aspheric cryogenic objectives
The IWDO and LWDO aspheric objectives constitute an economic alternative to the LT-APO objectives, for appliations where either the apochromaticity is not essential, or an intermediate working distance is required. Besides, both objectives are available as fiber-based versions, which enables transmission measurements (attoCFM III, attoCFM IV) in a toploading cryostat with only an optical top window (attoDRY1000, attoDRY2100). Due the comparatively large focal displacement (chromatic focal shift), they are significantly less suitable for broadband optical measurements than their LT-APO counterparts. For more details, please consult the specification datasheets, or contact our sales engineers.
|compatible with||attoCFM I||attoCFM II||attoCFM I||attoCFM II|
|numerical aperture (NA)||0.68||0.55|
|working distance||1.5 mm||2.7 mm|
|AR coating (> 80% trasnmission)||350 .. 1700 nm(1)||350 .. 1700 nm(1)|
(δf < +/- Δ)
|environments||low temperatures(mK .. 300K), high magnetic fields, high vacuum|
|clear aperture||5.0 mm||4.95 mm|
|focal length||3.1 mm||4.51 mm|
|diameter||12 mm||12 mm|
|length||32.9 mm||36.4 mm||31.8 mm||35.3 mm|
|suitable broadband collimator||RT-APO/VIS-NIR/0.13(3)|
|download specs||LT-IWDO/0.68 CFM I||LT-IWDO/0.68 CFM II||LT-LWDO/0.55 CFM I||LT-LWDO/0.55 CFM II|
(1) 4 options available: coating A 350-700 nm | coating B 600-1050 nm | coating C 1050-1700 nm | uncoated
(2) δf: chromatic focal shift, Δ = n*λref / (2*NA2): depth of focus, n: refractive index, λref : wavelength used to define focal plane with max. Δ
(3) RT-APO: > 96% transmission
The different objectives offered are distinguished and described by the following naming scheme:
RT is short for “Room Temperature (compatible)“.
LT is short for “Low Temperature (compatible)”.
IWDO is short for “Intermediate Working Distance Objective”.
LWD is short for “Long Working Distance”.
LWDO is short for “Long Working Distance Objective”.
APO is short for “Apochromatic”, and refers to the fact that the focal displacement curve is flat (i.e. within plus/minus one depth of focus) within the specified apochromatic range (see specification sheets of the respective objectives for further details).
/VIO indicates that the objective is most suitable in the ultra-violett to visible range
/VIS indicates that the objective is most suitable for the visible wavelength range.
/VISIR indicates that the objective is most suitable for the visible to (near-)infrared wavelength range.
/IR indicates that the objective is most suitable in the lower infrared range
/NIR indicates that the objective is most suitable for the near-infrared wavelength range.
/0.82 is indicating the numerical aperture (NA) of the respective objective, in this case NA = 0.82.