Patent: New Diffractive Optic Patents

Patent: New Diffractive Optic Patents

More DO Lenses?
A few patents in regards to diffractive optics have come about. 70-300 f/4.5-5.6 DO IS, 14 f/2.8 DO and a 600 f/4 DO IS.

Diffractive optic patents keep coming up, though no new products are being announced. It does appear Canon is invested in the technology and thinks there is a market for it. I am a big fan of the 400 DO and hope to see longer DO lenses in the future.

Read more about the patents after the break.

Patent Publication No. 2012-78397

  • 2012.4.19 Release Date
  • 2010.9.30 filing date

Example 1

  • Zoom ratio 4.01
  • 135.50 – - 290.90mm 72.50 focal length
  • Fno 4.66 -. 4.97 – 5.87
  • 9.07 – - 4.25deg 16.62 a half angle of view.
  • Image height 21.64mm
  • 171.47 – - 204.08mm 144.08 full-length lens
  • BF 40.08mm
  • 18 sheets 12 group lens configuration
  • 3 UD glass sheet
  • A plane diffraction
  • Seven-group zoom positive and negative positive positive and negative polarity
  • Inner Focus (Group 6)
  • Shake correction (group 2)

Example 2

  • Zoom ratio 2.84
  • 200.00 – - 292.50mm 103.00 focal length
  • Fno 4.67 -. 5.44 – 5.77
  • 6.17 – - 4.23deg 11.86 a half angle of view.
  • Image height 21.64mm
  • 189.12 – - 210.66mm 162.16 full-length lens
  • BF 45.16 – 58.25 – 70.16mm
  • 13 pieces in 11 groups Lens Construction
  • 2 UD glass sheet
  • A plane diffraction
  • Five-group zoom of positive and negative positive positive and negative
  • Rear focus

Example 3

  • 14.36mm focal length
  • Fno. 2.89
  • 56.38deg half angle of view.
  • Image height 21.60mm
  • Length 133.66mm lens
  • BF 38.47mm
  • 16 pieces in 10 groups Lens Construction
  • 2 UD glass sheet
  • Two surface diffraction
  • Two positive lens group a negative
  • (Part of the front group) Inner Focus

Example 4

  • 584.94mm focal length
  • Fno. 4.12
  • 2.12deg half angle of view.
  • Image height 21.64mm
  • Length 404.06mm lens
  • BF 123.32mm
  • 18 sheets 12 group lens configuration
  • 3 UD glass sheet
  • One fluorite
  • Two groups of positive-positive lens
  • (Part of the front group) Inner Focus

Conventional diffractive optical element

  • Because there is a thick diffraction grating, and obliquely incident light, the diffraction efficiency is reduced
  • When the diffraction efficiency is reduced, flare, ghost, imaging performance deterioration, such as contrast degradation occurs

Canon’s patent

  • Can be in close contact with another medium to a diffraction grating, to reduce the thickness
  • Capable of suppressing a decrease in diffraction efficiency
  • With another medium, and fine particle dispersion ultraviolet curing resin material

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