Laser Visuals Ltd - DPSS v Argon

Back in the 80's and early 90's Argon laser systems dominated the laser entertainment industry; now move over big and bulky systems and say hello to the compact Diode Pumped Solid State (DPSS) laser. DPSS laser have many advantages over the older Argon style systems:

Size is much smaller and compact	Our Scorpion laser system weighs typically only 6Kg, compared to an Argon system which weighs typically over 40Kg
Less maintenance	No mirror plates to keep aligned and no fragile glass tube to break
Lower electrical demands	1,000 mW Argon laser requires 30A @ 240V, compared to a DPSS laser with equivalent output this only draws <2A @ 240V
Longer life time	DPSS lasers averages 8,000 hours compared with only 2,000 hours for an Argon laser
Direct laser modulation	DPSS lasers can be modulated (switched on and off) up to 10,000 times per second (10KHz). It is not possible to modulate an Argon laser directly, a Z blanking Galvo must be purchased separately.
Look brighter	DPSS lasers look approximately 4 times brighter than an Argon laser for the same given output power

How can two lasers of the same output power have different brightness levels?

The human eye can see light in the visible spectrum ranging from Red to Violet, i.e. the colours of the rainbow. The eye's sensitivity is non linear, so different colours are perceived at different intensities to the eye. So for the same given power, a 100mW Red laser will appear much dimmer than a 100mw Green laser.

The colour the human eye is most sensitive to is a shade of Green which has a wavelength of 555nm.

DPSS Lasers produce a lime green which has frequency of 532nm, which is very close to the peak of the eye's sensitivity. The greens and blues produced by a typical argon are further away from the peak response of the eye, so they appear to be dimmer in comparison.

This is why DPSS laser are said to be 3 to 4 times brighter than a typical argon laser. So a 100mW DPSS laser will look the equivalent to a 300mw argon laser in terms of apparent brightness.

Taking this to an extreme, if you were to compare a 100mw 532nm Diode laser with a 2W Infrared Laser e.g. emitting 1064nm, the 100mW laser will look much brighter because the human eye can't see infrared wavelengths!

So you can see, Output Power is not everything!

For those of you who are interested a detailed description of how the calculations are made, are included below:-

A 1W Argon laser has, typically:

50% of its power at 514nm; 30% of its power at 488nm; 20% at other lines, mainly 440nm.

According to the "Relative Response of Cones" parameters, the apparent brightness is as follows:

514 nm : 0.58 (i.e. 58% as bright as the same beam at 555nm)

488 nm : 0.18

440 nm : 0.02

So, with 1 W, you'll have an apparent brightness of (0.58x0.5+0.18x0.3+0.02x0.2) = 0.35 i.e. 1 W argon is about 35% the brightness of 1 W of 555nm (if it existed!). We have 330 mW (typical) of 532nm, whose Cone Response is 0.92 giving us a brightness factor of 0.3.

So, from this it is clear that 330 mW of 532 nm is almost the same visibility as 1 W argon.