A modulated laser light detector that converts laser light energy into electrical signals which exhibit a frequency that is substantially the same as the laser light modulation frequency, in which these signals allow the detector unit to determine a position where the laser light is impacting upon a
A modulated laser light detector that converts laser light energy into electrical signals which exhibit a frequency that is substantially the same as the laser light modulation frequency, in which these signals allow the detector unit to determine a position where the laser light is impacting upon a photodiode array. A synchronous rectifier circuit is provided which, by use of a phase locked loop, converts a full-wave analog signal representative of the modulated laser energy into a half-wave analog signal, which is filtered and demodulated to generate a DC level that is indicative of the strength of the received laser light energy. At least two channels of these signals are used to determine the impacting position of the laser light energy.
대표청구항▼
The invention claimed is: 1. A modulated laser light detector, comprising: (a) at least one laser light photosensor, which generates at least one first electrical signal when receiving modulated laser light energy having at least one predetermined range of wavelengths and at least one predetermined
The invention claimed is: 1. A modulated laser light detector, comprising: (a) at least one laser light photosensor, which generates at least one first electrical signal when receiving modulated laser light energy having at least one predetermined range of wavelengths and at least one predetermined range of modulation frequencies; (b) at least one amplifier stage that receives said at least one first electrical signal and outputs at least one second electrical signal having a first waveform that exhibits voltage components of both positive-going and negative-going regions; (c) a phase and frequency detector that receives said at least one second electrical signal and generates a lock signal that corresponds to a zero crossing of said first waveform; (d) at least one synchronous rectifier stage that receives said lock signal and receives said at least one second electrical signal, and generates at least one third electrical signal of a second waveform that comprises a substantially rectified version of said first waveform; (e) at least one low pass filter that receives said at least one said third electrical signal and outputs at least one fourth electrical signal that comprises a substantially DC voltage; and (f) at least one signal strength detector that inspects the substantially DC voltage of said at least one fourth electrical signal, and determines a relative strength of said received modulated laser light energy. 2. The modulated laser light detector as recited in claim 1, further comprising: at least one automatic gain control circuit that is in electrical communication with said at least one amplifier stage; wherein said at least one signal strength detector comprises a processing circuit and an associated memory circuit having a plurality of memory elements which contain computer executable software. 3. The modulated laser light detector as recited in claim 2, wherein said processing circuit is configured: (i) to control said at least one automatic gain control circuit for at least two channels of said at least one amplifier stage, a first of said channels corresponding to a first input channel of said at least one first electrical signal, and a second of said channels corresponding to a second input channel of said at least one first electrical signal; (ii) to determine a first signal strength for a first channel of said at least one fourth electrical signal; (iii) to determine a second signal strength for a second channel of said at least one fourth electrical signal; and (iv) to compare said first signal strength and said second signal strength, thereby determining a relative position of said received modulated laser light energy impacting on said at least one laser light photosensor. 4. The modulated laser light detector as recited in claim 3, wherein said at least one laser light photosensor comprises a plurality of photocells, in which each of said plurality of photocells outputs one of said at least one first electrical signal; and further comprising: (a) a plurality of analog switches that, under the control of said processing circuit, connect each of said plurality of photocells to one of: (i) a channel 1 signal and (ii) a channel 2 signal, wherein said channel 1 signal and said channel 2 signal are indicative of said relative position of said received modulated laser light energy impacting on said at least one laser light photosensor. 5. The modulated laser light detector as recited in claim 1, further comprising: an analog summing stage that receives a first channel of said at least one second electrical signal and receives a second channel of said at least one second electrical signal, and outputs a summed electrical signal; and wherein said summed electrical signal is connected as an input to said phase and frequency detector, and is used for generating said lock signal. 6. An electronic circuit, comprising: (a) a first amplifier stage that outputs a first electrical signal having a first waveform that exhibits voltage components of both positive-going and negative-going regions; (b) a phase and frequency detector that receives said first electrical signal and generates a lock signal that corresponds to a zero crossing of said first waveform; (c) a first synchronous rectifier stage that receives said first electrical signal and generates a second electrical signal of a second waveform, in which said second waveform substantially comprises a rectified version of said first waveform and exhibits a voltage component having substantially only a single one of a positive-going and a negative-going region; (d) a first low pass filter that receives said second electrical signal and outputs a third electrical signal that comprises a substantially DC voltage; and (e) a laser light photosensor, which generates a fourth electrical signal when receiving modulated laser light energy having at least one predetermined range of wavelengths and at least one predetermined range of modulation frequencies. 7. The electronic circuit as recited in claim 6, further comprising: an automatic gain control circuit that is in electrical communication with said first amplifier stage. 8. The electronic circuit as recited in claim 6, wherein: (i) said fourth electrical signal is input to said first amplifier stage that outputs said first electrical signal; and (ii) said substantially DC voltage of the third electrical signal exhibits a predetermined magnitude for a particular signal strength of said received modulated laser light energy. 9. The electronic circuit as recited in claim 8, further comprising: a first signal strength detector that inspects the substantially DC voltage of said third electrical signal and determines a relative strength of said received modulated laser light energy. 10. The electronic circuit as recited in claim 9, wherein said laser light photosensor comprises a plurality of photocells, in which each of said plurality of photocells outputs a channel of said fourth electrical signal. 11. The electronic circuit as recited in claim 10, further comprising: (a) a processing circuit and an associated memory circuit having a plurality of memory elements which contain computer executable software; and (b) a plurality of analog switches that, under the control of said processing circuit, connect each of said plurality of photocells to one of: (i) a channel 1 signal and (ii) a channel 2 signal, wherein said channel 1 signal and said channel 2 signal are indicative of said relative position of said received modulated laser light energy impacting on said at least one laser light photo sensor; wherein said processing circuit is configured to perform the functions of said first signal strength detector. 12. The electronic circuit as recited in claim 11, further comprising: a first automatic gain control circuit that is in electrical communication with said first amplifier stage, and a second automatic gain control circuit that is in electrical communication with a second amplifier stage; wherein: said channel 1 signal is input to said first amplifier stage with said first automatic gain control circuit, said channel 2 signal is input to said second amplifier stage with said second automatic gain control circuit, and said first electrical signal exhibits two output channels; and wherein said processing circuit is configured to control said first and second automatic gain control circuits. 13. The electronic circuit as recited in claim 12, further comprising: a second synchronous rectifier stage which outputs a second channel of said second electrical signal, a second low pass filter which outputs a second channel of said third electrical signal, and a second signal strength detector that inspects the substantially DC voltage of the second channel of said third electrical signal and determines a relative strength of said received modulated laser light energy for said second channel. 14. The electronic circuit as recited in claim 13, wherein said processing circuit is configured: (i) to determine a first signal strength for said first channel of said third electrical signal; (ii) to determine a second signal strength for said second channel of said third electrical signal; and (iii) to compare said first signal strength and said second signal strength, thereby determining a relative position of said received modulated laser light energy impacting on said laser light photosensor. 15. The modulated laser light detector as recited in claim 14, further comprising: an analog summing stage that receives the first channel of said third electrical signal and receives the second channel of said third electrical signal, and outputs a summed electrical signal; and wherein said summed electrical signal is connected as an input to said phase and frequency detector, and is used for generating said lock signal.
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