Optical position measuring system with a graduation that causes essentially only first orders of diffraction

An optical position measuring system, comprising:

• a detection graduation that functions as a measuring graduation;
• a scanning unit spaced from said detection graduation and movable relative to said detection graduation in at least one measurement direction, said scanning unit comprising:
• a light source that emits light;
• a transmitting graduation that receives said light from said light source and transmits light;
• a projection graduation that receives said light transmitted by said transmitting graduation, said projection graduation comprising periodic amplitude and phase structures disposed in alternation in the measurement direction so as to generate a first set of beams of light that impinge upon said detection graduation;
• a plurality of optoelectronic detector elements that receive a second set of beams that are generated by said detection graduation in response to said detection graduation receiving said first set of beams;
• and
• wherein said light emitted from said light source interacts with said projection graduation so as to project a fringe pattern onto said detection graduation, so that via said plurality of optoelectronic detector elements, displacement-dependent output signals are detectable, and wherein said projection graduation has a structure such that in addition to even orders of diffraction and the zero order of diffraction, at least some of the (2n+1)th orders of diffraction are suppressed, where n=1, 2, 3, . . . , as a result of which essentially only the ±1st orders of diffraction contribute to generating said output signals;
• and
• wherein said amplitude and phase structures of said projection graduation have the periodicities TPAS, TPPS, respectively, for which:
• TPAS=½*TPPS
• and
• TPAS=1/η*TPDA,
• wherein
• η indicates a divergence-dictated enlargement factor, which results in accordance with the equation,
• η=1+D2/D1, and
• TPDA represents the period of the resultant fringe pattern immediately upstream of said detection graduation, which results in accordance with the equation:
• TPDA=(TPDET*.Λ)/.(Λ±TPDET),
• wherein
• η=((D1+D2)/(D1+D2+D3))*(TPPE/(n*m±1)),
• where
• TPDET:=graduation period of said detection graduation;
• D1:=spacing between said transmitting graduation and projection graduation, if a divergent system with said transmitting graduation is involved;
• D2:=spacing between said projection graduation and said detection graduation;
• D3:=spacing between said detection graduation and a detection plane that contains said plurality of optoelectronic elements;
• TPPE:=periodicity of said plurality of optoelectronic elements in said detection plane;
• n=1, 2, . . . :
• number of phase-shifted signal components that are to be furnished by said plurality of optoelectronic elements;
• and
• m=0, 1, 2, 3, . . .

An optical position measuring system, comprising:

• a detection graduation that functions as a measuring graduation;
• a scanning unit spaced from said detection graduation and movable relative to said detection graduation in at least one measurement direction, said scanning unit comprising:
• a light source that emits light;
• a projection graduation that receives said light emitted by said light source, said projection graduation comprising periodic amplitude and phase structures disposed in alternation in the measurement direction so as to generate a first set of beams of light that impinge upon said detection graduation;
• a plurality of optoelectronic detector elements that receive a second set of beams that are generated by said detection graduation in response to said detection graduation receiving said first set of beams;
• and
• wherein said light emitted from said light source interacts with said projection graduation so as to project a fringe pattern onto said detection graduation, so that via said plurality of optoelectronic detector elements, displacement-dependent output signals are detectable, and wherein said projection graduation has a structure such that in addition to even orders of diffraction and the zero order of diffraction, at least some of the (2n+1)th orders of diffraction are suppressed, where n=1, 2, 3, . . . , and wherein the ±3rd orders of diffraction are suppressed as a result of which essentially only the ±1st orders of diffraction contribute to generating said output signals;
• and
• wherein
• a) said phase structure of said projection graduation comprises periodically disposed phase structure subregions having the graduation period TPPS, with the width ½*TPPS and with a phase-shifting effect and a phase depth φ=π;
• and
• b) said amplitude structure of said projection graduation comprises periodically disposed amplitude structure subregions having said graduation period TPAS=TPPS/2, and said amplitude structure subregions are embodied as opaque to light striking them and have an approximate width in said measurement direction of TPAS/3.

An optical position measuring system, comprising:

• a detection graduation that functions as a measuring graduation;
• a scanning unit spaced from said detection graduation and movable relative to said detection graduation in at least one measurement direction, said scanning unit comprising:
• a light source that emits light;
• a projection graduation that receives said light emitted by said light source, said projection graduation comprising periodic amplitude and phase structures disposed in alternation in the measurement direction so as to generate a first set of beams of light that impinge upon said detection graduation;
• a plurality of optoelectronic detector elements that receive a second set of beams that are generated by said detection graduation in response to said detection graduation receiving said first set of beams;
• a transmitting graduation;
• and
• wherein said light emitted from said light source interacts with said projection orders of diffraction and the zero order of diffraction, at least some of the (2n+1)th orders of diffraction are suppressed, where n=1, 2, 3, . . . , as a result of which essentially only the ±+1st orders of diffraction contribute to generating said output signals;
• and wherein beams emitted by said light source reach said transmitting graduation, embodied as a reflection graduation, and from there a reflection in the direction of said projection graduation takes place, and finally, after passing through said projection graduation, said beams reach said plurality of optoelectronic detector elements.

An optical position measuring system, comprising:

• a scanning unit spaced from a projection graduation and movable relative to said projection graduation in at least one measurement direction, said scanning unit comprising:
• a light source that emits light;
• and
• a detection graduation;
• a projection graduation that functions as a measuring graduation, said projection graduation receives said light emitted by said light source, said projection graduation comprising periodic amplitude and phase structures disposed in alternation in the measurement direction so as to generate a first set of beams of light that impinge upon said detection graduation;
• a plurality of optoelectronic detector elements that receive a second set of beams that are generated by said detection graduation in response to said detection graduation receiving said first set of beams;
• and
• wherein said light emitted from said light source interacts with said projection graduation so as to project a fringe pattern onto said detection graduation, so that via said plurality of optoelectronic detector elements, displacement-dependent output signals are detectable, and wherein said projection graduation has a structure such that in addition to even orders of diffraction and the zero order of diffraction, at least some of the (2n+1)th orders of diffraction are suppressed, where n=1, 2, 3, . . . , as a result of which essentially only the ±1st orders of diffraction contribute to generating said output signals.