Transverse mode selection in lasers for holography

Claim 2

For use in an interferometric technique utilizing a laser for producing light output generally along an optical axis, transverse mode selection means, comprising: a first opaque mode selector disposed within the laser and along the optical axis of the laser, said mode selector having an aperture at the axis small enough to allow lasing only in a uniphase mode, and having an outer dimension selected to allow multimode lasing around said first mode selector without interference with the uniphase lasing through said aperture; beam splitting means for dividing the laser output from said first mode selector into a first beam and a second beam; and a second opaque mode selector located in the path of said first beam and having an aperture small enough to pass energy only in the uniphase mode and an outer dimension large enough to prevent transmission of multimode energy; whereby said first beam is limited to contain only uniphase energy, and said second beam utilizes both uniphase and multimode output from the laser to provide a high-energy source.

Claim 3

A mode selection means as set forth in claim 1, wherein said first mode selector is annular in shape.

Claim 4

A mode selection means as set fortH in claim 2, wherein said first mode selector comprises a generally flat plate suspended in a position substantially normal to the optical axis.

Claim 5

A mode selection means as set forth in claim 2, wherein said first mode selector comprises an inscribed pattern on an optical surface associated with the laser.

Claim 6

A mode selection means as set forth in claim 1, further including diffusing means located in said second beam for producing a diffuse object beam.

Claim 7

A mode seletion means as set forth in claim 1, wherein said beam splitting means in designed such that said second beam contains substantially more energy than said first beam, and whereby said second beam contains a substantial proportion of available output from the laser.

Claim 8

A pulsed laser holographic recording system including a pulsed laser producing light output from a laser cavity, and beam splitting means for dividing the laser light output into an object beam used to illuminate an object of which a hologram is to be made, and a reference beam of substantially less energy than said object beam, used to interfere with light from the object to produce the hologram, wherein the improvement comprises: an opaque annular mode selector located in the laser cavity, said selector having an aperture small enough to permit lasing therethrough only in a fundamental or TEM00 mode, and having an outside diameter selected to permit lasing around said mode selector in higher-order transverse modes without interference with the fundamental mode lasing through said aperture; and an opaque screen located in the reference beam and having an aperture therethrough to allow the transmission of only fundamental mode enegy in the reference beam; whereby a large proportion of the available multimode output from the laser is utilized in the object beam.

Claim 9

A pulsed laser holographic recording system including a pulsed laser producing light output from a laser cavity, and beam splitting means for dividing the laser light output into an object beam used to illuminate an object of which a hologram is to be made, and a reference beam of substantially less energy than said object beam, used to interfere with light from the object to produce the hologram, wherein the improvement comprises: an opaque annular mode selector located in the laser cavity, said selector having an aperture small enough to permit lasing therethrough only in a fundamental or TEM00 mode, and having an outside diameter selected to permit lasing around said mode selector in higher-order transverse modes without interference with the fundamental mode lasing through said aperture; and an opaque screen located in the reference beam and having an aperture therethrough to allow the transmission of only fundamental mode enegy in the reference beam; whereby a large proportion of the available multimode output from the laser is utilized in the object beam.

Claim 10

A pulsed laser holographic recording system as set forth in claim 7, wherein said mode selector comprises a plate suspended in the laser cavity.

Claim 11

A pulsed laser holographic recording system as set forth in claim 7, wherein said mode selector comprises an inscribed pattern on an optical surface within the laser cavity.

Claim 12

A pulsed laser holographic recording system as set forth in claim 7, further including diffusing means located in said object beam, for providing diffuse illumination for the object.

Claim 15

A method as set forth in claim 11, further including the step of diffusing the object before allowing it to illuminate the object.

Claim 16

A method as set forth in claim 12, wherein said steps of limiting the laser to operate in a fundamental transverse mode and simultaneously allowing the laser to operate in higher-order transverse modes are effected by limiting light in the laser to pass through and around an annular pattern inscribed on an optical surface of the laser.