about 2 mw and about 200 or 500 nanoseconds exposure time the reflectivity of the exposed part of the optical recording medium was monitored to know whether recording was successful the exposed part of the optical recording medium showed marked increase in reflectivity which means that the absorption at 830 nm of the exposed part was decreased thus increasing the out coming reflection from the aluminum reflective layer the optical recording media before and after exposure to the laser beam showed only 2 of additional change in optical properties after being left in an environment of 60 u00b0 c and 90 relative humidity for 1000 hrs 0 2 g of chloroaluminum chlorophthalocyanine and 0 2g of acetyl cellulose were dissolved into 9 5 g of dimethylformmmide some of the phthalocyanine remained insoluble the resultant solution was filtered through a teflon membrane filter of 0 2 micron pore size then spin coated on a glass substrate of 1 2 mm thickness at spin rates of 2000 rpm for 20 sec and then 4000 rpm for 20 sec a clear smooth and continuous film was obtained after dry at 100 u00b0 c for 5 min the thickness of the film was about 0 25 microns the film having an intence absorption around 830 nm was obtained by ethylalcohol vapor treatment for 30 min the film had both an intence absorption and reflection in near infrared wavelengths absorption maximum was at 830 nm with absorbance of 0 45 and reflectivity at 830 nm was about 21 which was high enough to be able to focus the laser beam on the film the.