laserdiode with smallest beam diameter

hi all, i am new at laser led technology and there is more to go :roll:

can anyone tell me, what is the smallest size of a beam diameter an uv laser diode?

i thought it must be very smal, coz uv laser diodes are being used in blue-ray dvd writers, but when i research on the internet
i couldnt see any laser diodes with 0.1mm beam diameter.

i really need a type of laser diode with 0.1 mm beam, do i have to use additional beam collimator?

Could you give a part number for the lasers you are looking at? Most of the low power lasers I have used are just a few microns wide. Even the pulsed diodes of several Watts are usually <100um.

Keith.

It's effectively impossible to create a 0.1 mm laser beam without considerable divergence. A CD/DVD laser is focussed on a small spot with rather short focal length and respective small focus depth, otherwise you would be unable to operate a dual layer disc.

About laserdiodes..............

Typical emitting source dimensions

From Health Physics June 2000, Volume 78, Number 6


Due to diffraction, the beam diverges (expands) rapidly after leaving the chip, typically at 30 degrees vertically by 10 degrees laterally. A lens must be used in order to form a collimated beam like that produced by a laser pointer. If a circular beam is required, cylindrical lenses and other optics are used. For single spatial mode lasers, using symmetrical lenses, the collimated beam ends up being elliptical in shape, due to the difference in the vertical and lateral divergences.

the light emitting from a laser diode is very pronounced with full width half maximum (FWHM) angles of up to 40 degrees in the perpendicular axis (θ⊥) and 10 degrees in the parallel axis (θ||).
This divergence results in a rapidly expanding elliptical cone.

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laser diode data ...look divergence values..........
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A lot of the lasers I have used are only 2um high sources but with widths up to 100um although some of the lower powered ones are only 4um wide. One thing to also bear in mind is that there is usually an astigmatism which makes it impossible to get a well imaged spot without special optics. A 4um laser with 25um of astigmatism is therefore tricky to image down to a tiny spot!

Keith.

The original post is talking about a beam which isn't the same thing as a spot. I would prefer to hear a clear specification.

FvM said:

It's effectively impossible to create a 0.1 mm laser beam without considerable divergence. A CD/DVD laser is focussed on a small spot with rather short focal length and respective small focus depth, otherwise you would be unable to operate a dual layer disc.

Click to expand...

i need a laser light which should be focused on a surface standig about 5 mm far from laser. 5 mm may be reducable if it is neccessary i can decrease the distance. the divergence is not that important at that distance ha?

---------- Post added at 10:37 ---------- Previous post was at 10:33 ----------

keith1200rs said:

A lot of the lasers I have used are only 2um high sources but with widths up to 100um although some of the lower powered ones are only 4um wide. One thing to also bear in mind is that there is usually an astigmatism which makes it impossible to get a well imaged spot without special optics. A 4um laser with 25um of astigmatism is therefore tricky to image down to a tiny spot!

Keith.

Click to expand...

thanx
as i said before i am new and dont know which laser diode is the best for my project. i need 405nm wavelenght and 0.1 beam diameter uv light, can you advice me any laser diode, i am not sure about the power of the diode i will be sure after a few experiments

guys, i just talked to someone from a laser diode production company, and she said the beam diameter of a laser diode is adjustable by a collimating lens.

now could you tell me how i can chose my lens in order to get 0.1 beam diameter,

here is the laser diodes i want to use,