What is a good lens holder material

[edmondng]

I am just wondering what is a good material or a material i should look for when choosing to make for the lens holder.

From my detector to the lens (focal length), does it need like a non-absorbing or non reflective material? When a manufacturer sells the complete camera set (regular camera) or IR camera, are these lens holder material made of plastic, metal, ..etc?

Thanks

 

[xez]

Hmm good is relevant only to your design parameters
of cost, weight, durability, size, fabrication processes,
mechanical precision required, stiffness required,
impact / stress resistance, operational temperature,
chemical environment, etc.

An important criterion is whether adjustability of the
lens positioning is required, or if it's a fixed mount.

Even for fixed mounting there's often a question as to
how or whether fine (tiny) positioning adjustments may be
needed in any direction, and, if so, how much.

You could certainly use a steel tube with a inner
lip to back the lens, and a threaded barrel section to
screw down a holder retention ring.

Or you could use a spring loaded retention ring to hold
the lens against some machined back plate.

You could use machinable plastics like delrin to machine
a holder from.

You could use ceramic or glass if that suited your design
and there was need for such low coefficients of thermal
expansion.

Certainly many mass produced consumer grade lens mounts in digital cameras are almost entirely made of
injection molded plastic these days.

It's common to use optically black / absorbing surface
finishes on the lens tube / holder materials to damp
undesired reflections / glare... black paint,
dye mixed in plastic resin, carbon black,
black anodization of aluminium, et. al. are all sometimes
used.

Generally metal allows for higher precision of machining,
adjustment, and higher stiffness and impact durability than
many kinds of plastic would offer unless the plastic
were of very high quality and much thicker than the metal.

Steel is generally best among metals for its strength and
environmental ruggedness, though for a light weight
application that can sacrifice some of the rigidity/strength,
aluminium may be quite suitable.

A factor to consider is your lens cell design and the
shape of the lens elements which will be external;
certainly it's easier to mount plane surfaces against
flat machined walls / lips than it might be to mount
highly curved convex surfaces. And if you're mounting
highly curved concave surfaces, you'll have to ensure that
the mounting periphery of the lens elements are going to
provide a good safe contact with the cell holder without
too much pressure on thin lens edge areas. Actually
that could be true of thin convex lenses or thin elements
of any kind.

If you want to machine something yourself or in a
"one of a kind" type small shop operation, you'll probably
find that something like aluminium or delrin would be
relatively cost effective to work with since they're soft
and easily machined.

If you want something very rugged look at steel, and
be prepared to pay a pretty penny for machining or
externally fabricated precision parts.

For something just easily hacked together as an
experiment even acrylic or cast epoxy/fiberglass
sheet/tube/block may not be bad.