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COMPONENT SPECIFICATION
DRWG NO. REV. GID
FARADAY ISOLATOR, 20mm
APPROVALS: DATE REV DCN NO BY CHK DCC DATE drawn: Michael Smith/Jonathan Kern 9/29/ CHECKED: APPROVED: DCC RELEASE:
CALIFORNIA INSTITUTE OF TECHNOLOGY MASSACHUSETTS INSTITUTE OF TECHNOLOGY SHEET (^) 1 OF (^) 7
1 SCOPE
This is a specification for a Faraday Isolator Assembly, which consists of 1) a housing with external mounting brackets, 2) a permanent magnet subassembly, 3) a Faraday optic subassembly, 4) input/output polarizers, 5) a return beam port cover, and 6) a polarization rotation plate. The Faraday Isolator Assembly will provide isola- tion of orthogonal polarization of a collimated laser beam and will restore the polarization orientation.
2 LIGO DOCUMENTS
LIGO-L970196, Part Numbers and Serialization of Detector Hardware
- http://ligo.caltech.edu/LIGO_web/dcc/docs/L970196.pdf LIGO-E960022-A, Vacuum Compatibility, Cleaning Methods and Compatibility Procedures - http://ligo.caltech.edu/LIGO_web/dcc/docs/E960022-03.pdf LIGO-E960050-A, Vacuum Compatible materials list - http://ligo.caltech.edu/LIGO_web/dcc/docs/E960050-A.pdf
2.1. Non-LIGO Documents
MIL-C-675C, Coating Adhesion and Durability EOT Mod. No. 1845-20 data sheet
3 REQUIREMENTS
3.1. PERFORMANCE CHARACTERISTICS
3.1.1. Faraday Isolator Performance
3.1.1.1 Transmitted Beam
Wavelength 1064 nm Clear Aperture 20 mm Transmissivity across clear aperture >98.5% Extinction ratio across clear aperture >30dB Wavefront distortion <0.7λ @ 633 nm wavelength Height of output beam above mounting surface 4.09 inches
COMPONENT SPECIFICATION
DRWG NO. REV. GID
CONTINUATION SHEET
FARADAY ISOLATOR, 20mm
CALIFORNIA INSTITUTE OF TECHNOLOGY MASSACHUSETTS INSTITUTE OF TECHNOLOGY SHEET 2 OF 7
3.1.2. Return Beam Port Cover
An optical port shall be provided to allow a return beam, which enters the output end, to exit from the polarizer housing. The port shall be covered with a movable cover to block the return beam.
3.1.3. Optical Reference Surface
The input side of the mechanical housing shall have a flat, optical reference surface which is perpendicular to the optical axis within <0.5 de grees. A removable mirror will be mounted against the reference surface to ret- roreflect an autocollimator beam for alignment purposes. The flat reference surface shall have fiducia l marks which define the center of the input optical axis within <0.5mm.
3.1.4. Polarizer Alignment
The polarization axis of both polarizers shall be rotatable about the optical axis to any angle with respect to the horizontal mounting surface of the Faraday isolator assembly, with an angle reproducibility of <0.5 degree.
3.1.4.1 Polarization Rotation
The half-wave polarization retardation plate shall be rotatable about the optical axis to any angle with respect to the horizontal mounting surface of the Faraday isolator assembly, with an angle reproducibility of <0.5 degree.
3.2. DESIGN AND CONSTRUCTION
3.2.1. Materials
3.2.1.1 Faraday Rotator Optic
material TGG crystal. input and output surface wedges angle >0.5 deg, An antiref lection coating shall be a pplied to both sur faces of the Far aday optic; to be purchased from REO (Research Electro Optics).
Wavelength 1064 nm Transmissivity per surface >99.9% Durability MIL-C-675C
3.2.1.2 Input/output Polarizer
material optical quality calcite. surface orientation Brewster’s angle @ 1060nm, all surfaces wavefront distortion <1/2 waves, @ 633 nm
3.2.1.3 Polarization Rotation Plate
material quartz phase retardation 1/2 wave @ 1064 nm
COMPONENT SPECIFICATION
DRWG NO. REV. GID
CONTINUATION SHEET
FARADAY ISOLATOR, 20mm
CALIFORNIA INSTITUTE OF TECHNOLOGY MASSACHUSETTS INSTITUTE OF TECHNOLOGY SHEET 4 OF 7
3.3. Quality Assurance/Control
3.3.1. Identification
Separate (non-welded) parts and assemblies shall be marked with laser marking or acid etch techniques. A vibratory tool with a minimum tip radius of 0.0005” is acceptable for marking on surfaces which are not hid- den from view. Engraving is also permitted.
Separate (non-welded) parts and assemblies to be serialized according to the document titled Part Numbers and Serialization of Detector Hardware, LIGO-L970196. This document allows for “bag-and-tag” type of identification for small parts.
3.3.1.1 Serial Number
3.3.1.1.1 Serial Number
3.3.1.1.2 A serial number shall be etched, embossed, or marked with a stylus on each fabricated piece part of the assembly.
3.3.1.1.3 Serial Number Format
The Serial number shall be of the format: Dxxxxxx-y S/N nnn Where
Dxxxxxx-y is the LIGO piece part or assembly drawing number, Dxxxxxx, including the revision letter, -y, to which the hardware item was built, and
nnn is the sequential serial number, 001 through 999, in the order produced.
3.3.2. Quality Assurance Provisions
A first article shall be produced and inspected for form, dimensions and workmanship.
3.3.3. Purchaser Access
Non-escort privileges for the buyer, owner, government and owner representatives to all areas of the facilities where work is being performed shall be arranged. This will include access to all areas where material is being processed and stored. The purchaser shall have the right to witness all manufacturing processes.
3.3.4. QA Approval
LIGO QA reserves the right to inspect and approve vendor/fabricator QA plan and processes.
COMPONENT SPECIFICATION
DRWG NO. REV. GID
CONTINUATION SHEET
FARADAY ISOLATOR, 20mm
CALIFORNIA INSTITUTE OF TECHNOLOGY MASSACHUSETTS INSTITUTE OF TECHNOLOGY SHEET 5 OF 7
4 TEST PROCEDURES
4.1. Optical Surfaces
4.1.1. Visual Surface Inspection Test
All optical surfaces shall be free of visible stains and surface defects, when illuminated with a high-intensity lightsource and viewed in a darkened environment with the unaided eye.
4.1.2. Extinction Ratio Test
Extinction ratio for orthogonal polarizations shall be measured, using the specified light source. See “Light Source” on page 5.
4.1.2.1 Light Source
A collimated laser beam with 1064 nm wavelength and >9.0 mm Gaussian beam waist diameter measured at
1/e 2 power diameter shall fill the clear aperture when making transmissivity and extinction ratio measure- ments.
4.1.3. Transmissivity Test
Transmissivity t hrough the cle ar ape rture shall be measured with the spec ified l ight s ource. See “ Light Source” on page 5.
4.1.4. Wavefront Distortion Test
Wavefront distortion over the clea r a perture shall be measur ed a t 633 nm wa velength with an appropriate interferometer.
5 DOCUMENTATION
- Interferogram of transmitted wavefront across clear aperture. See “Wavefront Distortion Test” on page 5.
- Transmissivity through clear aperture. See “Transmissivity Test” on page 5.
- Extinction ratio for orthogonal polarizations through clear aperture. See “Extinction Ratio Test” on page 5.
- Compliance Certification for this specification
- Calibration certification for the test equipment, as appropriate
- Inspection report
COMPONENT SPECIFICATION
DRWG NO. REV. GID
CONTINUATION SHEET
FARADAY ISOLATOR, 20mm
CALIFORNIA INSTITUTE OF TECHNOLOGY MASSACHUSETTS INSTITUTE OF TECHNOLOGY SHEET 7 OF 7
8 OUTLINE DRAWING
Figure 1: Figure 1: Approximate outline dimensions of Faraday Rotator Assembly
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