Statement of Work.docx

Statement of Work Infrared Telescope System Acronyms CLIN: Contract Line-Item Number OCA: Optical Cross Assembly OTA: Optical Telescope Assembly

I. Background Science objective:

NIST is working on a project that requires an infrared telescope system to make accurate spectral irradiance measurements of the light from standard stars in the wavelength range between 850 nm and 2500 nm. Observations will be made at high altitude above 2600 m (8600 feet) in dry (low precipitable water vapor) environments to maximize access to clear skies and minimize telluric effects (e.g., aerosols). These measurements will then serve as standard calibration spectra for multiple stakeholders who operate other astronomical instruments and satellite instruments.

Operational objective:

The operational objective is accurate spectral irradiance measurements of real stars in the sky relative to an artificial star (the absolute radiometric standard) on the ground. Therefore, the telescope system required in this procurement is best thought of as a light bucket: it must provide an image of the source focused onto the input face of a 600-micrometer core diameter optical fiber, which subsequently feeds the light into a spectrometer. The optical fiber’s numerical aperture is greater than that associated with the telescope, so that the telescope entrance aperture defines the entrance pupil diameter of the system.

Radiometric calibration of the telescope will be performed by the user in the field, using a 1-mm diameter artificial star placed at 100 m from the entrance aperture of the telescope. It is anticipated that the image position at the back of the telescope will shift about 2.5 inches depending on whether the imaged object is a real star at an infinite distance or the user-provided, artificial star at 100 m from the telescope system. This shift will be accommodated by a focuser provided by the user as described below. Image quality is important only for the on-axis source, and only to the degree that it affects the encircled energy function. To enable alignment and tracking, a beam splitter located between the telescope output and fiber input sends visible light to a dedicated guider camera. The beam splitter, guider camera, focuser, and optical fiber together comprise a separate user-provided component of the optical system, the Optical Cross Assembly (OCA) which is mounted behind the telescope. An interface plate on the back of the Optical Telescope Assembly (OTA) for mounting the OCA is part of this equipment acquisition, although the OCA and the fiber-coupled spectrometer are not. The OCA interface plate and the baffling structures inside the OTA must permit the installation and use of the focuser having a travel of at least 2.5 inches (or as required to accommodate the focus shift between a natural star and the artificial star with no vignetting of rays at the extremum of the travel.

The telescope operating site will be on Cerro Paranal, Chile. During nighttime operation, the telescope will be completely exposed to the outside. Calibration measurements will be made at regular intervals during the night, alternating with exposures of the stars. Measurements of the sky are obtained between star exposures. When not in use, the telescope is protected from the environment by an enclosure.

Typical operational conditions at Cerro Paranal, Chile

II. Scope of Work This equipment acquisition is for an infrared telescope system to be located at the high-altitude astronomical observatory on Cerro Paranal in Chile (2635 m altitude). The user must be able to point the telescope to and track stars from star rise to star set; and must also be able to point the telescope to an artificial star located approximately 100 m away from the telescope. Because the artificial star may be located 10 degrees below the horizon, the telescope must be capable of pointing to the zenith and to a sub-horizon point and be mechanically stable throughout the range of motion.

III. Minimum Requirements The system shall meet or exceed the minimum requirements identified below. All items must be new. The use of “gray market” components not authorized for sale in the U.S. by the proposer is not acceptable. All line items shall be shipped in the original manufacturer’s packaging and include all original documentation and software, when applicable.

Requirements are given separately for the four components of the infrared telescope system. The Contractor may provide pricing for one, some, or all items. The Contractor shall provide pricing for each item separately to facilitate the potential for a base + options contract.

The four components are A. Optical Telescope Assembly (OTA) B. Mechanical Mount, C. Motion Control, D. Installation

CLIN 0001: The Contractor shall provide an Optical Telescope Assembly (OTA) that meets Requirements as follows:

The telescope design shall be optimized for radiometry and spectroscopy. Light from an artificial star at 100 m and light from a natural star at infinity is delivered into an on-axis optical fiber, which directs light into a spectrometer.

1.1. The telescope type (e.g., Ritchey-Chretien, Dahl-Kirkham etc.) is unconstrained; but telescope will be used for on-axis spectroscopy of stars so optimizing imaging quality over a wide field of view is not necessary. The minimum field of view is less than 10 arcminutes.

1.2. The Government will provide a focusing assembly to accommodate focus position changes between the natural star and the artificial star (Section VI 1 Optical Cross Assembly and Requirement 15). Therefore, the telescope itself need not have Contractor-provided moveable parts to accommodate the focus change.

1.3. The optical telescope assembly shall interface with the Optical Cross Assembly.

The telescope design shall be optimized for astronomical spectroscopic measurements between 850 nm and 2500 nm and meet optical requirements at 1800 nm.

Primary mirror diameter may not exceed 508 mm (20 inches, clear aperture)

1.4. The minimum acceptable primary mirror diameter is 432mm (17 inches) with preference for a size that is standard for the Contractor.

1.5. The central hole diameter is determined by the need to not clip light in the presence of baffles from either an artificial or natural star.

The maximum (linear) obscuration (ratio of secondary mirror diameter to primary mirror diameter) shall not exceed 40%.

The mirror surface roughness shall be less than 10 nm RMS (root mean square) or the industry standard for reflecting telescopes at visible wavelengths, whichever is less.

The primary mirror base shall have a low coefficient of thermal expansion. (Section VI. X) Primary and secondary mirror coatings shall be protected aluminum.

The optical telescope assembly shall be stable at the expected operating temperature and humidity on Cerro Paranal:

1.6. Operating temperature between 10 and 40 degrees C.

1.7. Operating humidity between 0% and 20% relative humidity

The telescope mirrors shall meet storage temperature requirements:

1.8. range between 10 C and +60 degrees C The optical fiber is provided by the Government. It has a core diameter of 600 micrometers and an NA (numerical aperture) of 0.22, an outer diameter of 6 mm and a bend minimum radius of 50 mm. The telescope design shall be compatible with the optical fiber in the following manner:

1.9. The telescope shall have an f/# such that rays are not clipped on the receiving surface of the optical fiber.

1.10. The NIST-provided optical fiber will be located at the output of the Optical Cross Assembly.

The telescope shall have an aperture mask that defines the entrance pupil at a definite, planar location at the front of the telescope.

1.11. This defining aperture shall have a knife-like edge to define the beam cross section. The knife edge shall have a land that is minimally practical within the machining limitations, and the aperture shall be beveled on the side facing the telescope interior. The aperture shall provide a shadow margin no smaller than 4 mm from the primary perimeter, central obscuration, and central obscuration supports. (As a result, all incident light from a star shall only be incident on the aperture mask and primary.)

1.12. Locations of the primary perimeter, central obscuration, and central obscuration supports shall be knowable, so that one can determine definite distance between the telescope entrance aperture and the exit aperture of the artificial star to 10 cm over 100 meters

1.13. This defining aperture shall be field-replaceable by the user.

1.14. The surface of the defining aperture that faces inward to the telescope shall have a diffuse black coating like the baffles to capture stray light

1.15. A schematic figure of the aperture mask is shown in Section VI.

An offset of 10 arcsec from the optical axis shall result in a change of less than 0.2% in throughput into a 600-micrometer core diameter optical fiber.

Control of stray light is critical for radiometry. Stray light requirements are:

1.16. No more than 0.01% of the total light entering the fiber shall be light from points or angles outside the field of view. The baffle design must be such that when back illuminating the fiber, 99.99% of the total light seen by the virtual detector comes from within the field of view. For example, the baffles should block annular rings of light such as could be generated by light scattering off interior walls.

1.17. The Contractor shall provide their optical design to NIST, in an electronic format readable by Zemax optical design software.

1.18. NIST will verify by analysis that stray light requirements are met.

The OTA shall include the primary and secondary mirrors, mechanical supports for the primary mirror and primary mirror cell, primary mirror cover, secondary mirror cell, secondary mirror support, baffles, aperture mask, and interface plate for the Optical Cross Assembly to be supplied by NIST.

1.19. An open truss is preferred over a closed tube.

1.20. The Contractor shall provide a primary mirror cover.

1.20.1. For an open truss tube, the mirror cover shall be directly above the primary mirror and be mechanically controlled (preferred).

1.20.2. For a closed tube, the mirror cover shall be above the aperture mask, and be at least manually removable by the user.

Interface to NIST-supplied Optical Cross Assembly (OCA)

1.21. See Section VI. 1 for a description of the OCA.

1.22. The Contractor shall provide an Interface Plate fixed at the rear of the telescope to enable NIST to mount the OCA. The normal to the interface plate shall be parallel to the telescope optical axis. The plate must include a hole to allow the optical beam to pass through. The thickness of the interface plate shall be at least 0.375 inches.

1.23. NIST will provide the physical dimensions and mechanical details of the OCA to the Contractor to enable design of the interface plate.

1.24. NIST will provide the optical properties of the beam splitter to the Contractor.

1.25. The back working distance of the telescope, defined as the distance along the optical axis between the back surface of the Interface Plate and the location of the telescope focus for an object at infinity, shall be at least 123 millimeters.

1.26. The Contractor shall provide NIST with their estimate of the difference in focal position along the optical axis for natural star vs. artificial star during the design phase, to ensure the NIST-supplied OCA focus mechanism can accommodate the position shifts.

The top-level optical performance requirements of the OTA are:

1.27. At the focus for a natural star at infinity at a wavelength of 1800 nm, the encircled energy of the image within a 600-micrometer diameter circle in the focal plane normal to the optical axis shall contain at least 98.5 % of the total energy at that plane.

1.28. At the focus for a 1-mm diameter uniform source (the artificial star) placed 100 m from the entrance aperture of the telescope, the encircled energy of the image within a 600-micrometer diameter circle in the focal plane normal to the optical axis shall contain at least 98.5 % of the total energy at that plane, at a wavelength of 1800 nm.

1.29. When properly focused for each of the two sources defined above, the change of encircled energy within a 600-micrometer diameter circle in the focal plane normal to the optical axis shall be less than 0.15 % at a wavelength of 1800 nm.

1.30. These optical requirements apply to the OTA plus OCA. The optical prescription of the OCA beam splitter will be provided by NIST during the Contractor design process.

1.31. NIST will provide the Contractor with the design for mounting the OCA. The mechanical design must allow for sufficient space behind the primary mirror cell to locate the optical cross assembly (see 15). This space must be easily accessible and without mechanical interference from other components.

Before the hardware build, the Contractor shall provide NIST their predictions for the change of encircled energy for a point source at infinity and an artificial star at 100 m when the telescope is properly focused, for 12 wavelengths evenly spaced between and including 850 nm and 2500 nm. Analysis must be supported by a full optical chain prescription, including all parts that affect light propagation.

CLIN 0002: The Contractor shall provide a Telescope Mount that meets the Requirements as follows:

The Mount must support the OTA described in CLIN 0001 plus the weight of the NIST-supplied OCA, estimated to be 20 kg.

The Contractor shall provide minimum bend radius that would be induced in a fiber run through the Mount.

The Contractor shall provide an equatorial mount for Cerro Paranal's latitude of 24.6272 degrees South. A fork mount is preferred.

CLIN 0003: The Contractor shall provide Motion Control for the telescope mount that meets Requirements as follows:

The telescope shall point 10 degrees below the horizon, and to and through the zenith without mechanical deformation or changes that affect the above specifications in Section CLIN 0001.

The motion control shall provide pointing and tracking accuracy capability as follows:

1.32. Pointing accuracy: ≤10 arcsec RMS

1.33. Tracking accuracy: < 0.1 arcsec during a 30-second period.

The motion control shall provide motion range to allow sky coverage as follows:

1.34. Altitude Range: -10 to 90 degrees

1.35. Azimuth Range: +/- 360 degrees

The Contractor shall provide a software interface to telescope control software via e.g., an Application Programming Interface (API).

The Contractor’s software shall allow system state metadata to be accessible to the user.

The Contractor’s software shall allow the user to specify telescope pointing to objects below the horizon (for calibration by viewing the artificial star).

The Contractor’s software shall allow user to point telescope to any specified objects with the option of no refraction correction (e.g., objects near the horizon).

The Contractor shall provide an alignment/collimation kit.

CLIN 0004: The Contractor shall provide training on installation for CLINs 0001 – 0003 in accordance with the following:

NIST will prepare the telescope site on Cerro Paranal in Chile; this includes the concrete telescope pad and pier for placing the mount, and the telescope enclosure. Details of the pier-to-mount interface will be discussed with Contractor at telescope design review. The Contractor will ship the optical telescope assembly (OTA) to NIST in Gaithersburg for calibration. NIST will be responsible for then shipping the telescope to Cerro Paranal, Chile and for its installation on the site.

It is preferred that the Contractor install the telescope system at the NIST site on Cerro Paranal, Chile. In lieu of Contractor installation, the Contractor shall provide training for NIST personnel (see Section VII) at Contractor's worksite on installation procedures. NIST will pay for NIST staff travel to Contractor's site.

IV. Delivery For each item that Contractor has offered to provide, Contractor shall also deliver operation manual(s), software manual(s), electrical/mechanical manual(s) as specified by NIST.

Schedule. This is a suggested schedule and will need to be confirmed upon contract award. We assume 15 months (1.25 years) for delivery of OTA to NIST. Estimated dates are relative to the date on which the contract is awarded.

OTA shipped to Chile

+17 months

Mount shipped to Chile

+17 months

Motion Control to NIST

+17 months

OTA, Mount, Motion Control arrive on Cerro Paranal

+19 months

Delivery shall be FOB DESTINATION.

FOB Destination means: The contractor shall pack the system in the shipping containers and mark the shipment in conformance with carrier requirements, deliver the shipment in good order and condition to the point of delivery specified in the purchase order, be responsible for any loss of and/or damage to the goods occurring before receipt and acceptance of the shipment by the consignee at the delivery point specified in the purchase order; and pay all charges to the specified point of delivery.

NOTE: All hardware must be shipped in dedicated, metal or plastic, reusable crate/case(s). Wood or cardboard crates/cases are not allowed for shipments to Chile. Wheeled crate/case is desirable.

Contractor shall deliver the OTA (CLIN 0001) to:

National Institute of Standards and Technology 100 Bureau Drive, Building 217, Room A243 Gaithersburg, MD 20899-1640, United States of America NIST will ship the OTA to Chile after calibration of the OTA.

Contractor shall deliver Mount (CLIN 0002) to:

National Institute of Standards and Technology c/o ESO, Cerro Paranal, Chile

Contractor shall deliver Motion Control (CLIN 0003) to:

National Institute of Standards and Technology c/o ESO, Cerro Paranal, Chile

V. Inspection and Acceptance NIST COR or TPOC may visit Contractor’s site at final assembly and checkout before shipping to NIST In addition to the inspection and acceptance terms articulated above and inspection and acceptance done at the Contractor’s facility during training, the Government reserves the right to perform such performance tests and evaluations as defined below to verify specified system performance. Such tests and evaluations, if performed, shall be conducted within the environment that the system is to be operated. The Contractor has the right to be present during the tests and evaluations, if performed, at the Contractor’s expense.

1) Contractor shall provide NIST’s Contracting Officer Representative and Technical Point of Contact their optics design. NIST will check that radiometric specifications meet or exceed requirements for RMS Spot diagram, encircled energy, and stray light

2) The Government will test, inspect, and accept optics design within 15 business days after receiving a Zemax-compatible file

3) Contractor shall ship the OTA to NIST, in Gaithersburg, MD.

4) The NIST TPOC will visually inspect the OTA to identify surface defects or any form of indication that the system was damaged during transport to NIST. The Government shall have sole discretion to require repair or replacement of damaged and/or nonconforming supplies at no cost to the Government. The Government at any time prior to acceptance shall reject the system due to defects and/or nonconformance.

5) NIST technical staff will test and check that the supplied OTA complies with the optical performance specifications. Data will be collected and analyzed.

6) The Government will inspect and accept the equipment onsite within 15 business days of the receipt of the OTA.

VI. Government-Furnished Property, Material, Equipment, or Information (GFP, GFM, GFE, or GFI)

1) The Government shall provide the Optical Cross Assembly (see Requirements 10, 15, and 16). NIST shall provide the Contractor opto-mechanical design of the OCA. This paragraph is provided to help the Contractor understand the purpose of the OCA. The OCA consists of the focusing mechanism, a beam splitter, and two cameras. The OCA is centered around a beam splitter that directs most of the beam to the optical fiber and a small fraction to a camera. This enables the camera to view the star for tracking purposes. The OCA focus mechanism moves the OCA along the optical axis to accommodate the large focus position shift between the natural star and the artificial star. It also enables fine focus to adjust to ensure that the optical fiber input tip remains in focus. A second camera that is part of the optical cross is used to visualize the focused spot at the input face of the optical fiber. The OCA mass is 20 kg.

2) Design schematic (not to scale) of the entrance aperture mask as specified in Requirement 11.

3) An example of a 2-mirror design used by the Government in a related study of telescope performance is provided for illustrative purposes in the table below.

4) For accurate radiometric measurements the mirrors should be thermally stable. Therefore, it is important that the primary mirror base have a low coefficient of thermal expansion. This may be achieved mechanically (e.g. thinning the backside) and/or through choice of material, e.g. Zerodur vs. BK7.

VII. Training In lieu of Contractor installing the telescope system in Chile, Contractor shall conduct at Contractor’s location, training session for up to 4 NIST personnel on installation, alignment, and operation of the telescope system. The training shall provide a thorough demonstration of all system/solution functions, maintenance, data administration, and basic troubleshooting. The Government shall pay travel expenses of NIST personnel. Contractor will be available to NIST personnel during installation of telescope system via telephone and email.

VIII. Warranty The Contractor shall provide a warranty in accordance with commercial practices and in accordance with 52.212-4.

IX. Payment Schedule The Contractor shall be paid, in accordance with Net 30-day payment terms, upon receipt and acceptance of a proper invoice, in accordance with the following schedule:

1. CLIN 001: A 30% milestone payment will be made after NIST approval of the design, with remaining 70% paid after delivery of OTA to NIST,

2. CLIN 002 & CLIN 003. Payment in full within 14 days after delivery to NIST c/o ESO's Cerro Paranal Observatory in Chile.

3. CLIN 004: Payment in full within 7 days after installation on the NIST site at ESO's Cerro Paranal Observatory in Chile.

4. The Government anticipates inspection will occur upon final delivery after the testing procedures set forth in this document have been completed.

NOTE: Partial shipments/installation and partial invoices will not be accepted, unless otherwise requested and accepted by the Contracting Officer prior to award offer. Proposed payment schedules shall be submitted with Contractor’s response to the RFQ for consideration.

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