Modulated laser light detector
AssigneeApache Technologies, Inc.
InventorDuWain K. Ake
Life of this patent
Estimating the term…
Abstract
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.
Claims15
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.
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.
Dependencies are inferred from the claim text.