Distance Measurement Sensor - Ultrasonic or Optical

How much accurance do you hope to get?

Ultrasonic and laser are all work at the principle of reflection wave. opetical can has a more precision than ultrasonic sensor.

what does the pointer use for? a laser pointer could do?

there are lots of products on the market maybe.

Ultrasonic sensors will do an excellent job providing your job requirements are not outside their range and providing the environmental conditions are conducive to their use. This manufacturer has some exceptional units that can be ordered in a number of propagation patterns from narrow to wide and with a number of output options (serial data, analog or both, for example). You could then present their output to a serial port or an AToD input and, with a little software, express the results to a program or your screen display.

The costs for their sensors is quite reasonable (about $30 w/o power supply - you could power it from your computer) and they are relatively small, about 3/4" square at the edges of the attached circuit board. The transducer itself is about 0.6" in diameter. Voltage requirements are 2.5-5.5v. Practical examples for programming and power supply construction are given.

The site has a lot of information relative to ultrasonic transducer performance and, if you are unsure about the propagation pattern desired, you can order a sample kit of 5 units of different radiation patterns. Their sales people seemed very helpful and the company seemed to be aggressive relative to being in the forefront of the industry relative to their product type.

http://www.maxbotix.com/MaxbotixHome.html

Larry

The Windshield Wiper Lets Us See The Rain

Please give us some more information.

What distance are you talking about? Every device has it's limits (both short and long in this case). Since you said "I have limited space available in the housing" I COULD assume a fairly short distance, but how short? I prefer to not guess (usually incorrectly). For the most part, ultrasonic detectors have a "blanking" phase, so that the transmitted pulse isn't immediately detected as distance zero.

Since you wrote "into a medical device", I COULD assume that it is for determining the distance of a human head from the LCD screen (who is trying to keep their head/body still). Or it could be strapped to a mouse. If the objects distance is changing rapidly then optical would work better.

I ever used GP2D series from SHARP, but the dimension is 10 mm * 40 mm. You can search the data sheet by google or try to view the web site www.lynxmotion.com good luck

J., an information about your requirements concerning distance and resolution/accuracy would not only be helpful but necessary. Also you should have in mind how noisy your environment is - where "noise" means acoustic as well as optic and electric.

Acoustic devices may be disturbed by clatter of a bunch of keys, optical devices by sunlight or neon bulbs.
Texas instruments has a chipset once developed for ultrasonic autofocus applications in polaroid cameras. This one works fine and I used it in the very noisy carpet industry for quickly rotating carpets whose thickness of back coating had to be measured contactlessly. The measurement range was from some mm to nearly one meter with good resolution of <1mm and accuracy of <2mm.

Hope this helps.
Regards Uwe

I have another application for line-of-sight distance measurement in the 1 to 100 foot range, acuracy of +/-0.5 foot is OK. Outdoors, bright sunlight is possible, intermediate distance objects in view is possible,

Any ideas?

If your distance is less than a meter or so and your resolution need is no greater than a cm, I would recommend you tear down a couple of the $30 digital tape measures on sale at your local hardware store. This would give your DE a working circuit, that's already working in a low voltage/low current environment, with a high volume product that is in actual field use.

Thank you,

Interesting, I'll look for an existing one to do up to 30 meters.

Dan