Optical system for semiconductor laser beam

• US 4,832,469 A
• Filed: 04/01/1987
• Issued: 05/23/1989
• Est. Priority Date: 04/01/1986
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Miyagawa, Ichirou, Noguchi, Masaru
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/032,698
• Time in Patent Office: 783 Days
• Field of Search: 350/166, 350/404, 350/162.11, 350/385, 350/402, 350/162.12, 350/319, 372/100, 372/102, 372/103, 372/106
• US Class Current: 359/27
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0052 the light source comprising a laser diode coupling into light guides using intermediate optical elements G02B6/4204; semiconductor lasers having optical devices external to the laser cavity H01S5/005
• CPC Class Codes: G02B 27/09 Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 27/0972 Prisms prisms per se G02B5/04
• CPC Class Codes: G02B 27/0988 Diaphragms, spatial filters, masks for removing or filtering a part of the beam
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• CPC Class Codes: G02B 6/4204 the coupling comprising intermediate optical elements, e.g. lenses, holograms encapsulated active devices H01S5/02208, H01L33/52

Abstract

An optical system for a semiconductor laser beam comprises a semiconductor laser which generates light comprising both stimulated emission light and spontaneous emissions in accordance with the amount of electric current applied thereto, a convergent lens disposed in the light path of the beam emitted by the semiconductor laser, and an optical element disposed in the light path of the beam from the convergent lens which cuts more spontaneous emission than stimulated emission.

Claims

1. An optical system for a semiconductor laser beam comprising a semiconductor laser including a semiconductor laser chip operative to generate light in a low output region where spontaneous emissions having random polarization dominates and light in a high output region where stimulated emission having a single polarization dominates, a convergent lens disposed in the light path of the beam emitted by the semiconductor laser, and a polarizing filter disposed between said chip and said lens to pass only light traveling from said chip to said lens, said filter operative to pass only light polarized in the direction parallel to the junction plane of the semiconductor laser chip.

2. An optical system for a semiconductor laser beam comprising a semiconductor laser which generates both stimulated emission and spontaneous emission in accordance with the amount of electric current applied thereto, a convergent lens disposed in the light path of the beam emitted by the semiconductor laser, and an interference filter disposed between said laser and said lens to pass only light traveling from said chip to said lens, said filter operative to pass only light to wavelengths within a wavelength region that includes the wavelength region of the stimulated emission and wavelengths in the vicinity thereof.

3. An optical system for a semiconductor laser beam comprising a semiconductor laser which generates both stimulated emission and spontaneous emission in accordance with the amount of electric current applied thereto, a convergent lens disposed in the light path of the beam emitted by the semiconductor laser, and a light control plate disposed between said laser and said lens having an aperture which passes only the central portion of the light emitted by the semiconductor laser and traveling directly from said chip to said lens, each of the longitudinal and transverse magnitudes of the aperture of the light control plate being independently set at a value of 0.2 to 1.5 of the full width of half maximum (FWHM) of the stimulated emission intensity distribution.

4. An optical system for a semiconductor laser beam comprising a semiconductor laser, a collimator lens disposed in the path of the light emitted by the semiconductor laser, a dispersing optical element provided in the path of the light which has passed through the collimator for changing the path of the light issuing therefrom in accordance with the wavelength of the light incident thereon, a convergent optical element disposed in the path of the light issuing from the dispersing light element, a space filter which selectively transmits or reflects only a predetermined wavelength component of the light converged by the convergent optical element, a collimator optical element disposed in the path of the light of predetermined wavelength from the spatial filter for converting the light incident thereon to a parallel light beam, and an undispersing optical element disposed in the path of the light which has passed through the collimator element for subjecting the light incident thereon to dispersion opposite to that by the dispersing optical element.

5. An optical system for semiconductor laser beam as defined in claim 4 wherein the dispersing optical element is a prism and the spatial filter is a slit mirror which selectively reflects light of the predetermined wavelength, the light reflected by the slit mirror being passed through the convergent optical element and the prism, the convergent optical element being used as the collimator element and the prims being used as the undispersing element.

6. An optical system for a semiconductor laser beam as defined in claim 4 wherein the dispersing optical element and the convergent optical element are constituted by a convergent diffraction grating capable of carrying out the functions of both said elements.