초록

The invention relates to a frequency-shifted feedback radiation source, equipped with an element for increasing the beat intensity of the emission frequency component.

대표청구항 ▼

The invention claimed is: 1. A frequency shifted laser radiation source for distance measurements, comprising: a frequency shifted feedback laser resonator having a pumped gain medium therein with a gain greater than unity so as to emit laser light having a plurality of frequency components changin

The invention claimed is: 1. A frequency shifted laser radiation source for distance measurements, comprising: a frequency shifted feedback laser resonator having a pumped gain medium therein with a gain greater than unity so as to emit laser light having a plurality of frequency components changing with time in a chirping manner; a means for splitting said emitted laser light having said plurality of frequency components changing with time in a chirping manner into an object beam for irradiating an object and a reference beam; the emitted laser radiation being usable for determinations of distances of objects when using an object detection sensor which receives laser light radiation coming back from an object illuminated with the object beam light and being at a distance to be determined and which object detection sensor also receives said reference beam via a reference path not including the object in such a manner that the laser light radiation coming back from the object and the reference beam interfere with one another, said interference producing a signal by the beating of the plurality of frequency components that change with time in a chirping manner and which are comprised in laser light radiation coming back from said object illuminated with the object beam beating with the plurality of frequency components that change with time in a chirping manner and which are further comprised in the reference beam received at the sensor via said reference path not including the object said beat signal having a signal intensity allowing for the determination of the distance of the object in response to the intensity of the signal; wherein the frequency shifted feedback laser radiation source further comprises a means for injection of narrow banded, non-pumping, modulated seed laser light into the frequency shifted feedback resonator, said means for injection modulating the seed laser light such that said intensity of said beat signal is increased. 2. The laser radiation source according to claim 1, wherein the seed laser light is phase modulated. 3. The laser radiation source according to claim 1, wherein the seed light has a wavelength close to the wavelength where the gain of the pumped gain medium is unity so that amplification of the seed laser light occurs at latest after a few resonator round trips. 4. The laser radiation source according to claim 1, wherein the seed laser light is modulated around a signature frequency of δν=α×c×δ1, wherein α=chirp rate, c=speed of light, and δ1=distance to be determined. 5. The laser radiation source according to claim 4, wherein the modulation frequency is periodically varied around the signature frequency of δν=α×c×δ1. 6. The laser radiation source according to claim 1, wherein the seed laser light is modulated with a periodically varying modulation frequency. 7. The laser radiation source according to claim 1, wherein the means for injection of seed laser light is an injection laser adapted to increase the intensity of the beat signal of the frequency shifted laser emitted frequency components at the object sensor beyond the intensity which can be obtained with spontaneous emission in the resonator of the frequency shifted feedback laser only. 8. The laser radiation source according claim 7, wherein the injection laser injects the non-pumping injection laser light into the gain medium of the frequency shifted feedback laser. 9. The laser radiation source according claim 8, wherein the gain medium of the frequency shifted feedback laser is an optical fiber internal to the resonator and/or constituting the resonator. 10. The laser radiation source according claim 1, wherein the injection laser is a single mode laser. 11. The laser radiation source according claim 10, wherein the injection laser has a frequency width of less than 5% of the gain of the frequency shifted feedback laser radiation gain medium. 12. A frequency shifted laser radiation source for distance measurements, comprising: a frequency shifted feedback laser resonator having a pumped gain medium with a gain greater than unity therein so as to emit frequency shifted laser light changing with time in a chirping manner; a means for splitting said emitted frequency shifted laser light changing with time in a chirping manner into an object beam for irradiating an object and a reference beam, the emitted laser radiation being usable for determinations of distances of objects when using an object detection sensor which receives laser light radiation coming back from an object illuminated with the object beam light and being at a distance to be determined and which object detection sensor also receives said reference beam via a reference path not including the object in such a manner that the laser light radiation coming back from the object and the reference beam interfere with one another, said interference producing a beat signal having a given intensity the intensity of said beat signal being representative for the distance of the object so that said distance can be determined in response to the intensity of said beat signal; wherein the frequency shifted feedback laser radiation source further comprises a means for injection of narrow banded, non-pumping, modulated seed laser light into the frequency shifted feedback resonator, said means for injection modulates the seed laser light such that said intensity of said beat signal is increased. 13. The laser radiation source according to claim 12, wherein the seed light has a wavelength close to the wavelength where the gain of the pumped gain medium is unity so that amplification of the seed laser light occurs at latest after a few resonator round trips. 14. The laser radiation source according to claim 12, wherein the seed laser light is modulated around a signature frequency of δν=α×c×δ1, wherein α=chirp rate, c=speed of light, and δ1=distance to be determined. 15. The laser radiation source according to claim 14, wherein the modulation frequency is periodically varied around the signature frequency of δν=α×c×δ1. 16. The laser radiation source according claim 15, wherein the injection laser has a frequency width of less than 5% of the gain of the frequency shifted feedback laser radiation gain medium. 17. The laser radiation source according claim 14, wherein the injection laser has a frequency width of less than 5% of the gain of the frequency shifted feedback laser radiation gain medium. 18. The laser radiation source according to claim 12, wherein the seed laser light is modulated with a periodically varying frequency. 19. The laser radiation source according claim 18, wherein the injection laser has a frequency width of less than 5% of the gain of the frequency shifted feedback laser radiation gain medium. 20. The laser radiation source according claim 19, wherein the injection laser is a single mode laser. 21. The laser radiation source according claim 20, wherein the gain medium of the frequency shifted feedback laser is an optical fiber internal to the resonator and/or constituting the resonator. 22. The laser radiation source according claim 12, wherein the gain medium of the frequency shifted feedback laser is an optical fiber internal to the resonator and/or constituting the resonator. 23. A frequency shifted laser radiation source for distance measurements, comprising: a frequency shifted feedback laser resonator having a pumped gain medium therein with a gain greater than unity so as to emit laser light having a plurality of frequency components changing with time in a chirping manner; a means for splitting said emitted laser light having said plurality of frequency components changing with time in a chirping manner into an object beam for irradiating an object and a reference beam; the emitted laser radiation being usable for determinations of distances of objects when using an object detection sensor which receives laser light radiation coming back from an object illuminated with the object beam light and being at a distance to be determined and which object detection sensor also receives said reference beam via a reference path not including the object in such a manner that the laser light radiation coming back from the object and the reference beam interfere with one another, said interference producing a signal by the beating of the plurality of frequency components that change with time in a chirping manner and which are comprised in laser light radiation coming back from said object illuminated with the object beam beating with the plurality of frequency components that change with time in a chirping manner and which are further comprised in the reference beam received at the sensor via said reference path not including the object said beat signal having a signal intensity allowing for the determination of the distance of the object in response to the intensity of the signal; wherein the frequency shifted feedback laser radiation source further comprises a means for injection of narrow banded, non-pumping, modulated seed laser light into the frequency shifted feedback resonator, said means for injection modulating the seed laser light such that said intensity of said beat signal is increased, wherein the seed laser light is phase modulated; and wherein the means for injection is modulated such that said intensity of said beat signal is increased by modulating the seed laser light such that the seed laser light is modulated around a signature frequency of δν=α×c×δ1, wherein α=chirp rate, c=speed of light, and δ1=distance to be determined. 24. A frequency shifted laser radiation source for distance measurements, comprising: a frequency shifted feedback laser resonator having a pumped gain medium with a gain greater than unity therein so as to emit frequency shifted laser light changing with time in a chirping manner; a means for splitting said emitted frequency shifted laser light changing with time in a chirping manner into an object beam for irradiating an object and a reference beam, the emitted laser radiation being usable for determinations of distances of objects when using an object detection sensor which receives laser light radiation coming back from an object illuminated with the object beam light and being at a distance to be determined and which object detection sensor also receives said reference beam via a reference path not including the object in such a manner that the laser light radiation coming back from the object and the reference beam interfere with one another, said interference producing a beat signal having a given intensity the intensity of said beat signal being representative for the distance of the object so that said distance can be determined in response to the intensity of said beat signal; wherein the frequency shifted feedback laser radiation source further comprises a means for injection of narrow banded, non-pumping, modulated seed laser light into the frequency shifted feedback resonator, said means for injection modulating the seed laser light such that said intensity of said beat signal is increased; wherein the seed laser light is modulated around a signature frequency of δν=α×c×δ1, wherein α=chirp rate, c=speed of light, and δ1=distance to be determined; and wherein the seed laser light is adapted to vary the modulation frequency periodically linear with time.