Laser preamplifier

Claim 2

A detector system for detecting light at a known wavelength comprising: a. a laser preamplifier which amplifies said laser light by providing gain to said light; b. means for limiting the number of modes capable of being propagated within said laser preamplifier; c. means for blocking low frequency and DC spontaneous emission; and, d. means for converting the resulting amplified light into a recognizable signal.

Claim 3

A detector system as set forth in claim 1 wherein said laser preamplifier is a solid rod of laserable material and said means for limiting the number of modes capable of being propagated within said laser preamplifier is two pair of lenses, each pair including a mask defining an aperture therebetween; one pair of lenses and mask being positioned along the axis at the entrance end of the laser preamplifier, the second pair of lenses and mask being placed coaxial with the laser preamplifier at the exit end, each lens in a lens pair being spaced from each other by the sum of their focal lengths and said masks being positioned between the two lenses in a lens pair at a distance from each of the lenses equal to the focal lengths thereof and said aperture is a pinhole for passing only the lower order mode and eliminating other modes.

Claim 4

The detector system as set forth in claim 2 wherein said solid rod of laserable material is a crystalline host into which active ions are doped.

Claim 5

A detector system as set forth in claim 1 wherein said said laser light is at a wavelength of 1.06 microns and said laser preamplifier is doped with neodymium ions whereby said preamplifier is capable of providing gain at the wavelength of said laser light.

Claim 6

A detector system as set forth in claim 4 wherein said laser preamplifier is a glass laser into which said neodymium ions are doped.

Claim 7

A detector system set forth in claim 4 wherein said laser preamplifier is a crystal laser into which said neodymium ions are doped.

Claim 8

A detector system for detecting laser light comprising: a. a laser preamplifier said laser preamplifier consisting essentially of a host material into which active ions can be doped, said active ions being so selected so as to provide gain by stimulated emission to said light; b. means for limiting the number of modes capable of being propagated within said laser preamplifier; c. means for blocking low frequency and DC spontaneous emission; and, d. means for converting the resulting amplified light into a recognizable signal.

Claim 9

A detector system for detecting laser light comprising: a. a laser preamplifier said laser preamplifier consisting essentially of a host material into which active ions can be doped, said active ions being so selected so as to provide gain by stimulated emission to said light; b. means for limiting the number of modes capable of being propagated within said laser preamplifier; c. means for blocking low frequency and DC spontaneous emission; and, d. means for converting the resulting amplified light into a recognizable signal.

Claim 10

A detector system for detecting laser light comprising: a. a fiber laser preamplifier which provides gain to said laser light, said fiber laser preamplifier being capable of blocking all modes of propagation except the HE11 mode; b. means for blocking low frequency and DC spontaneous emission; and, c. means for converting the resulting amplified light into a recognizable signal.

Claim 11

A detector system for detecting laser light comprising: a. a fiber laser preamplifier which provides gain to said laser light, said fiber laser preamplifier being capable of blocking all modes of propagation except the HE11 mode; b. means for blocking low frequency and DC spontaneous emission; and, c. means for converting the resulting amplified light into a recognizable signal.

Claim 12

The detector system as set forth in claim 8 also including a narrow-band filter; said narrow-band filter being located at the output end of said fiber laser preamplifier; said narrow-band filter having a band-pass characteristic narrower than the linewidth for gain of the preamplifier.

Claim 13

A detector for detecting laser light comprising: a. a fiber laser preamplifier which amplifies said laser light by providing gain to said light; b. a beam splitter located at the entrance end of said fiber laser preamplifier; c. first and second detectors, said first detector being optically aligned at the exit end of said fiber laser, said second detector being optically aligned with said beam splitter, to receive the amplified spontaneous emission emerging from the entrance end of said laser preamplifier; and, d. said first and second detectors comprising means for comparing the resulting amplified light and resulting amplified spontaneous emission.

Claim 14

A detector for detecting laser light comprising: a. a fiber laser preamplifier which amplifies said laser light by providing gain to said light; b. a beam splitter located at the entrance end of said fiber laser preamplifier; c. first and second detectors, said first detector being optically aligned at the exit end of said fiber laser, said second detector being optically aligned with said beam splitter, to receive the amplified spontaneous emission emerging from the entrance end of said laser preamplifier; and, d. said first and second detectors comprising means for comparing the resulting amplified light and resulting amplified spontaneous emission.