Appeal No. 2005-0891 Page 4
Application No. 09/916,566
powdered material in a converging, conical pattern intersecting the minimum diameter
of the laser beam, thereby resulting in melting of the powdered material by the laser
beam, an optical pyrometer coaxially aligned with the laser beam to monitor the
temperature of the molten powder material and a feedback controller for outputting an
exposure error signal which is used to control the laser output power either through
direct control of the laser power supply or through the use of a continuously variable
beam attenuator (column 10, first paragraph). As explained in the second paragraph in
column 10, the pyrometer provides an electrical signal 112 which is proportional to the
temperature at the deposition area, the signal 112 then being input to a comparator
circuit 114 which compares the measured temperature value to a desired temperature
value 116 and produces an error signal 118 proportional to the difference between
values 112 and 116. The error signal 118 is then input to the ratiometer 108 to alter the
target exposure ratio value to control the laser output power as explained in column 10,
first paragraph. Jeantette teaches that “[t]he method of laser power control will be
dictated by the bandwidth of the attenuation mechanism” and that, for the disclosed
application, a response time of <1 ms is desired.
The examiner concedes that Jeantette does not disclose that the laser used is a
diode laser as called for in claims 1 and 5 but also points out that Jeantette discloses
that, while a cw or pulse Nd:YAG or CO2 laser will work for the system disclosed
therein, “any laser with sufficient power and reasonable absorption to melt the material
would suffice as a laser source” (column 9, lines 22-24). The examiner further relies on
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 Next
Last modified: November 3, 2007