12024B19Q0009_Specifications.pdf

RFQ 12024B19Q0009 U.S. Forest Service Infrared Mirrors National Office

NATIONAL INTERAGENCY INCIDENT COMMUNICATION DIVISION (NIICD)

INFRARED MIRRORS

SPECIFICATIONS

BACKGROUND AND INTRODUCTION

The United States Forest Service (USFS) has a requirement for two (2) sets of six (6) front surface mirrors. Each set of mirrors are used in a Texas Instruments RS-25 Kennedy Optics infrared line scanners used to map wildland fires from the air.

Ten months of the year, the US Forest operates two airborne wildland fire mapping systems and maintains a third system as a spare. Each system utilizes a Texas Instruments RS-25 Kennedy Optics infrared line scanner.

This solicitation is for making two sets of six front surface mirrors each from aluminum to be used within the .865um to 12um spectrum.

The RS-25 is housed in a pod that is attached to the bottom of the aircraft or a well that looks out the bottom of the aircraft and is subjected to condensation, rain, sleet, and occasionally some black sticky substance (suspected of originating from the landing gear mechanisms and/or the turboprop engines). After a season of operation the mirrors will have accumulated a fair amount of dust and small bit of foreign debris, with the upward facing parabolic mirror collecting the most debris. The reflective surface shall be durable, have an environmental protective coating or otherwise be abrasion resistant for the airborne operating environment.

Reflectivity and surface specifications are the same for each mirror surface and are listed by mirror name at the end of this document.

The RS-25 scanner and mirrors are subject to thermal cycling from tarmac temperatures of 60°C (120°F) to in flight altitude temperatures of -40°C (-40°F). This thermal cycling causes condensation and/or fogging/frosting of the mirrors. When landing the entire scan head will be wet with water, and the water may run or drip.

There is a plan to add two additional wavelength channels to the RS-25 scanner, an .865um and a 2.2um. The new mirrors must be optimized for the existing 3-5um & 8-12um wavelengths and also at the same time be functional at the new .865um and 2.2um wavelengths.

The honeycomb pattern shown in the drawings that is cut into the back of the mirrors (excluding rotating triangular mirror), is for weight reduction while still maintaining stiffness. There are likely several materials and many weight reduction strategies that would be acceptable for this purpose.

The US Forest Service is open to alternate weight reduction materials, designs or strategies that will decrease mirror weight if, they are structurally sufficient to maintain surface specifications and are more cost effective to make. Acceptable deviations from the provided solid model shall maintain similar weight reductions to the provided models, and also maintain mirror surface flatness throughout the operating temperature range. The finished outer mirror profiles shall match the provided Forest Service solid models within stated tolerances. The provided solid models represent the finished mirrors after plating. The solid models are available in SolidWorks format and can be provided in STEP, IGES, and several other formats if needed. If there is a discrepancy between the specifications and comments in the solid models, the specifications take precedence.

SPECIFICATIONS

SPECIFICATIONS

The mirrors shall be made to the following specifications:

1. The front surface mirrors will conform to or exceed MIL-PRF-13830B, 9 January 1997.

2. The front surface mirrors will be made of Protected Gold and have the following reflectivity figures;

a. >=95% @ 865um

b. >=97% @ 2.2um

c. >=97% @ 3-5um

d. >=97% @ 8-12um

3. A minimum of 1.75” thick raw material is acceptable for the parabolic, as just the tips on each corner will be a little short (chamfered). Maintain the distance between the vertex of the parabola to flat back side of mirror.

4. A minimum of 0.75” thick raw material is acceptable for the side mirror pairs. The primary goal is to have close to .75” thick mirror that is flat on the mirrored side.

5. The Forest Service will provide ABEC 7 hybrid ceramic ball bearings if needed for burst testing or balancing the rotating triangle mirror. The bearings will have to be returned to the Forest Service.

6. It is permissible to have a maximum radius of .09375” fillets in the corners of the hexagon weight reduction pattern.

7. Please note the center backside hole of the parabolic is required to be a circle and not a hexagon, as it mates with a locating ball on the mirror carrier.

8. Parabolic Mirror:

Mechanical

01. Material 6061-T6. Alternate acceptable base materials are 1.75 inch MIC-6, or ATP- 5 stress relieved aluminum.

02. Nickle plating 0.003 in. / 0.0035 in. thick all over

03. All dimensions after plating

04. All edges to have 0.01 inch chamfer

Optical

01. Parabola Focal point at 6.500 in. +/- 0.050 from vertex.

02. All edges to have 0.010 in. chamfer, 4 each tips of parabola corners can be chamfered to eliminate risk of bodily injury from sharp points.

SPECIFICATIONS

03. Collimated light incident upon the full aperture of the paraboloid shall be focused by the paraboloid so that 90% of the incident light will be contained within a circle of confusion of diameter 0.002 in. and 100% within a circle of confusion of diameter 0.004 in.

04. Surface of parabola to be coated with protected gold high reflecting surface for 0.865um, 2.2um, and 2.5um to 15um wavelengths. The surface reflectivity will be optimized for wavelengths 3um to 12um and the reflectivity will be >=95% Ravg for .865um, and >= 97% Ravg for 2.2um, 3-5um, and 8-12um. (Original 1963 specification was; Surface of the parabola to be coated with high reflecting surface opaque aluminum film deposit coated with Silicon Monoxide, 0.5 wavelength blue-light.)

04a. Uniformity of reflective coating +/- 1%, (approximately across entire mirror surface)

05. Center line of 0.5 in. diameter hole to be coincident with optical axis within 0.015 in.

06. Optical axis to be perpendicular to the side opposite the paraboloid to within 5 minute

07. Center line of 0.5 in. diameter hole to be perpendicular to the side opposite the paraboloid to within 30 minute

08. No orange peel visible to the unaided eye

09. No waviness or irregular surfaces, visible to the unaided eye

10. No greyness visible to the unaided eye

11. NO beauty defects objectionable to the potential use except 10 pits not over .010 in.

diameter and except 20 scratches not over 0.001 in. wide

12. All optical parameters are measured over the clear aperture on optical surface @ 6328 Angstroms unless otherwise specified.

13. Curvature uniformity: <= 1/2 wavelength per inch peak to valley

14. Irregularity: <= 1/2 wavelength per inch peak to valley

15. Surface Roughness: <= 50 Angstroms

16. Drilled hole tolerance +.005/-.001

9. Side Mirror:

Mechanical

01. Material 6061-T6. Alternate acceptable base materials are 1.75 inch MIC-6, or ATP- 5 stress relieved aluminum.

02. Nickle plating 0.003 in. / 0.0035 in. thick all over

SPECIFICATIONS

03. All dimensions after plating

04. All edges to have 0.01 inch chamfer

Optical

(All optical parameters are measured over the clear aperture on optical surface @ 6328 angstroms unless otherwise specified.)

05. Facet flatness: <= 1/2 wavelength per inch peak to valley.

06. Irregularity: <= 1/2 wavelength per inch peak to valley.

07. Optical quality: Scratch and dig, 60/40 per inch.

08. Surface roughness: <= 50 angstroms

09. Reflectivity: >= 95% Ravg @ .865 microns, and >= 97% Ravg @ 2.2um, 3-5um, and 8-12um.

10. Uniformity of reflective coating: +/- 1% (approximately across entire mirror surface)

10. Top Mirror:

Mechanical

01. Material 6061-T6. Alternate acceptable base materials are 1.75 inch MIC-6, or ATP- 5 stress relieved aluminum.

02. Nickle plating 0.003 in. / 0.0035 in. thick all over

03. All dimensions after plating

04. All edges to have 0.01 inch chamfer

Optical

(All optical parameters are measured over the clear aperture on optical surface @ 6328 angstroms unless otherwise specified.)

04. Facet flatness: <= 1/2 wavelength per inch peak to valley.

05. Irregularity: <= 1/2 wavelength per inch peak to valley.

06. Optical quality: Scratch and dig, 60/40 per inch.

07. Surface roughness: <= 50 angstroms

08. Reflectivity: >= 95% Ravg @ .865um, and >= 97% Ravg @ 2.2um, 3-5u, and 8- 12um.

09. Uniformity: +/- 1% (approximately across entire mirror surface)

SPECIFICATIONS

11. Rotating Triangle Mirror:

Mechanical

01. Material 7075-T6, 6061-T6. Offeror to recommend material, but note bearing journals and burst test requirement.

02. Nickle plating 0.003 in. / 0.0035 in. thick all over, except ~1/2” space between mirror faces.

03. All dimensions after plating

04. 1 each slip fit and user pinned bearing retainer on motor end of rotating mirror.

Material 6061-T6 aluminum.

05.The following two bushings A & B are triangle mirror bearing journals, that are heat shrink fit and precision ground for a hand interference fit of the bearings. These heat shrink bushings may not be necessary if the aluminum can tolerate installation and removal of the bearings where there is a slight interference fit. The old triangle mirror shaft was long ago adapted to accept new bearings with a different internal diameter so I am not sure the heat shrink bushings are needed today. The Forest Service will rely on offerors recommendation.

A. Bushing stainless steel (motor end)

B. Bushing stainless steel (Belleville washer end)

06. Ideally the small approximately 1/2” space between each triangle mirror face along the length of the mirror will be antireflective black. If antireflective black is not possible then this 1/2” space will be abraded to break the glazed surface of any plating so this space can be hand painted Acrylic flat black.

07. Please Note: ** The rotating triangle mirror is to be burst tested at 10,000 RPM +/- 100 RPM for 3 minutes at room temperature (60Deg F to 105Deg F). The triangle mirror also needs to be dynamically balanced to within .002 oz in.

08. Please note: ** The rotating triangle mirror may not need bushings A & B if the offeror can recommend that the 7075 or 6061 can tolerate removing and replacing bearings every 3-4 years where there is an interference fit, without galling. The pinned bearing retainer will still be required. If a determination is made to omit the bushings A & B, then the rotating triangle mirror shaft diameter will need to match the bushing OD size of 1.1808 +0/-.0002 inch.

Optical

(All optical parameters are measured over the clear aperture on optical surface @ 6328 angstroms unless otherwise specified.)

SPECIFICATIONS

04. Facet flatness: <= 1/2 wavelength per inch peak to valley.

05. Irregularity: <= 1/2 wavelength per inch peak to valley.

06. Optical quality: Scratch and dig, 60/40 per inch.

07. Surface roughness: <= 50 angstroms

08. Reflectivity: >= 95% Ravg @ .865um, and >= 97% Ravg @ 2.2um, 3-5um, and 8- 12um.

09. Uniformity: +/- 1% (approximately across entire mirror surface)

SPECIFICATIONS

BLUEPRINT DRAWING NOTES FROM 1960

The following notes are from 1960 blueprint drawings and are being provided for informational purposes only. In 1960 3-12um detectors were the only wavelengths in use. This notes are only included to provide additional insight in relation to the rotating mirror.

Rotating Triangular Mirror Special notes on 1963 blueprint

Sequence of Operations:

Chemplate

1. Machine shafts to dimensions shown

2. Grind and polish optical surfaces

3. Apply coating of S10 to mirror surfaces, coating thicknesses to be .5 wavelength at 5,000 angstroms.

4. Bake overcoated mirror @300Deg for 14 hours

5. Paint surfaces at 1.995 +.003/-.005 R Optical Black

6. Balance

Unless Otherwise Specified, General Tolerances;

1. Decimal .xx +/-.02 in., .xxx +/-.01 in.

2. Fractional +/-0.015625 in. (1/64)

3. Angular +/-1 Deg

4. Concentricity of Machined Surfaces .004 in. Total Indicator Runout (TIR).

5. All dimensions to be met before plating.

6. Remove all burrs & sharp edges.

7. All dimensions in inches.

Drilled Hole Tolerances:

1. .013” to .136” +.003”/-.002”

2. .136” to .250” +.005”/-.003”

3. .250” and above +/-.005”

Drawing Notes:

1. Chemplate entire mirror +.001”/-.000” This may not be true today because of Optical Black edges along three triangular lengths.

2. During plating, part must be suspended from pins located in ends of shaft.

3. ** Shaft diameter concentricity within .0002” TIR.

4. Three surfaces of mirror to be optically flat within ½ wavelength per inch, sodium light. Each surface to be parallel to axis of shaft (1”) within 15 seconds.

5. Three surface flats to have optical quality finish (100-60) except for a reasonable number of hairline sleeks or scratches.

6. No grayness of three mirror surfaces shall be visible.

7. ** To be burst tested at 10,000 RPM +/-100 RPM for 3 minutes at room temperature (60Deg F to 105Deg F).

8. To be dynamically balanced to within .002 oz in.

SPECIFICATIONS

Note: The end of triangle mirror ends may be used for metal removal during dynamic balancing. Maximum depth of lightening holes not to exceed .30”(typical 3 corners each end as marked by hatch area.)

9. Centerline of 3/8-16 threaded hole to be parallel with and concentric to centerline of 1-inch shaft within .0002” TIR

10. Surface area of triangular ends must be perpendicular to centerline of 1-inch shaft within .0001”

11. Clamp the drive end of the (¾” shaft) scan mirror in a Harding lathe or double EE lathe.

12. Place the end to be threaded in a bearing support using an MMS 8K bearing, and center the shaft within .0001” TIR. (This is a precision ground shaft for a ABEC 7 bearing.)

13. Bore the shaft to .5000” +/-.0005” Dia x 1” +/-.005” depth.

14. Using .625” brass round and a tap of known good quality, tap a 3/8-16 TPI thread x 1.1” deep on the center.

15. Cut of 1.050” of this threaded .625” round stock.

16. Make a mandrel with a 3/8-16 TPI, thread one end to fit securely into the threaded brass stock. Insert mandrel into threaded brass stock, put un-threaded mandrel shaft into lathe and turn the OD of the threaded brass sleeve to be a .0002” press fit into the .5000” +/-.0005” bore.

17. True up the open end of the turned down brass stock.

18. Press the threaded brass sleeve into the mirror shaft bore until it bottoms in the bore.

19. Rough off excess brass protruding beyond the mirror shaft end.

20. Install 2 each .0625” pins 180 Deg apart and .25” deep, half in the brass, and half in the mirror shaft.

21. With the shaft OD within .0001” TIR, true up the end of the shaft and brass bushing to .0001” TIR.

22. Using a threaded .75” diameter rod, 9.5” long, check threaded sleeve. End of rod should be within .004” TIR with bushed mirror shaft.