Yaakov Gridish - Academia.edu (original) (raw)

Papers by Yaakov Gridish

Proceedings of SPIE, Feb 9, 2006

High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and in... more High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and industrial applications, where repetitive cw (continuous wave) and pulsed cw operation modes are required. When operating in such modes, the lasers experience ...

Proceedings of SPIE, Jun 24, 2014

Cryogenically cooled infrared electro-optical payloads have to operate and survive frequent expos... more Cryogenically cooled infrared electro-optical payloads have to operate and survive frequent exposure to harsh vibrational and shock conditions typical of the modern battlefield. This necessitates the development of special approaches to ruggedizing their sensitive components. The ruggedization requirement holds true specifically for Integrated Dewar-Detector Assemblies (IDDA), where the infrared Focal Plane Array (FPA) is usually supported by a thin-walled cold finger enveloped by an evacuated tubular Dewar. Without sufficient ruggedization, harsh environmental vibration may give rise to structural resonance responses resulting in spoiled image quality and even mechanical fractures due to material fatigue. The authors present their approach for the ruggedization of the IDDA by attaching the FPA to a semi-rigid support extending from the dynamically damped Dewar envelope. A mathematical model relies on an experimentally evaluated set of frequency response functions for a reference system and a lumped model of a wideband dynamic absorber. By adding only 2% to the weight of the IDDA, the authors have managed to attenuate the relative deflection and absolute acceleration of the FPA by a factor of 3. The analytical predictions are in full agreement with experiment.

Proceedings of SPIE, Feb 7, 2008

High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industria... more High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industrial applications, where very high brightness and power are required. The high brightness is achieved either by increasing the power of each bar or by reducing the emitting area of the stacks. Two new products will be presented: Horizontal CW stacks with output power as high as 1kW using 80 W bars with emitting area width as low as 50 mum Vertical QCW stacks with output power as high as 1.2kW using 120 W bars. Heat removal from high power laser stacks often requires microchannel coolers operated with finely filtered deionized (DI) water. However, for certain industrial applications the reliability of this cooling method is widely considered insufficient due to leakage failures caused the highly corrosive DI water. Two solutions to the above problem will be discussed. A microchannel cooler-based package, which vastly reduces the corrosion problem, and a novel high-power laser diode stack that completely eliminates it. The latter solution is especially effective for pulsed applications in high duty cycle range.

SPIE Proceedings, 2015

Over the last decade SCD has established a "state of the art" VOx μ-Bolometer product l... more Over the last decade SCD has established a "state of the art" VOx μ-Bolometer product line. The market demands for low SWaP (Size, Weight and Power) uncooled engines is steadily growing, where low SWaP is especially critical in battery-operated applications such as goggles and Thermal Weapon Sights (TWS). In this approach, SCD has developed a low-SWaP, shutter-less uncooled video core, with a foot-print of 31x31mm and sub Watt power consumption. The video core contains a temperature calibrated, High Sensitivity (HS) 640x480 17μm pitch detector (NETD ≤ 32mK @ 30Hz, F/1), packaged in a new TEC-less ceramic package (26x23mm). The video core contains superior image processing algorithms including: local and global Dynamic Range Compression (DRC), and spatial and temporal de-noising algorithms providing low NETD and stable and low Residual Non Uniformity (RNU) video image.

L'invention concerne un procede permettant d'elaborer un module tridimensionnel multicouc... more L'invention concerne un procede permettant d'elaborer un module tridimensionnel multicouche (300) renfermant des dispositifs semi-conducteurs, des circuits integres et des dispositifs de systemes electromecaniques, notamment des dispositifs dans lesquels la forme modifie la fonction, comme dans des commutateurs optiques tridimensionnels utilisant des dispositifs de systemes micro-electromecaniques. Cette invention a egalement trait a un procede de creation d'un acces electrique lateral a des dispositifs contenus dans un boitier a puces empile tridimensionnel, ainsi qu'a la connexion du module tridimensionnel aux circuits externes. Les couches du module (110(a-e)) sont elaborees individuellement et testees avant l'assemblage. Ce procede permet de minimiser la necessite d'un alignement soigneux de puces et il est relativement simple et peu couteux. En outre, il permet la correction d'imprecisions qui emergent au cours de l'assemblage. Des couches adjace...

SPIE Proceedings, 2007

808 nm, QCW laser bars delivering peak power higher than 150 Watts were developed. The optimizati... more 808 nm, QCW laser bars delivering peak power higher than 150 Watts were developed. The optimization of the tensile strain in the QW structure, the design configuration of the laser cavity together with an improved packaging technology lead to more than 55% wall plug efficiency when assembled as stacks. Due to the high characteristic temperature (T0, T1) values and high

Infrared Technology and Applications XL, 2014

Cryogenically cooled infrared electro-optical payloads have to operate and survive frequent expos... more Cryogenically cooled infrared electro-optical payloads have to operate and survive frequent exposure to harsh vibrational and shock conditions typical of the modern battlefield. This necessitates the development of special approaches to ruggedizing their sensitive components. The ruggedization requirement holds true specifically for Integrated Dewar-Detector Assemblies (IDDA), where the infrared Focal Plane Array (FPA) is usually supported by a thin-walled cold finger enveloped by an evacuated tubular Dewar. Without sufficient ruggedization, harsh environmental vibration may give rise to structural resonance responses resulting in spoiled image quality and even mechanical fractures due to material fatigue. The authors present their approach for the ruggedization of the IDDA by attaching the FPA to a semi-rigid support extending from the dynamically damped Dewar envelope. A mathematical model relies on an experimentally evaluated set of frequency response functions for a reference system and a lumped model of a wideband dynamic absorber. By adding only 2% to the weight of the IDDA, the authors have managed to attenuate the relative deflection and absolute acceleration of the FPA by a factor of 3. The analytical predictions are in full agreement with experiment.

High-Power Diode Laser Technology and Applications IV, 2006

High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and in... more High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and industrial applications, where repetitive cw (continuous wave) and pulsed cw operation modes are required. When operating in such modes, the lasers experience numerous complete thermal cycles between "cold" heat sink temperature and the "hot" temperature typical of thermally equilibrated cw operation. It is clearly demonstrated that the main failure mechanism directly linked to repetitive cw operation is thermo-mechanical fatigue of the solder joints adjacent to the laser bars, especially when "soft" solders are used. Analyses of the bonding interfaces were carried out using scanning electron microscopy. It was observed that intermetallic compounds, formed already during the bonding process, lead to the solders fatigue both on the p- and n-side of the laser bar. Fatigue failure of solder joints in repetitive cw operation reduces useful lifetime of the stacks to hundreds hours, in comparison with more than 10,000 hours lifetime typically demonstrated in commonly adopted non-stop cw reliability testing programs. It is shown, that proper selection of package materials and solders, careful design of fatigue sensitive parts and burn-in screening in the hard pulse operation mode allow considerable increase of lifetime and reliability, without compromising the device efficiency, optical power density and compactness.

High-Power Diode Laser Technology and Applications VI, 2008

High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industria... more High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industrial applications, where very high brightness and power are required. The high brightness is achieved either by increasing the power of each bar or by reducing the emitting area of the stacks. Two new products will be presented: Horizontal CW stacks with output power as high as 1kW using 80 W bars with emitting area width as low as 50 µm; Vertical QCW stacks with output power as high as 1.2kW using 120 W bars. Heat removal from high power laser stacks often requires microchannel coolers operated with finely filtered deionized (DI) water. However, for certain industrial applications the reliability of this cooling method is widely considered insufficient due to leakage failures caused the highly corrosive DI water.

Proceedings of Spie the International Society For Optical Engineering, Feb 1, 2007

808 nm, QCW laser bars delivering peak power higher than 150 Watts were developed. The optimizati... more 808 nm, QCW laser bars delivering peak power higher than 150 Watts were developed. The optimization of the tensile strain in the QW structure, the design configuration of the laser cavity together with an improved packaging technology lead to more than 55% wall plug efficiency when assembled as stacks. Due to the high characteristic temperature (T 0, T I) values and high efficiency, the output power of these devices is almost insensitive to elevated heat sink temperatures. In addition, a collimation technique which significantly improves the beam quality of the laser stacks was developed. The active collimation method is flexible and control over the level of collimation is achievable. The use of this collimation technique alongside with high quality micro lenses allows for a reduction of the fast axis divergence to values as low as 3 mrad with minimal power losses. An automatic process control was developed allowing for the efficient attachment of the collimating micro lenses in a highly reproducible fashion. The combination of the collimation technique with a reliable mounting and stacking technology supports the serial manufacturing of devices delivering 1 kW peak power in QCW operation. These QCW collimated diode laser stacks demonstrate stable operation and high reliability in the course of more than 6*10 8shots at 2% duty cycle. Another important advantage of the collimated stacks is their capability to withstand severe environmental conditions, maintaining high beam quality and performance.

Proceedings of SPIE, Feb 9, 2006

High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and in... more High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and industrial applications, where repetitive cw (continuous wave) and pulsed cw operation modes are required. When operating in such modes, the lasers experience ...

Proceedings of SPIE, Jun 24, 2014

Cryogenically cooled infrared electro-optical payloads have to operate and survive frequent expos... more Cryogenically cooled infrared electro-optical payloads have to operate and survive frequent exposure to harsh vibrational and shock conditions typical of the modern battlefield. This necessitates the development of special approaches to ruggedizing their sensitive components. The ruggedization requirement holds true specifically for Integrated Dewar-Detector Assemblies (IDDA), where the infrared Focal Plane Array (FPA) is usually supported by a thin-walled cold finger enveloped by an evacuated tubular Dewar. Without sufficient ruggedization, harsh environmental vibration may give rise to structural resonance responses resulting in spoiled image quality and even mechanical fractures due to material fatigue. The authors present their approach for the ruggedization of the IDDA by attaching the FPA to a semi-rigid support extending from the dynamically damped Dewar envelope. A mathematical model relies on an experimentally evaluated set of frequency response functions for a reference system and a lumped model of a wideband dynamic absorber. By adding only 2% to the weight of the IDDA, the authors have managed to attenuate the relative deflection and absolute acceleration of the FPA by a factor of 3. The analytical predictions are in full agreement with experiment.

Proceedings of SPIE, Feb 7, 2008

High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industria... more High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industrial applications, where very high brightness and power are required. The high brightness is achieved either by increasing the power of each bar or by reducing the emitting area of the stacks. Two new products will be presented: Horizontal CW stacks with output power as high as 1kW using 80 W bars with emitting area width as low as 50 mum Vertical QCW stacks with output power as high as 1.2kW using 120 W bars. Heat removal from high power laser stacks often requires microchannel coolers operated with finely filtered deionized (DI) water. However, for certain industrial applications the reliability of this cooling method is widely considered insufficient due to leakage failures caused the highly corrosive DI water. Two solutions to the above problem will be discussed. A microchannel cooler-based package, which vastly reduces the corrosion problem, and a novel high-power laser diode stack that completely eliminates it. The latter solution is especially effective for pulsed applications in high duty cycle range.

SPIE Proceedings, 2015

Over the last decade SCD has established a "state of the art" VOx μ-Bolometer product l... more Over the last decade SCD has established a "state of the art" VOx μ-Bolometer product line. The market demands for low SWaP (Size, Weight and Power) uncooled engines is steadily growing, where low SWaP is especially critical in battery-operated applications such as goggles and Thermal Weapon Sights (TWS). In this approach, SCD has developed a low-SWaP, shutter-less uncooled video core, with a foot-print of 31x31mm and sub Watt power consumption. The video core contains a temperature calibrated, High Sensitivity (HS) 640x480 17μm pitch detector (NETD ≤ 32mK @ 30Hz, F/1), packaged in a new TEC-less ceramic package (26x23mm). The video core contains superior image processing algorithms including: local and global Dynamic Range Compression (DRC), and spatial and temporal de-noising algorithms providing low NETD and stable and low Residual Non Uniformity (RNU) video image.

L'invention concerne un procede permettant d'elaborer un module tridimensionnel multicouc... more L'invention concerne un procede permettant d'elaborer un module tridimensionnel multicouche (300) renfermant des dispositifs semi-conducteurs, des circuits integres et des dispositifs de systemes electromecaniques, notamment des dispositifs dans lesquels la forme modifie la fonction, comme dans des commutateurs optiques tridimensionnels utilisant des dispositifs de systemes micro-electromecaniques. Cette invention a egalement trait a un procede de creation d'un acces electrique lateral a des dispositifs contenus dans un boitier a puces empile tridimensionnel, ainsi qu'a la connexion du module tridimensionnel aux circuits externes. Les couches du module (110(a-e)) sont elaborees individuellement et testees avant l'assemblage. Ce procede permet de minimiser la necessite d'un alignement soigneux de puces et il est relativement simple et peu couteux. En outre, il permet la correction d'imprecisions qui emergent au cours de l'assemblage. Des couches adjace...

SPIE Proceedings, 2007

808 nm, QCW laser bars delivering peak power higher than 150 Watts were developed. The optimizati... more 808 nm, QCW laser bars delivering peak power higher than 150 Watts were developed. The optimization of the tensile strain in the QW structure, the design configuration of the laser cavity together with an improved packaging technology lead to more than 55% wall plug efficiency when assembled as stacks. Due to the high characteristic temperature (T0, T1) values and high

Infrared Technology and Applications XL, 2014

Cryogenically cooled infrared electro-optical payloads have to operate and survive frequent expos... more Cryogenically cooled infrared electro-optical payloads have to operate and survive frequent exposure to harsh vibrational and shock conditions typical of the modern battlefield. This necessitates the development of special approaches to ruggedizing their sensitive components. The ruggedization requirement holds true specifically for Integrated Dewar-Detector Assemblies (IDDA), where the infrared Focal Plane Array (FPA) is usually supported by a thin-walled cold finger enveloped by an evacuated tubular Dewar. Without sufficient ruggedization, harsh environmental vibration may give rise to structural resonance responses resulting in spoiled image quality and even mechanical fractures due to material fatigue. The authors present their approach for the ruggedization of the IDDA by attaching the FPA to a semi-rigid support extending from the dynamically damped Dewar envelope. A mathematical model relies on an experimentally evaluated set of frequency response functions for a reference system and a lumped model of a wideband dynamic absorber. By adding only 2% to the weight of the IDDA, the authors have managed to attenuate the relative deflection and absolute acceleration of the FPA by a factor of 3. The analytical predictions are in full agreement with experiment.

High-Power Diode Laser Technology and Applications IV, 2006

High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and in... more High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and industrial applications, where repetitive cw (continuous wave) and pulsed cw operation modes are required. When operating in such modes, the lasers experience numerous complete thermal cycles between "cold" heat sink temperature and the "hot" temperature typical of thermally equilibrated cw operation. It is clearly demonstrated that the main failure mechanism directly linked to repetitive cw operation is thermo-mechanical fatigue of the solder joints adjacent to the laser bars, especially when "soft" solders are used. Analyses of the bonding interfaces were carried out using scanning electron microscopy. It was observed that intermetallic compounds, formed already during the bonding process, lead to the solders fatigue both on the p- and n-side of the laser bar. Fatigue failure of solder joints in repetitive cw operation reduces useful lifetime of the stacks to hundreds hours, in comparison with more than 10,000 hours lifetime typically demonstrated in commonly adopted non-stop cw reliability testing programs. It is shown, that proper selection of package materials and solders, careful design of fatigue sensitive parts and burn-in screening in the hard pulse operation mode allow considerable increase of lifetime and reliability, without compromising the device efficiency, optical power density and compactness.

High-Power Diode Laser Technology and Applications VI, 2008

High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industria... more High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industrial applications, where very high brightness and power are required. The high brightness is achieved either by increasing the power of each bar or by reducing the emitting area of the stacks. Two new products will be presented: Horizontal CW stacks with output power as high as 1kW using 80 W bars with emitting area width as low as 50 µm; Vertical QCW stacks with output power as high as 1.2kW using 120 W bars. Heat removal from high power laser stacks often requires microchannel coolers operated with finely filtered deionized (DI) water. However, for certain industrial applications the reliability of this cooling method is widely considered insufficient due to leakage failures caused the highly corrosive DI water.

Proceedings of Spie the International Society For Optical Engineering, Feb 1, 2007

808 nm, QCW laser bars delivering peak power higher than 150 Watts were developed. The optimizati... more 808 nm, QCW laser bars delivering peak power higher than 150 Watts were developed. The optimization of the tensile strain in the QW structure, the design configuration of the laser cavity together with an improved packaging technology lead to more than 55% wall plug efficiency when assembled as stacks. Due to the high characteristic temperature (T 0, T I) values and high efficiency, the output power of these devices is almost insensitive to elevated heat sink temperatures. In addition, a collimation technique which significantly improves the beam quality of the laser stacks was developed. The active collimation method is flexible and control over the level of collimation is achievable. The use of this collimation technique alongside with high quality micro lenses allows for a reduction of the fast axis divergence to values as low as 3 mrad with minimal power losses. An automatic process control was developed allowing for the efficient attachment of the collimating micro lenses in a highly reproducible fashion. The combination of the collimation technique with a reliable mounting and stacking technology supports the serial manufacturing of devices delivering 1 kW peak power in QCW operation. These QCW collimated diode laser stacks demonstrate stable operation and high reliability in the course of more than 6*10 8shots at 2% duty cycle. Another important advantage of the collimated stacks is their capability to withstand severe environmental conditions, maintaining high beam quality and performance.