Cutting of organic solids by continuous wave ultraviolet irradiation
OwnerRangaswamy Srinivasaninventor
Life of this patent
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Abstract
A beam (12) of continuous wave ultraviolet light having a wavelength that is absorbed by an organic solid (20) is focused to a spot (18) on a surface of the organic solid (20). Relative motion is imparted between the beam (12) and organic solid (20) at a rate that defines, together with a dimension of the spot (18), an effective pulse width. Within prescribed ranges of the wavelength, power density and effective pulse width, a new cutting regime was discovered whereby organic solids can be cut at rates and with a quality of cuts previously requiring pulsed ultraviolet laser sources.
Claims16
A method of cutting organic solids with continuous wave ultraviolet radiation comprising the steps of:
- directing a beam of continuous wave ultraviolet light to a spot on a surface of an organic solid;
- irradiating the spot with the beam of continuous wave ultraviolet radiation at a wavelength absorbed by the organic solid and at a power density less than that required to initiate ablative photodecomposition in the organic solid;
- relatively moving the beam with respect to the organic solid at a rate that defines an effective pulse width as a quotient of a linear dimension of the spot in a direction of the relatively moving beam divided by a relative speed between the beam and the surface of the organic solid within a range of between 1 microsecond and 1000 microseconds for producing etching rates in the organic solid comparable to those obtained from ablative photodecomposition;
- depositing an amount of energy within the prescribed range of effective pulse widths greater than an amount of energy required to initiate ablative photodecomposition;
- adjusting (a) the effective pulse width to match absorptivity characteristics of the organic material and (b) the power density of the beam to control a rate of energy deposition within a range in which etching depth is dependent upon the rate of energy deposition;
- and
- limiting the power density of the beam between 1 kilowatt per centimeter squared and 1000 kilowatts per centimeter squared.
A method of cutting organic solids with continuous wave ultraviolet radiation at a controlled speed comprising the steps of:
- providing a coherent light source for emitting a continuous wave of substantially monochromatic ultraviolet light within a range of wavelengths between 180 nanometers and 400 nanometers:
- transmitting the ultraviolet light in the form of a beam that impinges against a surface of an organic solid forming a spot on the surface of the organic solid at a power density between 1 kilowatt per centimeter squared and 1000 kilowatts per centimeter squared;
- relatively translating the spot over the surface of the organic solid for defining an effective pulse width as a quotient of a linear dimension of the spot in a direction of the translation divided by a relative speed between the spot and the surface of the organic solid;
- and
- controlling the relative speed between the spot and the surface of the organic solid to define the effective pulse width in a range between 1 microsecond and 1000 microseconds.
A method of efficiently cutting organic solids without significant thermal damage to an organic substrate comprising the steps of:
- irradiating a surface of an organic solid with a beam of continuous wave ultraviolet light;
- concentrating the beam to a spot on the surface of the organic solid at a power density less than the power density required to initiate ablative photodecomposition;
- relatively moving the beam with respect to the surface of the organic solid along a path at a scanning rate that irradiates points along the path for predetermined intervals of time;
- and
- controlling at least one of the power density at which the beam is concentrated and the scanning rate at which the beam is relatively moved as a variable to initiate a photokinetic effect characterized by a multiple-fold increase in etching rates over those apparent from both greater and lesser values of the variable.
A system for decomposing selected areas of an organic polymer material with continuous wave ultraviolet radiation comprising:
- an organic polymer material that absorbs particular wavelengths of ultraviolet radiation;
- a coherent light source for emitting a continuous wave of substantially monochromatic ultraviolet radiation within a range of wavelengths that are absorbed by said organic polymer material;
- means for directing a beam of the continuous wave ultraviolet radiation at a power density less than 1000 kilowatts per centimeter squared to a spot defining a portion of a selected area of said organic polymer material to be decomposed from a substrate;
- means for relatively moving the spot irradiated by the continuous wave ultraviolet radiation to other portions of the selected area of the organic polymer material at a rate which irradiates each of the portions of the selected area for predetermined time intervals between 1 microsecond and 1000 microsecond;
- and
- control means for adjusting the rate at which the spot is relatively moved to initiate a photokinetic effect in the selected area characterized in part by a lack of detectable thermal damage to the substrate.
Dependencies are inferred from the claim text.