The use of diamond as a window material in a laser tool is known. Diamond is useful as a window material as it has low absorption for infrared wavelengths in order to transmit a high power laser beam.
One such use is in a medical laser probe comprising an optical fibre for transmitting a laser beam to a point within the body where a surgical procedure is to be performed. For example, JP 9028715, JP 5095962, U.S. Pat. No. 4,170,997 and U.S. Pat. No. 6,104,853 disclose the use of diamond as a window material disposed in the end of a medical laser probe. Medical laser probes can be used to perform surgical procedures including, for example, cutting and/or ablating tissue. Using a laser rather than a standard cutting tool can be advantageous in that the tissue is cauterized reducing blood loss and increasing healing rate. For such a use, diamond has the additional advantage over other possible window materials in that it is mechanically strong, inert, and biocompatible.
Many laser tools must be relatively small in size for their intended application. For example, in the medical device field, one use of laser tools is for treatment of the prostate, particularly for treatment of Benign Prostatic Hypertrophy (BPH). BPH is a common condition which involves the prostate becoming enlarged with aging causing the prostatic urethra to close off To treat this condition, a laterally firing laser tool can be placed within the prostatic urethra to direct a laser beam against the wall of the prostate to remove obstructing prostate tissue. Examples of such tools are described in U.S. Pat. No. 5,322,507, US 2009/0287197, and US 2009/0287199. Each of these documents discloses a laser tool comprising an optical fibre for transmitting a laser beam and an end component in the form of a tubular body defining an internal channel and an aperture through which the laser beam can pass out of the tubular body to the site requiring treatment. None of these documents disclose a diamond window.
The present inventors have envisaged using a diamond window in devices similar in structure to those described in U.S. Pat. No. 5,322,507, US 2009/0287197, and US 2009/0287199. However, it has been found that the diamond window has a tendency to de-bond from the device. A similar problem can also occur in devices of the type described in JP 9028715, JP 5095962, U.S. Pat. No. 4,170,997 and U.S. Pat. No. 6,014,853 where the diamond window is placed in the end of the tubular body rather than in a side thereof.
This may be particularly dangerous if de-bonding/delamination occurs while the medical device is being used as the diamond window is inherently very hard and can lacerate the surrounding tissue. More invasive surgery may then be required in order to remove the diamond window and repair any damage caused by the window.
It is an aim of certain embodiments of the present invention to solve the aforementioned problem. In particular, certain embodiments of the present invention seek to provide a laser tool which is stable, reliable, has improved lifetime, and can be made small in size.