From HacDC Wiki


Highly Safe (1mW)

Under some unusual conditions (eg. microscope viewing), extremely low optical power is appropriate to minimize risk.

Safe (5mW)

Low power lasers (<5mW) are eye-safe, useful for manual alignment, HUD prototypes, etc.

Moderate (~200mW)

Medium power lasers emit a beam powerful enough to cause severe permanent retinal damage if directly viewed. However, at substantially less than Class IV power, indirect viewing (ie. spot on wall, specular reflections, etc) is relatively safe. This compromise can be useful to illuminate large areas, project a near-daylight visible green beam under standard atmospheric conditions, and burn some darkly colored objects.

High-Power Class IV (>0.5W)

Above 0.5W, even indirect viewing is immediately blinding. Extremely dangerous, must be used with safety glasses and/or other shields. Use is generally restricted to members or trusted guests with safety training.

Despite the risks, high-power lasers are often necessary and justified for cutting, sintering, photoexposure, LIDAR, ICF, etc.




Large flat lenses, useful for low-divergence collimation of non-laser light sources (ie. spotlights), dim direct projection of ordinary displays.

$20/5 -

Large Diameter Short Focal-Length

HacDC has a variety of large diameter short-focal length lenses, typically used in projection. Additionally, the following can be obtained for unusual situations.

$40 -

Condenser Lenses

Aspheric lenses can provide faster collimation with better performance across a white-light spectrum. For microscopes and projectors, this can be important.


For a single wavelength, holographic optical elements may offer aggressive performance and ideal convergence.


Various lenses have been collected from scrap CD/DVD players, disposable cameras, scrap projectors and other sources.

Table Ready

Lenses with focal lengths that factor to the optical table tap spacing are efficient for prototyping optical beampaths.


Various diffuser materials are routinely extracted from dead or low-value LCD monitors. Note these may be combined with focused high-intensity light sources and wide-diameter lenses to achieve rapid beam expansion and homogenization. Adding vibration can achieve a speckle-free laser light source.



HacDC has a variety of dichroic mirrors, typically angle tunable. For specific situations, the following may be useful.

  • TODO 532nm
  • TODO 405nm


For scientific or industrial applications, diffusion is not efficient or adequate to clean up laser beam profiles. Pinhole filters are used instead. Note the result is typically NOT speckle free.


Various polarizing filters have been obtained from a variety of sources.



Semi-silvered mirrors can divide a beam in two. This effect can also be used to create one-way optical coupler, separating transmitted and received beams.


Ordinary mirrors have been obtained from scrap projectors. Hard disk platters can also be used.


As donated and documented by Julia "juri" Longtin at [1], the following aluminum extrusions are available.

  • 3 40mmx40mm mitsumi extrusions, 5 Ft in length
  • 4 40mmx40mm mitsumi extrusions, 2 Ft .5 in in length
  • 2 40mmx40mm mitsumi extrusions, 22.5 in in length
  • 2 40mmx40mm mitsumi extrusions, 19.5 in in length