JPS635741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a simultaneous multi-beam optical modulation device used in a laser recording device or the like.

In a laser recording device, it is necessary to modulate the laser beam, but the laser beam is simultaneously modulated using a single acousto-optic element according to multiple different pieces of information, and the first-order light of Black diffraction is extracted separately for each piece of information and recorded. What is being considered is what leads to the part. When recording five pieces of information simultaneously with this device, _for example _, as shown in _{FIG .} Signal line 3 ₁
~ ₃₅ , respectively, are amplitude modulated by a plurality of mutually different signals _S1 ~ _S5 . This modulator 1 ₁ to 1 ₅
The output signals are amplified by power amplifiers 4 ₁ to 4 ₅ , mixed by mixer 5 , and applied to acousto-optic element 6 . The acousto-optic element 6 is a transducer 7,
Consisting of an acousto-optic medium 8 and a sound absorber 9, a mixer 5
The output signal of the laser is converted into sound by the transducer 7, which passes through the acousto-optic medium 8 and is absorbed by the sound absorber 9. At the same time, the laser beam 10 from the laser is converted into sound from the transducer 7 by the acousto-optic medium 8. The light is modulated accordingly. A zero-order diffraction beam 11 and first-order diffraction beams 12 ₁ to 12 ₅ corresponding to each signal are emitted from this acousto-optic element 6, but the first-order diffraction beam 1
2 ₁ to 12 ₅ are guided to the recording section and recording is performed.

However, in such a laser recording device, the acousto-optic element is simultaneously driven by modulation signals obtained by amplitude modulating carrier waves with multiple signals, so the optical modulation intensity by each modulation signal is affected by other signals. Change. To give a concrete example, the signal S ₁
only is input and the other signals S ₂ to S ₅ are 0,
Even if the intensity of the signal S ₁ is the same when all the signals S ₁ to _{S 5} are input, the optical modulation output 12 ₁ is relatively larger in the former case than in the latter case. In this way, since the light modulation intensity changes depending on the number of input signals, density unevenness occurs in the recorded image.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a simultaneous multi-beam optical modulation device that can simultaneously perform optical modulation with a constant optical modulation intensity using a plurality of signals.

An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, the former laser recording device is equipped with a circuit that detects the number of input signals S ₁ to S ₅ and adjusts the signal strength according to the number, thereby preventing unevenness of the light modulation strength. This is what I did. That is, as shown in FIG. 2, the signals S ₁ to _{S 5} are applied to the signal discriminator 13 and the number of input signals is discriminated. For example, the signal discriminator 13 outputs one pulse when only the signal S ₁ is 1 and the other signals S ₂ to _{S 5} are 0, and outputs two pulses when only the signals S ₁ and S ₂ are 1. For example, a number of pulses equal to the number of input signals S ₁ to _{S 5} are applied to the clock signal C.
output in sync. The pulses output from this signal discriminator 13 are counted by a counter 14,
The count output of the counter 14 is converted into an analog quantity by a digital-to-analog converter 15. The signals S ₁ to _{S 5} are each delayed by a delay circuit 16 according to the signal processing time of the signal discriminator 13 , counter 14 and digital-to-analog converter 15 , and output signals from the digital-to-analog converter 15 by a modulator 17 . The amplitude is modulated by the modulators 1 ₁ to 1 ₅ . Here is the digital to analog converter 15
The conversion characteristics of are matched to the characteristics of the acousto-optic element 6,
For example, when the acousto-optic element 6 has the characteristics as shown in FIG. 3, the modulation characteristics of the modulator 17 are set so as to have the modulation characteristics as shown in FIG.
Therefore, as shown in FIG. 5, the optical output is 12 ₁ ~
12 ₅ is independent of the number of input signals S ₁ to _{S 5} , and the proportional relationship between the signal intensity and its optical modulation intensity is satisfied, and unevenness in the recorded image is removed.

As described above, according to the simultaneous multi-beam optical modulation device according to the present invention, since the amplitude of a plurality of signals is modulated according to the number of input signals, it is possible to prevent changes in optical modulation intensity due to the presence or absence of signals. Become.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional laser recording apparatus, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIGS. 3 to 5 are characteristic diagrams for explaining the embodiment. S ₁ to S ₅ ... Signal, 1 ₁ to 1 ₅ ... Modulator, 2 ₁ to
2 ₅ ... High frequency oscillator, 5 ... Mixer, 6 ... Acousto-optic element, 10 ... Laser beam, 12 ₁ ~1
2 ₅ ... Modulated beam, 13 ... Signal discriminator, 14
... Counter, 15 ... Digital-to-analog converter, 16 ... Delay circuit, 17 ... Modulator.

Claims (1)

[Claims] 1. A first modulating means that obtains a plurality of modulated signals by amplitude modulating each of a plurality of carrier waves with a plurality of input signals, and a plurality of modulated signals from this first modulation means are simultaneously applied to form an incident beam. In a simultaneous multi-beam optical modulation system that has an acousto-optic element that simultaneously divides the beam into a plurality of beams and modulates the beam,
a signal discrimination means for discriminating the number of a plurality of signals inputted to the first modulation means and outputting this number of pulses; a counter for counting pulses from the signal discrimination means; and the acousto-optic device. The optical output of the acousto-optic element, which has conversion characteristics that match the characteristics of the element and changes depending on the number of input signals, is adjusted to keep the count output of the above-mentioned counter constant and converted into an analog quantity. digital
A simultaneous multi-beam optical modulation device comprising an analog converter and a second modulation means for amplitude modulating a plurality of signals sent to the first modulation means using the output signal of the analog-to-digital converter. .