Optotronics FAQ

How long can my RPL laser run before it needs to cool off i.e. duty cycle?
What is the best choice of batteries for the PPL series?
What material is used to make the laser body, is it plastic?
How do you measure the output power of your laser products?
Do you charge my credit card before the item is shipped?
What filter goggles would you recommend for this level of output?
Are these high-power units modified in some way to increase their output?

How long can my RPL laser run before it needs to cool off i.e. duty cycle?

The adjustable RPL has the ability to tune the amount of IR diode current so that the optimum amount of IR goes to the crystal. If more than the optimum amount of IR hits the crystal, the crystal becomes over saturated and 532nm output no longer increases. Only more heat is produced and in fact this can cause output to decrease some. When the RPL laser is tested, the optimum current level setting is noted in the customer documentation and this is the same current level that the average output power tested and recorded for the customer. Most of the time, this current level is #4 or #5 and adjustable RPLs sold after 2/1/2007 will run until the battery dies at this level (no duty cycle). The reason we give a recommended duty cycle of 5 minutes on and two minutes off is that some users will buy the non-adjustable model and it's current cannot be tuned. It is safe to leave the RPL on until it shuts itself off, in fact that is what the battery protection circuit is for. The shut off is to protect the battery from excess discharge/low voltage as this can be dangerous for lithium-ion cells. The RPL diode is never ran at more than 80% of it's rated operating current, so as long as the ambient room temperature in the spec does not exceed 30C, the diode will be not be thermally damaged by extended use.

What is the best choice of batteries for the PPL series?

NiMH batteries are best choice for the PPL laser. They are rechargeable and they tend to hold their voltage higher right up to the end of the charge whereas alkaline batteries voltage continuously drops through the discharge. We highly recommend the AccuPower 6000 NiMH cells. These cells provide 6000 mA hr of power, the most I've found in a C cell. By comparison a Duracell Ultra Alkaline battery only provides 1400 mA hr of Power.

Here's a link to our tests showing a plot of the Duracell Ultra (Alkaline) vs the AccuPower 6000 (NiMH) under load levels that simulate an operating PPL laser module.

What material is used to make the laser body, is it plastic?

No, in fact the only plastic in the entire laser is the button of the on/off and adjustment switches. The rest is made of quality machined aluminum, with the highest quality glass lenses and crystals available.

How do you measure the output power of your RPL laser & laser system products?

We use a Coherent Field master-GS power meter coupled to a Coherent LM-3 HTD thermal power sensor that is calibrated to NIST standards annually. Output power is measured over a period of 60 seconds (beginning 30 seconds after power on so as not to include any initial output power spikes) with samples taken at 0.1 second intervals (600 samples). The average power output of the 600 samples are then recorded. This is done 3 times and then the high and low 60 second sample periods are discarded and the remaining (middle sample) is used to determine the power rating.

Do you charge my credit card before the item is shipped?

Your credit card is charged as soon as the order is placed. If the laser you ordered is not in stock, it holds your place in line (the order that orders are received determines the output to some degree as well, the oldest orders get the highest powers in each class). Of course if you place an order for an out of stock item, a complete refund can be made anytime before your item ships.

What filter goggles would you recommend for an output level of 300-400mW?

When looking for eye protection, shop for goggles or glasses that will block the 532nm wavelengths at high power levels with a rating of OD+2.5 or greater.

Are these high-power units modified in order to increase their output?

These lasers are not modified in anyway, to do so would void the manufacturer's warranty. They are designed from the ground up for high powered output. The PPL model line uses a 1.2W n-Light pump diode and the RPL model line uses the 2.5W n-Light pump diode. Both models also incorporate the highest quality crystals available and each laser is precision aligned at the manufacturer to provide maximum power output and minimum divergence.