Laser beam sensor

I need to send a light/laser (even maybe ultrasound) beam across about 70M (80 Yds) to detect a moving carriage.

The gap between can be quite steamy in winter not too dense but drifting across the beam path.

Does anyone have any experience with a reliable sender/reciever that would see for this distance in these conditions?

Do you want to detect the exact distance of the carrage? If so with what resolution? Does the carrage have a power supply? If so maybe a wireless comm for the carrage to the controller might do??

I'd love to know more details..

No, I dont need anything as sophisticated as the exact distance - just whether the beam is made or broken.

This carriage runs on rail tracks and fills and empties ovens (steam ovens - hence the drifting steam)
While the carriage is in the ovens (22 seperate ovens curing concrete blocks) the beam will be made and while it is travelling to and from the ovens it will be broken.

New safety gates have been fitted to this area with electro solenoid locks and if a gate is opened and the carriage is in an oven it will be allowed to come out, but once the beam is broken (meaning it is clear of the oven) the power will be cut to stop it travelling on the rails.

Looks like you need a thru-beam laser switch?? Talk to these people: http://www.sordselectric.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=SE&Category_Code=LS&referrer=google

Like a long distance photo-eye..

I think their website is messed up because it does not give distance ratings on the thru-beam, only retro-reflectives. You might have to call to find out for sure.

Goody
also look at the Erwin Sick Web site at their long distance sensors Ws/we12L
Long distance
Also you might try Keyence or IFM
SteveB

Goody,

I'm sorry, I can't comment on the steam. However, considering the pitfalls of the other possibilities you have considered, (distance, alternative beam/sound paths etc) I'd say a laser is the only means you would stand a chance with.

Regards,
Nigel

AB makes one that is good for around 250'. Will get the number and post it. However it has a transmitter and recever unit.

Regards,
Tom