasive or mechanical stress.

Borosilicate (PyrexTM) Glass:

The next step up from soda lime glass sight windows/sight glasses. Typically sealed into NPT and BSPT housings and CF and ASME flanges.
Common applications -  same as soda lime.
Usage -  A slightly higher cost material for better performance:  better clarity, higher temperature and pressure ratings, more scratch resistant.

UV grade fused silica and fused quartz:

When optical performance, UV transmission or thermal shock resistance is critical our fused silica and fused quartz sight windows/sight glasses are the best choice.  Transmission range from 170nm to over 3 microns and transmission over 92%. Housed in NPT and BSPT fittings and CF and ASME flanges
Common applications - UV and IR lasers, UV and IR analysis systems, FTIR and other analytical systems.
Usage - An ideal optical sight window: high UV and near IR transmission, high thermal shock resistance, more scratch resistant than soda lime and borosilicate.


The most optically clear and scratch, heat and chemically resistant material on the commercial market. Our sapphire sight windows/sight glasses are sealed into NPT and BSPT fittings and CF and ASME flanges.
        • Broadest range of optical transmission available, transmitting
          from below 170nm to over 6 microns.
        • Second only to diamond in hardness and scratch resistance
        • Most chemically resistant window commercially available
        • Exceptional strength allows for thin profile windows which
         decreases weight and parallax issues.
Common applications: IR sensors and surveillance system, hostile environment cameras, downhole systems, furnace windows, explosion and chemical windows, pyrometry windows and medical applications.
Usage: The superior material for optical transmission, clarity, strength, extreme high temperatures, harsh chemical and mechanical environments.  

Exotic window materials:

ZnSe, CaF, ZnS, YAG, diamond and other exotic window materials can be sealed into standard and specialty housings. Rayotek has developed sealing technologies that allow sealing of any optical material into a variety of housing.



Bookmark and Share

Home  /  Glass Products  /  Sapphire Products  /  Services  /  Tech & Specs  /  About  /  News  /  Contact

Site Map

©2014 Rayotek Scientific Inc.
11499 Sorrento Valley Road, San Diego, CA 92121 USA, Tel: 858-558-3671

Website Design: Guerrant Webworks

Employment Opportunities Surplus Inventory Home