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[Reply #15 on:]

Very interested in this. Let me know how i can get my hands on one of these!

[Reply #16 on:]

Very interested in this. Let me know how i can get my hands on one of these!

For further information about the Arduino Laser please contact Tracy at: info@lightware.co.za

[Reply #17 on:]

I'm very interested in using this for my master's thesis - your site says that the AL_01 is in production. How long after ordering would it take to get one of these to the southeast united states?

Thanks,
Tyler

[Reply #18 on:]

Optics

The optical components have arrived at last!

The lenses are 25mm diameter on both the laser and receiver. In the case of the laser, the purpose of the lens is to collimate the outgoing flash of laser light. This is necessary because, unfortunately, the light that comes from a semiconductor laser doesn't have a nice parallel beam. Instead, it comes out in a distorted cone shape that needs to be made parallel in order for the laser light to travel as far as possible without getting spread out and becoming too faint. This collimation process is often done with very fancy optics in order to get the maximum theoretical range. In this design however, a single lens element should be enough to get the laser beyond the 25m range specified for the design. The diameter of the laser beam will be the same as the laser lens (25mm) as you can see from the picture below.

The laser beam projected onto a Phosphor card

The lens in front of the receiver serves a different purpose. It acts as a light gathering area that focuses the rather weak return signals from the target onto the APD detector. The bigger this light gathering area is, the greater the distance that the range finder will be able to measure. This makes it very easy to increase the range - just use a bigger lens. For the purposes of this design, the 625 mm² of the receiver lens should give us the desired range.

Optics - front view

From the picture above you can see that the optical arrangement is very sturdy. This is necessary to ensure that the alignment of the lenses stays absolutely fixed. If this alignment changes then the laser will end up pointing in one direction whilst the receiver points in another - and that means no return signal!

To get the laser and the receiver lined up correctly in the first place there is an alignment and focus mechanism for both the laser and the receiver circuit boards (see below). These mechanisms have three degrees of freedom (the ability to be adjusted independently in three orthogonal axes, X, Y and Z). By adjusting the position of the laser and receiver whilst watching the strength of the return signal on an oscilloscope, it is quite easy to achieve almost perfect optical alignment.

Optics - rear view

[Reply #19 on:]

Hi it is good and you should sale a kit!  
How accurate it is in  closer range 10 cm to 2M? What is the power consummation?

[Reply #20 on:]

We've been hacking around with two AL_01 kits for a few weeks now in my research group and have enjoyed them immensely.  I wrote a short post on our early experiences here: research group blog

The rangefinding works quite well enough for our purposes, esp. once we configured averaging = off by default in the EEPROM.  We're using one of the kits to scan for movement at high relative speeds (30-50mph), so we learn more about the passing object from non-averaged data.  Good times are experienced with 20+ Hz sampling rate.

We have, however, hit the memory ceiling for the UNO board (32k) and want to switch to a Mega 2560 for the extra headroom (256k), but the SPI pin mapping is different (Mega = 50-53 vs. UNO = AL_01 = 10-13).  Is there a way to change the pins the laser board is looking for?  This isn't a design problem with the AL_01 kit at all, it is primarily an Arduino programming question, so, OK to punt if you need to.

So far we have found in constants.h from the AL_01 Arduino sketch files:

Code:

// SPI Hardware
#define SPI_CHIPSELECT_PIN        10
#define DATA_READYN_PIN           9

I should note that our setup is Mega2560 --> Wireless SD shield (for datalogging) --> AL_01 board all snugly stacked on the header pins.  

I also want to note that Tracy has been OUTSTANDING on support over email over the past month.  I thought other folks on the fence about buying these AL_01 kits should know that.  It is rare to get decent support these days but Lightware has really treated us well.  I have no commercial connection to them so I can say that without bias. 

[Reply #21 on:]

You may find a pretty good market for these LRFs in the small UAVs to be used for landing aids some of the smaller UAVs land by a controlled crash method as they do not have a reliable idea of how high above the landing surface they are.  A controlled crash from 5 feet is much preferable to one from 50 feet.