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Location: Main > Optical Lenses > Spherical Bi Concave Lenses > POL-BK7-BCV-50.8-250-SAR
Name: DIA50.8mm BK7 Bi-Concave Lens(SAR) f-250mm
P/N: POL-BK7-BCV-50.8-250-SAR
Keywords:Dia50.8mm,BK7,Bi-concave,EFL-250mm,SAR MgF2
Unit Price: S$120.00/pc
Available: In stock
Request: Add to Request List
Introduction:
Bi-concave lenses have a negative focal length and are best used to diverge a converging beam. Similar to a Plano-Concave lens, a Bi-Concave lens can diverge a collimated beam to a virtual focus as used in a Galilean type beam expander.
But it is usually preferrable to choose a bi-concave lens if the absolute conjugate ratio (object distance divided by image distance) is close to 1. When the desired absolute magnification is either less than 0.2 or greater than 5, the tendency is to choose a plano-concave lens instead.
Substrate Material: BK7 optical glass
Wavelength Range: 350-2000nm
Lens Configuration: Bi-concave 
Design Wavelength: 633nm(n=1.515082)
Outer Diameter(OD): 50.8,-0.2/+0.0mm
Center Thickness(Tc): 5.0mm
Edge Thickness(Te): 7.5mm
Effective Focal Length(EFL): -250mm designed @ 633nm
Surface Quality: 40/20 scratch and dig
Surface Figure: < lamda/4 @ 633nm inspected (clear aperture)
Centration: </=3 arc minutes
Clear Aperture(CL): >90%
Coating: AR coated,single-layer MgF2 (double surfaces)