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[Beamshots]
Photo © 2013 S. Beyer

General:

This page shows beamshots of various torches (both from us and from other manufacturers) and in various configurations, primarily with respect to excitation filters.

Photo:

The photo at the top right shows a tarpon hunting in the beam of two of our own blue light torches ("ProBlue", see below).

Beamshot photos

[BlueBright Beamshot]

A beamshot (under water) of the BlueBright I torch

(Click on image to enlarge)

[Beamshots Comparative Table]

See also this comparative table of beamshots.

This table may help you to select which type of torch best fits your needs (e.g. spot or flood, intensity, uniformity, etc.).

(You can also click on the image to jump to the table)

Beamshot videos

Note that you can play several of the following videos at the same time for easier comparison.

Beamshots of different torches in different configurations:

(Mostly with blue light and a single dichroic excitation filter except where stated otherwise)


Beamshot of torch with 430 nm LED - with dichroic excitation filter

Beamshot of torch with 430 nm LED - without dichroic excitation filter

Beamshot TillyTec MPL 500 UV torch (UV LED without excitation filter) - with yellow camera filter

Beamshot TillyTec MPL 500 UV torch (UV LED without excitation filter) - without yellow camera filter

Beamshot torch "BlueBright I" aka "Lightsaber I"

Beamshot of a modified torch from Brinyte / DRIS

Beamshot torch head "ProBlue"

Beamshot TillyTec LED 4500 torch head (white light) with sandwich excitation filter

Comparing a blue light torch and a white light torch with different filters:


Comparison torch head "ProBlue" (blue light with single dichroic excitation filter)
 

Comparison TillyTec LED 4500 torch head (white light) with double dichroic excitation filter

Comparison TillyTec LED 4500 torch head (white light) with sandwich excitation filter

Conclusion: A dedicated blue light torch (such as the "ProBlue" head, top left) is the optimal way to observe underwater fluorescence. Using a white light torch with a sandwich excitation filter (bottom right) is possible, however. Using two identical dichroic filters stacked together (bottom left) may be a viable alternative to such a sandwich filter (which is made from both an acrylic and a dichroic filter). As shown in other tests below, a single dichroic filter used with a white light torch does not give satisfying results.


Comparing different white light torches with different filters (#1):


Test #1.1 TillyTec LED 1500 torch head (white light) with sandwich excitation filter

Test #1.2 TillyTec LED 4500 torch head (white light) with sandwich excitation filter

Test #1.3 TillyTec LED 1500 torch head (white light) with dichroic excitation filter

Test #1.4 TillyTec LED 4500 torch head (white light) with dichroic excitation filter

Conclusion: When used with a white light torch, a sandwich filter (top) gives much better results than a single dichroic filter (bottom). This can be seen particularly well when the beam moves over a dead piece of coral or sand: With a single dichroic filter (bottom), the beam is a pale blueish gray, almost white, whereas with a sandwich filter (top), the beam is dark blue, and red fluorescence is much more prominent. The hotspot of the stronger torch (right) often oversaturates and blinds the camera's sensor, but in compensation lights up fluorescent corals at a greater distance. The less powerful light (left) is therefore fully sufficient. However, both torches fall short of a dedicated blue light torch with a broader and uniform beam such as the "ProBlue" head shown in another test above. This is also because about 80% of the energy of a white light torch gets thrown away by the filter (see also here).


Comparing different white light torches with different filters (#2):


Test #2.1 TillyTec LED 1500 torch head (white light) with sandwich excitation filter

Test #2.2 TillyTec LED 4500 torch head (white light) with sandwich excitation filter

Test #2.3 TillyTec LED 1500 torch head (white light) with dichroic excitation filter

Test #2.4 TillyTec LED 4500 torch head (white light) with dichroic excitation filter

Conclusion: When used with a white light torch, a sandwich filter (top) gives much better results than a single dichroic filter (bottom). This can be seen particularly well when the beam moves over a dead piece of coral or sand: With a single dichroic filter (bottom), the beam is a pale blueish gray, almost white, whereas with a sandwich filter (top), the beam is dark blue, and red fluorescence is much more prominent. The hotspot of the stronger torch (right) often oversaturates and blinds the camera's sensor, but in compensation lights up fluorescent corals at a greater distance. The less powerful light (left) is therefore fully sufficient. However, both torches fall short of a dedicated blue light torch with a broader and uniform beam such as the "ProBlue" head shown in another test above. This is also because about 80% of the energy of a white light torch gets thrown away by the filter (see also here).


Investigating red fluorescence with a green excitation light (and a blue excitation light to verify the higher effectiveness of green excitation light):


Torch head "ProBlue" (blue light) with red camera filter
 

Torch head "ProBlue" (green light) with red camera filter #1

Torch head "ProBlue" (green light) with red camera filter #2

Conclusion: Green excitation light (bottom) indeed stimulates red fluorescence more strongly than blue excitation light (top left), as predicted by Prof. Nico K. Michiels in a private communication. The fact that some objects remain dark or completely black (e.g. the little fish) shows that what we see is indeed red fluorescence and not just reflected excitation light, passing the red camera filter as crosstalk. See also the video supplement #1 and video supplement #2 by Prof. Nico K. Michiels et al. for comparison.

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