Showing papers on "Waveplate published in 1986"

Effects of circular birefringence on light propagation and reflection

Abstract: A gyrotropic (i.e., circularly birefringent) medium gives rise to a variety of interesting optical effects in addition to the well‐known one of optical activity, the rotation of a plane of linear polarization. This article considers manifestations of gyrotropy associated principally with light reflection from a transparent chiral medium. Such effects include the possible inequality of the angles of reflection and incidence, the generation of elliptically polarized light from incident linearly polarized light, and the differential reflection of right and left circularly polarized light. Reflection from a transparent gyrotropic medium is similar in some ways to, although distinct from, reflection from a conductor or absorbing medium.

Optical focusing in magneto-optic disk system

Abstract: In an optical head, a polarized laser beam is converged by an objective lens onto a magnetooptical disk to which a magnetic field is applied by a magnet unit in recording or erasing mode. The laser beam reflected from the disk is reflected by a half prism, passes through a half wave plate, and is applied to a polarizing beam splitter. The laser beam is splitted into first and second laser beams, which are applied to first and second photodetectors having a same structure, through cylindrical lenses. The detection signals output from the photodetectors are processed into a focusing error signal. The objective lens is moved along its optical axis by a voice coil driver in response to the focusing error signal.

Optical head having guide means with first and second polarizing surfaces

Abstract: In an optical head, a laser beam emitted from a semiconductor laser is collimatted by a convex lens and is reflected by a polarizing surface of a prism. The reflected laser beam passing through a quarter wave plate is converged by an objective lens onto an optical disk. The laser beam reflected from an optical disk is returned to the prism through the objective lens and quarter wave plate. The returned laser beam passes through the polarizing surface and is reflected from two segment surfaces of a prism coupled to the prism. The laser beam is reflected and separated into two beams by the segment surfaces. The separated beams passing through the polarizing surface are converged by the convex lens onto a photodetecting unit located close to the semiconductor laser.

Fringe scanning point diffraction interferometer by polarization

Abstract: A polarization fringe scanning digital interferometer includes an encoder r performing a phase polarization encoding on the wavefront coming from the optical component under test as it passes through the encoder. The encoded wavefront then passes through an analyzer into a video camera to produce electrical signals representing the interference pattern. The encoder includes in sequence, a polarizer having an adjustable polarization axis, a polarization film providing a polarization pinhole through the film and a quarter wave plate that preferably is a Fresnel plate.

Optical head device for information recording medium

Abstract: PURPOSE: To start the recording quickly by providing a semiconductor laser as a single light source projecting a linearly polarized light and constituting a projection section of light flux to an optical disk with a polarized beam splitter and a luminous flux reflecting means. CONSTITUTION: The semiconductor laser 22 as a single light source projecting a linearly polarized light is provided to a light source section 24 of an optical head 21. The way of feeding to a coil provided to a Farady cell 28 is varied in response to purposes of information erasure/recording/reproduction to make the linearly polarized light incident in the Farady cell emit as any luminous flux whose polarized planes are perpendicular to each other, and the luminous flux reflected in a polarized light beam splitter 29 and focused onto the optical disk and the luminous flux transmitted through the polarized beam splitter, reflected in a reflection mirror 31 and focused onto the optical disk are switched in response to the direction of the polarized plane of the luminous flux. Thus, high speed over-light starting the recording quickly is executed. COPYRIGHT: (C)1988,JPO&Japio

Nonlinear meter for laser detector

Abstract: The utility model relates to a nonlinear meter for laser detectors, which is an instrument for measuring the nonlinearity of a laser detector. The nonlinear meter for laser detectors is provided with an instrument which is composed of a one-half wave plate, a polarizing prism, a Gran-typed laser beam splitting prism, a reflector, an optical shutter, etc., referring to the present status of lacking the nonlinear meter for laser detectors and that the devices near to the function of the nonlinear meter for laser detectors have low testing precision. The nonlinear meter for laser detectors can make one beam of polarization laser resolved into e light and o light beams, the light intensity and beam splitting ratio of which all can be continuously regulated. By utilizing the responses of the e light and the o light beams on the laser detector, the nonlinearity of the laser detector is quickly and accurately measured.

Double refractive measurement for single mode optical fiber

Abstract: This method is specially suitable to measure the single mode fiber of short beat path In which, the polarization state of single mode fiber under different twistness is measured by the extinction method That is, at first to measure the absolute value of phase difference 2 dia of two output polarization states Then, the curve sin2 dia ~alpha2l2 is drawn (here, I2-the length of non-adherent part in fiber, alpha2-the twist coefficient)At last, by means of the said formula, the double refractive value is derived from the abscissa of extreme value on the curve In this measurement, the monochromatic light source, polariser, objective, fiber-holder, twister of fiber, 1/4 wave plate, and detector of light, etc are used

Polarizing plane converter

Abstract: PURPOSE:To control the plane of polarization over a wide angle of rotation and to attain rapid and highly accurate access by providing the titled device with the 1st driving means for rotating the 1st lambda/4 plate on the basis of a detecting signal outputted from the 1st detecting means and the 2nd driving means for rotating the 2nd lambda/4 plate on the basis of a detecting signal outputted from the 2nd detecting means. CONSTITUTION:The 1st phase shifter 6 is constituted of a stepping motor 7 and a lambda/4 plate 8 arranged in a hollow rotary shaft and information light converted into linearly polarized light is passed through a half mirror 9, made incident upon the 2nd phase shifter and converted into a circularly polarized light. The 2nd phase shifter 10 is also constituted of a stepping motor 11 having a hollow rotary shaft and a lambda/4 plate 12 arranged in the hollow rotary shaft and crystal axis of a lambda/4 plate 12 is rotated up to a position forming 45 deg. angle with the main axis of the linear polarized light to convert an optional linearly polarized light beam into circularly polarized light. The information light of the circularly polarized light is transmitted through a half mirror 13, made incident upon a lambda/4 plate 14 arranged so as to incline its crystal axis 45 deg. from the X axis and converted into linearly polarized light oscillating in the X axis direction and the converted light is made incident upon a photodetector 15.

Reflecting type wave plate

Abstract: PURPOSE:To obtain a reflecting type wave plate which can be produced easily, by reflecting a part of an optical beam by means of the surface of a light separating film and the other part by means of a reflecting surface after passing through the light separating film. CONSTITUTION:A reflecting film 14 provided with a reflecting surface 13 is formed on the surface of a substrate 12 b y multi-coating and a space layer 16 made of SiO2, silicon nitride, etc., is put on the reflecting film 14. Moreover, a polarized beam splitting film 18 is formed on the surface of the space layer 16 by multi-coating. When an optical beam L which is linearly polarized light having a plane of vibration inclined against the plane of incidence is made incident on the film 18, an S wave 22 and P wave 24 are respectively reflected by means of the polarized beam splitting film 18 and reflecting plane 13 and, therefore, a difference in the geometrical length of the optical path occurs between the S wave 22 and P wave 24 and a phase lag is produced. By utilizing the phase lag, a 1/2 or 1/4 wave plate is produced.