Lasers incorporating time variable reflectivity

Claim 2

In combination comprising: a laser cavity; substantially total reflection members at the ends of said laser cavity for providing substantially total reflection of light energy therefrom into said cavity; laser means disposed in said cavity for emitting light energy in a direction to be reflected by said reflection members; a radiant energy source adjacent said laser means for pumping said laser means when energized to establish an operational condition of excited atoms in excess of the threshold level for oscillatory lasing action of coherent light energy within said cavity; polarizer means within said cavity for permitting passage of light energy having an unrotated direction of polarization therethrough to said reflection members to achieve light energy amplification, and for diverting light energy having a rotated direction of polarization to reduce reflectivity within said cavity, and light energy having an other another rotated direction of polarization to discharge from said cavity; a pair of cells within said cavity for permitting passage of light energy having an unrotated direction of polarization therethrough to said reflection members when deenergized, and for rotating the polarization direction of said light energy to said rotated polarization directions when electrically energized, said cells being located on opposite sides of said polarizer means; and means for energizing said radiant energy source and for energizing and deenergizing said cells in a predetermined sequence to establish said condition of excited atoms and reduced reflectivity within said cavity, to achieve said light energy amplification, and to discharge said light energy at its peak amplified value from said cavity.

Claim 3

The combination according to claim 1 in which said reflection members are two roof prisms, one at each end of said cavity, said prisms having their respective longest sides facing said cavity and having their respective knife edges aligned at 90* with respect to each other whereby one of said prisms is self-aligning with respect to any elevation angle misalignment of said other prism and said other prism is self-aligning with respect to any azimuth angle misalignment of said one prism so as to make such cavity self-aligning in both angular directions.

Claim 4

The combination according to claim 1 wherein said cells are Kerr cells.

Claim 5

The combination according to claim 1 wherein said energizing means comprises: a trigger generator for generating a trigger signal; a power source connected to said trigger generator and said radiant energy source for supplying power to pump said laser means in response to said trigger signal; signal generator means connected to said trigger generator for generating fixed and variable delay output signals in response to said trigger signal; a voltage source connected to one of said cells and said signal generator means for normally applying a voltage to said one cell to rotate the polarization direction of said light energy to said one rotated direction of polarization to divert said light energy to reduce reflectivity within said cavity while said laser means is pumped, and for removing said voltage applied to said one cell to achieve light energy amplification in said cavity in response to said fixed delay output signal; and another voltage source connected to said other cell and said signal generator means for normally applying no voltage to said other cell while said laser means is pumped to achieve light energy amplification, and for applying a voltage to said other cell to rotate the polarization direction of said light energy to said other rotated direction of polarization to discharge said light energy at its peak amplified value from said cavity in response to said variable delay output signal.

Claim 6

The combination of claim 4 wherein said signal generator means comprises: time delay means responsive to said trigger signal for generating an output; and a trigger signal delay generator connected to said time delay means for generating said fixed and variable delay output signals in response to said time delay means output.

Claim 7

The combination according to claim 4 wherein said voltage source connected to said one cell comprises a laser modulator.

Claim 8

The combination according to claim 4 wherein said voltage source connected to said other cell comprises: a high voltage pulse generator for generating an output in response to said variable delay output signal; and a rectangular pulse generator network connected to said high voltage pulse generator for generating said voltage applied to said other cell in response to said high voltage pulse generator output, said applied voltage being a fast rising step voltage pulse.

Claim 9

The combination according to claim 1 wherein said energizing means comprises: a trigger generator for generating a trigger signal; a power source connected to said trigger generator and said radiant energy source for supplying power to pump said laser means in response to said trigger signal; signal generator means connected to said trigger generator for generating fixed and variable delay output signals in response to said trigger signal; a voltage source connected to one of said cells and said signal generator means for normally applying a voltage to said one cell to rotate the polarization direction of said light energy to said one rotated direction of polarization to divert said light energy to reduce reflectivity within said cavity while said laser means is pumped, and for removing said voltage applied to said one cell to achieve light energy amplification in said cavity in response to said fixed delay output signal, said voltage source providing a start signal when said laser means is pumped; delay line means connected to said signal generator means for providing time delay to said variable delay output signal in response to an electrical signal; another voltage source connected to said other cell and said delay line means for normally applying not voltage to said other cell while said laser means is pumped to achieve light energy amplification, and for applying a voltage to said other cell to rotate the polarization direction of said light energy at its peak amplified value from said cavity in response to said variable delay output signal; photodiode means positioned adjacent one of said reflection members for generating a stop signal in response to said light energy leaked through said one reflection member at its peak amplified value in said cavity; and time interval counter means connected to said diode means, said one voltage source, and said delay line means for generating said electrical signal in response to said start and stop signals which is a measure of the time interval between the pumping of said laser means and the achieving of said light energy amplification.