Dr. Santosh K. Jha Profile

Dr. Santosh K. Jha

at Surmet Corp

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Author

Publications (9)

Proceedings Article | 13 June 2023 Presentation + Paper

Improved strength scaling for large ALON windows

Lee Goldman, Uday Kashalikar, Mark Smith, Mohan Ramisetty, Santosh Jha, Suri Sastri

Proceedings Volume 12518, 125180A (2023) https://doi.org/10.1117/12.2664050

KEYWORDS: Windows, Polishing, Failure analysis, Ceramics, Spinel, Surface finishing, Optical fabrication

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ALON^® Transparent Ceramic (ALON) consists primarily of aluminum and oxygen, similar to that of alumina, with a small amount of nitrogen added to help stabilize its cubic phase. Importantly, materials with cubic symmetry are optically isotropic, and consequently, transparent in their polycrystalline form. This allows ALON to be manufactured by conventional powder processing methods. ALON is deployed in several Vis-MWIR Sensor Window applications and provides outstanding environmental durability. Further, ALON windows are available in very large sizes as required for Defense reconnaissance systems. The conventional approach for predicting how the strength of a ceramic material scales from the small strength coupons (~1” diameter), to full sized sensor windows, which may be orders of magnitude larger, is to use Weibull scaling as is described by Harris et al in reference 1. Weibull scaling assumes that as the window gets larger and larger, the strength controlling flaws get larger too. However, this ignores the microstructure of the window material, and the role that the microstructure may have in limiting the size of strength controlling flaws. All materials, amorphous, single crystal and polycrystalline are therefore treated as equivalent. Jeff Swab et al2 measured strength in ALON samples over a range of sizes. The largest strength samples measured were <11-in diameter. These ALON samples were purchased from Surmet with our standard commercial polish. We have the average strength and Weibull modulus data for samples produced with the same surface. Scaling the strength from coupons (~350MPa, and Weibull modulus m=3.11) to the largest samples broken by Swab et.al, predicts a strength of only 53 MPa. However, the actual strengths measured by Swab et.al. was 152+/-28 MPa, 3x higher than predicted. The potential role of ALON’s microstructure in this higher than predicted strength will be discussed, and future experiments will be proposed to determine an improved approach to scaling strength with area.

Proceedings Article | 13 June 2023 Paper

Recent developments in ALON and spinel transparencies at Surmet

Lee Goldman, Uday Kashalikar, Mark Smith, Mohan Ramisetty, Santosh Jha, Suri Sastri

Proceedings Volume 12518, 1251809 (2023) https://doi.org/10.1117/12.2664043

KEYWORDS: Windows, Spinel, Domes, Polishing, Ceramics, Inspection, Transparency

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Proceedings Article | 13 May 2019 Presentation + Paper

Conformal ALON and spinel windows

Lee Goldman, Mark Smith, Mohan Ramisetty, Santosh Jha, Suri Sastri

Proceedings Volume 10985, 109850G (2019) https://doi.org/10.1117/12.2518902

KEYWORDS: Spinel, Domes, Ceramics, Sensors, Heat treatments

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Proceedings Article | 13 May 2019 Presentation + Paper

Scale up of large ALON windows

Lee Goldman, Mark Smith, Mohan Ramisetty, Uday Kashalikar, Santosh Jha, Suri Sastri

Proceedings Volume 10985, 109850F (2019) https://doi.org/10.1117/12.2518899

KEYWORDS: Sensors, Ceramics, Polishing, Refractive index, Inspection, Birefringence

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Proceedings Article | 3 May 2017 Paper

Scale up of large ALON and Spinel windows

Lee Goldman, Uday Kashalikar, Mohan Ramisetty, Santosh Jha, Suri Sastri

Proceedings Volume 10179, 101790J (2017) https://doi.org/10.1117/12.2269467

KEYWORDS: Fourier transforms, Ceramics, Photography, Manufacturing, Lenses, Aluminum, Mid-IR, Sapphire, Spinel, Sensors

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Proceedings Article | 3 May 2017 Paper

Conformal ALON and spinel windows

Lee Goldman, Mark Smith, Mohan Ramisetty, Santosh Jha, Suri Sastri

Proceedings Volume 10179, 101790I (2017) https://doi.org/10.1117/12.2269466

KEYWORDS: Domes, Aluminum, Photography, Sensors, Ceramics, Sapphire, Heat treatments, Oxygen, Nitrogen, Spinel

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Proceedings Article | 17 May 2016 Paper

ALON GRIN optics for visible-MWIR applications

Nagendra Nag, Santosh Jha, Suri Sastri, Lee Goldman, Peter McCarthy, Greg Schmidt, Julie Bentley, Duncan Moore

Proceedings Volume 9822, 98220V (2016) https://doi.org/10.1117/12.2224961

KEYWORDS: GRIN lenses, Refractive index, Optics manufacturing, Imaging systems, Gradient-index optics, Ceramics, Domes, Refraction, Mid-IR, Diffusion

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Proceedings Article | 22 May 2015 Paper

Conformal ALON® windows

Lee Goldman, Sreeram Balasubramanian, Mark Smith, Nagendra Nag, Robyn Foti, Santosh Jha, Suri Sastri

Proceedings Volume 9453, 945306 (2015) https://doi.org/10.1117/12.2177236

KEYWORDS: Ceramics, Domes, Sensors, Manufacturing, Optics manufacturing, Optical fabrication, Polishing, Aluminum, Transparency, Photography

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Proceedings Article | 18 May 2005 Paper

Durable coatings for IR windows

Lee Goldman, Santosh Jha, Nilesh Gunda, Rick Cooke, Neeta Agarwal, Suri Sastri, Alan Harker, Jim Kirsch

Proceedings Volume 5786, (2005) https://doi.org/10.1117/12.607597

KEYWORDS: Optical coatings, Silicon carbide, Silicon, Absorption, Transmittance, Mid-IR, Nitrogen, Resistance, Refraction, Carbon

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Showing 5 of 9 publications

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