PROFESSIONAL AND TECHNICAL ACHIEVEMENT'S SUMMARY:

                      A.K.Saxena has been working in the field of Photonics Instrumentation and Optical Technology for the past 35 years. He obtained his M.Sc and Ph.D. degree in Physics from Lucknow University, India in 1968 and 1977 respectively. Early part of his research activities has been mainly directed towards developing some new polarization techniques for the study of refractive index fields. These techniques were found quite useful in the study of flames and in the study of concentration dependent diffusion in reactive and non-reactive liquid-liquid system. Also these techniques have potential application in wind tunnel studies.
 

Lucknow University

                      During the years 1974 to 1977 he had been working on instrumentation for high-resolution spectroscopic observation of sun and stars. He has successfully performed experiments on high resolution spectroscopic studies of solar corona using multislit spectrograph and experiments on coronal oscillations using multi channel photometer and CCD imaging during four solar eclipses of the last century, two on the Indian soil and one in Venezuela and last in Iran.

                                                    Solar

Eclipse

                      Since 1977, he has been involved in optical technology development and Instrumentation programs including design, fabrication and testing of optics used in Astronomical observations and related applications. He has developed a new polarization interferometer technique using a simple device (Babinet Compensator) for the precise quantitative evaluation of optical surfaces and wavefront sensing in situation like active and adaptive optics systems.

Nobel Laureate Chandrashekar having  a glimpse of the 2.34M mirror polishing along with Prof.M.K.V.Bappu

The 2.34M mirror is ready for aluminizing in the 2.8M vacuum coating plant at Kavalur.



2.34 M Telescope



                  Interferometric record for

Wavefront Sensing Method

                      He has set up Vacuum coating facilities at Indian Institute of Astrophysics. Setting up of 0.3M, 1.5M, 2.8M and recently the 2M Vacuum coating plant at Hanle are his important contributions.  Subsequent aluminizing of large mirrors up to 2.34M and various other types of optical coatings has been part of his responsibility.  The 2M coating plant is operational since Aug.2004.

Vacuum chamber fully assembled                     Hydraulic lifting arrangement for the top lid


   2.8 Vacuum Coating Plant

                   1.6 Vacuum Coating Plant


 Gold Coating Attachment

   2M Vacuum Coating Plant at Hanle

 

                      He has developed the technology for the fabrication of passive radiant cooler sun shield panels of highly specularly reflective surfaces for VHRR in INSAT Series of satellite. The passive radiant cooler houses IR detector and IR Channel's optical elements.  The cooler maintains a temperature 105 degree K utilizing deep space as the heat sink. It is an import substitute resulting in large savings in foreign exchange. Successful performance of VHRR in INSAT 2A, 2B, 3A and METSAT speaks of the quality and performance of the radiant cooler. Presently engaged in the development of sunshield panels for INSAT 3D imager and sounder coolers and W2M is the very recent one.

VHRR Sunshield Panels

                     He Shares the 1994 Republic Day Award of the National Research Development Corporation  for the innovative invention work related to the passive radiant cooler used in VHRR of INSAT II series of satellites. Other members are from ISRO & NAL.  

                      He has been part of Ultra Violet Imaging Telescope (UVIT) ASTROSAT (Indian Astronomy Satellite to be launched in 2008) team. Optical system design and realization of the optics is his responsibility. The optical configuration and design details have already been completed.

                      Developed the technology and  fabrication of optics for the Synchrotron  Radiation Beam Lines (61A, 450 Mev) and monochromators. These beam lines are to be used for photoemission spectroscopy and soft x-ray spectroscopy and beam line metrology.  A machine for grinding and polishing of spheroidal mirrors has been specially designed and fabricated. A pair of 500mm x 50mm flat mirror and 300mm x 50mm spheroidal mirror has been fabricated and delivered to BARC. Also, a setup for Chromium and Gold thin film coating on the above mirrors has been built and perfected for use.

                     Recently he has developed and built a Long Trace Profilometer (LTP) for measuring the slope errors /surface profile of long grazing incidence optics based on polarization shearing interferometer. The accuracy and sensitivity of this instrument matches with the best elsewhere in the world. It is in continuous use for testing Synchrotron Beam Line Optics for the past two years. Work on Second project to build an advanced version of the Long Trace Profilometer (LTP Version II) was completed in 2006. Building of such sophisticated Long Trace Profilometer (LTP) instrument by him has put INDIA in the world map of LTP builders.

  Long Trace Profilometer Version II

                      He is  spearheading a group on Adaptive Optics in the institute. Research is directed towards building a low cost adaptive optics system for astronomical applications. Using a Shack Hartmann sensor and CMOS detector, a laboratory model has been demonstrated. Efforts are on to reduce the closed loop timing to within 20 millisecs.  A  novel wavefront sensing method using polarization shearing interferometric technique was  established by him. This is a important requirement for  adaptive optics correction system. Two students have been awarded for the Ph.D degree on these works in the year 2007 and 2009 respectively..

  Laboratory Setup for Wavefront Sensing Using Polarizing Shearing Interferometer

                          Development of thin film technology for astronomical purposes is the thrust area of the present activity.                    

                     A new computer controlled multi-functional 0.3M coating plant has been recently acquired and is being used for research purposes. The present activity includes development of thin films for infra-red photo-detector, photo-voltaics and filters for astronomical purposes. The thin film characterization facilities such as Scanning Electron Microscope and Electron Density Spectrometer are being added for research activity.       

        0.3M Computer controlled vacuum coating plant at Bangalore campus

                    During his sabbatical leave from July to December 2003, he worked with Dr.Kenneth Lanzetta of SUNY Stony Brook,USA and Project Scientist Dr.Paul Hickson,UBC,Canada as Optical Designer for the Large Aperture Mirror Array (LAMA) project. Different optical configurations for LAMA prototype telescope were worked out.

Work carried out UBC, Vancouver, Canada:

                   The LAMA  telescope employs an array of fixed 8-meter liquid-mirror telescopes. These are located in a closely-packed configuration with an overall diameter of 54 meters. Approximately 62% of the light that falls within this area is collected and focused on a common detector. This gives the array a light-collecting power equivalent to that of a 42-metre telescope. As LAMA is a zenith pointing telescope, tracking secondary mirrors and active optics allows the array to follow objects for several minutes as they pass overhead. At any given time, the array can point anywhere within a 4-degree diameter circle centered on the zenith. This makes 2400 square degrees, about 6% of the entire sky, accessible to the telescope. Light from all the telescopes is brought to a common focus in a central beam-combining room. Here the light beams interfere constructively to produce an image with a resolution of several milliarcsec. Moving mirrors, controlled by a phase-tracking system, equalize the optical path lengths from all elements of the array to within a fraction of a micron.

                    Optical design for the above configuration of LAMA was carried out. It involved phase tracking system, path equalization and beam combination. A totally new concept has been finalized.

Following is the list of important world class instruments and projects to his credit.

Some of the typical ones are:

1.

75 cm telescope optics

2.

3 Element Wynn corrector for 2.34 M telescopes prime focus

3.

Optics of 2.34M Vainu Bappu Telescope

4.

60 cm/45 cm Schmidt telescope optics

5.

Prime focus photometer (VBT) including its design

6.

rotational shearing  interferometer  of  25 mm  beam   size  for high resolution astronomic imaging     

7.

Very High Resolution Radiometer passive radiant cooler system, its sunshields for INSAT II series of satellites and INSAT-3 D

8.

Lidar telescope optics for VSSC, Trivandrum

9.

Diffraction limited f/2 Gregorian Optics of the RocketBorne EUV telescope Spectroheliometer system for the Hires project.

10.

Synchrotron Radiation Beam Lines (61A, 450MeV) Optics for monochromators.

11.

Setting up of Veeco Profilometer for surface metrology & measurement of micro roughness.

12.

1M Zerodur primary was fabricated and installed in the telescope at Kavalur.

13.

Long Trace Profilometer for surface profile measurement of X-ray optics. (Slope error <0.5 arc sec for 1200 mm length of measurement)

 

     Rotational Shearing Interferometer

             RSI Zero path difference fringe record

 

   EUV Telescope Optics

 

Synchrotron Radiation Beam Line Mirrors

                     His name appears in MARQUIS INTERNATIONAL WHO'S WHO IN OPTICAL SCIENCE AND ENGINEERING.

                     He has published more than eighty scientific and technical papers in various reputed National and International Journals.

                    He has visited many scientific Institutions, Laboratories and Optical companies around the world and also attended many national and international scientific meetings and symposia.