74-series Lens Fixtures

The 74-series Collimating Lens Fixture is the common fiber optic-coupled lens fixture used throughout our extensive line of sampling accessories. Accessories include lenses of fused silica (74-UV), BK-7 glass (74-VIS) or a doublet of BaF10 and FD10 glass (74-ACR)

74-UV Collimating Lens (200-2000 nm)
The 74-UV has an f/2 fused silica lens for 200-2000 nm. When focused for collimation, beam divergence is 2° or less, depending on fiber diameter. The 74-UV can be adjusted for UV-VIS or VIS-NIR setups.

One white dot on the barrel identifies the 74-UV.

74-VIS Collimating Lens (350-2000 nm)
74-VIS Collimating Lens (350-2000 nm)

The 74-VIS -- the basic lens fixture in an LS-1 Light Source -- has a BK-7 lens suitable for the VIS-NIR. These single-lens systems have the disadvantage of chromatic aberration, due to dispersion or variation in refractive index with wavelength.

One yellow dot on the barrel identifies the 74-VIS.

74-ACR Collimating Lens (350-2000 nm)
The 74-ACR has two optical elements cemented together to form an achromatic doublet, optimized to correct for spherical and chromatic aberrations.

Two yellow dots on the barrel identify the 74-ACR. 

74-DA Collimating Lens (200-2000 nm)
The 74-DA Direct-attach Collimating Lens screws on to a spectrometer's SMA-905 Connector for increased light throughput. The lens collects collects collimated light in a straight path of open air and focuses it on to a spectrometer's slit.

Features

• Stainless steel with black oxide finish

• Inner barrel threaded for SMA 905 Connectors (1/4" OD FC barrels are available)

• Adjustable focusing

• Adjustable from converging to diverging FOV (~45°) is possible

Technical Tips

• The divergence (a) of a beam focused using a single lens is tan(a) = d/f where f is the focal length of the lens and d is the aperture or fiber diameter.

• The optical fibers Ocean Optics specifies for use with its spectrometers and light sources have FOV of ~25° -- an acceptance angle that may not be optimum for some experiments. Collimating lenses are adjustable, allowing the user to establish FOV angles from near- collimation (~ 0°) to ~45°.

• Be careful when adjusting collimating lenses, as inaccurate focusing of the lens can result in a de facto change of the sample path length.

Specifications