Title:
OPTICAL COMMUNICATION MODULE AND LENS FOR OPTICAL COMMUNICATION
Document Type and Number:
WIPO Patent Application WO/2014/073305
Kind Code:
A1
Abstract:
Provided is a lens for optical communication that can be produced easily at lower costs and is capable of achieving high accuracy optical communication, suppressing variation in the focal position even if significant change occurs to ambient temperature. Also provided is an optical communication module using the lens. A diffraction structure for correcting variation in the focal position due to temperature change is used. This makes it possible to, by utilizing the phenomenon that the wavelength of light incident to the lens varies with temperature, cancel the variation in the focal position due to change in a refractive index of a lens made of a resin, by changing diffraction power of light having passed through the diffraction structure. In other words, the variation in the focal position when change occurs to ambient temperature can be suppressed, whereby optical coupling efficiency can be improved. Since it is desirable that the wavelength of light used for optical communication is approximately constant irrespective of change in environments, it is desirable that an optical element having small change in the wavelength due to temperature change in a range as defined by the expression (2) is used. If the value defined by the expression (1) is above the lower limit, an enough diffraction power to cancel variation in the focal position that occurs to a lens made of a resin can be obtained in a wide ambient temperature range of, for example, -40°C to +100°C. On the other hand, if the value defined by the expression (1) is below the upper limit, the diffraction structure has a diffraction pitch that is not too small, thereby facilitating the processing of the same, and hence, facilitating the production of the same. By balancing the diffraction power so that it falls in the range satisfying the expression (1), it is possible to provide a lens that can be produced easily, with variation in the focal position being suppressed. 0.6 ≤ dP/P ≤ 0.8... (1) 0 < dλ/dt ≤ 0.2... (2) where dP represents a diffraction power [1/mm] by optical path difference imparting structure, P represents a power [1/mm] of entire lens system, and dλ/dt represents wavelength variation of optical element due to temperature change
Inventors:
TANAHASHI DAISUKE (JP)
Application Number:
PCT/JP2013/077200
Publication Date:
May 15, 2014
Filing Date:
October 07, 2013
Export Citation:
Assignee:
KONICA MINOLTA INC (JP)
International Classes:
G02B6/42; G02B5/18; G02B13/00; G02B13/18; G11B7/135
Foreign References:
| JP2012212753A | 2012-11-01 | |||
| JP2000035535A | 2000-02-02 |
Attorney, Agent or Firm:
TAMURA Keijiro et al. (JP)
Keijichiro Tamura (JP)
Keijichiro Tamura (JP)
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