F.0

Viewport

Introduction

Description
A viewport, sometimes referred
to as a window, is an optical component
that provides a means for visual, opticalor broad-band energy transmission in
and out of a vacuum system.
There are two types of viewports
offered, zero-length and tubulated. A
zero-length viewport has a thickness nolarger than that of its mounting flange.
This makes it easier to protect from accidental damage as there are no parts
protruding from the mounting flange.
It also allows for the best angle of view.
CeramTec’s precision-engineered
Ceramaseal® viewports are available
with a choice of two viewport materials:
sapphire or fused silica. Other viewportmaterials are available upon request.
CeramTec offers a UV grade fused silica
viewport with a 1.37” view diameterthat can be used for cryogenic applications.
Sapphire should be used in the mostdemanding applications, as this material
provides extended transmission, temperature, pressure and wear resistance.

VIEWPORT

To select the right window for yourapplications, you should consider size,transmission requirements, temperature,pressure, and aggressiveness of environment.

Standard Specifications

New Products• Viewing diameter of .50” or 1.1”

• Differentially Pumped Viewports• Anti-reflective (AR) coatings are
optional

Extreme / Custom Design

Typical Viewport Construction• Double viewports• Viewing diameters exceeding
7 inches• Internal pressures to 80,000 psig
• RF applications and special
configuration requirements

Installation
Standard installation mountings include:• Temperature Range: –269˚ C to 450˚ C• Weld (Pulse-TIG, TIG, Laser,E-Beam)• Standard transmission range 0.25 to4 microns• ConFlat flange• Internal Pressure 1 x 10-10 torrto 400 psig

Applications• ISO KF flange

Fused Silica:• Temperature Range:-65˚ C to 200˚ C

A few of the many applications in whichthese viewports are commonly used are:• Semiconductor processing
equipment• Accelerators• Standard Transmission Range
0.25 to 2 microns• Furnaces• Internal Pressure 1 x 10-10 torr
to 115 psig

• Analytical test and measurement
equipment• Viewing diameters from 1.13”
to 3.81”• CO2 lasers• Instrumentation• Multispectral applications

Extended Range:• Optical imaging• Optics: Zinc Selenide, Cleartran,
Magnesium Fluoride, Calcium Fluoride• Materials processing• Temperature Range: -8˚C to 204˚C• Extended Range Viewports• Braze (sapphire only)

Sapphire:• Viewing diameters from .55” to 1.94”

170• Standard transmission ranges from0.12 to 20 microns• Thermometry• Pyrometry

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Viewport

Section
Pages

Internal PressureRating (@ 20 ˚C)Temperature
RangeTransmission
Range

Sub-section

0.55 to1.94

to 400 psig-269˚ C to450˚ C

0.25 to 4Microns

Sapphire

F.1
172-173

1.13 to3.81to115 psig-269˚ C to200˚ C

0.25 to 2
Microns

Fused Silica

F.2
174-175.50 to
1.10–-8˚ C to204˚ C

0.12 to 18
Microns

ExtendedRange

F.3
176-177

1.10–-8˚ C to204˚ C

10.6 Micron
Optimized

Differentially
PumpedF.4
178-179

View Dia.

Type

F.0

Table of Contents(inches)

VIEWPORT**The 7056 Glass, Fused Silica, and Crystal Quartz transmission curves are based on a thickness of 1cm. The sapphire transmission curve is based on a thickness of 1 mm.

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F.1

Viewport

Sapphire

View Diameter: .55 [14]View Diameter: .94 [24]Weldable

Weldable

ISO KFISO KF

ConFlat

VIEWPORT

ConFlatView Diameter: 1.94 [49.3]
Weldable

Specifications
Materials
Housing: 52 Nickel iron
Optic: Sapphire
Magnetic Materials: Yes
Transmission Range (80% Min) 0.25 to 4 Microns

ConFlatTemperature Range -269°C to 450°C, ISO KF -25°C to 205°C
Pressure @ 20°C ISO KF 0 PSIG
.55 View Dia.: 400 PSIG (27.6 Bar)
.94 View Dia.: 160 PSIG (11 Bar)
1.94 View Dia.: 50 PSIG (3.4 Bar)

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Viewport

Weldable

Sapphire

VIEW
DIAMETERINSTALLATIONPARTNUMBER.55 [14].94 [24]
1.94 [49]

Weld
Weld
Weld

17105-01-W
17105-02-W
17105-03-W

F.1

ISO FLANGEISO KF.55 [14].94 [24]

NW16KF
NW40KF

17106-01-KF
17106-02-KF

CONFLAT FLANGE

ConFlat.55 [14].94 [24]
1.94 [49]

1 1/3” (NW16CF)
2 3/4” (NW35CF)
4 1/2” (NW63CF)9547-04-CF
18617-01-CF
18617-02-CF

VIEWPORT

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F.2

Viewport

Fused Silica

View Diameter: 1.13 [28.7]

View Diameter: 3.81 [96.8]

Weldable

Weldable

ISO KF

ConFlat

ConFlat

Cryogenic – View Diameter: 1.37 [35]

VIEWPORT

Weldable

View Diameter: 2.37 [60.2]
Weldable

ConFlat

ConFlat174

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Viewport

Fused Silica

Weldable

VIEW
DIAMETERINSTALLATION

1.13 [28.7]
2.37 [60.2]
3.81 [96.8]

WeldWeld
Weld

TEMPERATURE RANGE
MINMAX

MAGNETIC
MATERIALSPARTNUMBER-65-65-65200200200No
No
No

11466-09-W*11466-10-W*11466-11-W*-25200No

17109-01-KF*-65-65-65

200200200

No
No
No

11466-01-CF*11466-02-CF*11466-03-CF*

MAGNETIC
MATERIALSPARTNUMBER

F.2

ISO FLANGE
1.13 [28.7]

ISO KF

NW50KF

CONFLAT FLANGE

ConFlat

Cryogenic
Weldable

2 3/4” (NW35CF)
4 1/2” (NW63CF)
6” (NW100CF)

VIEW
DIAMETERINSTALLATION

1.37 [35]1.37 [35]

Weld
Weld

-196
-269

200200No
Yes4901-01-W*
9600-01-W*

1.37 [35]1.37 [35]

2 3/4” (NW35CF)
2 3/4” (NW35CF)-196-269

200200NoYes

4900-01-CF*
4900-21-CF*TEMPERATURE RANGEMINMAX

VIEWPORT

Cryogenic
ConFlat1.13 [28.7]
2.37 [60.2]
3.81 [96.8]*This part is not RoHS compliant.
Specifications
Materials
Housing: 304 Stainless steel
Optic: UV Grade Fused Silica
Magnetic Materials: See Table
Transmission Range (80% Min) 0.25 to 2 Microns
Temperature Range See Table
Pressure @ 20°C ISO KF 0 PSIG
1.13 View Dia.: 115 PSIG (7.9 Bar)
1.37 View Dia.: 35 PSIG (2.4 Bar)
2.37 View Dia.: 35 PSIG (2.4 Bar)
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F.3

Viewport

Extended Range

Description
Hermetic Extended Range
Transmission Ports
As its name suggests, an extended range
transmission port is an optical component
that provides for transmission of radiation ineither the ultra violet or infrared portion of theelectromagnetic spectrum. Standard viewports
made of either fused silica or sapphire have useful transmission from .25 microns to 2.5 or 5.0 microns respectively.
Extended range window materials have a combined transmission range from .12 microns to 18 microns.
Of course no single window material can offer good transmission over the entire spectrum. Alkali halides such as calcium
fluoride, CaF2, or magnesium fluoride, MgF2, offer excellent
transmission in the deep ultraviolet. Polycrystalline CVD
grown infrared transmitting materials such as Zinc Sulfide,ZnS, and Zinc Selenide, ZnSe, transmit radiation out to 14 and18 microns respectively.
Many factors govern the selection of optical materials for theconstruction of a high and ultra high vacuum assembly.
Whereas quartz and sapphire can be readily metalized andsealed to vacuum flanges by brazing, most optical materials
are too weak to join to by the high temperature joining
processes. Further, many optically transmitting materials arestrongly hygroscopic (such as sodium chloride) or melt at low
temperatures (such as glass). The physical and chemical properties of CeramTec’s extended range transmission ports havebeen selected on the basis of optical transmission, vacuum
compatibility, strength of materials and widespread usage by
optical engineers.

Calcium Fluoride – Best transmission by fluoride crystals in theUV (except very weak LiF). Relatively insoluble (non-to-verylow hygroscopic). Mechanically only slightly weaker than Zinc
Selenide and slightly harder. Single crystal material with cubic
symmetry, hence no birefringence. Calcium Fluoride is transparent in the visible (appears similar in color to quartz or glass)and in the UV down to 120nm, which services all excimer laser
applications. Low index of refraction, which means that thewindows rarely require anti-reflective coatings.
Magnesium Fluoride – Next best transmission of fluorides compared to CaF2 and similar in all other characteristics with thefollowing exceptions. MgF2 is stronger and harder and is naturally, strongly birefringent.

View Diameter: .50 [13]Ø.50 [13]View Diameter: 1.10 [28]8VIEWPORT

Accordingly, the following materials are offered standard as
extended range transmission ports:
Zinc Selenide – Best transmission available at 10.6 micron (CO2laser fundamental line) and in the visible. It has some absorption in the blue-green causing it to appear yellow. The indexof refraction is high and thus requires anti-reflection coatings
on both sides for optimum performance. This polycrystalline,
Specifications
CVD grown material is strong, though relatively soft comMaterials
pared to other crystalline, optical materials. It is non-hygroscopic. ZnSe sublimes at 300˚C and reacts violently with strong
Flange: 304 Stainless steel
mineral acids.
®
Cleartran™ Zinc Sulfide – Comparable to ZnSe in mostrespects, only slightly more absorbing at 10.6 microns.
Advantage is the transmission in the visible is better, noabsorption to only slight absorption in the blue-green thus
appearing clear (i.e. not yellow). It is much harder than ZnSeand thus offers increased scratch resistance.

O-ring: Viton
Optics: See Table
Magnetic Materials: Yes

Transmission Range 0.12 to 20 Microns (See table)
Temperature Range -8°C to 204°C

AR Coatings for both ZnSe and ZnS (Cleartran™) are standard
and highly recommended for most applications. The exception is possibly for wide range pyrometry or spectrometry
where artifacts from the coating materials leave a spectral“fingerprint” in regions beyond the useful transmission rangeof the coating. The standard coating has been specifically tailored to maximize transmission at 10.6 microns and will alsotransmit minimally 50% in the visible (i.e. remain at least partially transparent in the visible).

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Viewport.50 View Dia.
ConFlat1.10 View Dia.
ConFlat

F.3

Extended Range

TRANSMISSION
RANGE
%MIN

PART
NUMBER

MATERIAL

INSTALLATIONANTI-REFLECTIVE
COATINGS

Zinc Selenide
Cleartran™
Magnesium Fluoride
Calcium Fluoride
Zinc Selenide

1 1/3” (NW16CF)
1 1/3” (NW16CF)
1 1/3” (NW16CF)
1 1/3” (NW16CF)
1 1/3” (NW16CF)

10.6 Micron
10.6 Micron
NoNoNo10.6 Micron opimized
10.6 Micron opimized
0.12 to 7 Microns
0.12 to 9 Microns
0.55 to 18 Microns

98
98
-

19485-01-CF
19485-02-CF
19485-03-CF
19485-04-CF
19485-05-CF

Zinc Selenide
Cleartran™
Magnesium Fluoride
Calcium Fluoride
Zinc Selenide

2 3/4” (NW35CF)
2 3/4” (NW35CF)
2 3/4” (NW35CF)
2 3/4” (NW35CF)
2 3/4” (NW35CF)

10.6 Micron
10.6 Micron
NoNoNo10.6 Micron opimized
10.6 Micron opimized
0.12 to 7 Microns
0.12 to 9 Microns
0.55 to 18 Microns

9898-19163-01-CF
19163-02-CF
19163-03-CF
19163-04-CF
19163-05-CF

Extended Range Transmission Curves

VIEWPORT

Transmission charts are for reference only. These transmission
curves are based on a 10mm window thickness. Thermal gradientshould not exceed 10˚C/minute.

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F.4

Viewport

Differentially Pumped

Description
Differentially Pumped, Extended
Range, Viewports for Extreme High
Vacuum (EHV) Applications
EHV applications demand exceedingly
high seal reliability. These requirements for vacuum integrity lead to consideration of two limits to commercial leakdetection. First, what is the typical helium sensitivity forcommercially available leak detectors; and second, what
are the practical limitations of helium mass spectrometer (MS) leak rate certification.

• Different optics are available upon request. For
example, Silicon, Germanium, Zinc Sulfide• Specialized coatings are also available.
• Custom pumping port termination options areavailable.
Installation
All of CeramTec’s standard differentially pumped viewports are mounted within a 2 3/4” or 4 1/2” ConFlat
flange. For information on ConFlat flange installation,refer to the Technical Reference section.
Applications
A few of the many applications in which these differentially pumped viewports are commonly used are:

VIEWPORT

While helium MS leak detection systems are sensitive
to leak rates less than 10-11 STD cc/sec, commercial
vacuum seals are certified only for leak rates of less than • Geochronology• Geology
10-10 STD cc/sec. In these instances, the discrepancy• Argon Dating
between that achievable versus the reported sensitivity
is not due to the presence of small, measurable leaks(<10-11 STD cc/sec). Rather, the reduced certification isView Diameter: 1.10 [28]due to the difficulty of performing a reliable leak testwith de-mountable hardware. An all metal welded joint
to an MS leak detector, for example, could readily andreliably be certified to leak rates less than 10-11. This
type of joint is not practical for most de-mountable vacuum components. Even in the case of a copper gasket
seal, the process of sealing is not only too time consum8ing but also would cosmetically alter the finished part.
In other instances, such as in inert gas chronology
measurements, where the desired background levels
due to atmospheric argon or helium are actually below
the level of instrument sensitivity; it is not possible tomeasure with sensitivity at the desired leak rate withcommercially available Helium MS leak detectors.

VCR Female

VCR MaleFlange See Table

Pumping PortIn both instances, a differentially pumpedvacuum seal can ensure EHV reliability. Arranging twoSpecifications
or more seals such that the space between the seals isMaterials
accessible to an appended vacuum pump creates a difFlange: 304 Stainless steel
ferentially pumped seal. Typically, each seal is readily
O-ring: Viton®
qualified to have leak rates <10-10 STD cc/sec. By activeOptics: Zinc Selenide or Cleartranly pumping the region between the seals, minute leakMagnetic Materials: Yes
age through the atmospheric seal is further rarified toensure that leakage through the inner seal is reduced
Transmission Range 10.6 Micron optimized
by several orders of magnitude. Thus, differential
Anti-reflective Coating Yes
pumping ensures EHV reliability.
Temperature Range -8°C to 204°C
CeramTec’s differentially pumped, extended range,
viewports have been designed specifically for suchextreme high vacuum (EHV) applications including inert
gas chronology.
Extreme / Custom Design• Larger viewport view diameters to fit within a 4 1/2”
ConFlat flange.

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Viewport

1.10 View Dia.
ConFlat

F.4

Differentially Pumped

MATERIAL

INSTALLATION

Zinc Selenide
Zinc SelenideZinc Selenide
Zinc Selenide
Cleartran™
Cleartran™
Cleartran™
Cleartran™
Zinc Selenide
Zinc Selenide
Zinc Selenide
Zinc Selenide
Cleartran™
Cleartran™
Cleartran™
Cleartran™

2 3/4” (NW35CF)
2 3/4” (NW35CF)
2 3/4” (NW35CF)
2 3/4” (NW35CF)
2 3/4” (NW35CF)
2 3/4” (NW35CF)
2 3/4” (NW35CF)
2 3/4” (NW35CF)
4 1/2” (NW63CF)
4 1/2” (NW63CF)
4 1/2” (NW63CF)
4 1/2” (NW63CF)
4 1/2” (NW63CF)
4 1/2” (NW63CF)
4 1/2” (NW63CF)
4 1/2” (NW63CF)TRANSMISSION
RANGE
%MIN
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized
10.6 Micron optimized

98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98

TERMINATIONOPTIONSPARTNUMBERTube
1 1/3” ConFlat
Male VCR
Female VCR
Tube
1 1/3” ConFlatMale VCR
Female VCR
Tube
1 1/3” ConFlat
Male VCR
Female VCR
Tube
1 1/3” ConFlat
Male VCR
Female VCR

19286-01-A
19286-01-CF
19286-01-VM
19286-01-VF
19286-02-A
19286-02-CF
19286-02-VM
19286-02-VF
19781-01-A
19781-01-CF
19781-01-VM
19781-01-VF
19781-02-A
19781-02-CF
19781-02-VM
19781-02-VF

VIEWPORT

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