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Collimating and Focusing Lenses for Laser Diodes
While glass lenses are
preferred for their superior optical characteristics (beam quality), there are
many product applications where a high quality plastic lens can be effectively
utilized. The 300 Series plastic aspheric collimating and objective lenses offer
a lower cost alternative to glass and still perform well over a temperature
range actually exceeding the upper limit for most laser diodes. Plastic lenses
are used in products such as DVD players, laser pointers, construction levels,
and less critical alignment and position sensing devices.
If you need a collimated beam with smaller dimensions, consider using the 300-0380-780 lens or, the Laser Diode Mounting Kit P/N LDM 4500 KIT. For example... when used with the Hitachi HL6312G (635nm/5mW) laser diode, a collimated beam measures approximately 0.715 mm in the parallel axis by 2.85 mm in the perpendicular axis, with divergence angles of 1.2 mrad x 0.34 mrad respectively. (The figures mentioned may vary from one diode to another or, with other manufacturers diodes).
The 300-0380-780 plastic lens mentioned above is now obsolete and should not be considered for new applications.
The replacement lens is Optima part number 300-0330-780 – this
P/N is the
basic unmounted plastic lens. There are
also two mounted versions available – P/N 302-0330-780
(which is used in the Laser Diode Mounting Kit's P/N LDM 4300 and LDM 4356 KIT). The
302-0330-780 is intended to be a direct replacement for customers that were
previously using the 302-0380-780 lens.
Another mounted version P/N 303-0330-780 is also available; this is a compact
mount which is not compatible with the Laser Diode Mounting Kits and therefore
not intended as a replacement for the 302-0380-780 lens.
This may be confusing… click on the part number in the tables below for the PDF data sheet. In this case, a picture should definitely help clear up the confusion. The data for the 300-0380-780 and 302-0380-780 lenses has been left in the tables for reference only – no stock available.
Part number 300-0340-780 is an intended replacement for Optima's P/N 300-0355-780 and 300-0360-780
Optima's 300-0360-780 and 300-0355-780 were very popular lenses
when laser diodes began finding application in products besides CD players.
Thirty years later we're often asked for a similar replacement – because their physical size made them very easy to handle.
Injection Molded Aspheric Lens Specifications:
|Part Number (unmounted lens)||300-0330-780||300-0340-780||300-0380-780||300-0395-780|
|Unit price (Qty 1-49)||$3.90||$3.60||$4.70 – NLA||$4.20|
|Description||Injection Molded Plastic Aspheric Lens, unmounted|
|Design Wavelength||660 / 780 nm||780 nm|
|Focal Length||3.05 / 3.07 mm||3.851 mm||3.40 mm||16 mm|
|Working/Source Distance||1.68 / 1.43 mm||2.131 mm||1.43 mm||13.79 mm|
|Numerical Aperture||0.662 /0.53||0.45||0.471||0.144|
|Clear Aperture||4.04 / 3.254 mm||3.47 mm||3.20 mm||4.60 mm|
|F#||0.775 / 0.943||1.10||1.06||3.48|
|Field Size (diameter) *||0.150 mm||0.559 mm|
|AR Coating, MgF2||780 nm|
|Transmission||> 95%||> 97%||> 95%||> 97%|
|Cover Glass Thickness||0.6 / 1.2 mm||1.2 mm||1.2 mm||1.25 mm|
|Cover Glass Index (n)||1.58 / 1.57||1.55||1.55||1.51|
|Temperature Range||Storage Temperature -30 ~ +75 °C Working Temperature -10 ~ +65 °C|
|Dimensions (diameter x length)||Ř5.0 x 1.73 mm||Ř7.4 x 3.4 mm||Ř5.0 x 2.11 mm||Ř6.5 x 2.33 mm|
* The Field
Diameter of a collimating lens defines the largest size emitter the lens will
accommodate and still maintain other optical specifications,
such as the wavefront aberration specification.
Example: If the field diameter specification is 100 microns, then the size of the laser diode emitter must be less than 100 microns in either axis. Generally, when using lower powered diodes (1mW to 100mW) the emitter size is not a concern, as the emitter is typically only a few microns in the perpendicular or parallel axis. When using higher power diodes, diodes arrays, or LED’s the emitter can be significantly larger – emitters larger than 100 microns are common.
Mounted Injection Molded Aspheric Lens Specifications:
The unmounted plastic lenses listed above are available in a black anodized aluminum mount with a .375-64 external thread. The extra-fine pitch thread allows precise adjustment of the lens when collimating or focusing the beam.
|Part Number (thread mount)||302-0330-780||303-0330-780||302-0340-780||303-0340-780||302-0395-780|
|Unit price (Qty 1-49)||$12.15||
|Description||Injection Molded Plastic Aspheric Lens, with 3/8-64 Threaded Mount|
|Optical Specifications||Basic optical specifications as listed in the following section|
|Dimensions||diameter||Outside diameter has an extra fine pitch 3/8-64 thread|
|length||6.99 mm||3.81 mm||5.78 mm||4.83 mm*||3.81 mm|
*TBD – Not in production, final design to be determined.
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