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Modulator mirror

  • US 4,973,131 A
  • Filed: 02/03/1989
  • Issued: 11/27/1990
  • Est. Priority Date: 02/03/1989
  • Status: Expired due to Term
First Claim
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1. A modulator for an optical system utilizing a beam of light containing energy in a narrow range about a wavelength of interest, the modulator comprising:

  • a first interference filter having two sides comprising a plurality of alternating first and second layers, both layers having an individual optical thickness equal to a precisely controlled fraction of the wavelength of the beam, the first layer comprising a high index of refraction material, and the second layer comprising a low index of refraction material, the first side of the filter being attached to a first transparent substrate through which the beam first enters the modulator;

    a second interference filter having two sides comprising a plurality of alternating first and second layers, both layers having an individual optical thickness equal to a precisely controlled fraction of the wavelength of the beam, the first layer comprising a high index of refraction material, and the second layer comprising a low index of refraction material, the first side of the filter being attached to a second transparent substrate through which the beam exits the modulator when a beam transmission maximum exists;

    wherein the second sides of the two interference filters face each other and are separated by sufficient spacer pads of equal thickness to define a parallel gap which is maintained at a relative vacuum between the second sides; and

    means to cause relative motion of about one quarter wavelength between the two filters referenced to a first spacing of the parallel gap of an even multiple of quarter wavelength at which the transmission of the beam out of the modulator will be at a maximum wherein the means to cause relative motion comprises a first conductive metallization mechanically connected to the first interference filter and a second conductive metallization mechanically connected to the second interference filter wherein each metallization is connected to the modulated voltage source whereby modulation is the voltage connected to each metallization will cause th relative motion between the filters due to the action of the electrostatic forces acting between the two metallizations.

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