Laser Beam Diagnostic Accessories

Avoiding Multi-Filter Beam Distortion

The wavefront distortion through a number of optical filters can be calculated by taking the square root of the sum of the squares of the wavefront distortion of the individual components. In general, a camera cannot sense less than ~λ/4 total distortion in the beam, so if a series of filters is used, they must be made to very exacting laser-grade specifications. Attenuating optics from Coherent are manufactured to better than a λ/10 surface specification, so at least six optics in series can be used. Calculate the Low-Distortion Face Plate (LDFP) and each BCUBE as one optic, and the VARM or C-VARM as three optics each.

Attenuator Selection

Attenuation is selected on the basis of power density in W/cm2 or energy density in J/cm². The attenuation from the camera’s Low-Distortion Face Plate (LDFP) will allow an average power density of up to 1.2 mW/cm². There are then only two more steps to attenuation selection:

1) Choose either the VARM or the C-VARM for up to 1W/cm2.
2) In addition or alternatively, use a BCUBE beamsplitter module to pick off between 2% and 10% of the beam (depending on polarization and wavelength).

Specifications	VARM	C-VARM	UV C-VARM	BCUBE	UV-BCUBE	BARREL-SET
						(Barrels, 3 C- Mount Flanges)
Wavelength
Min. (nm)	380	380	190	380	190	–
Max. (nm)	2200	2200	1100	2200	2200	–
Attenuation
From	4x105:1	107:1	105:1	50:1	50:1	–
To	1:1	3000:1	300:1	10:1	10:1	–
Aperture (mm)	19	15	15	19	19	–
Max. Power Density (W/cm2)	1*	1*	1*	2.0x109	2.0x109	–
Max. Energy Density (J/cm2)	0.1*	0.1*	0.008	50	50	–
Beam Offset (mm)	–	–	–	4.0	4.0	–
Part Number	33-3328-000	Quick Ship Items labeled as C24 ship next day. Click icon to learn more about our C24 program 33-3336-000	Quick Ship Items labeled as C24 ship next day. Click icon to learn more about our C24 program 33-6859-000	Quick Ship Items labeled as C24 ship next day. Click icon to learn more about our C24 program 1098403	1098466	1098426

* The maximum power and energy density listed are the levels at which thermal lensing occurs.

Drawing Packages
Click the links below to download a complete drawing package for these products.
	VARM (33-3328-000)		C-VARM (33-3336-000), UV C-VARM (33-6859-000)
	BCUBE (1098403), UV-BCUBE (1098466)		BARREL SET (1098426)