ATTENUATIONS OPTICS FOR CAMERAS

BCUBE, UV-BCUBE, VARM, C-VARM, UV C-VARM and all other Coherent cameras have female C-Mount threading, making them easy to connect with the male C-Mount connection flange provided with each attenuator. Also, all attenuators have 1/4-20 tapped holes for independent post or plate mounting. 

The C-Mount flanges (threaded rings) also have a female RMS microscope thread. This allows a microscope objective to be coupled to the attenuators and extension barrels in order to create a flexible close-up imaging system for analysis of small/focused beams, fiber optics, laser diodes or LEDs.

VARM, LaserCam-HR-InGaAs, C-VARM, BCUBE, C-Mount Flanges and Barrel

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. For example, if the individual optics are made to λ/10 specifications and six are used, a total λ/4 RMS wavefront distortion will be introduced to the beam: 

√(0.1² + 0.1² + 0.1² + 0.1²  + 0.1²  + 0.1² ) = 0.25

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)

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

** 1 Day Ship program: eligible for next business day shipment.