Simultaneous multi-beam optical modulation system

• US 4,336,981 A
• Filed: 07/25/1980
• Issued: 06/29/1982
• Est. Priority Date: 10/25/1977
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Mori, Masaaki
• Primary Examiner(s): Sikes, William L.
• Application Number:
  US06/172,148
• Time in Patent Office: 704 Days
• Field of Search: 350/358
• US Class Current: 359/312
• CPC Class Codes: G02F 1/113 Circuit or control arrangements
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0298 with sub-carrier multiplexing [SCM]

Abstract

The simultaneous multi-beam optical modulation system comprises the steps of producing a dummy signal in such a manner that the sum of a plurality of signals and the dummy signal is kept constant, modulating the amplitudes of assigned carriers by the dummy signal and the plurality of the signals so as to produce a modulated output and applying the modulated output to an acoustic optical element.

Claims

1. In a simultaneous multi-beam optical modulation system having a signal source for producing a plurality of image signals, a plurality of amplitude modulators connected to the signal source each for modulating one of the image signals, a high-frequency carrier oscillator connected to each of the modulators for producing a carrier to modulate each image signal, and an acoustic optical element for deflecting light connected to each of the amplitude modulators for producing a plurality of output light beams each corresponding to one of the image signals, the improvement comprising, addition-reduction inverting means connected to the signal source for receiving each of the image signals, setting voltage means connected to said addition-reduction inverting means for supplying a setting voltage which is of opposite polarity to the image signals, the signal voltage being applied to said addition-reduction inverting means, said setting voltage being provided for setting an overall deflection efficiency of the acoustic optical element, means in said addition-reduction inverting means for adding said setting voltage to the image signals to produce a sum and inverting said sum to produce a dummy signal, an assigned amplitude modulator connected to said addition-reduction inverting means for receiving said dummy signal, a high-frequency carrier connected to said assigned amplitude modulator for modulating said dummy signal and gain control means connected between each of said amplitude modulators and the acoustic optical element for adjustably amplifying each of said modulated image signals to equalize the intensity of the output light beams produced by the acoustic optical element.

2. The improvement of claim 1, wherein said addition-reduction inverting means comprises a plurality of resistors each connected on one side thereof to one of said image signals and on the other side thereof in common, a D.C. amplifier connected to said common connection of said resistors and to said voltage setting means for producing said dummy signal.

3. The improvement of claim 2, wherein said voltage setting means comprises a variable resistor connected to a negative potential.

4. The improvement of claim 1, wherein said gain control means comprises a plurality of gain control amplifiers each being variable and each connected to one of said amplitude modulators, a mixer connected to each of said gain control amplifiers, and a power amplifier connected between said mixer and the acoustic optical element.

5. The improvement of claim 1, further including a laser source for producing a laser beam, focusing means disposed between said laser source and the acoustic optical element for focusing the laser beam onto the acoustic optical element, said signal source comprising a light transducer connected to the acoustic optical amplifier for dividing the laser beam into a plurality of the output light beams and a zero-order light beam, a stopper facing said acoustic optical element for blocking said zero-order light beam, a light sensitive member spaced from the acoustical optical element and a focusing lens disposed between said photo-sensitive surface and the acoustic optical element for focusing said output light beams onto said photo-sensitive surface.

6. The improvement of claim 5 wherein said focusing lens comprises a lens system (71) and a f9 lens system (72) spaced from said lens system.

7. In a simultaneous multi-beam optical modulation system, a process comprising producing a plurality of image signals, modulating each of said image signals with a carrier to produce a modulated image signal, providing a setting voltage of polarity opposite to that of the image signal, adding each of the image signals to each other and to the setting voltage for producing a sum, inverting the sum to produce a dummy signal, modulating the dummy signal with an assigned carrier to produce a modulated dummy signal, mixing each of said modulated image signals and modulated dummy signal to each other to produce a combined signal, providing an acoustic optical element for receiving the combined signal and producing a plurality of output light beams corresponding to said image signals and said dummy signal, and adjustably amplifying each of said modulated image signals to render the intensity of each of said corresponding light beams equal.