Anyone ever seen a laser diode like this?

[Alaskan]

I've seen TO-3 mounted laser diodes (sometimes a c-mount inside them) but I've never seen one quite like this. I don't know if this is purely a pulse LD, or a CW LD being pulsed or what wavelength, but this is part of a Instro laser range finder rated for 5 kilometers.

 

[paul1598419]

I have seen many TO-3 case laser diodes, but not this particular one. I suspect it is a CW diode that is being pulsed to be used in the IR range finder.

 

[RedCowboy]

That's cool.

Depending on how old it is it could be a 1550nm LD, most the new ones should be around 1550nm

Looking at the inserts where the diode mounts it could be case positive, looks like either isolators or centering rings.

 

[Encap]

I've seen TO-3 mounted laser diodes (sometimes a c-mount inside them) but I've never seen one quite like this. I don't know if this is purely a pulse LD, or a CW LD being pulsed or what wavelength, but this is part of a Instro laser range finder rated for 5 kilometers.

Instro lists all their current production as 1540-1550nm units see: http://www.instro.com/instro-products/lrf-modules/lrf100

Am sure if you emailed them they could give you any information you need as your pictures clearly identify the item

 

[RedCowboy]

Big brother > http://www.instro.com/instro-products/lrf-modules/lrf700

 

[paul1598419]

Interesting they would use a TO-3 package for a class I diode. Most of these I have seen are class IV, but those were VIS or NIR.

 

[RedCowboy]

There have been 5 watt NIR diodes on ebay for a while now in T0-3 package, here's one with fast axis correction which is not an issue being TO-3 as most people won't service the FAC lens, actually the T0-3 can just protects it.

I suppose the C-mount is more common as it fit's into smaller devices and everything is going as small as possible, I was thinking that LRF looks like an older build but a small specialty company, especially dealing with military, may not worry about trimming everything to the minimum for mass production.

It may withstand shock better than a C-mount held with a single screw, just a guess.

https://www.ebay.com/itm/FAC-TO3-Pa...212678?hash=item2c7805e2c6:g:NYoAAOSwZB9Z~7~1

 

[kecked]

How does it measure such a short distance with a light pulse? Even 5km is a small time delay. Doppler?

 

[RedCowboy]

You know that radio also travels at the speed of light, but it doesn't send out a single blip, it sends out a pulse train ( modulation ) and then it compares the pulse train going out against the one being received and measures the differential, but what about all the multiple echoes from rocks and walls ect... Well it uses the Barker code to process the signal and get an accurate measurement. Also read about Avalanche photodiode.

https://en.wikipedia.org/wiki/Laser_rangefinder

https://en.wikipedia.org/wiki/Pulse_compression

http://www.ipcsit.com/vol28/017-CoimbatoreConferences-S00021.pdf

 

[Benm]

I guess this TO-3 packages houses some corrective optics too - the circuit board is designed to take several form factor diodes, and at this power level TO-3 makes no sense otherwise.

If you really want to know you could de-can it, though that would probably misalign those optics at best and destroy it at worst.

The could also have chosen the TO-3 form factor at lower power just because the already have the assembly line ready for them, and they are a really good mechanical form factor if you want something to stay in place very precisely. It's also good for items subject to mechanical shock and vibrations.

 

[RedCowboy]

Most the 1550nm diodes I have seen on ebay with a spec sheet on say 1.4v is the typical forward voltage although I have seen 1.0v, you could limit your PS to 1.0v and slowly turn up the current, as long as you have the diode in a heat sink I expect you can find where it runs CW, I think a 5w pulsed diode can run CW at a lower output IINM, here's a list you can sort by FILTER criteria, just click on the spec sheets

https://www.laserdiodesource.com/laser-diodes-filtered-by-wavelength/1550nm-laser-diodes

 

[DashApple]

I know TO3 packages are common when temperature control is needed in a small space as they can have a TEC and thermistor placed inside the housing

 

[Benm]

I know TO3 packages are common when temperature control is needed in a small space as they can have a TEC and thermistor placed inside the housing

This is possible, but in those cases the package is TO-3 sized, but has more pins - probably 2 for the diode and 2 for the TEC, unless they use the case as a common for both. With many of these IR diodes being case-positive that would not be a very practical solution though, and if you want to use TEC you would probably want to have to have some feedback lines too.

Those packages do exist though, i've seen them with up to 7 leads (plus the case) for some specific applications, all within the TO-3 envelope.

 

[hakzaw1]

Your rep looked low so I just gave you a free bump!!I am staying on tonite until I reach 10 mil.

 

[paul1598419]

Hi, Len. I can't rep you again as I already did once today. But, someone ought to come around and push you over the top. I hope so, anyway.

 

[hakzaw1]

you guys are the best- and always make me smile...

repped you back!!