On Fri, 30 Apr 2004 07:59:08 +0100, Michael Rigby-Jones wrote: >> From: "Robert Rolf" >>> Can you read a page with a 1W bulb at 1 meter? >>> Your laser is hundredth the power. > >> From: Jason S [mailto:pic@CANADASPEAKS.COM] >> It's not nearly that bad. The wattage of a lightbulb is the >> total power consumed by the bulb (most of which is lost as >> heat, not given off as light). For a laser, the wattage is >> the power emitted in the form of light. > > It is that bad. Robert was talking about radiant power, not consumed > power. > > > Regards > > Mike > You might want to look into more powerful diode lasers, preferably green ones as your eye has higher sesnitivity (about 10* more a 525nm than at 650nm). I have a 10mW green laser and by shining this through things like broken glass i have spread the beam over about 1m^2 which is about the limit of good visibility in a darkened room, so for your 5mw red which is about 20x dimmer it would suggest a limit of about 20 cm * 20 cm for visibility in a dark room, which isn't too bad. an interesting point was that i also used a stepper motor an a rather unusual way, if you get a really small bipolar stepper motor with the biggest step angle you can find (about 12 degrees is common) and then drive one of the coils with DC and apply your signal to the other coil, this results in a rotational movement between two step positions that is actually pretty proportional to the applied signal, if you want you can even implement a feedback system based on the back EMF induced in the DC winding - this works far better than the more common speaker-mirror trick. FWIW a 15W incandecent light bulb emits around 1W of visible light Regards Alex -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics