Sigma Koki

It is the product that was reduced by one rank from the surface quality of Plano Concave Lens (SLB-N). It can be use in an optical system such as observation or lighting applications that high surface quality is not required.

  • It has the same specification of Plano Concave Lens (SLB-N) except the surface quality. Unless a laser is used for high-precision experiments, it is recommended.
  • There are two types of lens. One is a Plano Concave Lens with low spherical aberration and the other is a biconcave lens that is possible to shorten the focal length by a large refraction.
  • In addition to uncoated products, there are three types of anti-reflection coating for visible, near-infrared, and infrared.
Material BK7
Design Wavelength 546.1mm
Refractive Index 1.519
Centration <3′
Coating Uncoated: the end of the part ‘N’
Anti-reflection coating: the end of the part number ‘NM’, ‘NIR1′, ‘NIR2′
Laser Damage Threshold Anti-reflection coating: 4J/cm2
Laser pulse with 10ns, repetition frequency 20Hz
Clear Aperture 90% of actual aperture: uncoated
85% of actual aperture: with coating
83% of actual aperture: with coating
Surface Quality (Scratch-Dig) 60-40


In case of specifying a anti-reflection coating 633nm-1064nm to near infrared lens of S-SLB-30-200N.

→ S-SLB-30-200NIR1


Type Of AR Coat Wavelength Range [NM] Transmittance [%]
Visible Range 400-700 > Average 99
Near-infrared 633-1064 > Average 98.5
Infrared 750-1550 > Average 98.5

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