An optics cannot be fabricated with better accuracy than with which it could be tested. A full fledged Optical Metrology Laboratory facilitates the testing of high precision optics. A vertical testing tower of 15M height for testing long radius of curvature mirror and 1.2M F/1.45 high accuracy spherical mirror for auxiliary testing are some of the facilities available in the campus.

The Photonics Division is equipped with very sophisticated Optical Metrology instruments to conduct various tests on optics. The facilities include Focault test setup, OPD interferometric test setup, polarization interferometric test setup - fiber optics spectrometers and other flat testing instruments. Some of the instruments details are given below: These instruments are kept in a clean and controlled temperature environment.

Digital Spherometer | Fiber Optic Spectrometer | WYCO Profilometer | ZYGO Interferometer | Long Trace Profilometer

  • Digital SpherometerThe Digital Spherometer provides a method of measuring the radius of curved optical surfaces with extreme accuracy. The instrument can be used for the precision measurement of 1. Lens- Concave, 2. Lens- Convex, 3. Flats, Balls, Spheres, Spherical segments.

    Spherical zone, Lenticular shapes, and Comparator against Master Optics. Measurement are provided to 0.0001 inch on sagitta height. Radius of curvature is automatically computed in inches or millimeters. It is equipped with a dedicated microprocessor chip which provides the calculation capability. The inputs are received from the position encoder and the ball diameter thumbwheels. The output is on a LED number display.

  • Fiber Optic SpectrometerThe new S1000 spectrometer from Ocean Optics is optimized for UV, VIS & NIR spectroscopy. The system interfaces to a PC and can be easily configured for absorbance, transmittance, reflectance or fluorescence. It provides excellent spectral resolution, high light throughput and low levels of stray light energy in an extremely small package. The system capable of high precision measurements of light energy over 7 orders of magnitude combined with the built in software offers versatility, flexibility and ease.

  • WYCO ProfilometerThe WYCO NT 1000 is an extremely precise automated surface measurement, non-contact 3-D surface metrology instrument. It is based on phase shifting interferometry and vertical scanning interference microscopy.

    It provides optimized measurement determination of specific surface characteristics. Phase shifting facilitates measurement of smooth surfaces with vertical resolutions as low as 0.1 nm, while vertical scanning provides an optional measurement range to several millimeters. It is useful in any industry requiring accurate precise measurement of surfaces with roughness from 0.1nm to several millimeters.

    Some of the areas it is used are advanced Materials/functional surfaces, Ceramics, plastics, Sensors, Semiconductor, Flip-chip packaging, Optics, Coatings, Biomedical and many more.

  • ZYGO InterferometerThe Zygo interferometer is an interferomteric system used for the metrology of the optical components. It is based on non-contact, non-destructive method of measurement. The system consists of a mainframe interferometer and a ZYMOD phase shifting device. A nine inch view screen on the video monitor allows the user to carefully evaluate each full scale fringe pattern.

    The fringes are captured by the built in CCD camera and processed by a dedicated computer. A wide range of operational features like, surface contour map, phase map, Zernike polynomials, PSF, MTF, spot diagram, energy distribution and radial profile etc. are available.

  • Long Trace ProfilometerThe Long Trace Profilometer (LTP) is a non-contact optical profiling instrument designed to measure the absolute surface figure to nanometer accuracy of long strip flat, spherical and aspherical surfaces of up to 900mm in length. The LTP works on a shearing.

    The key feature of the LTP is the wide range of shapes that it can measure. The ease of alignment and great flexibility are a result of the unique LTP optical system.


    Synchrotron Radiation Beam Line (SRBL) Optics.
    Fabricated under grants supported by BRNS, DAE.

    This is a fully computer controlled instrument unique in its operation, accuracy and performance. This is the only instrument of its kind in the country, indigenously designed and developed. The results are comparable to that of other LTP presently available in the world.

    The main features of the optical head are:

    Lateral shearing/two beam interferometer for +/-5mrad(~15min) surface slope range

    Minimum detectable slope error ~ 0.25 arc sec or lower

    Diode laser with Fiber Optic delivery system

    12 bit, 1056 x 1024 CCD detector, 12m pixel

    External reference mirror for real time slope error correction and stability check

Last updated on: November 20, 2020