阅读说明：本技术 用于调谐多波长气体激光器的外部光学反馈元件 (External optical feedback element for tuning multi-wavelength gas lasers ) 是由 J·利马诺维奇 J·贝瑟尔 R·威勒 P·克尔施 于 2018-05-09 设计创作，主要内容包括：用于调谐具有多个波长的气体激光器(102)的输出光束的外部光学反馈元件(108),包括位于气体激光器(102)的内部光学腔外部的输出光束(106)的光束路径上的部分反射光学元件(108),以及支撑该光学元件并调整该光学元件相对于光束路径的旋转、水平倾斜角和垂直倾斜角的平台(114)。输出光束(106)在该光学元件(108)处被部分反射,并反馈到气体激光器(102)的内部光学腔中,其强度针对多个波长而变化,并通过改变光学元件的旋转、水平倾斜角和垂直倾斜角进行调节。由此,提供了输出光束到气体激光器的内部光学腔中的可变反馈,其导致气体激光器的单线或同时多线的选择性输出波长。该设置使得可以控制商用CO<Sub>2</Sub>气体激光器的波长。(An external optical feedback element (108) for tuning an output beam of a gas laser (102) having a plurality of wavelengths, comprising a portion located on a beam path of the output beam (106) outside an internal optical cavity of the gas laser (102)A partially reflective optical element (108), and a platform (114) that supports the optical element and adjusts the rotation, horizontal tilt angle, and vertical tilt angle of the optical element relative to the beam path. An output beam (106) is partially reflected at the optical element (108) and fed back into the internal optical cavity of the gas laser (102), with an intensity that varies for multiple wavelengths and is adjusted by varying the rotation, horizontal tilt angle, and vertical tilt angle of the optical element. Thereby, a variable feedback of the output beam into the internal optical cavity of the gas laser is provided, which results in a selective output wavelength of a single line or simultaneous multiple lines of the gas laser. This arrangement makes it possible to control commercial CO 2 Wavelength of the gas laser.)

1. An external optical feedback element for tuning an output beam of a gas laser having a plurality of wavelengths, the external optical feedback element comprising:

a partially reflective optical element located in a beam path of an output beam outside an internal optical cavity of the gas laser; and

a stage supporting the optical element and adjusting a rotation, a horizontal tilt angle, and a vertical tilt angle of the optical element relative to a beam path of the output beam,

wherein the output beam is partially reflected at the optical element and fed back into an internal optical cavity of the gas laser through the beam path,

the intensity of the reflected beam is different for the plurality of wavelengths,

adjusting an intensity of the reflected beam for each of the plurality of wavelengths by varying a rotation, a horizontal tilt angle, and a vertical tilt angle of the optical element, and

thereby selecting a wavelength at which the output beam is fed back into the internal optical cavity of the gas laser, thereby enhancing the output beam of the gas laser at the selected wavelength.

2. The external optical feedback element according to claim 1,

transparent optics are used with dielectric coatings that can provide wavelength dependent reflectivity.

3. The external optical feedback element according to claim 1,

the gas laser is a carbon dioxide laser, and

the plurality of wavelengths of the output beam of the gas laser is between 8.5 μm and 11.2 μm.

4. The external optical feedback element of claim 1, further comprising:

a beam splitter that splits an output beam of the gas laser into a transmitted beam path and a reflected beam path,

wherein the optical element supported by the platform is located on the reflected beam path,

the platform adjusts the rotation, horizontal tilt angle and vertical tilt angle of the optical element relative to the reflected beam path, and

the output beam is partially reflected at the optical element and fed via the reflected beam path, the beam splitter and the beam path to an internal optical cavity of the gas laser.

5. The external optical feedback element of claim 4, further comprising:

a mirror in the reflected beam path, wherein a portion of the output beam transmitted through the optical element is reflected back in the reflected beam path.

6. A method of tuning an output beam of a gas laser having a plurality of wavelengths, comprising:

a partially reflective optical element supported by the platform and positioned in a beam path of the output beam outside of the internal optical cavity of the gas laser;

varying the intensity of the reflected output beam for the plurality of wavelengths;

adjusting the intensity of the reflected output beam for each of the plurality of wavelengths by adjusting the rotation, horizontal tilt angle, and vertical tilt angle of the optical element relative to the beam path of the output beam, thereby selecting a wavelength at which the output beam is fed back into the internal optical cavity of the gas laser;

feeding back the reflected output beam at the selected wavelength into an internal optical cavity of the gas laser; and

the output beam of the gas laser is enhanced at a selected wavelength.

7. The method of claim 6, wherein,

the optical element includes a dielectric coating that provides wavelength-dependent reflectivity.

8. The method of claim 6, wherein,

the stage adjusts the rotation, horizontal tilt angle, and vertical tilt angle of the optical element relative to the beam path of the output beam.

9. The method of claim 6, further comprising:

the output beam of said gas laser is split by a beam splitter into a transmitted beam path and a reflected beam path,

wherein the optical element supported by the platform is located on the reflected beam path.

10. The method of claim 8, further comprising:

a portion of the output beam transmitted through the optical element is reflected back at a mirror in the reflected beam path.

11. An external optical feedback element for tuning an output beam of a gas laser having a plurality of wavelengths, the external optical feedback element comprising:

a partially reflective optical element located in a beam path of an output beam outside an internal optical cavity of the gas laser; and

a wavelength-dependent optical element (WDOE); and

a second partially reflective optical element located in the beam path; and

a series of detectors, each detector spaced to receive a particular wavelength band; and

a controller coupled to the WDOE and the series of detectors,

wherein the output beam is partially reflected at the optical element and fed by WDOE to the second partially reflective optical element, which reflects a portion of the beam back to the laser and transmits a portion of the beam to the series of detectors,

the controller adjusts the WDOE so that the beam reflected back to the laser has a wavelength that can be stabilized and controlled so that the laser can operate in any particular wavelength band.

12. The external optical feedback element according to claim 11, wherein the specific wavelength band is between 8.5 μ ι η and 11.2 μ ι η.

13. The external optical feedback element according to claim 11, wherein the specific wavelength band is selected from the group consisting of 9.3 μ ι η, 9.6 μ ι η, 10.2 μ ι η, and 10.6 μ ι η.

Technical Field

The present invention generally relates to an external optical feedback element for tuning the output wavelength of a gas laser.

Background

In carbon dioxide (CO)₂) In a gas laser, CO₂The dense vibrational-rotational transitions within the molecule result in emission wavelengths between 8.5 μm and 11.2 μm. Single wavelength operation and simultaneous lasing in multiple frequency bands can be observed. CO for industrial use₂The emission wavelength of the laser is typically centered at 10.6 μm, 10.2 μm, 9.6 μm or 9.3 μm (using isotopic labeling)¹⁸9.4 μm for O). Many industrial or medical applications require that CO be introduced₂The output wavelength of the laser is matched to the absorption characteristics of the target material to achieve optimal material processing, such as marking, cutting or welding.

For tuning CO₂The output beam of the laser and thus providing multi-wavelength CO₂The prior art of lasers relates to wavelength selective elements such as diffraction gratings, etalons, absorption filters, birefringent tuners and dielectric coatings. Common to these methods is the insertion of an optical element into the internal optical cavity of the laser.

Other techniques rely on the use of several laser optical resonators combined together by beam steering options.

Disclosure of Invention

In one aspect, one or more embodiments of the invention are directed to an external optical feedback element for tuning an output beam of a gas laser having a plurality of wavelengths, the external optical feedback element comprising a partially reflective optical element positioned in a beam path of the output beam outside an internal optical cavity of the gas laser and a platform supporting the optical element and adjusting a rotation, a horizontal tilt angle, and a vertical tilt angle of the element relative to the beam path of the output beam. In this external optical feedback element, the output beam is partially reflected on the optical element and fed back into the internal optical cavity of the gas laser via a beam path. The intensity of the reflected beam is different for a plurality of wavelengths and is adjusted by changing the rotation, horizontal tilt angle and vertical tilt angle of the optical element. Thus, wavelength selective feedback into the internal optical cavity of the gas laser is provided, which sets the output wavelength of the gas laser.

In another aspect, one or more embodiments of the invention relate to a method of tuning an output beam of a gas laser having a plurality of wavelengths, the method comprising: reflecting an output beam of the gas laser at a partially reflective optical element supported by the platform and located in a beam path of the output beam outside an internal optical cavity of the gas laser; varying the intensity of the reflected output beam for the plurality of wavelengths; adjusting the intensity of the reflected output beam for each of the plurality of wavelengths by adjusting the varied rotational, horizontal tilt, and vertical tilt angles of the optical element relative to the beam path of the output beam, thereby selecting the wavelength at which the output beam is fed back to the internal optical cavity of the gas laser; feeding back the reflected output beam at the selected wavelength to an internal optical cavity of the gas laser; and enhancing the output beam of the gas laser at the selected wavelength.

Other aspects and advantages of the invention will become apparent from the following description and the appended claims.

Drawings

Embodiments of the present invention will be described with reference to the accompanying drawings. The drawings, however, illustrate certain aspects or embodiments of one or more embodiments of the invention by way of example only and are not intended to limit the scope of the claims.

FIG. 1 shows a schematic diagram of a system in accordance with one or more embodiments of the invention.

Fig. 2A, 2B, and 2C illustrate experimental data recorded for an output wavelength as a function of the rotation angle of a partially reflective optical element according to one or more embodiments of the present invention.

FIG. 3 shows a schematic diagram of a system in accordance with one or more embodiments of the invention.

FIG. 4 shows a schematic diagram of a system in accordance with one or more embodiments of the invention.

FIG. 5 shows a system in accordance with one or more embodiments of the invention.

FIG. 6 shows a flow diagram in accordance with one or more embodiments of the invention.

Detailed Description

Specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals for consistency.

In the following detailed description of embodiments of the invention, numerous specific details are set forth in order to provide a more thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known features have not been described in detail to avoid unnecessarily complicating the description.

In general, embodiments of the claimed invention relate to an external optical feedback element for tuning the wavelength of an output beam from a multi-wavelength gas laser having a fixed internal optical cavity. For example, an external feedback element according to one or more embodiments includes a partial reflection with a dielectric coatingAn optical element or a mirror. Such external components provide feedback into the laser cavity to selectively enhance the desired output beam wavelength, either at the output wavelength (single line) or at multiple wavelengths simultaneously (multiple lines). The intensity of the feedback can be varied for different wavelengths by the dielectric coating being designed and can be adjusted by changing the position of the partially reflective optical element or mirror in the path of the output beam from the laser. CO can be tuned in the conventional band between 8.5 μm and 11.2 μm₂The output wavelength range of the laser.

CO will be used below₂The example of a laser describes more details of embodiments of the invention. This example is for illustration purposes only. Accordingly, the scope of the invention should not be considered limited to these particular applications.

FIG. 1 shows a schematic diagram of a system 100 according to one or more embodiments of the invention. As shown, the system 100 includes a CO having an internal optical cavity 104₂The laser 102, the internal optical cavity 104 is filled with an active lasing medium containing carbon dioxide. CO 2₂The laser 102 emits a laser beam along a beam path 106. The optical element 108 includes an optically flat or curved partially transparent substrate 110 and a dielectric coating 112. The dielectric coating 112 may be on either or both sides of the substrate 110. The optical element 108 may be positioned on the beam path 106 and may be supported by a manual or automated stage 114. The rotation, vertical tilt angle, and horizontal tilt angle of the optical element 108 may be adjusted by the platform 114.

The beam on the beam path 106 may be partially transmitted through the optical element 108 and partially reflected at the dielectric coating 112 on the optical element 108. The partially reflected beam is fed as feedback into the internal optical cavity 104 of the laser 102 via a beam path 106. The intensity of the reflected light beams of different wavelengths may depend on the properties of the dielectric coating. In one or more embodiments, the dielectric coating can have a maximum transmission at 10.6 μm (e.g., > 99.5%) and an increasing reflectivity with decreasing wavelength (e.g., down to 25% at 9.3 μm).

Furthermore, the optical element 108 may be changed relative toThe rotation, vertical tilt angle, and horizontal tilt angle of the beam path 106 change the reflectivity of the dielectric coating at a certain wavelength. CO corresponding to wavelength of feedback₂The vibrational-rotational transitions within the molecule will be enhanced. Thus, rotation and/or tilting of the optical element 108 may select the output wavelength of the laser 102 to be enhanced and thus tune the output beam of the laser 102.

Fig. 2A, 2B and 2C show experimental data of the output wavelength of the recording system 100 as a function of the rotation angle of the optical element 108. The laser 102 used was a 400W pulsed CO₂A laser (e.g., a pulsetar series P400 laser without a beam conditioning unit, produced by Synrad, inc.). The angle of rotation and orientation of the optical element 108 is manually changed by the optics mount. An image of the spectrometer readings is shown in figure 2. Fig. 2 shows that the wavelength is reversibly tunable to around 9.3 μm, 10.2 μm or 10.6 μm as the rotation angle of the optical element 108 changes. Those skilled in the art will appreciate that various other wavelengths may be obtained in view of the different materials and conditions of the lasers involved.

FIG. 3 shows a schematic diagram of a system 300 according to one or more embodiments of the invention. As shown, the system 300 includes a CO having an internal optical cavity 104₂The laser 102, the internal optical cavity 104 is filled with an active lasing medium containing carbon dioxide. CO 2₂The laser 102 emits a laser beam along a beam path 106. The beam on beam path 106 is split by beam splitter 316 into a transmitted beam path 318 and a reflected beam path 320. The optical element 108 includes an optically flat partially transparent substrate 110 and a dielectric coating 112. The optical element 108 may be positioned on the reflected beam path 320 and supported by the manual or automated stage 114. The rotation, vertical tilt angle, and horizontal tilt angle of the optical element 108 may be adjusted by the platform 114. The light beam reflected at the optical element 108 is fed as feedback into the internal optical cavity 104 of the laser 102 via the reflected light beam path 320, the beam splitter 316 and the beam path 106. The intensity of the reflected light beams of different wavelengths may depend on the properties of the dielectric coating.

Furthermore, the optical element 108 may be altered with respect to reflected lightThe rotation, vertical tilt angle, and horizontal tilt angle of beam path 320 changes the reflectivity of the dielectric coating at a certain wavelength. CO corresponding to wavelength of feedback₂The vibrational-rotational transitions or energy bands within the molecule will be enhanced. Thus, rotation and/or tilting of the optical element 108 may select the output wavelength of the laser 102 to be enhanced, and thus may tune the output wavelength of the laser 102.

FIG. 4 shows a schematic diagram of a system 400 according to one or more embodiments of the invention. As shown, the system 100 includes a CO having an internal optical cavity 104₂The laser 102, the internal optical cavity 104 is filled with an active lasing medium containing carbon dioxide. CO 2₂The laser 102 emits a laser beam along a beam path 106. The beam on beam path 106 is split by beam splitter 316 into a transmitted beam path 318 and a reflected beam path 320. The optical element 108 includes an optically flat partially transparent substrate 110 and a dielectric coating 112. The optical element 108 may be positioned on the reflected beam path 320 and supported by the manual or automated stage 114. The rotation, vertical tilt angle, and horizontal tilt angle of the optical element 108 may be adjusted by the platform 114. The light beam reflected at the optical element 108 is fed as feedback into the internal optical cavity 104 of the laser 102 via the reflected light beam path 320, the beam splitter 316 and the beam path 106. A portion of the light beam on the reflected beam path 320 that is transmitted through the optical element 108 is reflected back by the mirror 422 in the reflected beam path 320.

In addition, the reflectivity of the dielectric coating at a certain wavelength can be changed by changing the rotation, vertical tilt angle, and horizontal tilt angle of the optical element 108 relative to the reflected beam path 320. CO corresponding to wavelength of feedback₂The vibrational-rotational transitions within the molecule will be enhanced. Thus, rotation and/or tilting of the optical element 108 may select the output wavelength of the laser 102 to be enhanced and thus tune the output beam of the laser 102.

Fig. 5 shows another embodiment of a system 500 by which the output wavelength of the device can be stabilized and the wavelength can be tuned on a fast time scale. As shown, the system 500 includes a CO having an internal optical cavity 104₂Laser device102, the internal optical cavity 104 is filled with an active lasing medium containing carbon dioxide. CO 2₂The laser 102 emits a laser beam along a beam path 106. The beam on beam path 106 is split by beam splitter 316 into a transmitted beam path 318 and a reflected beam path 320. The reflected beam 320 passes through a Wavelength Dependent Optical Device (WDOD) 510, which transmits beams 550 a-550 d at different angles depending on the Wavelength. The WDOD may be an active or passive device, such as an acousto-optic modulator or electro-optic modulator or a diffractive optical element (e.g., a grating).

550a is a laser beam having a wavelength corresponding to a 9.2 μm wavelength band, 550b is a laser beam having a wavelength corresponding to a 9.6 μm wavelength band, 550c is a laser beam having a wavelength corresponding to a 10.2 μm wavelength band, and 550d is a laser beam having a wavelength corresponding to a 10.6 μm wavelength band. If CO is used₂Isotopic mixtures of laser gases, such as C12O18, C13O16, C13O16, C14O16, C14O18, etc., will vary in wavelength band. The beams 550 a-550 d will pass through the flat or curved partially reflective optical element 520 and a portion of the beam will be reflected back along 320 and reflected from the beam splitter 316 back to the laser and another portion of the beam transmitted through the optical element 520 will strike one of the four detectors 540. Those skilled in the art will appreciate that the beam transmitted through optical element 520 may impinge on one or more of the four detectors 540, depending on the exact configuration employed.

Signals from these detectors 540 are transmitted to the controller 530 via 560. The controller 530 then transmits a signal back to the WDOD 510 through the feedback loop 570. The controller 530, in conjunction with the detector 540, WDOD 510, and feedback loop 570, allows control of the wavelength and, if desired, the power in each wavelength produced by the laser system. These wavelengths will be tuned in a shorter time range than usual, e.g. about 1 to 5 microseconds.

Although fig. 1, 3, 4, and 5 illustrate particular configurations or arrangements according to one or more embodiments, other configurations or arrangements may be employed without departing from the scope of the present disclosure.

FIG. 6 shows a flow diagram in accordance with one or more embodiments of the invention. Having the benefit of this detailed description, those skilled in the art will appreciate that the steps may be carried out by other components without departing from the scope of the invention. In one or more embodiments of the invention, one or more of the steps shown in fig. 6 may be omitted, repeated, and/or performed in a different order than shown in fig. 6. Accordingly, the scope of the present invention should not be considered limited to the particular arrangement of steps shown in FIG. 6.

First, in step 610, the output beam of the gas laser is reflected on a partially reflective optical element supported by the platform and located in the beam path of the output beam outside the internal optical cavity of the gas. The optical element may include a dielectric coating that provides wavelength-dependent reflectivity. The stage can adjust the rotation, horizontal tilt angle, and vertical tilt angle of the optical element relative to the beam path of the output beam.

The beam path of the output beam may be split into a transmitted beam path and a reflected beam path. The optical element and the platform may be positioned in a reflected beam path. In addition, a portion of the output beam transmitted through the optical element may be reflected back at a mirror in the reflected beam path.

In step 620, the intensity of the reflected output beam at the optical element is varied for different wavelengths.

In step 630, the intensity of the reflected output beam is adjusted for each of the plurality of wavelengths by changing the rotation, horizontal tilt angle, and vertical tilt angle of the optical element relative to the beam path of the output beam. This selects the wavelength at which the output beam is fed back into the internal optical cavity of the gas laser.

In step 640, the reflected output beam at the selected wavelength is fed back into the internal optical cavity of the gas laser. This enhances the output beam of the gas laser at the selected wavelength.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.