Game Laser Sensor

[Bwinter]

Very much an amateur here, and I'm working on a basic laser-maze for a game. My goal a simple module that can send a low-power laser (class II), reflect off a few mirrors and back to the module into a photo-transistor. My design (below) uses a feed-back from the laser-beam back into the photo-transistor (Q3), activating Q1 (keeping the laser powered). Once the beam is broken, Q1 shuts the power off to the laser. An external TRIGGER (from an Arduino) initializes the laser (through Q2) and keeps the laser ON during set-up (then disable during "game-play"). I also have a SENSOR that feeds back to the Arduino when the photo-transistor is off.

I know I could also use the Arduino to trigger/inactivate the laser based off the input from the photo-transistor, but I'd like to keep this feedback loop as-is (and not rely on any of my equally-amateur Arduino programming).

So far, my prototype works properly on my bench (which is good). But I'm simply wondering (and attempting to learn):

1. Is there a better way to do what I'm trying to do?
2. Am I using the components correctly?
3. How would I go about adding a simply LED (on this module) to indicate when the beam is correctly activating the sensor (while in set-up mode, with the TRIGGER providing the ON)?
4. My eventual goal is to have multiple of these modules synchronized through an Arduino. When the Arduino detects a laser-trip (from one SENSOR), the Arduino would then turn off the remaining modules. Right now, the Arduino simply kills the power to all the modules (turning them off). Without using an additional pin on the Arduino, is there a way to also disable the laser through only the TRIGGER/SENSOR?

 

[Bwinter]

If you need detection accuracy for volume production I suggest you use a photo diode instead that will be very precise and not have the wide tolerance of a hFE.

This is just a simple mechanism for a game (that was, at least the original intention). I don't need precision, robustness or absolute reliability. I think I settled with a phototransistor, simply because of the form-factor of an LED was easier to work with (and house).

 

[Tony Stewart]

If it works perfectly at all intended ranges, no problemo.
Photodiodes also come in 5mm form factor.

I've heard of people also using LED's as photo diodes with an xx mV comparator.