United Technologies Corporation

Aristotle Parasco

John A Benda

Conrad M Banas

Gary E Palma

Sallie S Townsend

A method of optical fiber manufacture involves the writing of a grating on the fiber using a laser. A first laser beam is directed on a first locality of the fiber having a circumference. A second laser beam is then directed on a second locality circumferentially displaced from the first locality. The first laser beam may be the second laser beam. In this way, a grating is formed on the fiber. The fiber may have a core and a cladding layer. The fiber may also comprise two gratings to form an interferometer.

Long period fiber Bragg gratings written with alternate side IR laser illumination

The present invention is a method which customizes the penetration depth of a heat-fusible powder used in solid freeform fabrication process such as laser sintering. The penetration depth of the heat-fusible powder is customized by combining opaque and transparent powders at a ratio which ensures that the beam contacts a portion of powder beneath its surface, thereby promoting complete layer sintering as well as adherence to previously sintered layers.

Absorption tailored laser sintering

A temperature-controlled laser sintering system includes a laser beam 12 which is focussed onto a sintering bed 38 by a focussing mirror 26 and a set of scanning mirrors 32, 34. Thermal radiation 114 emitted from the sintering bed 38 are imaged to the scanning mirrors and to a dichroic beamsplitter 110 which reflects such radiation but passes the wavelength of the laser beam 12. The radiation 118 is focussed onto an optical detector 126 which provides a signal on a line 128 to a power control circuit 104. The power control circuit 104 controls a modulator 100 which modulates the power of the laser beam 112 so as to maintain the thermal radiation emission 114 (and thus the temperature at the sintering location) at a substantially constant level.

Apparatus for temperature controlled laser sintering

A multiple beam laser sintering device includes a sintering beam 64 having a focal point at a powder bed 68 and at least one defocussed laser beam 116 incident on a region near the focal point of the focussed beam 64. The sintering beam 64 raises the temperature of the powder 84 to the sintering temperature. The defocussed beam 116 raises the temperature of the material surrounding the sintering beam 64 to a level below the sintering temperature, thereby reducing the temperature gradient between the sintering location and the surrounding material. Thermal radiation may be measured from one or both beams and used to control the power of one or both beams and the power of one or both beams may be controlled to maintain the temperature at a desired level. Alternatively, a plurality of defocussed beams may be used to provide either a plurality of thermal gradient steps, or to control the temperature of each region around the sintering point independently.

Apparatus for multiple beam laser sintering

A temperature-controlled laser sintering system includes a laser beam 12 which is focussed onto a sintering bed 38 by a focussing mirror 26 and a set of scanning mirrors 32,34. Thermal radiation 114 emitted from the sintering bed 38 are imaged to the scanning mirrors and to a dichroic beamsplitter 110 which reflects such radiation but passes the wavelength of the laser beam 12. The radiation 118 is focussed onto an optical detector 126 which provides a signal on a line 128 to a power control circuit 104. The power control circuit 104 controls a modulator 100 which modulates the power of the laser beam 112 so as to maintain the thermal radiation emission 114 (and thus the temperature at the sintering location) at a substantially constant level.

Method for performing temperature-controlled laser sintering

Method for performing multiple beam laser sintering employing focussed

An unstable laser resonator is controlled in polarization by the use of a control leg coupled to the parent resonator and having a polarization control element therein, so that control of a low power beam in said control leg serves to control the polarization of the parent resonator.

Linear polarization control of high power lasers

Gas delivery means for providing a flow of gas to the kerf in a workpiece which is being cut by a beam of laser radiation is disclosed. The distribution means consists of a thin wafer which is placed in the path of the cutting beam adjacent to the workpiece and a stream of gas directed along the axis of laser propagation blows the kerf clean. An upper gas port and a lower gas port allow the laser radiation to pass through the wafer without any transmissive optics. Use of the gas delivery means with various gases at high pressure and with laser beams at power levels which were previously impractical are discussed.

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Bolton, CT, United States of America

Aristotle Parasco