That is the full spectrum meter and it only measures photons in millimoles/square meters/second. That is the most commonly used units for expressing the instantaneous measured light intensity in the PAR range (400-700 nanometers of wavelength).
To get to DLI (daily light integral) you multiply this by the number of seconds in a day. Data from the natural light world (mostly greenhouse) showed Dendrobiums grown successfully in Texas with a DLI varying from 2 in the winter to 10 in the summer. Miltoniopsis varied in another experiment from 2-6 and Phalaenopsis from 2.5-4.0. So, I think of higher light orchids being successful in the 10-14 DLI range and lower light orchids in the 2-6 range. There is obviously an intermediate range for some things.
The advantage of calculating your DLI is that day length matters. A green house in northern climates could have day lengths varying from 9 hours to 15 hours without any artificial light, and yet the light intensity would also vary a lot as the sun angle changes throughout the year. This is radically different from the natural environments of most of the orchids we grow. Many orchids have photoperiod clocks so they can respond to even subtle changes in day length. Using a lower light intensity but excessive day length can get to a target DLI number, but some orchids will respond sub optimally because of the extreme day length.
Greenhouse owners in northern climates are stuck with day lengths of 15 hours in the summer but the light intensity in early morning and later afternoon falls off, so the DLI does not become excessive. Yet, some orchids can "stall out" in mid summer and then pick up again in early fall when day length (and maybe temperature) is more in their comfort zone. An indoor artificial light grower can have more precise control of day length, light intensity, and temperature. I run my room with day lengths varying from a low of 11.0 hours in mid-winter to a high of 13.5 hours in mid-summer. My low light orchids get peak photon flux density (PPFD) in the PAR range of 50-70, some intermediate things (Phrags) get 80-110, and my Cattleya group stuff get 150-300 peaks. I vary the light intensity only modestly through the year because that is what happens naturally. That gives me my target DLI range for the groups throughout the year.