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ASTRONOMY INSTRUMENTAL ACTIVITIES

• SESO was founded in 1965 to meet the needs of
  large, multinational, astronomical observatories.
  Currently, SESO remains a major supplier of
  astronomical devices.
• To fulfil increasingly difficult requirements,
  SESO has developed specific technologies in
  different fields such as
• Optical design,
• Manufacturing tolerance analysis,
• Mechanical design,
• Aspheric mirrors and lenses,
• Polishing,
• Optical cementing and contacting,
• Optical coatings,
• Mechanical integration.

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POLISHING AND CEMENTING

• POLISHING
• All type of glass or crystal or metal
• Up to 1.4 m CaF2 up to 300 mm
• Control by interferometry
• Spherical, aspherical
• POST-POLISHING ON ASPHERICAL SURFACES
• Aspherical surface on CaF2 post-polished after
  diamond turning

Roughness achieved lt 20 Å RMS
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ASPHERICAL CALCIUM FLUORIDE LENSES
PHOTOGRAPH (with the courtesy of LAS)
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POLISHING AND CEMENTING

• SUPERPOLISHING
• In the framework of X-Ray mirrors for
  synchrotrons use, SESO has developed
  super-polishing technique (surface roughness lt 2
  Å RMS) on different materials. This technology is
  useful in the case of solar experiments
• CEMENTING
• Suitable optical cement for gluing large lenses
  with different CTE to withstand storage
  temperature (- 10C to 40C).
• This technology has been applied, for instance,
  on quadruplet of VIMOS/CAM or doublet of UVES red
  camera.

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UVES SUBSYSTEMS EXAMPLE Uves Blue and Red Camera
250 mm
Ø 220 mm F 360 mm blue camera made of 7
lenses. Ø 245 mm F 500 mm red camera made of 8
lenses. Image quality 20 of energy in a spot
of less than 20 µm diameter Athermalization in
order to avoid focussing devices and associated
electronic and software
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VIMOS AND NIRMOS SPECTROGRAPH SUBSYSTEMS
EXAMPLES Focal plane assembly lenses
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COMPUTER CONTROLLED POLISHING MACHINE
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Flat mirror of 600 mm diameter
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Off-axis parabola with 20 off-axis
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Off-axis parabola with 20 off-axis
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SURFACE QUALITY OBTAINED BY C.C.P. Real
interferogram example for 1 meter diameter
parabolic mirror Surface quality l/54 RMS
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EXAMPLES OF OPTICAL COATING Wideband anti
reflection coating on a 8 lenses objective (from
365 nm to 1000 nm)
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EXAMPLES OF OPTICAL COATING Enhanced Silver
coating results (from 350 nm to 800 nm)
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EXAMPLES OF OPTICAL COATING Hard Gold coating
results (from 0.7 µm to 25 µm)
Wavelength (µm)
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NASMITH CORRECTOR FOR V.L.T. Two lenses of 900 mm
diameter in their mount