[Newbie] Can you help identify the laser diode I need?

[ArKi]

Hi!

I am interested in purchasing a laser diode for the following application: I have two 5um pinholes that are placed ~1.5mm apart from one another. The laser should be able to pass through both pinholes and illuminate an image sensor that is ~1 cm away from the pinholes. (I am attempting to build a holographic microscope.)

Can you advise on the required power output / diode I might be able to use for this project? I am looking for a diode primarily in the blue part of the visible spectrum, so either 450 nm or 462-465 nm.

I understand that this is asking a lot, so even pointing me to the right set of equations would be super helpful. Thanks so much for taking the time to read this!

P.S. I didn't know where else to post this, so I hope the "General" section is okay.

 

[diachi]

Can't really give you advice on power because I have no idea how much you'd need - sounds like you'd need to experiment some there. I'd guess you'd need a fair bit of power to have any decent illumination through a 5um pinhole, unless you're focusing the beam into the pinhole?

That said, illuminating both pinholes shouldn't be an issue - plenty of the lasers we use have a beam diameter >1.5mm, the ones that don't could easily be expanded to something larger using either just a beam expander or a even a single lens if you don't need a collimated output.

Plenty of blue diodes available at those wavelengths, primarily from DTR's store, although you should be able to either get something read built on here or even on eBay (If you're not too worried about quality!)

 

[Alien Laser]

Welcome to the forum :wave:

 

[ArKi]

Thanks for the welcome and the response!

So going to DTR's store (https://sites.google.com/site/dtrlpf/home/diodes/450nm-pl450-diodes), I found a bunch of different options that range between acrylic, 3-element, and G-2 lens, as well as a driver. What is the difference between them? I searched through the forum to look at the pros and cons, but am curious as why lens are required in the first place.

 

[Isaac Clarke]

to collimate the laser

 

[diachi]

to collimate the laser

To expand on that ... some lenses will give you better divergence, some will give a smaller beam diameter (But worse divergence), some will give you more power (You lose some power through all optics).